| blob | 024d88e82001c6b5aaab3cd8e83d21abca5f7db7 |
1 .\" $Xorg: Xnest.man,v 1.3 2000/08/17 19:53:28 cpqbld Exp $
2 .\" Copyright (c) 1993, 1994 X Consortium
3 .\"
4 .\" Permission is hereby granted, free of charge, to any person obtaining
5 .\" a copy of this software and associated documentation files (the
6 .\" "Software"), to deal in the Software without restriction, including
7 .\" without limitation the rights to use, copy, modify, merge, publish,
8 .\" distribute, sublicense, and/or sell copies of the Software, and to
9 .\" permit persons to whom the Software is furnished to do so, subject to
10 .\" the following conditions:
11 .\"
12 .\" The above copyright notice and this permission notice shall be included
13 .\" in all copies or substantial portions of the Software.
14 .\"
15 .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
16 .\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
18 .\" IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR
19 .\" OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
20 .\" ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
21 .\" OTHER DEALINGS IN THE SOFTWARE.
22 .\"
23 .\" Except as contained in this notice, the name of the X Consortium shall
24 .\" not be used in advertising or otherwise to promote the sale, use or
25 .\" other dealings in this Software without prior written authorization
26 .\" from the X Consortium.
27 .\"
28 .\" $XFree86: xc/programs/Xserver/hw/xnest/Xnest.man,v 1.6 2001/01/27 18:21:00 dawes Exp $
29 .\"
30 .TH Xnest __appmansuffix__ __xorgversion__
31 .SH NAME
32 Xnest \- a nested X server
33 .SH SYNOPSIS
34 .B Xnest
35 [
36 .I options
37 ]
38 .SH DESCRIPTION
39 .B Xnest
40 is both an X client and an X server.
41 .B Xnest
42 is a client of the real server which manages windows and graphics requests on
43 its behalf.
44 .B Xnest
45 is a server to its own clients.
46 .B Xnest
47 manages windows and graphics requests on their behalf.
48 To these clients,
49 .B Xnest
50 appears to be a conventional server.
51 .SH OPTIONS
52 .B Xnest
53 supports all standard options of the sample server implementation.
54 For more details, please see
55 .BR Xserver (__appmansuffix__).
56 The following additional arguments are supported as well.
57 .TP
58 .BI "\-display " string
59 This option specifies the display name of the real server that
60 .B Xnest
61 should try to connect to.
62 If it is not provided on the command line,
63 .B Xnest
64 will read the
65 .I DISPLAY
66 environment variable in order to find out this information.
67 .TP
68 .B \-sync
69 This option tells
70 .B Xnest
71 to synchronize its window and graphics operations with the real server.
72 This is a useful option for debugging, but it will slow down
73 .BR Xnest 's
74 performance considerably.
75 It should not be used unless absolutely necessary.
76 .TP
77 .B \-full
78 This option tells
79 .B Xnest
80 to utilize full regeneration of real server objects and reopen a new connection
81 to the real server each time the nested server regenerates.
82 The sample server implementation regenerates all objects in the server when the
83 last client of this server terminates.
84 When this happens,
85 .B Xnest
86 by default maintains the same top-level window and the same real server
87 connection in each new generation.
88 If the user selects full regeneration, even the top-level window and the
89 connection to the real server will be regenerated for each server generation.
90 .TP
91 .BI "\-class " string
92 This option specifies the default visual class of the nested server.
93 It is similar to the
94 .B \-cc
95 option from the set of standard options except that it will accept a string
96 rather than a number for the visual class specification.
97 The
98 .I string
99 must be one of the following six values:
100 .BR StaticGray ,
101 .BR GrayScale ,
102 .BR StaticColor ,
103 .BR PseudoColor ,
104 .BR TrueColor ,
105 or
106 .BR DirectColor .
107 If both the
108 .B \-class
109 and
110 .B \-cc
111 options are specified, the last instance of either option takes precedence.
112 The class of the default visual of the nested server need not be the same as the
113 class of the default visual of the real server, but it must be supported by the
114 real server.
115 Use
116 .BR xdpyinfo (__appmansuffix__)
117 to obtain a list of supported visual classes on the real server before starting
118 .BR Xnest .
119 If the user chooses a static class, all the colors in the default color map will
120 be preallocated.
121 If the user chooses a dynamic class, colors in the default color map will be
122 available to individual clients for allocation.
123 .TP
124 .BI "\-depth " int
125 This option specifies the default visual depth of the nested server.
126 The depth of the default visual of the nested server need not be the same as the
127 depth of the default visual of the real server, but it must be supported by the
128 real server.
129 Use
130 .BR xdpyinfo (__appmansuffix__)
131 to obtain a list of supported visual depths on the real server before starting
132 .BR Xnest .
133 .TP
134 .B \-sss
135 This option tells
136 .B Xnest
137 to use the software screen saver.
