docs/tech/tn0014.txt

   1                       XRC resources format specification
   2                       ==================================
   3
   4                          !!!!! NOT YET FINISHED !!!!!
   5
   6 0. Introduction
   7 ===============
   8
   9 This note describes the file format used for storing XRC resources that are
  10 used by wxXmlResource class. It is probably only useful for those implementing
  11 dialog editors with XRC support.
  12
  13 If you only want to use the resources, you can choose from a number of editors:
  14   a) wxDesigner (http://www.roebling.de)
  15   b) XRCed (wxPython/tools)
  16   c) wxWorkshop (http://wxworkshop.sf.net)
  17   b) wxrcedit (contrib/utils/wxrcedit)
  18
  19 The XRC format is based on XML 1.0 (please consult W3C's specification). There
  20 is no DTD available since it is not possible to fully describe the format with
  21 the limited expressive power of DTDs.
  22
  23
  24
  25 1. Terminology
  26 ==============
  27
  28 The usual XML terminology applies. In particular, we shall use the terms
  29 NODE, PROPERTY and VALUE in the XML sense:
  30
  31     <node property1="value1" property2="value2">...</node>
  32
  33 The term ATTRIBUTE is specific to XRC and refers to a subnode
  34 of an <object> or <object_ref> node that is itself not <object> or <object_ref>.
  35 In the example bellow, <pos>, <label> and <style> are attributes, while neither
  36 <resource> nor either of <object>s is:
  37
  38     <?xml version="1.0" encoding="utf-8">
  39     <resource xmlns="http://www.wxwindows.org/wxxrc" version="2.3.0.1">
  40         <object class="wxPanel">
  41             <style>wxSUNKEN_BORDER</style>             <!-- attr -->
  42             <object class="wxStaticText">
  43                 <label>A label</label>                 <!-- attr -->
  44                 <pos>10,10</pos>                       <!-- attr -->
  45             </object>
  46         </object>
  47     </resource>
  48
  49 ATTRIBUTE VALUE is the content of all text elements within attribute tag. In the
  50 above example, "wxSUNKEN_BORDER", "A label" and "10,10" are attribute values.
  51 ATTRIBUTE TYPE defines what attribute values are valid for given attribute (you
  52 can think of it as attribute value syntax definition).
  53
  54
  55
  56 2. Elementary description
  57 =========================
  58
  59 XRC resource file is a well-formed XML 1.0 document. All elements of XRC file are
  60 from the http://www.wxwindows.org/wxxrc namespace.
  61
  62 The root node of XRC document must be <resource>. The <resource> node has
  63 optional "version" property. Default version  (in absence of the version
  64 property) is "0.0.0.0". The version consists of four integers separated by
  65 periods. Version of XRC format changes only if there was an incompatible
  66 change introduced (i.e. either the library cannot understand old resource
  67 files or older versions of the library wouldn't understand the new format).
  68 The first three integers are major, minor and release number of the wxWindows
  69 release when the change was introduced, the last one is revision number and
  70 is 0 for the first incompatible change in given wxWindows release, 1 for
  71 the second etc.
  72
  73 Differences between versions are described within this document in paragraphs
  74 entitled "Version Note".
  75
  76 The <resource> node contains namespace declaration, too:
  77
  78     <resource xmlns="http://www.wxwindows.org/wxxrc" version="2.3.0.1">
  79
  80 The <resource> node is only allowed to have <object> and <object_ref>
  81 subnodes, all of which must have the "name" property.
  82
  83 The <object> node represents a single object (GUI element) and it usually maps
  84 directly to a wxWindows class instance. It three properties: "name", "class"
  85 and "subclass". "class" must always be present, it tells XRC what wxWindows
  86 object should be created in this place. The other two are optional.
