0024722: Move functionality of WOK command wgendoc to OCCT tool gendoc
[occt.git] / dox / user_guides / ocaf / ocaf.md
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ba06f8bb 1OCAF {#occt_user_guides__ocaf}
72b7576f 2========================
3
e5bd0d98 4@tableofcontents
5
72b7576f 6@section occt_ocaf_1 Introduction
7
8This manual explains how to use the Open CASCADE Application Framework (OCAF).
9It provides basic documentation on using OCAF. For advanced information on OCAF
10and its applications, see our offerings on our web site at
11<a href="http://www.opencascade.org/support/training/">www.opencascade.org/support/training/</a>
12
13OCAF (the Open CASCADE Application Framework) is a RAD (Rapid Application Development) framework used for
14specifying and organizing application data. To do this, OCAF provides:
15
16 * Ready-to-use data common to most CAD/CAM applications,
17 * A scalable extension protocol for implementing new application specific data,
18 * An infrastructure
19 * To attach any data to any topological element
20 * To link data produced by different applications (*associativity of data*)
21 * To register the modeling process - the creation history, or parametrics, used to carry out the modifications.
22
23Using OCAF, the application designer concentrates on the functionality and its specific algorithms. In this way, he avoids architectural problems notably implementing Undo-redo and saving application data.
24
25In OCAF, all of the above are already handled for the application designer, allowing him to reach a significant increase in productivity.
26
27In this respect, OCAF is much more than just one toolkit among many in the CAS.CADE Object Libraries. Since it can handle any data and algorithms in these libraries - be it modeling algorithms, topology or geometry - OCAF is a logical supplement to these libraries.
28
29The table below contrasts the design of a modeling application using object libraries alone and using OCAF.
30
31**Table 1: Services provided by OCAF**
32
33|Development tasks |Comments | Without OCAF | With OCAF |
34|------------------:|---------:|---------------:|-----------:|
35|Creation of geometry| Algorithm Calling the modeling libraries | To be created by the user | To be created by the user|
36| Data organization | Including specific attributes and modeling process | To be created by the user | Simplified|
37| Saving data in a file | Notion of document | To be created by the user | Provided |
38| Document-view management | | To be created by the user | Provided |
39| Application infrastructure | New, Open, Close, Save and Save As File menus | To be created by the user | Provided |
40| Undo-Redo | Robust, multi-level | To be created by the user | Provided |
41| Application-specific dialog boxes | | To be created by the user | To be created by the user |
42
43
44
45The relationship between OCAF and the Open CASCADE Technology (**OCCT**) Object Libraries can be seen in the image below.
46
3d68eaf5 47@figure{/user_guides/ocaf/images/ocaf_image003.svg, "OCAF Architecture"}
72b7576f 48
49In the image, the OCAF (Open CASCADE Application Framework) is shown with black rectangles and OCCT Object Libraries required by OCAF are shown with white rectangles.
50
51The subsequent chapters of this document explain the concepts and show how to use the services of OCAF.
52
53@section occt_ocaf_2 Basic Concepts
54
55@subsection occt_ocaf_2_1 Overview
56
57In most existing geometric modeling systems, the data structure is shape driven. They usually use a brep model, where solids and surfaces are defined by a collection of entities such as faces, edges etc., and by attributes such as application data. These attributes are attached to the entities. Examples of application data include:
58
59 * color,
60 * material,
61 * information that a particular edge is blended.
62
63A shape, however, is inevitably tied to its underlying geometry. And geometry is highly subject to change in applications such as parametric modeling or product development. In this sort of application, using a brep (boundary representation) data structure proves to be a not very effective solution. A solution other than the shape must be found, i.e. a solution where attributes are attached to a deeper invariant structure of the model. Here, the topology itself will be one attribute among many.
64
65In OCAF, data structure is reference key-driven. The reference key is implemented in the form of labels. Application data is attached to these labels as attributes. By means of these labels and a tree structure they are organized in, the reference key aggregates all user data, not just shapes and their geometry. These attributes have similar importance; no attribute is master in respect of the others.
66
67The reference keys of a model - in the form of labels - have to be kept together in a single container. This container is called a document.
68
dba69de2 69@image html /user_guides/ocaf/images/ocaf_image004.png "Topology-driven vs. reference key-driven approaches"
70@image latex /user_guides/ocaf/images/ocaf_image004.png "Topology-driven vs. reference key-driven approaches"
72b7576f 71
72@subsection occt_ocaf_2_2 Applications and documents
73
74OCAF documents are in turn managed by an OCAF application, which is in charge of:
75
76 * Creating new documents
77 * Saving documents and opening them
78 * Initializing document views.
79
80Apart from their role as a container of application data, documents can refer to each other; Document A, for example, can refer to a specific label in Document B. This functionality is made possible by means of the reference key.
81
3d68eaf5 82@subsection occt_ocaf_2_3 The document and the data framework
72b7576f 83
84Inside a document, there is a data framework, a model, for example. This is a set of labels organized in a tree structure characterized by the following features:
85 * The first label in a framework is the root of the tree;
86 * Each label has a tag expressed as an integer value;
87 * Sub-labels of a label are called its children;
88 * Each label which is not the root has one father – label from an upper level of the framework;
89 * Labels which have the same father are called brothers;
90 * Brothers cannot share the same tag;
91 * A label is uniquely defined by an entry expressed as a list of tags (entry) of fathers from the root: this list of tags is written from right to left: tag of label, tag of its father, tag of father of its father,..., 0 (tag of the root label).
92
dba69de2 93@image html /user_guides/ocaf/images/ocaf_image005.png "A simple framework model"
94@image latex /user_guides/ocaf/images/ocaf_image005.png "A simple framework model"
72b7576f 95
96In the above figure inside the circles are the tags of corresponding labels. Under the circles are the lists of tags. The root label always has a zero tag.
97
98The children of a root label are middle-level labels with tags 1 and 3. These labels are brothers.
99
dba69de2 100List of tags of the right-bottom label is "0:3:4": this label has tag 4, its father (with entry "0:3") has tag 3, father of father has tag 0 (the root label always has "0" entry).
72b7576f 101
102For example, an application for designing table lamps will first allocate a label for the lamp unit (the lamp is illustrated below). The root label never has brother labels, so, for a lot of lamps in the framework allocation, one of the root label sub-labels for the lamp unit is used. By doing so, you would avoid any confusion between table lamps in the data framework. Parts of the lamp have different material, color and other attributes, so, for each sub-unit of the lamp a child label of the lamp label with specified tags is allocated:
103
104 * a lamp-shade label with tag 1
105 * a bulb label with tag 2
106 * a stem label with tag 3
107
108Label tags are chosen at will. They are just identifiers of the lamp parts. Now you can refine all units: set to the specified label geometry, color, material and other information about the lamp or it’s parts. This information is placed into special attributes of the label: the pure label contains no data – it is only a key to access data.
109
110The thing to remember is that tags are private addresses without any meaning outside the data framework. It would, for instance, be an error to use part names as tags. These might change or be removed from production in next versions of the application, whereas the exact form of that part might be what you wanted to use in your design, the part name could be integrated into the framework as an attribute.
111
dba69de2 112@image html /user_guides/ocaf/images/ocaf_image006.png
113@image latex /user_guides/ocaf/images/ocaf_image006.png
72b7576f 114
115So, after the user changes the lamp design, only corresponding attributes are changed, but the label structure is maintained. The lamp shape must be recreated by new attribute values and attributes of the lamp shape must refer to a new shape.
116
dba69de2 117@image html /user_guides/ocaf/images/ocaf_image007.png
118@image latex /user_guides/ocaf/images/ocaf_image007.png
72b7576f 119
120
121The previous figure shows the table-lamps document structure: each child of the root label contains a lamp shape attribute and refers to the sub-labels, which contain some design information about corresponding sub-units.
122
123The data framework structure allows to create more complex structures: each lamp label sub-label may have children labels with more detailed information about parts of the table lamp and its components.
124
125Note that the root label can have attributes too, usually global attributes: the name of the document, for example.
126
dba69de2 127As in the case of the table lamp example above, OCAF documents aggregate a battery of ready-to-use attributes, which represent typical data used in CAD. This data includes not only the Shape attribute, but a wide range of Standard attributes corresponding to the following types:
72b7576f 128
129 * Geometric attributes
130 * General attributes
131 * Relationship attributes
132 * Auxiliary attributes
133
134@subsubsection occt_ocaf_2_3_1 Documents
135
136Documents offer access to the data framework and manage the following items:
137
138 * Manage the notification of changes
139 * Update external links
140 * Manage the saving and restoring of data
141 * Store the names of software extensions.
142 * Manage command transactions
143 * Manage Undo and Redo options.
144
145@subsubsection occt_ocaf_2_3_2 Shape attribute
146
147The shape attribute implements the functionality of the OCCT topology manipulation:
148
149 * reference to the shapes
150 * tracking of shape evolution
151
152@subsubsection occt_ocaf_2_3_3 Standard attributes
153
154Several ready-to-use base attributes already exist. These allow operating with simple common data in the data framework (for example: integer, real, string, array kinds of data), realize auxiliary functions (for example: tag sources attribute for the children of the label counter), create dependencies (for example: reference, tree node)....
155
156@subsubsection occt_ocaf_2_3_4 Visualization attributes
157
158These attributes allow placing viewer information to the data framework, visual representation of objects and other auxiliary visual information, which is needed for graphical data representation.
159
160@subsubsection occt_ocaf_2_3_5 Function services
161
162Where the document manages the notification of changes, a function manages propagation of these changes. The function mechanism provides links between functions and calls to various algorithms.
163
dba69de2 164@image html /user_guides/ocaf/images/ocaf_image008.png "Document structure"
165@image latex /user_guides/ocaf/images/ocaf_image008.png "Document structure"
72b7576f 166
dba69de2 167@section occt_ocaf_3 Data Framework Services
72b7576f 168
169@subsection occt_ocaf_3_1 Overview
170
171The data framework offers a single environment in which data from different application components can be handled.
172
173This allows you to exchange and modify data simply, consistently, with a maximum level of information, and with stable semantics.
174
175The building blocks of this approach are:
176
177 * The tag
178 * The label
179 * The attribute
180
181As it has been mentioned earlier, the first label in a framework is the root label of the tree. Each label has a tag expressed as an integer value, and a label is uniquely defined by an entry expressed as a list of tags from the root, 0:1:2:1, for example.
182
183Each label can have a list of attributes, which contain data, and several attributes can be attached to a label. Each attribute is identified by a GUID, and although a label may have several attributes attached to it, it must not have more than one attribute of a single GUID.
184
185The sub-labels of a label are called its children. Conversely, each label, which is not the root, has a father. Brother labels cannot share the same tag.
186
187The most important property is that a label’s entry is its persistent address in the data framework.
188
dba69de2 189@image html /user_guides/ocaf/images/ocaf_image009.png "Contents of a document"
190@image latex /user_guides/ocaf/images/ocaf_image009.png "Contents of a document"
72b7576f 191
192@subsection occt_ocaf_3_2 The Tag
193
194A tag is an integer, which identifies a label in two ways:
195
196 * Relative identification
197 * Absolute identification.
198
199In relative identification, a label’s tag has a meaning relative to the father label only. For a specific label, you might, for example, have four child labels identified by the tags 2, 7, 18, 100. In using relative identification, you ensure that you have a safe scope for setting attributes.
200
dba69de2 201In absolute identification, a label’s place in the data framework is specified unambiguously by a colon-separated list of tags of all the labels from the one in question to the root of the data framework. This list is called an entry. *TDF_Tool::TagList* allows retrieving the entry for a specific label.
