Mercurial > sdl-ios-xcode
annotate docs/html/sdlcreatesemaphore.html @ 1629:ef4a796e7f24
Fixed bug #55
From Christian Walther:
When writing my patch for #12, I ended up doing all sorts of changes to the way
application/window activating/deactivating is handled in the Quartz backend,
resulting in the attached patch. It does make the code a bit cleaner IMHO, but
as it might be regarded as a case of "if it ain't broken, don't fix it" I'd
like to hear other people's opinion about it. Please shout if some change
strikes you as unnecessary or wrong, and I'll explain the reasons behind it. As
far as I tested it, it does not introduce any new bugs, but I may well have
missed some.
- The most fundamental change (that triggered most of the others) is irrelevant
for the usual single-window SDL applications, it only affects the people who
are crazy enough to display other Cocoa windows alongside the SDL window (I'm
actually doing this currently, although the additional window only displays
debugging info and won't be present in the final product): Before, some things
were done on the application becoming active, some on the window becoming key,
and some on the window becoming main. Conceptually, all these actions belong to
the window becoming key, so that's what I implemented. However, since in a
single-window application these three events always happen together, the
previous implementation "ain't broken".
- This slightly changed the meaning of the SDL_APPMOUSEFOCUS flag from
SDL_GetAppState(): Before, it meant "window is main and mouse is inside window
(or mode is fullscreen)". Now, it means "window is key and mouse is inside
window (or mode is fullscreen)". It makes more sense to me that way. (See
http://developer.apple.com/documentation/Cocoa/Conceptual/WinPanel/Concepts/ChangingMainKeyWindow.html
for a discussion of what key and main windows are.) The other two flags are
unchanged: SDL_APPACTIVE = application is not hidden and window is not
minimized, SDL_APPINPUTFOCUS = window is key (or mode is fullscreen).
- As a side effect, the reorganization fixes the following two issues (and
maybe others) (but they could also be fixed in less invasive ways):
* A regression that was introduced in revision 1.42 of SDL_QuartzVideo.m
(http://libsdl.org/cgi/cvsweb.cgi/SDL12/src/video/quartz/SDL_QuartzVideo.m.diff?r1=1.41&r2=1.42)
(from half-desirable to undesirable behavior):
Situation: While in windowed mode, hide the cursor using
SDL_ShowCursor(SDL_DISABLE), move the mouse outside of the window so that the
cursor becomes visible again, and SDL_SetVideoMode() to a fullscreen mode.
What happened before revision 1.42: The cursor is visible, but becomes
invisible as soon as the mouse is moved (half-desirable).
What happens in revision 1.42 and after (including current CVS): The cursor is
visible and stays visible (undesirable).
What happens after my patch: The cursor is invisible from the beginning
(desirable).
* When the cursor is hidden and grabbed, switch away from the application using
cmd-tab (which ungrabs and makes the cursor visible), move the cursor outside
of the SDL window, then cmd-tab back to the application. In 1.2.8 and in the
current CVS, the cursor is re-grabbed, but it stays visible (immovable in the
middle of the window). With my patch, the cursor is correctly re-grabbed and
hidden. (For some reason, it still doesn't work correctly if you switch back to
the application using the dock instead of cmd-tab. I haven't been able to
figure out why. I can step over [NSCursor hide] being called in the debugger,
but it seems to have no effect.)