  87 "name" is ID used to identify the object. It is the value passed to the XRCID() macro
  88 and is also used to construct wxWindow's id and name attributes and must be unique
  89 among all children of the neareset container object (wxDialog, wxFrame, wxPanel,
  90 wxNotebook) upside from the object in XML nodes hiearchy (two distinct containers
  91 may contain objects with same "name", though). "subclass" is
  92 optional name of class whose constructor will be called instead of the constructor
  93 for "class". Subclass must be available in the program that loads the resource,
  94 must be derived from "class" and must be registered within wxWindows' RTTI system.
  95
  96 Example:
  97
  98     <object name="MyList1" class="wxListCtrl" subclass="MyListCtrlClass">
  99         ...
 100     </object>
 101
 102 <object> node may have arbitrary child nodes. What child nodes and their semantics
 103 are class-dependent and are defined later in this document. The user is allowed
 104 to register new object handlers within XRC and extend it to accept new <object>
 105 classes (and therefore different <object>'s child nodes).
 106
 107 <object_ref> node is identical to <object>, except that it does _not_ have "class"
 108 property and has additonal required property "ref". It's concept is similar to Unix
 109 symlinks: value of the "ref" property is equal to the value of "name" property of
 110 some existing node (called referred node) in the resources (not neccessary top-level).
 111 Referred node's "class" property and all subnodes are copied in place of the referee
 112 <object_ref> node which is then processed as regular <object> node. If the <object_ref>
 113 node itself has child nodes, then these nodes _override_ any nodes from the referred node.
 114
 115 Example:
 116
 117     <object name="foo" class="wxTextCtrl">
 118         <value>hello</value>
 119         <size>100,-1d</size>
 120     </object>
 121     <object_ref name="bar" ref="foo">
 122         <value>bar</value>               <!-- override! -->
 123     </object_ref>
 124
 125 is identical to:
 126
 127     <object name="foo" class="wxTextCtrl">
 128         <value>hello</value>
 129         <size>100,-1d</size>
 130     </object>
 131     <object name="bar" class="wxTextCtrl">
 132         <value>bar</value>
 133         <size>100,-1d</size>
 134     </object>
 135
 136
 137
 138 3. Common attribute types
 139 =========================
 140
 141 There are several attribute types (see section 1. Terminology) that are common
 142 to many attributes of different classes:
 143
 144 String
 145 ------
 146 Any text. Some characters have special interpretation and are translated
 147 by XRC parser according to this table:
 148     "_"    -> "&"  ('&' is used to underline e.g. menu items in wxWindows)
 149     "__"   -> "_"
 150     "\n"   -> line break (C character '\n')
 151     "\r"   -> carriage return (C character '\r')
 152     "\t"   -> tabelator (C character '\t')
 153
 154 Version Note:
 155     '$' was used instead of '_' prior to version 2.3.0.1.
 156
 157
 158 I18nString
 159 ----------
 160 Like String, but the value is translated to native language using wxLocale
 161 at runtime (unless it was disabled by not passing wxXRC_USE_LOCALE flag to
 162 wxXmlResource constructor). Used for strings that are "visible" in the GUI.
 163
 164
 165 UnsignedInteger
 166 ---------------
 167 This is obvious. Only digits 0-9 may be present and there must be at least
 168 one digit.
 169
 170
 171 Integer
 172 -------
 173 Like UnsignedInteger but may be prefixed with '-' (ints less than zero).
 174
 175
 176 Position
 177 --------
 178 Specifies (window's) position in 2D space. Syntax is <integer>,<integer>[d]
 179 where <integer> is valid value of Integer type.
 180
 181
 182 Size
 183 ----
 184 Syntax is same as Position's syntax, but the values are interpreted as window
 185 size (wxSize type) and not position (wxPosition type).
 186
 187
 188 Style[wxSomeClass]
 189 ------------------
 190 List of style flags that can be passed to wxSomeClass' constructor. Flags are
 191 written in same way as in C++ code (e.g. "wxSUNKEN_BORDER", "wxHW_SCROLLBAR_NEVER")
 192 and are delimined with any combination of whitespaces and '|'. Possible flags
 193 are class-dependent and are not described in this technote. Please refer to wxWindows
 194 manual for all styles that given class can accept; if XRC does not accept a flag
 195 listed in wxWindows documentation, it is a bug.