72b7576f 202
203In both relative and absolute identification, it is important to remember that the value of an integer has no intrinsic semantics whatsoever. In other words, the natural sequence that integers suggest, i.e. 0, 1, 2, 3, 4 ... - has no importance here. The integer value of a tag is simply a key.
204
205The tag can be created in two ways:
206
207 * Random delivery
208 * User-defined delivery
209
210As the names suggest, in random delivery, the tag value is generated by the system in a random manner. In user-defined delivery, you assign it by passing the tag as an argument to a method.
211
212@subsubsection occt_ocaf_3_2_1 Creating child labels using random delivery of tags
213
dba69de2 214To append and return a new child label, you use *TDF_TagSource::NewChild*. In the example below, the argument *level2*, which is passed to *NewChild,* is a *TDF_Label*.
215
72b7576f 216
72b7576f 217~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
218TDF_Label child1 = TDF_TagSource::NewChild (level2);
219TDF_Label child2 = TDF_TagSource::NewChild (level2);
220~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
221
222@subsubsection occt_ocaf_3_2_2 Creation of a child label by user delivery from a tag
223
224The other way to create a child label from a tag is by user delivery. In other words, you specify the tag, which you want your child label to have.
225
dba69de2 226To retrieve a child label from a tag which you have specified yourself, you need to use *TDF_Label::FindChild* and *TDF_Label::Tag* as in the example below. Here, the integer 3 designates the tag of the label you are interested in, and the Boolean false is the value for the argument *create*. When this argument is set to *false*, no new child label is created.
227
72b7576f 228
72b7576f 229~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
230TDF_Label achild = root.FindChild(3,Standard_False);
231if (!achild.IsNull()) {
232Standard_Integer tag = achild.Tag();
233}
234~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
235
236@subsection occt_ocaf_3_3 The Label
237
238The tag gives a persistent address to a label. The label – the semantics of the tag – is a place in the data framework where attributes, which contain data, are attached. The data framework is, in fact, a tree of labels with a root as the ultimate father label (refer to the following figure):
239
dba69de2 240@image html /user_guides/ocaf/images/ocaf_image007.png
241@image latex /user_guides/ocaf/images/ocaf_image007.png
72b7576f 242
243
244Label can not be deleted from the data framework, so, the structure of the data framework that has been created can not be removed while the document is opened. Hence any kind of reference to an existing label will be actual while an application is working with the document.
245
246@subsubsection occt_ocaf_3_3_1 Label creation
247
dba69de2 248Labels can be created on any labels, compared with brother labels and retrieved. You can also find their depth in the data framework (depth of the root label is 0, depth of child labels of the root is 1 and so on), whether they have children or not, relative placement of labels, data framework of this label. The class *TDF_Label* offers the above services.
72b7576f 249
250@subsubsection occt_ocaf_3_3_2 Creating child labels
251
dba69de2 252To create a new child label in the data framework using explicit delivery of tags, use *TDF_Label::FindChild*.
253
72b7576f 254
72b7576f 255~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
256//creating a label with tag 10 at Root
257TDF_Label lab1 = aDF->Root().FindChild(10);
258
259//creating labels 7 and 2 on label 10
260TDF_Label lab2 = lab1.FindChild(7);
261
262TDF_Label lab3 = lab1.FindChild(2);
263~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dba69de2 264You could also use the same syntax but add the Boolean *true* as a value of the argument **create**. This ensures that a new child label will be created if none is found. Note that in the previous syntax, this was also the case since **create** is *true* by default.
265
72b7576f 266
72b7576f 267~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
268TDF_Label level1 = root.FindChild(3,Standard_True);
269TDF_Label level2 = level1.FindChild(1,Standard_True);
270~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
271@subsubsection occt_ocaf_3_3_3 Retrieving child labels
272
273You can retrieve child labels of your current label by iteration on the first level in the scope of this label.
274
dba69de2 275
72b7576f 276~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
277TDF_Label current;
278//
279for (TDF_ChildIterator it1 (current,Standard_False); it1.More(); it1.Next()) {
280achild = it1.Value();
281//
282// do something on a child (level 1)
283//
284}
285~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
286You can also retrieve all child labels in every descendant generation of your current label by iteration on all levels in the scope of this label.
287~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
288for (TDF_ChildIterator itall (current,Standard_True); itall.More(); itall.Next()) {
289achild = itall.Value();
290//
291// do something on a child (all levels)
292//
293}
294~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dba69de2 295Using *TDF_Tool::Entry* with *TDF_ChildIterator* you can retrieve the entries of your current label’s child labels as well.
72b7576f 296
dba69de2 297
72b7576f 298~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
299void DumpChildren(const TDF_Label& aLabel)
300{
301 TDF_ChildIterator it;
302 TCollection_AsciiString es;
303 for (it.Initialize(aLabel,Standard_True); it.More(); it.Next()){
304 TDF_Tool::Entry(it.Value(),es);
305 cout = as.ToCString() = endl;
306 }
307}
308~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
309@subsubsection occt_ocaf_3_3_4 Retrieving the father label
310
311Retrieving the father label of a current label.
312
dba69de2 313
72b7576f 314~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
315TDF_Label father = achild.Father();
316isroot = father.IsRoot();
317~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
318@subsection occt_ocaf_3_4 The Attribute
319
320The label itself contains no data. All data of any type whatsoever - application or non-application - is contained in attributes. These are attached to labels, and there are different types for different types of data. OCAF provides many ready-to-use standard attributes such as integer, real, constraint, axis and plane. There are also attributes for topological naming, functions and visualization. Each type of attribute is identified by a GUID.
321
dba69de2 322The advantage of OCAF is that all of the above attribute types are handled in the same way. Whatever the attribute type is, you can create new instances of them, retrieve them, attach them to and remove them from labels, "forget" and "remember" the attributes of a particular label.
72b7576f 323
324@subsubsection occt_ocaf_3_4_1 Retrieving an attribute from a label
325
dba69de2 326To retrieve an attribute from a label, you use *TDF_Label::FindAttribute*. In the example below, the GUID for integer attributes, and *INT*, a handle to an attribute are passed as arguments to *FindAttribute* for the current label.
327
72b7576f 328
72b7576f 329~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
330if(current.FindAttribute(TDataStd_Integer::GetID(),INT))
331{
332 // the attribute is found
333}
334else
335{
336 // the attribute is not found
337}
338~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
339@subsubsection occt_ocaf_3_4_2 Identifying an attribute using a GUID
340
dba69de2 341You can create a new instance of an attribute and retrieve its GUID. In the example below, a new integer attribute is created, and its GUID is passed to the variable *guid* by the method ID inherited from *TDF_Attribute*.
342
72b7576f 343
72b7576f 344~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
345Handle(TDataStd_Integer) INT = new TDataStd_Integer();
346Standard_GUID guid = INT->ID();
347~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dba69de2 348
72b7576f 349@subsubsection occt_ocaf_3_4_3 Attaching an attribute to a label
350
dba69de2 351To attach an attribute to a label, you use *TDF_Label::Add*. Repetition of this syntax raises an error message because there is already an attribute with the same GUID attached to the current label.
352
353*TDF_Attribute::Label* for *INT* then returns the label *attach* to which *INT* is attached.
72b7576f 354
72b7576f 355
72b7576f 356~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
357current.Add (INT); // INT is now attached to current
358current.Add (INT); // causes failure
359TDF_Label attach = INT->Label();
360~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
361@subsubsection occt_ocaf_3_4_4 Testing the attachment to a label
362
dba69de2 363You can test whether an attribute is attached to a label or not by using *TDF_Attribute::IsA* with the GUID of the attribute as an argument. In the example below, you test whether the current label has an integer attribute, and then, if that is so, how many attributes are attached to it. *TDataStd_Integer::GetID* provides the GUID argument needed by the method IsAttribute.
364
365*TDF_Attribute::HasAttribute* tests whether there is an attached attribute, and *TDF_Tool::NbAttributes* returns the number of attributes attached to the label in question, e.g. *current*.
72b7576f 366
72b7576f 367
72b7576f 368~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
369// Testing of attribute attachment
370//
371if (current.IsA(TDataStd_Integer::GetID())) {
372// the label has an Integer attribute attached
373}
374if (current.HasAttribute()) {
375// the label has at least one attribute attached
376Standard_Integer nbatt = current.NbAttributes();
377// the label has nbatt attributes attached
378}
379~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
380@subsubsection occt_ocaf_3_4_5 Removing an attribute from a label
381
dba69de2 382To remove an attribute from a label, you use *TDF_Label::Forget* with the GUID of the deleted attribute. To remove all attributes of a label, *TDF_Label::ForgetAll*.
383
72b7576f 384
72b7576f 385~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
386current.Forget(TDataStd_Integer::GetID());
387// integer attribute is now not attached to current label
388current.ForgetAll();
389// current has now 0 attributes attached
390~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
391@subsubsection occt_ocaf_3_4_6 Specific attribute creation
392
dba69de2 393If the set of existing and ready to use attributes implementing standard data types does not cover the needs of a specific data presentation task, the user can build his own data type and the corresponding new specific attribute implementing this new data type.
72b7576f 394
dba69de2 395There are two ways to implement a new data type: create a new attribute (standard approach), or use the notion of User Attribute by means of a combination of standard attributes (alternative way)
72b7576f 396
397In order to create a new attribute in the standard way do the following:
dba69de2 398* Create a class inherited from *TDF_Attribute* and implement all purely virtual and necessary virtual methods:
399 + **ID()** – returns a unique GUID of a given attribute
400 + **Restore(attribute)** – sets fields of this attribute equal to the fields of a given attribute of the same type
401 + **Paste(attribute, relocation_table)** – sets fields of a given attribute equal to the field values of this attribute ; if the attribute has references to some objects of the data framework and relocation_table has this element, then the given attribute must also refer to this object .
402 + **NewEmpty()** - returns a new attribute of this class with empty fields
403 + **Dump(stream)** - outputs information about a given attribute to a given stream debug (usually outputs an attribute of type string only)
72b7576f 404* Create the persistence classes for this attribute according to the file format chosen for the document (see below).
405
dba69de2 406Methods *NewEmpty, Restore* and *Paste* are used for the common transactions mechanism (Undo/Redo commands). If you don’t need this attribute to react to undo/redo commands, you can write only stubs of these methods, else you must call the Backup method of the *TDF_Attribute* class every time attribute fields are changed.
72b7576f 407
408If you use a standard file format and you want your new attributes to be stored during document saving and retrieved to the data framework whenever a document is opened, you must do the following:
409
dba69de2 410 1. If you place an attribute to a new package, it is desirable (although not mandatory) if your package name starts with letter "T" (transient), for example: attribute *TMyAttributePackage_MyAttribute* in the package *TMyAttributePackage*.
411 2. Create a new package with name "P[package name]" (for example *PMyAttributePackage*) with class *PMyAttributePackage_MyAttribute* inside. The new class inherits the *PDF_Attribute* class and contains fields of attributes, which must be saved or retrieved ("P" - persistent).
