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7
8<!-- lifted from troff+ms+XMan by doclifter -->
9<book id="dpmslib">
10
11<bookinfo>
12   <title>X Display Power Management Signaling (DPMS) Extension</title>
13   <subtitle>X Consortium Standard</subtitle>
14   <releaseinfo>X Version 11, Release &fullrelvers;</releaseinfo>
15   <releaseinfo>Version 1.0</releaseinfo>
16   <authorgroup>
17      <author>
18         <firstname>Rob</firstname><surname>Lembree</surname>
19         <affiliation><orgname>Digital Equipment Corporation</orgname></affiliation>
20         <email>lembree@zk3.dec.com</email>
21      </author>
22   </authorgroup>
23   <copyright><year>1996</year><holder>Digital Equipment Corporation</holder></copyright>
24
25<legalnotice>
26<para>
27Permission to use, copy, modify, distribute, and sell this
28documentation for any purpose is hereby granted without fee,
29provided that the above copyright notice and this permission
30notice appear in all copies.  Digital Equipment Corporation
31makes no representations about the suitability for any purpose
32of the information in this document.  This documentation is
33provided "as is" without express or implied warranty.
34</para>
35
36<para>X Window System is a trademark of The Open Group.</para>
37</legalnotice>
38
39</bookinfo>
40
41<chapter id='overview'>
42<title>Overview</title>
43
44<para>This extension provides X Protocol control over the VESA Display
45Power Management Signaling (DPMS) characteristics of video boards
46under control of the X Window System.
47</para>
48
49<para>
50Traditionally, the X Window System has provided for both blanking and
51non-blanking screen savers.  Timeouts associated with these built-in
52screen saver mechanisms are limited to idle (dwell) time, and a change
53timeout that specifies the change interval for non-blanking screen savers.
54</para>
55
56<para>
57The United States' Environmental Protection Agency (EPA) Energy Star program
58requires that monitors power down after some idle time by default.
59While it is possible to simply overload the existing screen saver timeouts,
60this solution leaves the non-privileged user little to no control over
61the DPMS characteristics of his or her system.  For example, disabling
62DPMS would require some unintended side effect in the core screen saver,
63such as disabling the changing of a non-blanking screen saver.  Providing
64clients with this control requires an extension to the core X Window System
65Protocol, and this extension seeks to fill this gap.
66</para>
67
68<para>
69There are four power levels specified by the Video Electronics Standards
70Association (VESA) Display Power Management Signaling (DPMS) standard.
71These are mapped onto the X DPMS Extension like this:
72</para>
73
74<literallayout remap='Ds'>
75<function>DPMS Extension Power Levels</function>
76     0     DPMSModeOn               In use
77     1     DPMSModeStandby          Blanked, low power
78     2     DPMSModeSuspend          Blanked, lower power
79     3     DPMSModeOff               Shut off, awaiting activity
80</literallayout> <!-- remap='De' -->
81
82</chapter>
83
84<chapter id='dpms_functions'>
85<title>DPMS Functions</title>
86
87
88<funcsynopsis id='DPMSQueryExtention'>
89<funcprototype>
90  <funcdef>Bool <function>DPMSQueryExtention</function></funcdef>
91    <paramdef>Display <parameter>*display</parameter></paramdef>
92    <paramdef>int <parameter>event_base</parameter></paramdef>
93    <paramdef>int <parameter>error_base</parameter></paramdef>
94</funcprototype>
95</funcsynopsis>
96
97<variablelist remap='IP'>
98  <varlistentry>
99    <term><emphasis remap='I'>*display</emphasis></term>
100    <listitem><para>Specifies the connection to the X server.</para></listitem>
101  </varlistentry>
102  <varlistentry>
103    <term><emphasis remap='I'>event_base</emphasis></term>
104    <listitem><para>Specifies the return location for the assigned base event</para></listitem>
105  </varlistentry>
106  <varlistentry>
107    <term><emphasis remap='I'>error_base</emphasis></term>
108    <listitem><para>Specifies the return location for the assigned base error</para></listitem>
109  </varlistentry>
110</variablelist>
111
112<para>
113The DPMSQueryExtension function queries the X server to determine the
114availability of the DPMS Extension.  If the extension is available, the
115return value is TRUE, and <emphasis remap='I'>event_base</emphasis> and
116<emphasis remap='I'>error_base</emphasis> are set to the base event number
117and base error number for the extension, respectively.  Otherwise, the
118return value is FALSE, and the values of
119<emphasis remap='I'>event_base</emphasis> and
120<emphasis remap='I'>error_base</emphasis> are undefined.