- The patch includes my patch for #12 (it was easier to obtain using cvs diff
that way). If you apply both of them, you will end up with 6 duplicate lines in
SDL_QuartzEvents.m.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Thu, 13 Apr 2006 14:17:48 +0000 |
parents | 355632dca928 |
children |
rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_CreateSemaphore</TITLE | |
5 ><META | |
6 NAME="GENERATOR" | |
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
0 | 8 "><LINK |
9 REL="HOME" | |
10 TITLE="SDL Library Documentation" | |
11 HREF="index.html"><LINK | |
12 REL="UP" | |
13 TITLE="Multi-threaded Programming" | |
14 HREF="thread.html"><LINK | |
15 REL="PREVIOUS" | |
16 TITLE="SDL_mutexV" | |
17 HREF="sdlmutexv.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_DestroySemaphore" | |
20 HREF="sdldestroysemaphore.html"></HEAD | |
21 ><BODY | |
22 CLASS="REFENTRY" | |
23 BGCOLOR="#FFF8DC" | |
24 TEXT="#000000" | |
25 LINK="#0000ee" | |
26 VLINK="#551a8b" | |
27 ALINK="#ff0000" | |
28 ><DIV | |
29 CLASS="NAVHEADER" | |
30 ><TABLE | |
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31 SUMMARY="Header navigation table" |
0 | 32 WIDTH="100%" |
33 BORDER="0" | |
34 CELLPADDING="0" | |
35 CELLSPACING="0" | |
36 ><TR | |
37 ><TH | |
38 COLSPAN="3" | |
39 ALIGN="center" | |
40 >SDL Library Documentation</TH | |
41 ></TR | |
42 ><TR | |
43 ><TD | |
44 WIDTH="10%" | |
45 ALIGN="left" | |
46 VALIGN="bottom" | |
47 ><A | |
48 HREF="sdlmutexv.html" | |
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49 ACCESSKEY="P" |
0 | 50 >Prev</A |
51 ></TD | |
52 ><TD | |
53 WIDTH="80%" | |
54 ALIGN="center" | |
55 VALIGN="bottom" | |
56 ></TD | |
57 ><TD | |
58 WIDTH="10%" | |
59 ALIGN="right" | |
60 VALIGN="bottom" | |
61 ><A | |
62 HREF="sdldestroysemaphore.html" | |
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63 ACCESSKEY="N" |
0 | 64 >Next</A |
65 ></TD | |
66 ></TR | |
67 ></TABLE | |
68 ><HR | |
69 ALIGN="LEFT" | |
70 WIDTH="100%"></DIV | |
71 ><H1 | |
72 ><A | |
73 NAME="SDLCREATESEMAPHORE" | |
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74 ></A |
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75 >SDL_CreateSemaphore</H1 |
0 | 76 ><DIV |
77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN7936" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_CreateSemaphore -- Creates a new semaphore and assigns an initial value to it.</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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87 NAME="AEN7939" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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94 NAME="AEN7940" |
0 | 95 ></A |
96 ><P | |
97 ></P | |
98 ><PRE | |
99 CLASS="FUNCSYNOPSISINFO" | |
100 >#include "SDL.h" | |
101 #include "SDL_thread.h"</PRE | |
102 ><P | |
103 ><CODE | |
104 ><CODE | |
105 CLASS="FUNCDEF" | |
106 >SDL_sem *<B | |
107 CLASS="FSFUNC" | |
108 >SDL_CreateSemaphore</B | |
109 ></CODE | |
110 >(Uint32 initial_value);</CODE | |
111 ></P | |
112 ><P | |
113 ></P | |
114 ></DIV | |
115 ></DIV | |
116 ><DIV | |
117 CLASS="REFSECT1" | |
118 ><A | |
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119 NAME="AEN7946" |
0 | 120 ></A |
121 ><H2 | |
122 >Description</H2 | |
123 ><P | |
124 ><TT | |
125 CLASS="FUNCTION" | |
126 >SDL_CreateSemaphore()</TT | |
127 > creates a new semaphore and | |
128 initializes it with the value <TT | |
129 CLASS="PARAMETER" | |
130 ><I | |
131 >initial_value</I | |
132 ></TT | |
133 >. | |
134 Each locking operation on the semaphore by | |
135 <A | |
136 HREF="sdlsemwait.html" | |
137 >SDL_SemWait</A | |
138 >, | |
139 <A | |
140 HREF="sdlsemtrywait.html" | |
141 >SDL_SemTryWait</A | |
142 > or | |
143 <A | |
144 HREF="sdlsemwaittimeout.html" | |