412 3. Create a new package with name "M[package name]" (for example *MMyAttributePackage*) with classes *MMyAttributePackage_MyAttributeRetrievalDriver* and *MMyAttributePackage_MyAttributeStorageDriver* inside. The new classes inherit *MDF_ARDriver* and *MDF_ASDriver* classes respectively and contain the translation functionality: from T... attribute to P... and vice versa (M - middle) (see the realization of the standard attributes).
ba06f8bb 413 4. M... package must contain *AddStorageDrivers(aDriverSeq : ASDriverHSequence* from MDF) and *AddRetrievalDrivers(aDriverSeq : ASDriverHSequence* from MDF) methods, which append to the given sequence *\<aDriverSeq\>* of drivers a sequence of all new attribute drivers (see the previous point), which will be used for the attributes storage/retrieval.
dba69de2 414 5 Use the standard schema (*StdSchema* unit) or create a new one to add your P-package and compile it.
72b7576f 415
416If you use the XML format, do the following:
dba69de2 417 1. Create a new package with the name Xml[package name] (for example *XmlMyAttributePackage*) containing class *XmlMyAttributePackage_MyAttributeDriver*. The new class inherits *XmlMDF_ADriver* class and contains the translation functionality: from transient to persistent and vice versa (see the realization of the standard attributes in the packages *XmlMDataStd*, for example). Add package method AddDrivers which adds your class to a driver table (see below).
418 2. Create a new package (or do it in the current one) with two package methods:
419 * Factory, which loads the document storage and retrieval drivers; and
420 * AttributeDrivers, which calls the methods AddDrivers for all packages responsible for persistence of the document.
421 3. Create a plug-in implemented as an executable (see example *XmlPlugin*). It calls a macro PLUGIN with the package name where you implemented the method Factory.
72b7576f 422If you use the binary format, do the following:
dba69de2 423 1. Create a new package with name Bin[package name] (for example *BinMyAttributePackage*) containing a class *BinMyAttributePackage_MyAttributeDriver*. The new class inherits *BinMDF_ADriver* class and contains the translation functionality: from transient to persistent and vice versa (see the realization of the standard attributes in the packages *BinMDataStd*, for example). Add package method *AddDrivers*, which adds your class to a driver table (see below).
424 2. Create a new package (or do it in the current one) with two package methods:
425 * Factory, which loads the document storage and retrieval drivers; and
426 * AttributeDrivers, which calls the methods AddDrivers for all packages responsible for persistence of the document.
427 3. Create a plug-in implemented as an executable (see example *BinPlugin*). It calls a macro PLUGIN with the package name where you implemented the method Factory.
428See <a href="#occt_ocaf_4_3_3">Saving the document</a> and <a href="#occt_ocaf_4_3_4">Opening the document from a file</a> for the description of document save/open mechanisms.
72b7576f 429
dba69de2 430If you decided to use the alternative way (create a new attribute by means of *UAttribute* and a combination of other standard attributes), do the following:
431 1. Set a *TDataStd_UAttribute* with a unique GUID attached to a label. This attribute defines the semantics of the data type (identifies the data type).
432 2. Create child labels and allocate all necessary data through standard attributes at the child labels.
433 3. Define an interface class for access to the data of the child labels.
72b7576f 434
dba69de2 435Choosing the alternative way of implementation of new data types allows to forget about creating persistence classes for your new data type. Standard persistence classes will be used instead. Besides, this way allows separating the data and the methods for access to the data (interfaces). It can be used for rapid development in all cases when requirements to application performance are not very high.
72b7576f 436
dba69de2 437Let’s study the implementation of the same data type in both ways by the example of transformation represented by *gp_Trsf* class. The class *gp_Trsf* defines the transformation according to the type (*gp_TrsfForm*) and a set of parameters of the particular type of transformation (two points or a vector for translation, an axis and an angle for rotation, and so on).
72b7576f 438
dba69de2 4391. The first way: creation of a new attribute. The implementation of the transformation by creation of a new attribute is represented in the <a href="#occt_ocaf_11">Samples</a>.
72b7576f 440
4412. The second way: creation of a new data type by means of combination of standard attributes. Depending on the type of transformation it may be kept in data framework by different standard attributes. For example, a translation is defined by two points. Therefore the data tree for translation looks like this:
442 * Type of transformation (gp_Translation) as TDataStd_Integer;
443 * First point as TDataStd_RealArray (three values: X1, Y1 and Z1);
444 * Second point as TDataStd_RealArray (three values: X2, Y2 and Z2).
445
dba69de2 446@image html /user_guides/ocaf/images/ocaf_image010.png "Data tree for translation"
447@image latex /user_guides/ocaf/images/ocaf_image010.png "Data tree for translation"
72b7576f 448
449If the type of transformation is changed to rotation, the data tree looks like this:
450 * Type of transformation (gp_Rotation) as TDataStd_Integer;
451 * Point of axis of rotation as TDataStd_RealArray (three values: X, Y and Z);
452 * Axis of rotation as TDataStd_RealArray (three values: DX, DY and DZ);
453 * Angle of rotation as TDataStd_Real.
454
dba69de2 455@image html /user_guides/ocaf/images/ocaf_image011.png "Data tree for rotation"
456@image latex /user_guides/ocaf/images/ocaf_image011.png "Data tree for rotation"
72b7576f 457
458The attribute TDataStd_UAttribute with the chosen unique GUID identifies the data type. The interface class initialized by the label of this attribute allows access to the data container (type of transformation and the data of transformation according to the type).
459
460
461@section occt_ocaf_4_ Standard Document Services
462
463@subsection occt_ocaf_4_1 Overview
464
465Standard documents offer ready-to-use documents containing a TDF-based data framework. Each document can contain only one framework.
466
467The documents themselves are contained in the instantiation of a class inheriting from TDocStd_Application. This application manages the creation, storage and retrieval of documents.
468
469You can implement undo and redo in your document, and refer from the data framework of one document to that of another one. This is done by means of external link attributes, which store the path and the entry of external links.
470
471To sum up, standard documents alone provide access to the data framework. They also allow you to:
472
473 * Update external links
474 * Manage the saving and opening of data
475 * Manage the undo/redo functionality.
476
477
478@subsection occt_ocaf_4_2 The Application
479
dba69de2 480As a container for your data framework, you need a document, and your document must be contained in your application. This application will be a class inheriting from *TDocStd_Application*.
72b7576f 481
482@subsubsection occt_ocaf_4_2_1 Creating an application
483
484To create an application, use the following syntax.
485
72b7576f 486~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
487Handle(TDocStd_Application) app
488= new MyApplication_Application ();
489~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dba69de2 490Note that *MyApplication_Application* is a class, which you have to create and which will inherit from *TDocStd_Application*.
72b7576f 491
492@subsubsection occt_ocaf_4_2_2 Creating a new document
493
dba69de2 494To the application which you declared in the previous example (4.2.1), you must add the document *doc* as an argument of *TDocStd_Application::NewDocument*.
72b7576f 495
72b7576f 496~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
497Handle(TDocStd_Document) doc;
498app->NewDocument("NewDocumentFormat", doc);
499~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dba69de2 500
72b7576f 501@subsubsection occt_ocaf_4_2_3 Retrieving the application to which the document belongs
502
503To retrieve the application containing your document, you use the syntax below.
504
72b7576f 505~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
506app = Handle(TDocStd_Application)::DownCast
507(doc->Application());
508~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
509@subsection occt_ocaf_4_3 The Document
510
511The document contains your data framework, and allows you to retrieve this framework, recover its main label, save it in a file, and open or close this file.
512
513@subsubsection occt_ocaf_4_3_1 Accessing the main label of the framework
514
dba69de2 515To access the main label in the data framework, you use *TDocStd_Document::Main* as in the example below. The main label is the first child of the root label in the data framework, and has the entry 0:1.
72b7576f 516
72b7576f 517~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
518TDF_Label label = doc->Main();
519~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
520@subsubsection occt_ocaf_4_3_2 Retrieving the document from a label in its framework
521
522To retrieve the document from a label in its data framework, you use TDocStd_Document::Get as in the example below. The argument *label *passed to this method is an instantiation of TDF_Label.
72b7576f 523~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
524doc = TDocStd_Document::Get(label);
525~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dba69de2 526
72b7576f 527@subsubsection occt_ocaf_4_3_3 Saving the document
528
529If in your document you use only standard attributes (from the packages TDF, TDataStd, TNaming, TFunction, TPrsStd and TDocStd), you just do the following steps:
530
dba69de2 531* In your application class (which inherits class *TDocStd_Application*) implement two methods:
ba06f8bb 532 + Formats (TColStd_SequenceOfExtendedString& theFormats), which append to a given sequence \<theFormats\> your document format string, for example, "NewDocumentFormat" – this string is also set in the document creation command
dba69de2 533 + ResourcesName(), which returns a string with a name of resources file (this file contains a description about the extension of the document, storage/retrieval drivers GUIDs...), for example, "NewFormat"
534* Create the resource file (with name, for example, "NewFormat") with the following strings:
72b7576f 535
536~~~~~
537formatlist:NewDocumentFormat
538NewDocumentFormat: New Document Format Version 1.0
539NewDocumentFormat.FileExtension: ndf
540NewDocumentFormat.StoragePlugin: bd696000-5b34-11d1-b5ba-00a0c9064368
541NewDocumentFormat.RetrievalPlugin: bd696001-5b34-11d1-b5ba-00a0c9064368
542NewDocumentFormatSchema: bd696002-5b34-11d1-b5ba-00a0c9064368
543NewDocumentFormat.AttributeStoragePlugin:57b0b826-d931-11d1-b5da-00a0c9064368
544NewDocumentFormat.AttributeRetrievalPlugin:57b0b827-d931-11d1-b5da-00a0c9064368
545~~~~~
546
dba69de2 547* Create the resource file "Plugin" with GUIDs and corresponding plugin libraries, which looks like this:
72b7576f 548
549**Example**
550~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
551! Description of available plugins
552! ************
553
554b148e300-5740-11d1-a904-080036aaa103.Location: libFWOSPlugin.so
555!
556! standard document drivers plugin
557!
558bd696000-5b34-11d1-b5ba-00a0c9064368.Location: libPAppStdPlugin.so
559bd696001-5b34-11d1-b5ba-00a0c9064368.Location: libPAppStdPlugin.so
560!
561! standard schema plugin
562!
563bd696002-5b34-11d1-b5ba-00a0c9064368.Location: libPAppStdPlugin.so
564!
565! standard attribute drivers plugin
566!
56757b0b826-d931-11d1-b5da-00a0c9064368.Location: libPAppStdPlugin.so
56857b0b827-d931-11d1-b5da-00a0c9064368.Location: libPAppStdPlugin.so
569~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
570
dba69de2 571In order to set the paths for these files it is necessary to set the environments: *CSF_PluginDefaults* and *CSF_NewFormatDefaults*. For example, set the files in the directory *MyApplicationPath/MyResources*:
72b7576f 572
573~~~~~
574setenv CSF_PluginDefaults MyApplicationPath/MyResources
575setenv CSF_NewFormatDefaults MyApplicationPath/MyResources
576~~~~~
577
dba69de2 578Once these steps are taken you may run your application, create documents and Save/Open them. These resource files already exist in the OCAF (format "Standard").
72b7576f 579
dba69de2 580If you use your specific attributes from packages, for example, P-, M- and TMyAttributePackage, see "Specific attribute creation" on page 20; you must take some additional steps for the new plugin implementation:
72b7576f 581
dba69de2 5821. Add our "P" package to the standard schema. You can get an already existing (in Open CASCADE Technology sources) schema from StdSchema unit and add your package string to the cdl-file: "package PMyAttributePackage".
5832. Next step consists of implementation of an executable, which will connect our documents to our application and open/save them. Copy the package PAppStdPlugin and change its name to MyTheBestApplicationPlugin. In the PLUGIN macros type the name of your factory which will be defined in the next step.