121</para>
122
123<funcsynopsis id='DPMSGetVersion'>
124<funcprototype>
125  <funcdef>Status <function>DPMSGetVersion</function></funcdef>
126    <paramdef>Display <parameter>*display</parameter></paramdef>
127    <paramdef>int <parameter>*major_version</parameter></paramdef>
128    <paramdef>int <parameter>*minor_version</parameter></paramdef>
129</funcprototype>
130</funcsynopsis>
131
132<variablelist remap='IP'>
133  <varlistentry>
134    <term><emphasis remap='I'>display</emphasis></term>
135    <listitem><para>Specifies the connection to the X server.</para></listitem>
136  </varlistentry>
137  <varlistentry>
138    <term><emphasis remap='I'>major_version</emphasis></term>
139    <listitem><para>Specifies the return location for the extension major version.</para></listitem>
140  </varlistentry>
141  <varlistentry>
142    <term><emphasis remap='I'>minor_version</emphasis></term>
143    <listitem><para>Specifies the return location for the extension minor version.</para></listitem>
144  </varlistentry>
145</variablelist>
146
147
148<para>
149The DPMSGetVersion function returns the version of the DPMS extension
150implemented by the X server.  The version is returned in
151<emphasis remap='I'>major_version</emphasis> and
152<emphasis remap='I'>minor_version</emphasis>.
153The major version and minor version for this specification are '1' and '1',
154respectively.  The major version will be incremented for protocol
155incompatible changes, and the minor version will be incremented for small,
156upwardly compatible changes.
157</para>
158
159<funcsynopsis id='DPMSCapable'>
160<funcprototype>
161  <funcdef>Bool <function>DPMSCapable</function></funcdef>
162    <paramdef>Display <parameter>*display</parameter></paramdef>
163</funcprototype>
164</funcsynopsis>
165
166<variablelist remap='IP'>
167  <varlistentry>
168    <term><emphasis remap='I'>display</emphasis></term>
169    <listitem><para>Specifies the connection to the X server.</para></listitem>
170  </varlistentry>
171</variablelist>
172
173
174<para>
175The DPMSCapable function returns the DPMS capability of the X server, either
176TRUE (capable of DPMS) or FALSE (incapable of DPMS).  The capability of an
177X server is implementation defined.  For example, if a multi-headed  X server
178is capable of DPMS on one head, and incapable on another, the truth value of
179this function is defined by the X server implementation.
180</para>
181
182<funcsynopsis id='DPMSSetTimeouts'>
183<funcprototype>
184  <funcdef>Status <function>DPMSSetTimeouts</function></funcdef>
185    <paramdef>Display <parameter>*display</parameter></paramdef>
186    <paramdef>CARD16 <parameter>standby</parameter></paramdef>
187    <paramdef>CARD16 <parameter>suspend</parameter></paramdef>
188    <paramdef>CARD16 <parameter>off</parameter></paramdef>
189</funcprototype>
190</funcsynopsis>
191
192<variablelist remap='IP'>
193  <varlistentry>
194    <term><emphasis remap='I'>display</emphasis></term>
195    <listitem><para>Specifies the connection to the X server.</para></listitem>
196  </varlistentry>
197  <varlistentry>
198    <term><emphasis remap='I'>standby</emphasis></term>
199    <listitem><para>Specifies the new standby timeout in seconds.</para></listitem>
200  </varlistentry>
201  <varlistentry>
202    <term><emphasis remap='I'>suspend</emphasis></term>
203    <listitem><para>Specifies the new suspend timeout in seconds.</para></listitem>
204  </varlistentry>
205  <varlistentry>
206    <term><emphasis remap='I'>off</emphasis></term>
207    <listitem><para>Specifies the new off timeout in seconds.</para></listitem>
208  </varlistentry>
209</variablelist>
210
211<para>
212The DPMSSetTimeouts function permits applications to set the timeout values
213used by the X server for DPMS timings.