 196
 197
 198 Bitmap
 199 ------
 200 Attribute value is interpreted as filename (either absolute or relative to
 201 the location of XRC resource file). In addition, attribute node may have
 202 "stock_id" and "stock_client" properties. Their values may be any of wxArtID (or
 203 wxArtClient respectively) values as used by wxArtProvider (because the user may
 204 define own constants, efectively any string is legal here). Examples are
 205 "wxART_FILE_OPEN" (id) or "wxART_MENU" (client).
 206
 207 Any of "stock_id" or "stock_client" properties or the filename may be omitted. XRC
 208 determines the bitmap to use according to this algorithm:
 209   1. If there is non-empty "stock_id" property, query wxArtProvider for the bitmap
 210      (if there is no "stock_client", use default one, which is usually wxART_OTHER;
 211      exceptions are noted in class-specific sections bellow). If the query fails,
 212      continue to 2.
 213   2. Load the bitmap from the file in attribute value.
 214
 215
 216 Boolean
 217 -------
 218 Boolean value, either "0" (false) or "1" (true).
 219
 220
 221
 222 4. Supported classes
 223 ====================
 224
 225 Attributes are listed in tables in the following format:
 226 attribute name             attribute type          default value, if any
 227                            [(optional remarks....................
 228                            ...................................)]
 229
 230 wxBitmap
 231 --------
 232 This is a special case, because it does not create a wxWindow instance but
 233 creates wxBitmap instead. Another exceptional thing is that it does not have
 234 any attributes. Instead, the node itself is interpreted as if it were attribute
 235 of type Bitmap.
 236
 237 Example: <object class="wxBitmap">bitmaps/foo.gif</object>
 238
 239
 240 wxIcon
 241 ------
 242 Identical to wxBitmap class, except that it creates wxIcon instead of wxBitmap.
 243
 244
 245 wxButton
 246 --------
 247 position                   Position                -1,-1
 248 size                       Size                    -1,-1
 249 style                      Style[wxButton]
 250
 251 label                      I18nString
 252 default                    Boolean                 false
 253                            (Is the button default button?)
 254
 255
 256 wxCalendarCtrl
 257 --------------
 258 position                   Position                -1,-1
 259 size                       Size                    -1,-1
 260 style                      Style[wxCalendarCtrl]
 261
 262
 263 wxCheckBox
 264 ----------
 265 position                   Position                -1,-1
 266 size                       Size                    -1,-1
 267 style                      Style[wxCheckBox]
 268 checked                    Boolean                 false
 269
 270
 271 wxCheckList
 272 -----------
 273 position                   Position                -1,-1
 274 size                       Size                    -1,-1
 275 style                      Style[wxCheckList]
 276 content                    (see bellow)            (empty)
 277
 278 Optional "content" attribute does not have attribute value. Instead,
 279 arbitrary number of <item> nodes may be rooted under it (the control
 280 is filled with strings contained in these nodes). Each <item>
 281 node must contain I18nString value and may have "checked" property
 282 with possible values "0" or "1" indicating the the item is initially
 283 checked.
 284
 285 Example:
 286 <object class="wxCheckList">
 287     <content>
 288       <item>One</item>
 289       <item checked="1">Two</item>
 290       <item checked="1">Three</item>
 291       <item>Four</item>
 292     </content>
 293 </object>
 294
 295
 296 wxScrolledWindow
 297 ----------------
 298 position                   Position                -1,-1
 299 size                       Size                    -1,-1
 300 style                      Style[wxScrolledWindow] wxHSCROLL | wxVSCROLL
 301
 302
 303
 304 5. More features
 305 ================
 306
 307 FIXME -- "platform" property handling
 308
 309
 310 === EOF ===
 311
 312 Version: $Id$