145 >SDL_SemWaitTimeout</A | |
146 > | |
147 will atomically decrement the semaphore value. The locking operation will be blocked | |
148 if the semaphore value is not positive (greater than zero). Each unlock operation by | |
149 <A | |
150 HREF="sdlsempost.html" | |
151 >SDL_SemPost</A | |
152 > | |
153 will atomically increment the semaphore value.</P | |
154 ></DIV | |
155 ><DIV | |
156 CLASS="REFSECT1" | |
157 ><A | |
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158 NAME="AEN7955" |
0 | 159 ></A |
160 ><H2 | |
161 >Return Value</H2 | |
162 ><P | |
163 >Returns a pointer to an initialized semaphore or | |
164 <SPAN | |
165 CLASS="RETURNVALUE" | |
166 >NULL</SPAN | |
167 > if there was an error.</P | |
168 ></DIV | |
169 ><DIV | |
170 CLASS="REFSECT1" | |
171 ><A | |
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172 NAME="AEN7959" |
0 | 173 ></A |
174 ><H2 | |
175 >Examples</H2 | |
176 ><P | |
177 ><PRE | |
178 CLASS="PROGRAMLISTING" | |
179 >SDL_sem *my_sem; | |
180 | |
181 my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE); | |
182 | |
183 if (my_sem == NULL) { | |
184 return CREATE_SEM_FAILED; | |
185 }</PRE | |
186 ></P | |
187 ></DIV | |
188 ><DIV | |
189 CLASS="REFSECT1" | |
190 ><A | |
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191 NAME="AEN7963" |
0 | 192 ></A |
193 ><H2 | |
194 >See Also</H2 | |
195 ><P | |
196 ><A | |
197 HREF="sdldestroysemaphore.html" | |
198 ><TT | |
199 CLASS="FUNCTION" | |
200 >SDL_DestroySemaphore</TT | |
201 ></A | |
202 >, | |
203 <A | |
204 HREF="sdlsemwait.html" | |
205 ><TT | |
206 CLASS="FUNCTION" | |
207 >SDL_SemWait</TT | |
208 ></A | |
209 >, | |
210 <A | |
211 HREF="sdlsemtrywait.html" | |
212 ><TT | |
213 CLASS="FUNCTION" | |
214 >SDL_SemTryWait</TT | |
215 ></A | |
216 >, | |
217 <A | |
218 HREF="sdlsemwaittimeout.html" | |
219 ><TT | |
220 CLASS="FUNCTION" | |
221 >SDL_SemWaitTimeout</TT | |
222 ></A | |
223 >, | |
224 <A | |
225 HREF="sdlsempost.html" | |
226 ><TT | |
227 CLASS="FUNCTION" | |
228 >SDL_SemPost</TT | |
229 ></A | |
230 >, | |
231 <A | |
232 HREF="sdlsemvalue.html" | |
233 ><TT | |
234 CLASS="FUNCTION" | |
235 >SDL_SemValue</TT | |
236 ></A | |
237 ></P | |
238 ></DIV | |
239 ><DIV | |
240 CLASS="NAVFOOTER" | |
241 ><HR | |
242 ALIGN="LEFT" | |
243 WIDTH="100%"><TABLE | |
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244 SUMMARY="Footer navigation table" |
0 | 245 WIDTH="100%" |
246 BORDER="0" | |
247 CELLPADDING="0" | |
248 CELLSPACING="0" | |
249 ><TR | |
250 ><TD | |
251 WIDTH="33%" | |
252 ALIGN="left" | |
253 VALIGN="top" | |
254 ><A | |
255 HREF="sdlmutexv.html" | |
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256 ACCESSKEY="P" |
0 | 257 >Prev</A |
258 ></TD | |
259 ><TD | |
260 WIDTH="34%" | |
261 ALIGN="center" | |
262 VALIGN="top" | |
263 ><A | |
264 HREF="index.html" | |
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265 ACCESSKEY="H" |
0 | 266 >Home</A |
267 ></TD | |
268 ><TD | |
269 WIDTH="33%" | |
270 ALIGN="right" | |
271 VALIGN="top" | |
272 ><A | |
273 HREF="sdldestroysemaphore.html" | |
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274 ACCESSKEY="N" |
0 | 275 >Next</A |
276 ></TD | |
277 ></TR | |
278 ><TR | |
279 ><TD | |
280 WIDTH="33%" | |
281 ALIGN="left" | |
282 VALIGN="top" | |
283 >SDL_mutexV</TD | |
284 ><TD | |
285 WIDTH="34%" | |
286 ALIGN="center" | |
287 VALIGN="top" | |
288 ><A | |
289 HREF="thread.html" | |
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290 ACCESSKEY="U" |
0 | 291 >Up</A |
292 ></TD | |
293 ><TD | |
294 WIDTH="33%" | |
295 ALIGN="right" | |
296 VALIGN="top" | |
297 >SDL_DestroySemaphore</TD | |
298 ></TR | |
299 ></TABLE | |
300 ></DIV | |
301 ></BODY | |
302 ></HTML | |
303 > |