214</para>
215
216<para>
217The value <emphasis remap='I'>standby</emphasis> is the amount of time of
218inactivity in seconds before standby mode is invoked. The actual effects of
219this mode are implementation defined, but in the case of DPMS compliant
220hardware, it is implemented by shutting off the horizontal sync signal,
221and pulsing the vertical sync signal.
222Standby mode provides the quickest monitor recovery time.  Note also that
223many monitors implement this mode identically to suspend mode.  A value
224of zero disables this mode.
225</para>
226
227<para>
228The value <emphasis remap='I'>suspend</emphasis> is the amount of time of
229inactivity in seconds before the second level of power savings is invoked.
230Suspend mode's physical and electrical characteristics are implementation
231defined, but in DPMS compliant hardware, results in the pulsing of the
232horizontal sync signal, and shutting off of the vertical sync signal.
233Suspend mode recovery is considered to be slower than standby mode, but
234faster than off mode, however this is monitor dependent.  As noted above,
235many monitors implement this mode identically to standby mode.  A value of
236zero disables this mode.
237</para>
238
239<para>
240The value <emphasis remap='I'>off</emphasis> is the amount of time of
241inactivity in seconds before the third and final level of power savings is
242invoked. Off mode's physical and electrical characteristics are
243implementation defined, but in DPMS compliant hardware, is implemented by
244shutting off both horizontal and vertical sync signals, resulting in
245the power-down of the monitor.  Recovery time is implementation dependent,
246but frequently is similar to the power-up time of the monitor.  A value
247of zero disables this mode.
248</para>
249
250<para>
251Chronologically, standby mode occurs before or simultaneously with
252suspend mode, and suspend mode must occur before or simultaneously with
253off mode.  Therefore, non-zero mode timeout values must be greater than
254or equal to the timeout values of earlier modes.  If inconsistent values
255are supplied, a BadValue error will result.
256</para>
257
258<funcsynopsis id='DPMSGetTimeouts'>
259<funcprototype>
260  <funcdef>Status <function>DPMSGetTimeouts</function></funcdef>
261    <paramdef>Display <parameter>*display</parameter></paramdef>
262    <paramdef>CARD16 <parameter>*standby</parameter></paramdef>
263    <paramdef>CARD16 <parameter>*suspend</parameter></paramdef>
264    <paramdef>CARD16 <parameter>*off</parameter></paramdef>
265</funcprototype>
266</funcsynopsis>
267
268<variablelist remap='IP'>
269  <varlistentry>
270    <term><emphasis remap='I'>display</emphasis></term>
271    <listitem><para>Specifies the connection to the X server.</para></listitem>
272  </varlistentry>
273  <varlistentry>
274    <term><emphasis remap='I'>standby</emphasis></term>
275    <listitem><para>Specifies the new standby timeout in seconds.</para></listitem>
276  </varlistentry>
277  <varlistentry>
278    <term><emphasis remap='I'>suspend</emphasis></term>
279    <listitem><para>Specifies the new suspend timeout in seconds.</para></listitem>
280  </varlistentry>
281  <varlistentry>
282    <term><emphasis remap='I'>off</emphasis></term>
283    <listitem><para>Specifies the new off timeout in seconds.</para></listitem>
284  </varlistentry>
285</variablelist>
286
287<para>
288The DPMSGetTimeouts function retrieves the timeout values used by the X
289server for DPMS timings.
290</para>
291
292<para>
293The value <emphasis remap='I'>standby</emphasis> is the amount of time of
294inactivity in seconds before standby mode is invoked. A value of zero
295indicates that this mode has been disabled.
296</para>
297
298<para>
299The value <emphasis remap='I'>suspend</emphasis> is the amount of time of
300inactivity in seconds before the second level of power savings is invoked.
301A value of zero indicates that this mode has been disabled.
302</para>
303
304<para>
305The value <emphasis remap='I'>off</emphasis> is the amount of time of
306inactivity in seconds before the third and final level of power savings is
307invoked. A value of zero indicates that this mode has been disabled.
