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10 <TITLE>1 Class and object hierarchies</TITLE>
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60 <!--Table of Child-Links-->
61 <A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
63 <UL CLASS="ChildLinks">
64 <LI><A NAME="tex2html83"
65 HREF="node2.html#SECTION00021000000000000000"><SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">1</SPAN> Class hierarchy</A>
66 <LI><A NAME="tex2html84"
67 HREF="node2.html#SECTION00022000000000000000"><SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">2</SPAN> Object hierarchies: WRegion parents and managers</A>
69 <LI><A NAME="tex2html85"
70 HREF="node2.html#SECTION00022100000000000000"><SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">2</SPAN>.<SPAN CLASS="arabic">1</SPAN> Parent-child relations</A>
71 <LI><A NAME="tex2html86"
72 HREF="node2.html#SECTION00022200000000000000"><SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">2</SPAN>.<SPAN CLASS="arabic">2</SPAN> Manager-managed relations</A>
75 <LI><A NAME="tex2html87"
76 HREF="node2.html#SECTION00023000000000000000"><SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">3</SPAN> Summary</A>
78 <!--End of Table of Child-Links-->
81 <H1><A NAME="SECTION00020000000000000000"></A>
82 <A NAME="sec:objects"></A>
84 <SPAN CLASS="arabic">1</SPAN> Class and object hierarchies
88 While Ion does not not have a truly object-oriented design
90 HREF="#foot215"><SUP><SPAN CLASS="arabic">1</SPAN></SUP></A>,
91 things that appear on the computer screen are, however, quite
92 naturally expressed as such ``objects''. Therefore Ion implements
93 a rather primitive OO system for these screen objects and some
97 It is essential for the module writer to learn this object
98 system, but also people who write their own binding configuration files
99 necessarily come into contact with the class and object hierarchies
100 - you need to know which binding setup routines apply where,
101 and what functions can be used as handlers in which bindings.
102 It is the purpose of this section to attempt to explain these
103 hierarchies. If you do not wish the read the full section, at least
104 read the summary at the end of it, so that you understand the very
108 For simplicity we consider only the essential-for-basic-configuration
109 Ioncore, <SPAN CLASS="textit">mod_tiling</SPAN> and <SPAN CLASS="textit">mod_query</SPAN> classes.
110 See Appendix <A HREF="#app:fullhierarchy"><IMG ALIGN="BOTTOM" BORDER="1" ALT="[*]" SRC="crossref.png"></A> for the full class hierarchy visible
115 <H2><A NAME="SECTION00021000000000000000">
116 <SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">1</SPAN> Class hierarchy</A>
120 One of the most important principles of object-oriented design methodology
121 is inheritance; roughly how classes (objects are instances of classes)
122 extend on others' features. Inheritance gives rise to class hierarchy.
123 In the case of single-inheritance this hierarchy can be expressed as a
124 tree where the class at the root is inherited by all others below it
125 and so on. Figure <A HREF="#fig:classhierarchy">1</A> lists out the Ion class
126 hierarchy and below we explain what features of Ion the classes
131 <DIV ALIGN="CENTER"><A NAME="fig:classhierarchy"></A><A NAME="322"></A>
133 <CAPTION ALIGN="BOTTOM"><STRONG>Figure 1:</STRONG>
134 Partial Ioncore, <SPAN CLASS="textit">mod_tiling</SPAN> and <SPAN CLASS="textit">mod_query</SPAN>
135 class hierarchy.</CAPTION>
144 | | | `-->WRootWin
145 | | `-->WInput (mod_query)
146 | | |-->WEdln (mod_query)
147 | | `-->WMessage (mod_query)
151 | `-->WTiling (mod_tiling)
152 `-->WSplit (mod_tiling)
162 <DT><STRONG>Obj</STRONG></DT>
163 <DD><A NAME="332"></A>
164 Is the base of Ion's object system.
168 <DT><STRONG>WRegion</STRONG></DT>
169 <DD><A NAME="333"></A>
170 is the base class for everything corresponding to something on the
171 screen. Each object of type WRegion has a size and position
172 relative to the parent WRegion. While a big part of Ion
173 operates on these instead of more specialised classes, WRegion
174 is a ``virtual'' base class in that there are no objects of ``pure''
175 type WRegion; all concrete regions are objects of some class
176 that inherits WRegion.
180 <DT><STRONG>WClientWin</STRONG></DT>
181 <DD><A NAME="334"></A> is a class for
182 client window objects, the objects that window managers are
187 <DT><STRONG>WWindow</STRONG></DT>
188 <DD><A NAME="335"></A> is the base class for all
189 internal objects having an X window associated to them
190 (WClientWins also have X windows associated to them).
194 <DT><STRONG>WMPlex</STRONG></DT>
195 <DD>is a base class for all regions that ``multiplex''
196 other regions. This means that of the regions managed by the multiplexer,
197 only one can be displayed at a time.
201 <DT><STRONG>WScreen</STRONG></DT>
202 <DD><A NAME="336"></A> is an instance of WMPlex
207 <DT><STRONG>WRootWin</STRONG></DT>
208 <DD><A NAME="337"></A> is the class for
209 root windows<A NAME="249"></A> of X screens<A NAME="250"></A>.
210 It is an instance of WScreen.
211 Note that an ``X screen'' or root window is not necessarily a
212 single physical screen<A NAME="252"></A> as a root window
213 may be split over multiple screens when ugly hacks such as
214 Xinerama<A NAME="253"></A> are used. (Actually there can be only
215 one root window when Xinerama is used.)
219 <DT><STRONG>WFrame</STRONG></DT>
220 <DD><A NAME="338"></A> is the class for frames.
221 While most Ion's objects have no graphical presentation, frames
222 basically add to WMPlexes the decorations around client
223 windows (borders, tabs).