5843. Factory is a method, which returns drivers (standard drivers and our defined drivers from the "M" package) by a GUID. Copy the package where the standard factory is defined (it is PAppStd in the OCAF sources). Change its name to MyTheBestSchemaLocation. The Factory() method of the PappStd package checks the GUID set as its argument and returns the corresponding table of drivers. Set two new GUIDs for your determined storage and retrieval drivers. Append two "if" declarations inside the Factory() method which should check whether the set GUID coincides with GUIDs defined by the Factory() method as far as our storage and retrieval drivers are concerned. If the GUID coincides with one of them, the method should return a table of storage or retrieval drivers respectively.
5854. Recompile all. Add the strings with GUIDs – in accordance with your plugin library GUID - to the "Plugin" file.
72b7576f 586
587@subsubsection occt_ocaf_4_3_4 Opening the document from a file
588
589To open the document from a file where it has been previously saved, you use TDocStd_Application::Open as in the example below. The arguments are the path of the file and the document saved in this file.
590
72b7576f 591~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
592app->Open("/tmp/example.caf", doc);
593~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
594
595@subsection occt_ocaf_4_4 External Links
596
dba69de2 597External links refer from one document to another. They allow you to update the copy of data framework later on.
72b7576f 598
dba69de2 599@image html /user_guides/ocaf/images/ocaf_image012.png "External links between documents"
600@image latex /user_guides/ocaf/images/ocaf_image012.png "External links between documents"
72b7576f 601
602Note that documents can be copied with or without a possibility of updating an external link.
603
604@subsubsection occt_ocaf_4_4_1 Copying the document
605
dba69de2 606#### With the possibility of updating it later
72b7576f 607
608To copy a document with a possibility of updating it later, you use TDocStd_XLinkTool::CopyWithLink.
609
72b7576f 610~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
611Handle(TDocStd_Document) doc1;
612Handle(TDocStd_Document) doc2;
613
614TDF_Label source = doc1->GetData()->Root();
615TDF_Label target = doc2->GetData()->Root();
616TDocStd_XLinkTool XLinkTool;
617
618XLinkTool.CopyWithLink(target,source);
619~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
620
621Now the target document has a copy of the source document. The copy also has a link in order to update the content of the copy if the original changes.
622
623In the example below, something has changed in the source document. As a result, you need to update the copy in the target document. This copy is passed to TDocStd_XLinkTool::UpdateLink as the argument *target*.
624
72b7576f 625~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
626XLinkTool.UpdateLink(target);
627~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
628
dba69de2 629#### Without any link between the copy and the original
72b7576f 630
631You can also create a copy of the document with no link between the original and the copy. The syntax to use this option is TDocStd_XLinkTool::Copy; the copied document is again represented by the argument *target*, and the original – by *source.*
632
72b7576f 633~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
634XLinkTool.Copy(target, source);
635
636~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
637
638
639@section occt_ocaf_5_ OCAF Shape Attributes
640@subsection occt_ocaf_5_1 Overview
641
642OCAF shape attributes are used for topology objects and their evolution access. All topological objects are stored in one TNaming_UsedShapes attribute at the root label of the data framework. This attribute contains a map with all topological shapes used in a given document.
643
644The user can add the TNaming_NamedShape attribute to other labels. This attribute contains references (hooks) to shapes from the TNaming_UsedShapes attribute and an evolution of these shapes. The TNaming_NamedShape attribute contains a set of pairs of hooks: to the *Old* shape and to a *New* shape (see the following figure). It allows not only to get the topological shapes by the labels, but also to trace the evolution of the shapes and to correctly update dependent shapes by the changed one.
645
646If a shape is newly created, then the old shape of a corresponding named shape is an empty shape. If a shape is deleted, then the new shape in this named shape is empty.
647
dba69de2 648@image html /user_guides/ocaf/images/ocaf_image013.png
649@image latex /user_guides/ocaf/images/ocaf_image013.png
72b7576f 650
651Different algorithms may dispose sub-shapes of the result shape at the individual labels depending on whether it is necessary to do so:
652
653* If a sub-shape must have some extra attributes (material of each face or color of each edge). In this case a specific sub-shape is placed to a separate label (usually to a sub-label of the result shape label) with all attributes of this sub-shape.
654* If the topological naming algorithm is needed, a necessary and sufficient set of sub-shapes is placed to child labels of the result shape label. As usual, for a basic solid and closed shells, all faces of the shape are disposed.
655
656
657TNaming_NamedShape may contain a few pairs of hooks with the same evolution. In this case the topology shape, which belongs to the named shape is a compound of new shapes.
658
659Consider the following example. Two boxes (solids) are fused into one solid (the result one). Initially each box was placed to the result label as a named shape, which has evolution PRIMITIVE and refers to the corresponding shape of the TNaming_UsedShapes map. The box result label has a material attribute and six child labels containing named shapes of Box faces.
660
dba69de2 661@image html /user_guides/ocaf/images/ocaf_image014.png "Resulting box"
662@image latex /user_guides/ocaf/images/ocaf_image014.png "Resulting box"
72b7576f 663
664After the fuse operation a modified result is placed to a separate label as a named shape, which refers to the old shape – one of the boxes, as well as to the new shape – the shape resulting from the fuse operation – and has evolution MODIFY (see the following figure).
665
666Named shapes, which contain information about modified faces, belong to the fuse result sub-labels: sub-label with tag 1 – modified faces of the first box, sub-label with tag 2 – generated faces of the box 2.
667
dba69de2 668@image html /user_guides/ocaf/images/ocaf_image015.png
669@image latex /user_guides/ocaf/images/ocaf_image015.png
72b7576f 670
671This is necessary and sufficient information for the functionality of the right naming mechanism: any sub-shape of the result can be identified unambiguously by name type and set of labels, which contain named shapes:
672
dba69de2 673 * face F1’ as a modification of F11 face
72b7576f 674 * face F1’’ as generation of F12 face
675 * edges as an intersection of two contiguous faces
676 * vertices as an intersection of three contiguous faces
677
678After any modification of source boxes the application must automatically rebuild the naming entities: recompute the named shapes of the boxes (solids and faces) and fuse the resulting named shapes (solids and faces) that reference to the new named shapes.
679
680@subsection occt_ocaf_5_2 Services provided
681
682@subsubsection occt_ocaf_5_2_1 Registering shapes and their evolution
683
684When using TNaming_NamedShape to create attributes, the following fields of an attribute are filled:
685
dba69de2 686* A list of shapes called the "old" and the "new" shapes A new shape is recomputed as the value of the named shape. The meaning of this pair depends on the type of evolution.
72b7576f 687* The type of evolution: a term of the TNaming_Evolution enumeration:
688* PRIMITIVE – newly created topology, with no previous history
dba69de2 689* GENERATED – as usual, this evolution of a named shape means, that the new shape is created from a low-level old shape ( a prism face from an edge, for example )
72b7576f 690* MODIFY – the new shape is a modified old shape
691* DELETE – the new shape is empty; the named shape with this evolution just indicates that the old shape topology is deleted from the model
dba69de2 692* SELECTED – a named shape with this evolution has no effect on the history of the topology; it is
72b7576f 693used for the selected shapes that are placed to the separate label
694
695Only pairs of shapes with equal evolution can be stored in one named shape.
696
697@subsubsection occt_ocaf_5_2_2 Using naming resources
698
699The class TNaming_Builder allows you to create a named shape attribute. It has a label of a future attribute as an argument of the constructor. Respective methods are used for the evolution and setting of shape pairs. If for the same TNaming_Builder object a lot of pairs of shapes with the same evolution are given, then these pairs would be placed in the resulting named shape. After the creation of a new object of the TNaming_Builder class, an empty named shape is created at the given label.
700
72b7576f 701~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
dba69de2 702// a new empty named shape is created at "label"
72b7576f 703TNaming_Builder builder(label);
704// set a pair of shapes with evolution GENERATED
705builder.Generated(oldshape1,newshape1);
706// set another pair of shapes with the same evolution
707builder.Generated(oldshape2,newshape2);
708// get the result – TNaming_NamedShape attribute
709Handle(TNaming_NamedShape) ns = builder.NamedShape();
710~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
711@subsubsection occt_ocaf_5_2_3 Reading the contents of a named shape attribute
712
dba69de2 713You can use TNaming_NamedShape class to get evolution of this named shape (method TNaming_NamedShape::Evolution()) and "value" of the named shape – compound of new shapes of all pairs of this named shape (method TNaming_NamedShape::Get()).
714
72b7576f 715More detailed information about the contents of the named shape or about the modification history of a topology can be obtained with the following:
716
717* TNaming_Tool provides a common high-level functionality for access to the named shapes contents:
718* GetShape(Handle(TNaming_NamedShape)) method returns a compound of new shapes of the given named shape
719* CurrentShape(Handle(TNaming_NamedShape)) method returns a compound of the shapes – last modifications ( latest versions ) of the shapes from the given named shape
720* NamedShape(TopoDS_Shape,TDF_Label) method returns a named shape, which contains a given shape as a new shape. Given label is any label from the data framework – it just gives access to it
721* TNaming_Iterator given access to the named shape hooks pairs.
722
72b7576f 723~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
724// create an iterator for a named shape
725TNaming_Iterator iter(namedshape);
726// iterate while some pairs are not iterated
727while(iter.More()) {
728// get the new shape from the current pair
729TopoDS_Shape newshape = iter.NewShape();
730// get the old shape from the current pair
731TopoDS_Shape oldshape = iter.OldShape();
732// do something...
733
734// go to the next pair
735iter.Next();
736}
737~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
738
739
740@subsubsection occt_ocaf_5_2_4 Selection Mechanism
741
742One of user interfaces for topological naming resources is the TNaming_Selector class. You can use this class to:
743
744 * Store a selected shape on a label
745 * Access the named shape
746 * Update this naming
747
dba69de2 748Selector places a new named shape with evolution SELECTED to the given label. By the given context shape (main shape, which contains a selected sub-shape), its evolution and naming structure the selector creates a "name" of the selected shape – unique description how to find a selected topology.
72b7576f 749
750After any modification of a context shape and updating of the corresponding naming structure, you must call the TNaming_Selector::Solve method. If the naming structure is right, then the selector automatically updates the selected shape in the corresponding named shape, else it fails.
751
752@subsubsection occt_ocaf_5_2_5 Exploring shape evolution
753
754The class TNaming_Tool provides a toolkit to read current data contained in the attribute.
755
756If you need to create a topological attribute for existing data, use the method NamedShape.