138 By default,
139 .B Xnest
140 will use the screen saver that corresponds to the hardware screen saver in the
141 real server.
142 Of course, even this screen saver is software-generated since
143 .B Xnest
144 does not control any actual hardware.
145 However, it is treated as a hardware screen saver within the sample server code.
146 .TP
147 .B \-geometry \fIW\fBx\fIH\fB+\fIX\fB+\fIY\fP
148 This option specifies the geometry parameters for the top-level
149 .B Xnest
150 window.
151 See \(lqGEOMETRY SPECIFICATIONS\(rq in
152 .BR X (__miscmansuffix__)
153 for a discusson of this option's syntax.
154 This window corresponds to the root window of the nested server.
155 The width
156 .I W
157 and height
158 .I H
159 specified with this option will be the maximum width and height of each
160 top-level
161 .B Xnest
162 window.
163 .B Xnest
164 will allow the user to make any top-level window smaller, but it will not
165 actually change the size of the nested server root window.
166 .B Xnest
167 does not yet support the RANDR extension for resizing, rotation, and reflection
168 of the root window.
169 If this option is not specified,
170 .B Xnest
171 will choose
172 .I W
173 and
174 .I H
175 to be 3/4ths the dimensions of the root window of the real server.
176 .TP
177 .BI "\-bw " int
178 This option specifies the border width of the top-level
179 .B Xnest
180 window.
181 The integer parameter
182 .I int
183 must be positive.
184 The default border width is 1.
185 .TP
186 .BI "\-name " string
187 This option specifies the name of the top-level
188 .B Xnest
189 window as
190 .IR string .
191 The default value is the program name.
192 .TP
193 .BI "\-scrns " int
194 This option specifies the number of screens to create in the nested server.
195 For each screen,
196 .B Xnest
197 will create a separate top-level window.
198 Each screen is referenced by the number after the dot in the client display name
199 specification.
200 For example,
201 .B xterm \-display :1.1
202 will open an
203 .BR xterm (__appmansuffix__)
204 client in the nested server with the display number
205 .B :1
206 on the second screen.
207 The number of screens is limited by the hard-coded constant in the server sample
208 code, which is usually 3.
209 .TP
210 .B \-install
211 This option tells
212 .B Xnest
213 to do its own color map installation by bypassing the real window manager.
214 For it to work properly, the user will probably have to temporarily quit the
215 real window manager.
216 By default,
217 .B Xnest
218 will keep the nested client window whose color map should be installed in the
219 real server in the
220 .I WM_COLORMAP_WINDOWS
221 property of the top-level
222 .B Xnest
223 window.
224 If this color map is of the same visual type as the root window of the nested
225 server,
226 .B Xnest
227 will associate this color map with the top-level
228 .B Xnest
229 window as well.
230 Since this does not have to be the case, window managers should look primarily
231 at the
232 .I WM_COLORMAP_WINDOWS
233 property rather than the color map associated with the top-level
234 .B Xnest
235 window.
236 .\" Is the following still true? This sentence is several years old.
237 Unfortunately, window managers are not very good at doing that yet so this
238 option might come in handy.
239 .TP
240 .BI "\-parent " window_id
241 This option tells
242 .B Xnest
243 to use
244 .I window_id
245 as the root window instead of creating a window.
246 .\" XRX is dead, dead, dead.
247 .\" This option is used by the xrx xnestplugin.
248 .SH "EXTENDED DESCRIPTION"
249 Starting up
250 .B Xnest
251 is just as simple as starting up
252 .BR xclock (__appmansuffix__)
253 from a terminal emulator.
254 If a user wishes to run
255 .B Xnest
256 on the same
257 workstation as the real server, it is important that the nested server is given
258 its own listening socket address.
259 Therefore, if there is a server already running on the user's workstation,
260 .B Xnest
261 will have to be started up with a new display number.
262 Since there is usually no more than one server running on a workstation,
263 specifying
264 .RB \(oq "Xnest :1" \(cq
265 on the command line will be sufficient for most users.
266 For each server running on the workstation, the display number needs to be
267 incremented by one.
268 Thus, if you wish to start another
269 .BR Xnest ,
270 you will need to type
271 .RB \(oq "Xnest :2" \(cq
272 on the command line.
273 .PP
274 To run clients in the nested server, each client needs to be given the same
275 display number as the nested server.
276 For example,
277 .RB \(oq "xterm \-display :1" \(cq
278 will start up an
279 .B xterm
280 process in the first nested server
281 and
282 .RB \(oq "xterm \-display :2" \(cq
283 will start an
284 .B xterm
285 in the second nested server from the example above.
286 Additional clients can be started from these
287 .BR xterm s
288 in each nested server.
289 .SS "Xnest as a client"
290 .B Xnest
291 behaves and looks to the real server and other real clients as another real
292 client.
293 It is a rather demanding client, however, since almost any window or graphics
294 request from a nested client will result in a window or graphics request from
295 .B Xnest
296 to the real server.