308</para>
309
310<funcsynopsis id='DPMSEnable'>
311<funcprototype>
312  <funcdef>Status <function>DPMSEnable</function></funcdef>
313    <paramdef>Display <parameter>*display</parameter></paramdef>
314</funcprototype>
315</funcsynopsis>
316
317<variablelist remap='IP'>
318  <varlistentry>
319    <term><emphasis remap='I'>display</emphasis></term>
320    <listitem><para>Specifies the connection to the X server.</para></listitem>
321  </varlistentry>
322</variablelist>
323
324<para>
325The DPMSEnable function enables DPMS on the specified display.  When
326enabled, DPMS will use the currently saved timeout values, and will
327invoke the DPMS power mode appropriate for the amount of time that
328the workstation input devices have been idle.  If DPMSEnable is invoked
329on a display with DPMS already enabled, no change is made, and no
330error is returned.  If DPMSEnable is invoked on a display without
331support for DPMS, no change is made and no error is returned.
332</para>
333
334<funcsynopsis id='DPMSDisable'>
335<funcprototype>
336  <funcdef>Status <function>DPMSDisable</function></funcdef>
337    <paramdef>Display <parameter>*display</parameter></paramdef>
338</funcprototype>
339</funcsynopsis>
340
341<variablelist remap='IP'>
342  <varlistentry>
343    <term><emphasis remap='I'>display</emphasis></term>
344    <listitem><para>Specifies the connection to the X server.</para></listitem>
345  </varlistentry>
346</variablelist>
347
348<para>
349The DPMSDisable function disables DPMS on the specified display.  When
350disabled, DPMS returns the display to DPMSModeOn.  If DPMSDisable is
351invoked on a display with DPMS already disabled, no change is made,
352and no error is returned.  If DPMSDisable is invoked on a display
353without support for DPMS, no change is made and no error is returned.
354</para>
355
356<funcsynopsis id='DPMSForceLevel'>
357<funcprototype>
358  <funcdef>Status <function>DPMSForceLevel</function></funcdef>
359    <paramdef>Display <parameter>*display</parameter></paramdef>
360    <paramdef>CARD16 <parameter>level</parameter></paramdef>
361</funcprototype>
362</funcsynopsis>
363
364<variablelist remap='IP'>
365  <varlistentry>
366    <term><emphasis remap='I'>display</emphasis></term>
367    <listitem><para>Specifies the connection to the X server.</para></listitem>
368  </varlistentry>
369  <varlistentry>
370    <term><emphasis remap='I'>level</emphasis></term>
371    <listitem><para>Specifies the level to force power to.</para></listitem>
372  </varlistentry>
373</variablelist>
374
375<para>
376The DPMSForceLevel function forces a DPMS capable display into the
377specified power level.  The <emphasis remap='I'>level</emphasis> must be one of
378DPMSModeOn, DPMSModeStandby, DPMSModeSuspend, or DPMSModeOff.
379Values other than these will result in a BadValue error.  If DPMS
380is disabled on the display, a BadMatch protocol error will result.
381</para>
382
383<para>Status DPMSInfo(<emphasis remap='I'>display, power_level, state</emphasis>)</para>
384
385<funcsynopsis id='DPMSInfo'>
386<funcprototype>
387  <funcdef>Status <function>DPMSInfo</function></funcdef>
388    <paramdef>Display <parameter>*display</parameter></paramdef>
389    <paramdef>CARD16 <parameter>power_level</parameter></paramdef>
390    <paramdef>BOOL <parameter>*state</parameter></paramdef>
391</funcprototype>
392</funcsynopsis>
393
394<variablelist remap='IP'>
395  <varlistentry>
396    <term><emphasis remap='I'>display</emphasis></term>
397    <listitem><para>Specifies the connection to the X server.</para></listitem>
398  </varlistentry>
399  <varlistentry>
400    <term><emphasis remap='I'>power_level</emphasis></term>
401    <listitem><para>Specifies the current power level.</para></listitem>
402  </varlistentry>
403  <varlistentry>
404    <term><emphasis remap='I'>state</emphasis></term>
405    <listitem><para>Specifies the current DPMS state.</para></listitem>
406  </varlistentry>
407</variablelist>
408
409<para>
410The DPMSInfo function returns information about the current DPMS state.
411The <emphasis remap='I'>state</emphasis> return parameter indicates whether
412or not DPMS is enabled (TRUE) or disabled (FALSE).  The
413<emphasis remap='I'>power_level</emphasis> return parameter indicates the
414current power level (one of DPMSModeOn, DPMSModeStandby, DPMSModeSuspend,
415or DPMSModeOff.)
416</para>
417
418</chapter>
419</book>
420