757
72b7576f 758~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
759class MyPkg_MyClass
760{
761public: Standard_Boolean SameEdge (const Handle(CafTest_Line)& L1, const Handle(CafTest_Line)& L2);
762};
763
764Standard_Boolean CafTest_MyClass::SameEdge (const Handle(CafTest_Line)& L1, const Handle(CafTest_Line)& L2)
765{
766 Handle(TNaming_NamedShape) NS1 = L1->NamedShape();
767 Handle(TNaming_NamedShape) NS2 = L2->NamedShape();
768 return BRepTools::Compare(NS1,NS2);
769}
770~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
771
772@section occt_ocaf_6_ Standard Attributes
773
774@subsection occt_ocaf_6_1 Overview
775
776There are several ready-to-use attributes, which allow creating and modifying attributes for many basic data types. They are available in the packages TDataStd, TDataXtd and TDF. Each attribute belongs to one of four types:
777
778 * Geometric attributes
779 * General attributes
780 * Relationship attributes
781 * Auxiliary attributes
782
dba69de2 783### Geometric attributes
784
72b7576f 785
786 * Axis – simply identifies, that the concerned TNaming_NamedShape attribute with an axis shape inside belongs to the same label
dba69de2 787 * Constraint – contains information about a constraint between geometries: used geometry attributes, type, value (if exists), plane (if exists), "is reversed", "is inverted" and "is verified" flags
72b7576f 788 * Geometry – simply identifies, that the concerned TNaming_NamedShape attribute with a specified-type geometry belongs to the same label
789 * Plane – simply identifies, that the concerned TNaming_NamedShape attribute with a plane shape inside belongs to the same label
dba69de2 790 * Point – simply identifies, that the concerned TNaming_NamedShape attribute with a point shape inside belongs to the same label
72b7576f 791 * Shape – simply identifies, that the concerned TNaming_NamedShape attribute belongs to the same label
dba69de2 792 * PatternStd – identifies one of five available pattern models (linear, circular, rectangular, circular rectangular and mirror)
72b7576f 793 * Position – identifies the position in 3d global space
794
dba69de2 795### General attributes
796
72b7576f 797
798 * AsciiString – contains AsciiString value
799 * BooleanArray – contains an array of Boolean
800 * BooleanList – contains a list of Boolean
801 * ByteArray – contains an array of Byte (unsigned char) values
802 * Comment – contains a string – some comment for a given label (or attribute)
803 * Expression – contains an expression string and a list of used variables attributes
804 * ExtStringArray – contains an array of ExtendedString values
805 * ExtStringList – contains a list of ExtendedString values
806 * Integer – contains an integer value
dba69de2 807 * IntegerArray – contains an array of integer values
72b7576f 808 * IntegerList – contains a list of integer values
809 * IntPackedMap – contains a packed map of integers
810 * Name – contains a string – some name of a given label (or attribute)
811 * NamedData – may contain up to 6 of the following named data sets (vocabularies): DataMapOfStringInteger, DataMapOfStringReal, DataMapOfStringString, DataMapOfStringByte, DataMapOfStringHArray1OfInteger, DataMapOfStringHArray1OfReal
812 * NoteBook – contains a NoteBook object attribute
813 * Real – contains a real value
dba69de2 814 * RealArray – contains an array of real values
815 * RealList – contains a list of real values
72b7576f 816 * Relation – contains a relation string and a list of used variables attributes
817 * Tick – defines a boolean attribute
dba69de2 818 * Variable – simply identifies, that a variable belongs to this label; contains the "is constraint" flag and a string of used units ("mm", "m"...)
72b7576f 819 * UAttribute – attribute with a user-defined GUID. As a rule, this attribute is used as a marker, which is independent of attributes at the same label (note, that attributes with the same GUIDs can not belong to the same label)
820
dba69de2 821### Relationship attributes
822
72b7576f 823
824 * Reference – contains reference to the label of its own data framework
825 * ReferenceArray – contains an array of references
826 * ReferenceList – contains a list of references
827 * TreeNode – this attribute allows to create an internal tree in the data framework; this tree consists of nodes with the specified tree ID; each node contains references to the father, previous brother, next brother, first child nodes and tree ID.
828
dba69de2 829### Auxiliary attributes
830
72b7576f 831 * Directory – hi-level tool attribute for sub-labels management
832 * TagSource – this attribute is used for creation of new children: it stores the tag of the last-created child of the label and gives access to the new child label creation functionality.
833
834All of these attributes inherit class TDF_Attribute, so, each attribute has its own GUID and standard methods for attribute creation, manipulation, getting access to the data framework.
835
836
837@subsection occt_ocaf_6_2 Services common to all attributes
838
839@subsubsection occt_ocaf_6_2_1 Accessing GUIDs
840
841To access the GUID of an attribute, you can use two methods:
842
dba69de2 843 * Method *GetID* is the static method of a class. It returns the GUID of any attribute, which is an object of a specified class (for example, TDataStd_Integer returns the GUID of an integer attribute). Only two classes from the list of standard attributes do not support these methods: TDataStd_TreeNode and TDataStd_Uattribute, because the GUIDs of these attributes are variable.
844 * Method *ID* is the method of an object of an attribute class. It returns the GUID of this attribute. Absolutely all attributes have this method: only by this identifier you can discern the type of an attribute.
72b7576f 845
846@subsubsection occt_ocaf_6_2_2 Conventional Interface of Standard Attributes
847
848It is usual to create standard named methods for the attributes:
849
dba69de2 850 * Method *Set(label, [value])* is the static method, which allows to add an attribute to a given label. If an attribute is characterized by one value this method may set it.
851 * Method *Get()* returns the value of an attribute if it is characterized by one value.
852 * Method *Dump(Standard_OStream)* outputs debug information about a given attribute to a given stream.
72b7576f 853
dba69de2 854@section occt_ocaf_7 Visualization Attributes
72b7576f 855
856@subsection occt_ocaf_7_1 Overview
857
858Standard visualization attributes implement the Application Interactive Services (see Open CASCADE Technology Visualization User’s Guide) in the context of Open CASCADE Technology Application Framework. Standard visualization attributes are AISViewer and Presentation and belong to the TPrsStd package.
859
860@subsection occt_ocaf_7_2 Services provided
861
862@subsubsection occt_ocaf_7_2_1 Defining an interactive viewer attribute
863
dba69de2 864The class TPrsStd_AISViewer allows you to define an interactive viewer attribute. There may be only one such attribute per one data framework and it is always placed to the root label. So, it could be set or found by any label ("access label") of the data framework. Nevertheless the default architecture can be easily extended and the user can manage several Viewers per one framework by himself.
72b7576f 865
866To initialize the AIS viewer as in the example below, use method Find.
867
72b7576f 868~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
dba69de2 869// "access" is any label of the data framework
72b7576f 870Handle(TPrsStd_AISViewer) viewer = TPrsStd_AISViewer::Find(access)
871~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
872
873@subsection occt_ocaf_7_2_2 Defining a presentation attribute
874
dba69de2 875The class TPrsStd_AISPresentation allows you to define the visual presentation of document labels contents. In addition to various visual fields (color, material, transparency, "isDisplayed", etc.), this attribute contains its driver GUID. This GUID defines the functionality, which will update the presentation every time when needed.
72b7576f 876
877@subsubsection occt_ocaf_7_2_3 Creating your own driver
878
879The abstract class TPrsStd_Driver allows you to define your own driver classes. Simply redefine the Update method in your new class, which will rebuild the presentation.
880
881If your driver is placed to the driver table with the unique driver GUID, then every time the viewer updates presentations with a GUID identical to your driver’s GUID, the Update method of your driver for these presentations must be called:
dba69de2 882@image html /user_guides/ocaf/images/ocaf_image016.png
883@image latex /user_guides/ocaf/images/ocaf_image016.png
72b7576f 884
885As usual, the GUID of a driver and the GUID of a displayed attribute are the same.
886
887@subsubsection occt_ocaf_7_2_4 Using a container for drivers
888
889You frequently need a container for different presentation drivers. The class TPrsStd_DriverTable provides this service. You can add a driver to the table, see if one is successfully added, and fill it with standard drivers.
890
891To fill a driver table with standard drivers, first initialize the AIS viewer as in the example above, and then pass the return value of the method InitStandardDrivers to the driver table returned by the method Get. Then attach a TNaming_NamedShape to a label and set the named shape in the presentation attribute using the method Set. Then attach the presentation attribute to the named shape attribute, and the AIS_InteractiveObject, which the presentation attribute contains, will initialize its drivers for the named shape. This can be seen in the example below.
892
893**Example**
894~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
895DriverTable::Get() -> InitStandardDrivers();
896// next, attach your named shape to a label
897TPrsStd_AISPresentation::Set(NS};
898// here, attach the AISPresentation to NS.
899~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
900
dba69de2 901@section occt_ocaf_8 Function Services
72b7576f 902
903Function services aggregate data necessary for regeneration of a model. The function mechanism - available in the package TFunction - provides links between functions and any execution algorithms, which take their arguments from the data framework, and write their results inside the same framework.
904
905When you edit any application model, you have to regenerate the model by propagating the modifications. Each propagation step calls various algorithms. To make these algorithms independent of your application model, you need to use function services.
906
907Take, for example, the case of a modeling sequence made up of a box with the application of a fillet on one of its edges. If you change the height of the box, the fillet will need to be regenerated as well.
908
dba69de2 909@subsection occt_ocaf_8_1 Finding functions, their owners and roots
72b7576f 910
911The class TFunction_Function is an attribute, which stores a link to a function driver in the data framework. In the static table TFunction_DriverTable correspondence links between function attributes and drivers are stored.
912
913You can write your function attribute, a driver for such attribute (which updates the function result in accordance to a given map of changed labels), and set your driver with the GUID to the driver table.
914
915Then the solver algorithm of a data model can find the Function attribute on a corresponding label and call the Execute driver method to update the result of the function.
916
dba69de2 917@subsection occt_ocaf_8_2 Storing and accessing information about function status
72b7576f 918
919For updating algorithm optimization, each function driver has access to the TFunction_Logbook object that is a container for a set of touched, impacted and valid labels. Using this object a driver gets to know which arguments of the function were modified.
920
dba69de2 921@subsection occt_ocaf_8_3 Propagating modifications
72b7576f 922
923An application must implement its functions, function drivers and the common solver for parametric model creation. For example, check the following model (see the following illustration):
924
dba69de2 925@image html /user_guides/ocaf/images/ocaf_image017.png
926@image latex /user_guides/ocaf/images/ocaf_image017.png
72b7576f 927
928The procedure of its creation is as follows:
929 * create a rectangular planar face F with height 100 and width 200
930 * create prism P using face F as a basis
931 * create fillet L at the edge of the prism
932 * change the width of F from 200 to 300:
933 * the solver for the function of face F starts
934 * the solver detects that an argument of the face *F* function has been modified
dba69de2 935 * the solver calls the driver of the face F function for a regeneration of the face
72b7576f 936 * the driver rebuilds face F and adds the label of the face *width* argument to the logbook as touched and the label of the function of face F as impacted
937
938 * the solver detects the function of P – it depends on the function of F
939 * the solver calls the driver of the prism P function
dba69de2 940 * the driver rebuilds prism P and adds the label of this prism to the logbook as impacted
941 * the solver detects the function of L – it depends on the function of P
72b7576f 942 * the solver calls the L function driver
943 * the driver rebuilds fillet L and adds the label of the fillet to the logbook as impacted
944
945@section occt_ocaf_9 XML Support
946
947Writing and reading XML files in OCCT is provided by LDOM package, which constitutes an integral part
948of XML OCAF persistence, which is the optional component provided on top of Open CASCADE Technology.
949
950The Light DOM (LDOM) package contains classes maintaining a data structure whose main principles conform to W3C DOM Level 1 Recommendations. The purpose of these classes as required by XML OCAF persistence schema is to:
951* Maintain a tree structure of objects in memory representing the XML document. The root of the structure is an object of the LDOM_Document type. This object contains all the data corresponding to a given XML document and contains one object of the LDOM_Element type named "document element". The document element contains other LDOM_Element objects forming a tree. Other types of nodes (LDOM_Attr, LDOM_Text, LDOM_Comment, LDOM_CDATASection) represent the corresponding XML types and serve as branches of the tree of elements.
952* Provide class LDOM_Parser to read XML files and convert them to LDOM_Document objects.
953* Provide class LDOM_XmlWriter to convert LDOM_Document to a character stream in XML format and store it in file.