297 Therefore, it is desirable that
298 .B Xnest
299 and the real server are on a local network, or even better, on the same machine.
300 .B Xnest
301 assumes that the real server supports the SHAPE extension.
302 There is no way to turn off this assumption dynamically.
303 .B Xnest
304 can be compiled without the SHAPE extension built in, in which case the real
305 server need not support it.
306 Dynamic SHAPE extension selection support may be considered in further
307 development of
308 .BR Xnest .
309 .PP
310 Since
311 .B Xnest
312 need not use the same default visual as the the real server, the top-level
313 window of the
314 .B Xnest
315 client always has its own color map.
316 This implies that other windows' colors will not be displayed properly while the
317 keyboard or pointer focus is in the
318 .B Xnest
319 window, unless the real server has support for more than one installed color map
320 at any time.
321 The color map associated with the top window of the
322 .B Xnest
323 client need not be the appropriate color map that the nested server wants
324 installed in the real server.
325 In the case that a nested client attempts to install a color map of a different
326 visual from the default visual of the nested server,
327 .B Xnest
328 will put the top window of this nested client and all other top windows of the
329 nested clients that use the same color map into the
330 .I WM_COLORMAP_WINDOWS
331 property of the top-level
332 .B Xnest
333 window on the real server.
334 Thus, it is important that the real window manager that manages the
335 .B Xnest
336 top-level window looks at the
337 .I WM_COLORMAP_WINDOWS
338 property rather than the color map associated with the top-level
339 .B Xnest
340 window.
341 Since most window managers don't yet appear to implement this convention
342 properly,
343 .B Xnest
344 can optionally do direct installation of color maps into the real server
345 bypassing the real window manager.
346 If the user chooses this option, it is usually necessary to temporarily disable
347 the real window manager since it will interfere with the
348 .B Xnest
349 scheme of color map installation.
350 .PP
351 Keyboard and pointer control procedures of the nested server change the keyboard
352 and pointer control parameters of the real server.
353 Therefore, after
354 .B Xnest
355 is started up, it will change the keyboard and pointer controls of the real
356 server to its own internal defaults.
357 .SS "Xnest as a server"
358 .B Xnest
359 as a server looks exactly like a real server to its own clients.
360 For the clients, there is no way of telling if they are running on a real or a
361 nested server.
362 .PP
363 As already mentioned,
364 .B Xnest
365 is a very user-friendly server when it comes to customization.
366 .B Xnest
367 will pick up a number of command-line arguments that can configure its default
368 visual class and depth, number of screens, etc.
369 .PP
370 The only apparent intricacy from the users' perspective about using
371 .B Xnest
372 as a server is the selection of fonts.
373 .B Xnest
374 manages fonts by loading them locally and then passing the font name to the real
375 server and asking it to load that font remotely.
376 This approach avoids the overload of sending the glyph bits across the network
377 for every text operation, although it is really a bug.
378 The consequence of this approach is that the user will have to worry about two
379 different font paths \(em a local one for the nested server and a remote one for
380 the real server \(em since
381 .B Xnest
382 does not propagate its font path to the real server.
383 The reason for this is because real and nested servers need not run on the same
384 file system which makes the two font paths mutually incompatible.
385 Thus, if there is a font in the local font path of the nested server, there is
386 no guarantee that this font exists in the remote font path of the real server.
387 The
388 .BR xlsfonts (__appmansuffix__)
389 client, if run on the nested server, will list fonts in the local font path and,
390 if run on the real server, will list fonts in the remote font path.
391 Before a font can be successfully opened by the nested server, it has to exist
392 in local and remote font paths.
393 It is the users' responsibility to make sure that this is the case.
394 .SH "FUTURE DIRECTIONS"
395 Make dynamic the requirement for the SHAPE extension in the real server, rather
396 than having to recompile
397 .B Xnest
398 to turn this requirement on and off.
399 .PP
400 Perhaps there should be a command-line option to tell
401 .B Xnest
402 to inherit the keyboard and pointer control parameters from the real server
403 rather than imposing its own.
404 .PP
405 .B Xnest
406 should read a customization input file to provide even greater freedom and
407 simplicity in selecting the desired layout.
408 .PP
409 There is no support for backing store and save unders, but this should also be
410 considered.
411 .PP
412 .\" Is the following still true now that client-side font rendering is
413 .\" considered the way to go?
414 The proper implementation of fonts should be moved into the
415 .I os
416 layer.
417 .SH BUGS
418 Doesn't run well on servers supporting different visual depths.
419 .PP
420 Still crashes randomly.
421 .PP
422 Probably has some memory leaks.
423 .SH AUTHOR
424 Davor Matic, MIT X Consortium
425 .SH "SEE ALSO"
426 .BR Xserver (__appmansuffix__),
427 .BR xdpyinfo (__appmansuffix__),
428 .BR X (__miscmansuffix__)