227 <DT><STRONG>WGroup</STRONG></DT>
228 <DD><A NAME="339"></A> is the base class for groups.
229 Particular types of groups are workspaces
230 (WGroupWS<A NAME="340"></A>)
231 and groups of client windows
232 (WGroupCW<A NAME="341"></A>).
237 Classes implemented by the <SPAN CLASS="textit">mod_tiling</SPAN> module:
241 <DT><STRONG>WTiling</STRONG></DT>
242 <DD><A NAME="344"></A> is the class for tilings
246 <DT><STRONG>WSplit</STRONG></DT>
247 <DD><A NAME="345"></A> (or, more specifically, classes
248 that inherit it) encode the WTiling tree structure.
253 Classes implemented by the <SPAN CLASS="textit">mod_query</SPAN> module:
257 <DT><STRONG>WInput</STRONG></DT>
258 <DD><A NAME="348"></A> is a virtual base class for the
262 <DT><STRONG>WEdln</STRONG></DT>
263 <DD><A NAME="349"></A> is the class for the ``queries'',
264 the text inputs that usually appear at bottoms of frames and sometimes
265 screens. Queries are the functional equivalent of ``mini buffers'' in
269 <DT><STRONG>WMessage</STRONG></DT>
270 <DD><A NAME="350"></A> implements the boxes for
271 warning and other messages that Ion may wish to display to the user.
272 These also usually appear at bottoms of frames.
277 There are also some other ``proxy'' classes that do not refer
278 to objects on the screen. The only important one of these for
279 basic configuration is WMoveresMode that is used for
280 binding callbacks in the move and resize mode.
284 <H2><A NAME="SECTION00022000000000000000">
285 <SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">2</SPAN> Object hierarchies: WRegion parents and managers</A>
290 <H3><A NAME="SECTION00022100000000000000">
291 <SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">2</SPAN>.<SPAN CLASS="arabic">1</SPAN> Parent-child relations</A>
293 Each object of type WRegion has a parent and possibly a manager
294 associated to it. The parent<A NAME="285"></A> for an object is always a
295 WWindow and for WRegion with an X window (WClientWin,
296 WWindow) the parent WWindow is given by the same relation of
297 the X windows. For other WRegions the relation is not as clear.
298 There is generally very few restrictions other than the above on the
299 parent--child relation but the most common is as described in
300 Figure <A HREF="#fig:parentship">2</A>.
304 <DIV ALIGN="CENTER"><A NAME="fig:parentship"></A><A NAME="296"></A>
306 <CAPTION ALIGN="BOTTOM"><STRONG>Figure 2:</STRONG>
307 Most common parent-child relations</CAPTION>
312 |-->WClientWins in full screen mode
316 |-->WFrames for transients
317 `-->a possible WEdln or WMessage
323 WRegions have very little control over their children as a parent.
324 The manager<A NAME="300"></A> WRegion has much more control over its
325 managed WRegions. Managers, for example, handle resize requests,
326 focusing and displaying of the managed regions. Indeed the manager--managed
327 relationship gives a better picture of the logical ordering of objects on
328 the screen. Again, there are generally few limits, but the most common
329 hierarchy is given in Figure <A HREF="#fig:managership">3</A>. Note that sometimes
330 the parent and manager are the same object and not all regions may have
331 a manager, but all have a parent-a screen if not anything else.
335 <H3><A NAME="SECTION00022200000000000000">
336 <SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">2</SPAN>.<SPAN CLASS="arabic">2</SPAN> Manager-managed relations</A>
341 <DIV ALIGN="CENTER"><A NAME="fig:managership"></A><A NAME="308"></A>
343 <CAPTION ALIGN="BOTTOM"><STRONG>Figure 3:</STRONG>
344 Most common manager-managed relations</CAPTION>
347 |-->WGroupCWs for full screen WClientWins
349 | `-->WFrames for transients (dialogs)
351 |-->WGroupWSs for workspaces
354 | | | `-->WGroupCWs (with contents as above)
355 | | `-->possibly a WStatusBar or WDock
356 | |-->WFrames for floating content
357 | |-->possibly a WEdln, WMessage or WMenu
358 | `-->possibly a WStatusBar or WDock (if no tiling)
359 `-->WFrames for sticky stuff, such as the scratchpad
365 Note that a workspace can manage another workspace. This can be
366 achieved with the <A HREF="#fn:attach_new"><TT>attach_new</TT></A> function, and allows you to nest
367 workspaces as deep as you want.
371 <H2><A NAME="SECTION00023000000000000000">
372 <SPAN CLASS="arabic">1</SPAN>.<SPAN CLASS="arabic">3</SPAN> Summary</A>
376 In the standard setup, keeping queries, messages and menus out of
382 <LI>The top-level objects that matter are screens and they correspond
383 to physical screens. The class for screens is WScreen.
385 <LI>Screens contain (multiplex) groups (WGroup) and other
386 objects, such as WFrames. Some of these are mutually exclusive
387 to be viewed at a time.
389 <LI>Groups of the specific kind WGroupWS often contain a
390 WTiling tiling for tiling frames (WFrame), but
391 groups may also directly contain floating frames.
393 <LI>Frames are the objects with decorations such as tabs and borders.
394 Frames contain (multiplex) among others (groups of) client windows,
395 to each of which corresponds a tab in the frame's decoration. Only
396 one client window (or other object) can be shown at a time in each
397 frame. The class for client windows is WClientWin.
402 <BR><HR><H4>Footnotes</H4>
404 <DT><A NAME="foot215">... design</A><A
405 HREF="node2.html#tex2html1"><SUP><SPAN CLASS="arabic">1</SPAN></SUP></A></DT>
406 <DD>the author doesn't like such artificial designs
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