954
955This package covers the functionality provided by numerous products known as "DOM parsers". Unlike most of them, LDOM was specifically developed to meet the following requirements:
956* To minimize the virtual memory allocated by DOM data structures. In average, the amount of memory of LDOM is the same as the XML file size (UTF-8).
957* To minimize the time required for parsing and formatting XML, as well as for access to DOM data structures.
958
959Both these requirements are important when XML files are processed by applications if these files are relatively large (occupying megabytes and even hundreds of megabytes). To meet the requirements, some limitations were imposed on the DOM Level 1 specification; these limitations are insignificant in applications like OCAF. Some of these limitations can be overridden in the course of future developments. The main limitations are:
960* No Unicode support as well as various other encodings; only ASCII strings are used in DOM/XML. Note: There is a data type TCollection_ExtendedString for wide character data. This type is supported by LDOM_String as a sequence of numbers.
961* Some superfluous methods are deleted: getPreviousSibling, getParentNode, etc.
962* No resolution of XML Entities of any kind
963* No support for DTD: the parser just checks for observance of general XML rules and never validates documents.
964* Only 5 available types of DOM nodes: LDOM_Element, LDOM_Attr, LDOM_Text, LDOM_Comment, LDOM_CDATASection.
965* No support of Namespaces; prefixed names are used instead of qualified names.
966* No support of the interface DOMException (no exception when attempting to remove a non-existing node).
967
968LDOM is dependent on Kernel OCCT classes only. Therefore, it can be used outside OCAF persistence in various algorithms where DOM/XML support may be required.
969
970@subsection occt_ocaf_9_1 Document Drivers
971
972The drivers for document storage and retrieval manage conversion between a transient OCAF
973Document in memory and its persistent reflection in a container (disk, memory, network ...). For XML Persistence, they are defined in the package XmlDrivers.
974
975The main methods (entry points) of these drivers are:
976* *Write()* - for a storage driver;
977* *Read()* - for a retrieval driver.
978
979The most common case (which is implemented in XML Persistence) is writing/reading document to/from a regular OS file. Such conversion is performed in two steps:
980
981First it is necessary to convert the transient document into another form (called persistent), suitable for writing into a file, and vice versa.
982In XML Persistence LDOM_Document is used as the persistent form of an OCAF Document and the DOM_Nodes are the persistent objects.
983An OCAF Document is a tree of labels with attributes. Its transformation into a persistent form can be functionally divided into two parts:
984* Conversion of the labels structure, which is performed by the method XmlMDF::FromTo()
985* Conversion of the attributes and their underlying objects, which is performed by the corresponding attribute drivers (one driver per attribute type).
986
987The driver for each attribute is selected from a table of drivers, either by attribute
988type (on storage) or by the name of the corresponding DOM_Element (on retrieval).
989The table of drivers is created by by methods *XmlDrivers_DocumentStorageDriver::AttributeDrivers()*
990and *XmlDrivers_DocumentRetrievalDriver::AttributeDrivers()*.
991
992Then the persistent document is written into a file (or read from a file).
993In standard persistence Storage and FSD packages contain classes for writing/reading the persistent document into a file. In XML persistence LDOMParser and LDOM_XmlWriter are used instead.
994
995Usually, the library containing document storage and retrieval drivers is loaded at run time by a plugin mechanism. To support this in XML Persistence, there is a plugin XmlPlugin and a Factory()method in the XmlDrivers package. This method compares passed GUIDs with known GUIDs and returns the corresponding driver or generates an exception if the GUID is unknown.
996
997The application defines which GUID is needed for document storage or retrieval and in which library it should be found. This depends on document format and application resources. Resources for XML Persistence and also for standard persistence are found in the StdResource unit. They are written for the XmlOcaf document format.
998
999@subsection occt_ocaf_9_2 Attribute Drivers
1000
1001There is one attribute driver for XML persistence for each transient attribute from a set of standard OCAF attributes, with the exception of attribute types, which are never stored (pure transient). Standard OCAF attributes are collected in six packages, and their drivers also follow this distribution. Driver for attribute T*_* is called XmlM*_*. Conversion between transient and persistent form of attribute is performed by two methods Paste() of attribute driver.
1002
1003*XmlMDF_ADriver* is the root class for all attribute drivers.
1004
1005At the beginning of storage/retrieval process, one instance of each attribute driver is created and appended to driver table implemented as XmlMDF_ADriverTable. During OCAF Data storage, attribute drivers are retrieved from the driver table by the type of attribute. In the retrieval step, a data map is created linking names of DOM_Elements and attribute drivers, and then attribute drivers are sought in this map by DOM_Element qualified tag names.
1006
1007Every transient attribute is saved as a DOM_Element (root element of OCAF attribute) with attributes and possibly sub-nodes. The name of the root element can be defined in the attribute driver as a string passed to the base class constructor. The default is the attribute type name. Similarly, namespace prefixes for each attribute can be set. There is no default value, but it is possible to pass NULL or an empty string to store attributes without namespace prefixes.
1008
1009The basic class XmlMDF_ADriver supports errors reporting via the method *WriteMessage(const TCollection_ExtendedString&)*. It sends a message string to its message driver which is initialized in the constructor with a Handle(CDM_MessageDriver) passed from the application by Document Storage/Retrieval Driver.
1010
1011@subsection occt_ocaf_9_3 XML Document Structure
1012
ba06f8bb 1013Every XML Document has one root element, which may have attributes and contain other nodes. In OCAF XML Documents the root element is named "document" and has attribute "format" with the name of the OCAF Schema used to generate the file. The standard XML format is "XmlOcaf". The following elements are sub-elements of \<document\> and should be unique entries as its sub-elements, in a specific order. The order is:
72b7576f 1014* **Element info** - contains strings identifying the format version and other parameters of the OCAF XML document. Normally, data under the element is used by persistence algorithms to correctly retrieve and initialize an OCAF document. The data also includes a copyright string.
ba06f8bb 1015* **Element comments** - consists of an unlimited number of \<comment\> sub-elements containing necessary comment strings.
72b7576f 1016* **Element label** is the root label of the document data structure, with the XML attribute "tag" equal to 0. It contains all the OCAF data (labels, attributes) as tree of XML elements. Every sub-label is identified by a tag (positive integer) defining a unique key for all sub-labels of a label. Every label can contain any number of elements representing OCAF attributes (see OCAF Attributes Representation below).
ba06f8bb 1017* **Element shapes** - contains geometrical and topological entities in BRep format. These entities being referenced by OCAF attributes written under the element \<label\>. This element is empty if there are no shapes in the document. It is only output if attribute driver XmlMNaming_NamedShapeDriver has been added to drivers table by the DocumentStorageDriver.
72b7576f 1018
dba69de2 1019### OCAF Attributes Representation
72b7576f 1020
1021In XML documents, OCAF attributes are elements whose name identifies the OCAF attribute type. These elements may have a simple (string or number) or complex (sub-elements) structure, depending on the architecture of OCAF attribute. Every XML type for OCAF attribute possesses a unique positive integer "id" XML attribute identifying the OCAF attribute throughout the document. To ensure "id" uniqueness, the attribute name "id" is reserved and is only used to indicate and identify elements which may be referenced from other parts of the OCAF XML document.
1022For every standard OCAF attribute, its XML name matches the name of a C++ class in Transient data model. Generally, the XML name of OCAF attribute can be specified in the corresponding attribute driver.
1023XML types for OCAF attributes are declared with XML W3C Schema in a few XSD files where OCAF attributes are grouped by the package where they are defined.
1024
dba69de2 1025### Example of resulting XML file
1026
ba06f8bb 1027The following example is a sample text from an XML file obtained by storing an OCAF document with two labels (0: and 0:2) and two attributes - TDataStd_Name (on label 0:) and TNaming_NamedShape (on label 0:2). The \<shapes\> section contents are replaced by an ellipsis.
72b7576f 1028
1029~~~~~
1030<?xml version="1.0" encoding="UTF-8"?>
1031<document format="XmlOcaf" xmlns="http://www.opencascade.org/OCAF/XML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1032xsi:schemaLocation="http://www.opencascade.org/OCAF/XML http://www.opencascade.org/OCAF/XML/XmlOcaf.xsd">
1033
1034<info date="2001-10-04" schemav="0" objnb="3">
1035<iitem>Copyright: Open Cascade, 2001</iitem>
1036<iitem>STORAGE_VERSION: PCDM_ReadWriter_1</iitem>
1037<iitem>REFERENCE_COUNTER: 0</iitem>
1038<iitem>MODIFICATION_COUNTER: 1</iitem>
1039</info>
1040<comments/>
1041<label tag="0">
1042<TDataStd_Name id="1">Document_1</TDataStd_Name>
1043<label tag="2">
1044<TNaming_NamedShape id="2" evolution="primitive">
1045<olds/>
1046<news>
1047<shape tshape="+34" index="1"/>
1048</news>
1049</TNaming_NamedShape>
1050</label>
1051</label>
ba06f8bb 1052\<shapes\>
72b7576f 1053...
1054</shapes>
1055</document>
1056
1057~~~~~
1058
1059@subsection occt_ocaf_9_4 XML Schema
1060
1061The XML Schema defines the class of a document.
1062
1063The full structure of OCAF XML documents is described as a set of XML W3C Schema files with definitions of all XML element types. The definitions provided cannot be overridden. If any application defines new persistence schemas, it can use all the definitions from the present XSD files but if it creates new or redefines existing types, the definition must be done under other namespace(s).
1064
1065There are other ways to declare XML data, different from W3C Schema, and it should be possible to use them to the extent of their capabilities of expressing the particular structure and constraints of our XML data model. However, it must be noted that the W3C Schema is the primary format for declarations and as such, it is the format supported for future improvements of Open CASCADE Technology, including the development of specific applications using OCAF XML persistence.
1066
1067The Schema files (XSD) are intended for two purposes:
1068* documenting the data format of files generated by OCAF;
1069* validation of documents when they are used by external (non-OCAF) applications, e.g., to generate reports.
1070
1071The Schema definitions are not used by OCAF XML Persistence algorithms when saving and restoring XML documents. There are internal checks to ensure validity when processing every type of data.
1072
dba69de2 1073### Management of Namespaces
1074
72b7576f 1075Both the XML format and the XML OCAF persistence code are extensible in the sense that every new development can reuse everything that has been created in previous projects. For the XML format, this extensibility is supported by assigning names of XML objects (elements) to different XML Namespaces. Hence, XML elements defined in different projects (in different persistence libraries) can easily be combined into the same XML documents. An example is the XCAF XML persistence built as an extension to the Standard OCAF XML persistence [File XmlXcaf.xsd]. For the correct management of Namespaces it is necessary to:
dba69de2 1076* Define *targetNamespace* in the new XSD file describing the format.
72b7576f 1077* Declare (in XSD files) all elements and types in the targetNamespace to appear without a namespace prefix; all other elements and types use the appropriate prefix (such as "ocaf:").
dba69de2 1078* Add (in the new *DocumentStorageDriver*) the *targetNamespace* accompanied with its prefix, using method *XmlDrivers_DocumentStorageDriver::AddNamespace*. The same is done for all namespaces objects which are used by the new persistence, with the exception of the "ocaf" namespace.
1079* Pass (in every OCAF attribute driver) the namespace prefix of the *targetNamespace* to the constructor of *XmlMDF_ADriver*.
72b7576f 1080
1081@section occt_ocaf_10 GLOSSARY
1082
dba69de2 1083* **Application** - a document container holding all documents containing all application data.
1084* **Application data** - the data produced by an application, as opposed to data referring to it.
1085* **Associativity of data** - the ability to propagate modifications made to one document to other documents, which refer to such document. Modification propagation is:
72b7576f 1086 * unidirectional, that is, from the referenced to the referencing document(s), or
1087 * bi-directional, from the referencing to the referenced document and vice-versa.
dba69de2 1088* **Attribute** - a container for application data. An attribute is attached to a label in the hierarchy of the data framework.
1089* **Child** - a label created from another label, which by definition, is the father label.
1090* **Compound document** - a set of interdependent documents, linked to each other by means of external references. These references provide the associativity of data.
1091* **Data framework** - a tree-like data structure which in OCAF, is a tree of labels with data attached to them in the form of attributes. This tree of labels is accessible through the services of the *TDocStd_Document* class.
1092* *Document* - a container for a data framework which grants access to the data, and is, in its turn, contained by an application. A document also allows you to:
1093 * Manage modifications, providing Undo and Redo functions
1094 * Manage command transactions
1095 * Update external links
1096 * Manage save and restore options
1097 * Store the names of software extensions.
1098* **Driver** - an abstract class, which defines the communications protocol with a system.
1099* **Entry** - an ASCII character string containing the tag list of a label.
1100
72b7576f 1101
72b7576f 1102~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
11030:3:24:7:2:7
1104~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1105
dba69de2 1106* **External links** - references from one data structure to another data structure in another document.
72b7576f 1107To store these references properly, a label must also contain an external link attribute.
dba69de2 1108* **Father** - a label, from which other labels have been created. The other labels are, by definition, the children of this label.
1109* **Framework** - a group of co-operating classes which enable a design to be re-used for a given category of problem. The framework guides the architecture of the application by breaking it up into abstract classes, each of which has different responsibilities and collaborates in a predefined way. Application developer creates a specialized framework by:
72b7576f 1110
1111 * defining new classes which inherit from these abstract classes
1112 * composing framework class instances
1113 * implementing the services required by the framework.
1114
1115In C++, the application behavior is implemented in virtual functions redefined in these derived classes. This is known as overriding.
1116
dba69de2 1117* **GUID** - Global Universal ID. A string of 37 characters intended to uniquely identify an object.
72b7576f 1118
72b7576f 1119~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
11202a96b602-ec8b-11d0-bee7-080009dc3333
1121~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1122
dba69de2 1123* **Label** - a point in the data framework, which allows data to be attached to it by means of attributes. It has a name in the form of an entry, which identifies its place in the data framework.
1124* **Modified label** - containing attributes whose data has been modified.
1125* **Reference key** - an invariant reference, which may refer to any type of data used in an application. In its transient form, it is a label in the data framework, and the data is attached to it in the form of attributes. In its persistent form, it is an entry of the label. It allows an application to recover any entity in the current session or in a previous session.
1126* **Resource file** - a file containing a list of each document’s schema name and the storage and retrieval plug-ins for that document.
1127* **Root** - the starting point of the data framework. This point is the top label in the framework. It is represented by the [0] entry and is created at the same time with the document you are working on.
1128* **Scope** - the set of all the attributes and labels which depend on a given label.
1129* **Tag list** - a list of integers, which identify the place of a label in the data framework. This list is displayed in an entry.
1130* **Topological naming** - systematic referencing of topological entities so that these entities can still be identified after the models they belong to have gone through several steps in modeling. In other words, topological naming allows you to track entities through the steps in the modeling process. This referencing is needed when a model is edited and regenerated, and can be seen as a mapping of labels and name attributes of the entities in the old version of a model to those of the corresponding entities in its new version. Note that if the topology of a model changes during the modeling, this mapping may not fully coincide. A Boolean operation, for example, may split edges.
1131* **Topological tracking** - following a topological entity in a model through the steps taken to edit and regenerate that model.
1132* **Valid label** - in a data framework, this is a label, which is already recomputed in the scope of regeneration sequence and includes the label containing a feature which is to be recalculated. Consider the case of a box to which you first add a fillet, then a protrusion feature. For recalculation purposes, only valid labels of each construction stage are used. In recalculating a fillet, they are only those of the box and the fillet, not the protrusion feature which was added afterwards.
72b7576f 1133
dba69de2 1134@section occt_ocaf_11 Samples
1135@subsection occt_ocaf_11_1 Implementation of Attribute Transformation in a CDL file
72b7576f 1136
1137~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
1138class Transformation from MyPackage inherits Attribute from TDF
1139
dba69de2 1140 ---Purpose: This attribute implements a transformation data container.
72b7576f 1141
1142uses
1143
dba69de2 1144 Attribute from TDF,
1145 Label from TDF,
1146 GUID from Standard,
1147 RelocationTable from TDF,
1148 Pnt from gp,
1149 Ax1 from gp,
1150 Ax2 from gp,
1151 Ax3 from gp,
1152 Vec from gp,
1153 Trsf from gp,
1154 TrsfForm from gp
72b7576f 1155
1156is
1157
dba69de2 1158 ---Category: Static methods
1159 -- ===============
1160
1161 GetID (myclass)
1162 ---C++: return const &
1163 ---Purpose: The method returns a unique GUID of this attribute.
1164 -- By means of this GUID this attribute may be identified
1165 -- among other attributes attached to the same label.
1166 returns GUID from Standard;
1167
1168 Set (myclass; theLabel : Label from TDF)
1169 ---Purpose: Finds or creates the attribute attached to <theLabel>.
1170 -- The found or created attribute is returned.
1171 returns Transformation from MyPackage;
1172
1173
1174 ---Category: Methods for access to the attribute data
1175 -- ========================================
1176
1177 Get (me)
1178 ---Purpose: The method returns the transformation.
1179 returns Trsf from gp;
1180
1181
1182 ---Category: Methods for setting the data of transformation
1183 -- ==============================================
1184
1185 SetRotation (me : mutable;
1186 theAxis : Ax1 from gp;
1187 theAngle : Real from Standard);
1188 ---Purpose: The method defines a rotation type of transformation.
1189
1190 SetTranslation (me : mutable;
1191 theVector : Vec from gp);
1192 ---Purpose: The method defines a translation type of transformation.
1193
1194 SetMirror (me : mutable;
1195 thePoint : Pnt from gp);
1196 ---Purpose: The method defines a point mirror type of transformation
1197 -- (point symmetry).
1198
1199 SetMirror (me : mutable;
1200 theAxis : Ax1 from gp);
1201 ---Purpose: The method defines an axis mirror type of transformation
1202 -- (axial symmetry).
1203
1204 SetMirror (me : mutable;
1205 thePlane : Ax2 from gp);
1206 ---Purpose: The method defines a point mirror type of transformation
1207 -- (planar symmetry).
1208
1209 SetScale (me : mutable;
1210 thePoint : Pnt from gp;
1211 theScale : Real from Standard);
1212 ---Purpose: The method defines a scale type of transformation.
1213
1214 SetTransformation (me : mutable;
1215 theCoordinateSystem1 : Ax3 from gp;
1216 theCoordinateSystem2 : Ax3 from gp);
1217 ---Purpose: The method defines a complex type of transformation
1218 -- from one co-ordinate system to another.
1219
1220
1221 ---Category: Overridden methods from TDF_Attribute
1222 -- =====================================
1223
1224 ID (me)
1225 ---C++: return const &
1226 ---Purpose: The method returns a unique GUID of the attribute.
1227 -- By means of this GUID this attribute may be identified
1228 -- among other attributes attached to the same label.
1229 returns GUID from Standard;
1230
1231 Restore (me: mutable;
1232 theAttribute : Attribute from TDF);
1233 ---Purpose: The method is called on Undo / Redo.
1234 -- It copies the content of <theAttribute>
1235 -- into this attribute (copies the fields).
1236
1237 NewEmpty (me)
1238 ---Purpose: It creates a new instance of this attribute.
1239 -- It is called on Copy / Paste, Undo / Redo.
1240 returns mutable Attribute from TDF;
1241
1242 Paste (me;
1243 theAttribute : mutable Attribute from TDF;
1244 theRelocationTable : mutable RelocationTable from TDF);
1245 ---Purpose:: The method is called on Copy / Paste.
1246 -- It copies the content of this attribute into
1247 -- <theAttribute> (copies the fields).
1248
1249 Dump(me; anOS : in out OStream from Standard)
1250 ---C++: return;
1251 ---Purpose: Prints the content of this attribute into the stream.
1252 returns OStream from Standard is redefined;
1253
1254
1255 ---Category: Constructor
1256 -- ===========
1257
1258 Create
1259 ---Purpose: The C++ constructor of this atribute class.
1260 -- Usually it is never called outside this class.
1261 returns mutable Transformation from MyPackage;
72b7576f 1262
1263
1264fields
1265
dba69de2 1266 -- Type of transformation
1267 myType : TrsfForm from gp;
72b7576f 1268
dba69de2 1269 -- Axes (Ax1, Ax2, Ax3)
1270 myAx1 : Ax1 from gp;
1271 myAx2 : Ax2 from gp;
1272 myFirstAx3 : Ax3 from gp;
1273 mySecondAx3 : Ax3 from gp;
1274
1275 -- Scalar values
1276 myAngle : Real from Standard;
1277 myScale : Real from Standard;
1278
1279 -- Points
1280 myFirstPoint : Pnt from gp;
1281 mySecondPoint : Pnt from gp;
72b7576f 1282
1283
1284end Transformation;
1285~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1286
dba69de2 1287@subsection occt_ocaf_11_2 Implementation of Attribute Transformation in a CPP file
1288
72b7576f 1289~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
1290#include MyPackage_Transformation.ixx;
1291
1292//=======================================================================
1293//function : GetID
dba69de2 1294//purpose : The method returns a unique GUID of this attribute.
1295// By means of this GUID this attribute may be identified
1296// among other attributes attached to the same label.
72b7576f 1297//=======================================================================
1298const Standard_GUID& MyPackage_Transformation::GetID()
1299{
dba69de2 1300 static Standard_GUID ID("4443368E-C808-4468-984D-B26906BA8573");
1301 return ID;
72b7576f 1302}
1303
1304//=======================================================================
1305//function : Set
dba69de2 1306//purpose : Finds or creates the attribute attached to <theLabel>.
1307// The found or created attribute is returned.
72b7576f 1308//=======================================================================
1309Handle(MyPackage_Transformation) MyPackage_Transformation::Set(const TDF_Label& theLabel)
1310{
dba69de2 1311 Handle(MyPackage_Transformation) T;
1312 if (!theLabel.FindAttribute(MyPackage_Transformation::GetID(), T))
1313 {
1314 T = new MyPackage_Transformation();
1315 theLabel.AddAttribute(T);
1316 }
1317 return T;
72b7576f 1318}
1319
1320//=======================================================================
1321//function : Get
dba69de2 1322//purpose : The method returns the transformation.
72b7576f 1323//=======================================================================
1324gp_Trsf MyPackage_Transformation::Get() const
1325{
dba69de2 1326 gp_Trsf transformation;
1327 switch (myType)
1328 {
1329 case gp_Identity:
1330 {
1331 break;
1332 }
1333 case gp_Rotation:
1334 {
1335 transformation.SetRotation(myAx1, myAngle);
1336 break;
1337 }
1338 case gp_Translation:
1339 {
1340 transformation.SetTranslation(myFirstPoint, mySecondPoint);
1341 break;
1342 }
1343 case gp_PntMirror:
1344 {
1345 transformation.SetMirror(myFirstPoint);
1346 break;
1347 }
1348 case gp_Ax1Mirror:
1349 {
1350 transformation.SetMirror(myAx1);
1351 break;
1352 }
1353 case gp_Ax2Mirror:
1354 {
1355 transformation.SetMirror(myAx2);
1356 break;
1357 }
1358 case gp_Scale:
1359 {
1360 transformation.SetScale(myFirstPoint, myScale);
1361 break;
1362 }
1363 case gp_CompoundTrsf:
1364 {
1365 transformation.SetTransformation(myFirstAx3, mySecondAx3);
1366 break;
1367 }
1368 case gp_Other:
1369 {
1370 break;
1371 }
1372 }
1373 return transformation;
72b7576f 1374}
1375
1376//=======================================================================
1377//function : SetRotation
dba69de2 1378//purpose : The method defines a rotation type of transformation.
72b7576f 1379//=======================================================================
1380void MyPackage_Transformation::SetRotation(const gp_Ax1& theAxis, const Standard_Real theAngle)
1381{
dba69de2 1382 Backup();
1383 myType = gp_Rotation;
1384 myAx1 = theAxis;
1385 myAngle = theAngle;
72b7576f 1386}
1387
1388//=======================================================================
1389//function : SetTranslation
dba69de2 1390//purpose : The method defines a translation type of transformation.
72b7576f 1391//=======================================================================
1392void MyPackage_Transformation::SetTranslation(const gp_Vec& theVector)
1393{
dba69de2 1394 Backup();
1395 myType = gp_Translation;
1396 myFirstPoint.SetCoord(0, 0, 0);
1397 mySecondPoint.SetCoord(theVector.X(), theVector.Y(), theVector.Z());
72b7576f 1398}
1399
1400//=======================================================================
1401//function : SetMirror
dba69de2 1402//purpose : The method defines a point mirror type of transformation
1403// (point symmetry).
72b7576f 1404//=======================================================================
1405void MyPackage_Transformation::SetMirror(const gp_Pnt& thePoint)
1406{
dba69de2 1407 Backup();
1408 myType = gp_PntMirror;
1409 myFirstPoint = thePoint;
72b7576f 1410}
1411
1412//=======================================================================
1413//function : SetMirror
dba69de2 1414//purpose : The method defines an axis mirror type of transformation
1415// (axial symmetry).
72b7576f 1416//=======================================================================
1417void MyPackage_Transformation::SetMirror(const gp_Ax1& theAxis)
1418{
dba69de2 1419 Backup();
1420 myType = gp_Ax1Mirror;
1421 myAx1 = theAxis;
72b7576f 1422}
1423
1424//=======================================================================
1425//function : SetMirror
dba69de2 1426//purpose : The method defines a point mirror type of transformation
1427// (planar symmetry).
72b7576f 1428//=======================================================================
1429void MyPackage_Transformation::SetMirror(const gp_Ax2& thePlane)
1430{
dba69de2 1431 Backup();
1432 myType = gp_Ax2Mirror;
1433 myAx2 = thePlane;
72b7576f 1434}
1435
1436//=======================================================================
1437//function : SetScale
dba69de2 1438//purpose : The method defines a scale type of transformation.
72b7576f 1439//=======================================================================
1440void MyPackage_Transformation::SetScale(const gp_Pnt& thePoint, const Standard_Real theScale)
1441{
dba69de2 1442 Backup();
1443 myType = gp_Scale;
1444 myFirstPoint = thePoint;
1445 myScale = theScale;
72b7576f 1446}
1447
1448//=======================================================================
1449//function : SetTransformation
dba69de2 1450//purpose : The method defines a complex type of transformation
1451// from one co-ordinate system to another.
72b7576f 1452//=======================================================================
1453void MyPackage_Transformation::SetTransformation(const gp_Ax3& theCoordinateSystem1,
dba69de2 1454 const gp_Ax3& theCoordinateSystem2)
72b7576f 1455{
dba69de2 1456 Backup();
1457 myFirstAx3 = theCoordinateSystem1;
1458 mySecondAx3 = theCoordinateSystem2;
72b7576f 1459}
1460
1461//=======================================================================
1462//function : ID
dba69de2 1463//purpose : The method returns a unique GUID of the attribute.
1464// By means of this GUID this attribute may be identified
1465// among other attributes attached to the same label.
72b7576f 1466//=======================================================================
1467const Standard_GUID& MyPackage_Transformation::ID() const
1468{
dba69de2 1469 return GetID();
72b7576f 1470}
1471
1472//=======================================================================
1473//function : Restore
dba69de2 1474//purpose : The method is called on Undo / Redo.
1475// It copies the content of <theAttribute>
1476// into this attribute (copies the fields).
72b7576f 1477//=======================================================================
1478void MyPackage_Transformation::Restore(const Handle(TDF_Attribute)& theAttribute)
1479{
dba69de2 1480 Handle(MyPackage_Transformation) theTransformation = Handle(MyPackage_Transformation)::DownCast(theAttribute);
1481 myType = theTransformation->myType;
1482 myAx1 = theTransformation->myAx1;
1483 myAx2 = theTransformation->myAx2;
1484 myFirstAx3 = theTransformation->myFirstAx3;
1485 mySecondAx3 = theTransformation->mySecondAx3;
1486 myAngle = theTransformation->myAngle;
1487 myScale = theTransformation->myScale;
1488 myFirstPoint = theTransformation->myFirstPoint;
1489 mySecondPoint = theTransformation->mySecondPoint;
72b7576f 1490}
1491
1492//=======================================================================
1493//function : NewEmpty
dba69de2 1494//purpose : It creates a new instance of this attribute.
1495// It is called on Copy / Paste, Undo / Redo.
72b7576f 1496//=======================================================================
1497Handle(TDF_Attribute) MyPackage_Transformation::NewEmpty() const
dba69de2 1498{
1499 return new MyPackage_Transformation();
72b7576f 1500}
1501
1502//=======================================================================
1503//function : Paste
dba69de2 1504//purpose : The method is called on Copy / Paste.
1505// It copies the content of this attribute into
1506// <theAttribute> (copies the fields).
72b7576f 1507//=======================================================================
1508void MyPackage_Transformation::Paste(const Handle(TDF_Attribute)& theAttribute,
dba69de2 1509 const Handle(TDF_RelocationTable)& ) const
72b7576f 1510{
dba69de2 1511 Handle(MyPackage_Transformation) theTransformation = Handle(MyPackage_Transformation)::DownCast(theAttribute);
1512 theTransformation->myType = myType;
1513 theTransformation->myAx1 = myAx1;
1514 theTransformation->myAx2 = myAx2;
1515 theTransformation->myFirstAx3 = myFirstAx3;
1516 theTransformation->mySecondAx3 = mySecondAx3;
1517 theTransformation->myAngle = myAngle;
1518 theTransformation->myScale = myScale;
1519 theTransformation->myFirstPoint = myFirstPoint;
1520 theTransformation->mySecondPoint = mySecondPoint;
72b7576f 1521}
1522
1523//=======================================================================
1524//function : Dump
dba69de2 1525//purpose : Prints the content of this attribute into the stream.
72b7576f 1526//=======================================================================
1527Standard_OStream& MyPackage_Transformation::Dump(Standard_OStream& anOS) const
dba69de2 1528{
1529 anOS = "Transformation: ";
1530 switch (myType)
1531 {
1532 case gp_Identity:
1533 {
1534 anOS = "gp_Identity";
1535 break;
1536 }
1537 case gp_Rotation:
1538 {
1539 anOS = "gp_Rotation";
1540 break;
1541 }
1542 case gp_Translation:
1543 {
1544 anOS = "gp_Translation";
1545 break;
1546 }
1547 case gp_PntMirror:
1548 {
1549 anOS = "gp_PntMirror";
1550 break;
1551 }
1552 case gp_Ax1Mirror:
1553 {
1554 anOS = "gp_Ax1Mirror";
1555 break;
1556 }
1557 case gp_Ax2Mirror:
1558 {
1559 anOS = "gp_Ax2Mirror";
1560 break;
1561 }
1562 case gp_Scale:
1563 {
1564 anOS = "gp_Scale";
1565 break;
1566 }
1567 case gp_CompoundTrsf:
1568 {
1569 anOS = "gp_CompoundTrsf";
1570 break;
1571 }
1572 case gp_Other:
1573 {
1574 anOS = "gp_Other";
1575 break;
1576 }
1577 }
1578 return anOS;
72b7576f 1579}
1580
1581//=======================================================================
1582//function : MyPackage_Transformation
dba69de2 1583//purpose : A constructor.
72b7576f 1584//=======================================================================
1585MyPackage_Transformation::MyPackage_Transformation():myType(gp_Identity){
1586
1587}
dba69de2 1588~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1589
1590@subsection occt_ocaf_11_3 Implementation of typical actions with standard OCAF attributes.
1591
ba06f8bb 1592There are four sample files provided in the directory 'OpenCasCade/ros/samples/ocafsamples'. They present typical actions with OCAF services (mainly for newcomers).
dba69de2 1593The method *Sample()* of each file is not dedicated for execution 'as is', it is rather a set of logical actions using some OCAF services.
1594
1595### TDataStd_Sample.cxx
1596This sample contains templates for typical actions with the following standard OCAF attributes:
1597- Starting with data framework;
1598- TDataStd_Integer attribute management;
1599- TDataStd_RealArray attribute management;
1600- TDataStd_Comment attribute management;
1601- TDataStd_Name attribute management;
1602- TDataStd_UAttribute attribute management;
1603- TDF_Reference attribute management;
1604- TDataXtd_Point attribute management;
1605- TDataXtd_Plane attribute management;
1606- TDataXtd_Axis attribute management;
1607- TDataXtd_Geometry attribute management;
1608- TDataXtd_Constraint attribute management;
1609- TDataStd_Directory attribute management;
1610- TDataStd_TreeNode attribute management.
1611
1612### TDocStd_Sample.cxx
1613This sample contains template for the following typical actions:
1614- creating application;
1615- creating the new document (document contains a framework);
1616- retrieving the document from a label of its framework;
1617- filling a document with data;
1618- saving a document in the file;
1619- closing a document;
1620- opening the document stored in the file;
1621- copying content of a document to another document with possibility to update the copy in the future.
1622
1623### TPrsStd_Sample.cxx
1624This sample contains template for the following typical actions:
1625- starting with data framework;
1626- setting the TPrsStd_AISViewer in the framework;
1627- initialization of aViewer;
1628- finding TPrsStd_AISViewer attribute in the DataFramework;
1629- getting AIS_InteractiveContext from TPrsStd_AISViewer;
1630- adding driver to the map of drivers;
1631- getting driver from the map of drivers;
ba06f8bb 1632- setting TNaming_NamedShape to \<ShapeLabel\>;
1633- setting the new TPrsStd_AISPresentation to \<ShapeLabel\>;
dba69de2 1634- displaying;
1635- erasing;
1636- updating and displaying presentation of the attribute to be displayed;
1637- setting a color to the displayed attribute;
1638- getting transparency of the displayed attribute;
1639- modify attribute;
1640- updating presentation of the attribute in viewer.
1641
1642### TNaming_Sample.cxx
1643This sample contains template for typical actions with OCAF Topological Naming services.
1644The following scenario is used:
1645- data framework initialization;
1646- creating Box1 and pushing it as PRIMITIVE in DF;
1647- creating Box2 and pushing it as PRIMITIVE in DF;
1648- moving Box2 (applying a transformation);
1649- pushing the selected edges of the top face of Box1 in DF;
1650- creating a Fillet (using the selected edges) and pushing the result as a modification of Box1;
1651- creating a Cut (Box1, Box2) as a modification of Box1 and push it in DF;
1652- recovering the result from DF.
1653