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annotate docs/html/thread.html @ 1212:7663bb0f52c7
To: sdl@libsdl.org
From: Christian Walther <cwalther@gmx.ch>
Date: Thu, 15 Dec 2005 21:19:53 +0100
Subject: [SDL] More mouse enhancements for Mac OS X
The attached patch brings two more enhancements to mouse handling on Mac
OS X (Quartz):
1. Currently, after launching an SDL application, SDL's notion of the
mouse position is stuck in the top left corner (0,0) until the first
time the mouse is moved. That's because the UpdateMouse() function isn't
implemented in the Quartz driver. This patch adds it.
2. When grabbing input while the mouse cursor is hidden, the function
CGAssociateMouseAndMouseCursorPosition(0) is called, which prevents the
system's notion of the mouse location from moving (and therefore leaving
the SDL window) even when the mouse is moved. However, apparently the
Wacom tablet driver (and maybe other special pointing device drivers)
doesn't care about that setting and still allows the mouse location to
go outside of the window. Interestingly, the system cursor, which is
made visible by the existing code in SDL in that case, does not follow
the mouse location, but appears in the middle of the SDL window. The
mouse location being outside of the window however means that mouse
button events go to background applications (or the dock or whatever is
there), which is very confusing to the user who sees no cursor outside
of the SDL window.
I have not found any way of intercepting these events (and that's
probably by design, as "normal" applications shouldn't prevent the user
from bringing other applications' windows to the front by clicking on
them). An idea would be placing a fully transparent, screen-filling
window in front of everything, but I fear that this might affect
rendering performance (by doing unnecessary compositing, using up
memory, or whatever).
The deluxe solution to the problem would be talking to the tablet
driver using AppleEvents to tell it to constrain its mapped area to the
window (see Wacom's "TabletEventDemo" sample app,
http://www.wacomeng.com/devsupport/mac/downloads.html), but I think that
the bloat that solution would add to SDL would outweigh its usefulness.
What I did instead in my patch is reassociating mouse and cursor when
the mouse leaves the window while an invisible grab is in effect, and
restoring the grab when the window is entered. That way, the grab can
still be effectively broken by a tablet, but at least it's obvious to
the user that it is broken. That change is minimal - it doesn't affect
operation with a mouse (or a trackpad), and the code that it adds is not
executed on every PumpEvents() call, only when entering and leaving the
window.
Unless there are any concerns about the patch, please apply. Feel free
to shorten the lengthy comment in SDL_QuartzEvents.m if you think it's
too verbose.
Thanks
-Christian
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Mon, 02 Jan 2006 00:31:00 +0000 |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >Multi-threaded Programming</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="SDL Reference" | |
14 HREF="reference.html"><LINK | |
15 REL="PREVIOUS" | |
16 TITLE="SDL_CDtrack" | |
17 HREF="sdlcdtrack.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_CreateThread" | |
20 HREF="sdlcreatethread.html"><META | |
21 NAME="KEYWORD" | |
22 CONTENT="threads"><META | |
23 NAME="KEYWORD" | |
24 CONTENT="function"></HEAD | |
25 ><BODY | |
26 CLASS="CHAPTER" | |
27 BGCOLOR="#FFF8DC" | |
28 TEXT="#000000" | |
29 LINK="#0000ee" | |
30 VLINK="#551a8b" | |
31 ALINK="#ff0000" | |
32 ><DIV | |
33 CLASS="NAVHEADER" | |
34 ><TABLE | |
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35 SUMMARY="Header navigation table" |
0 | 36 WIDTH="100%" |
37 BORDER="0" | |
38 CELLPADDING="0" | |
39 CELLSPACING="0" | |
40 ><TR | |
41 ><TH | |
42 COLSPAN="3" | |
43 ALIGN="center" | |
44 >SDL Library Documentation</TH | |
45 ></TR | |
46 ><TR | |
47 ><TD | |
48 WIDTH="10%" | |
49 ALIGN="left" | |
50 VALIGN="bottom" | |
51 ><A | |
52 HREF="sdlcdtrack.html" | |
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53 ACCESSKEY="P" |
0 | 54 >Prev</A |
55 ></TD | |
56 ><TD | |
57 WIDTH="80%" | |
58 ALIGN="center" | |
59 VALIGN="bottom" | |
60 ></TD | |
61 ><TD | |
62 WIDTH="10%" | |
63 ALIGN="right" | |
64 VALIGN="bottom" | |
65 ><A | |
66 HREF="sdlcreatethread.html" | |
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67 ACCESSKEY="N" |
0 | 68 >Next</A |
69 ></TD | |
70 ></TR | |
71 ></TABLE | |
72 ><HR | |
73 ALIGN="LEFT" | |
74 WIDTH="100%"></DIV | |
75 ><DIV | |
76 CLASS="CHAPTER" | |
77 ><H1 | |
78 ><A | |
79 NAME="THREAD" | |
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80 ></A |
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81 >Chapter 12. Multi-threaded Programming</H1 |
0 | 82 ><DIV |
83 CLASS="TOC" | |
84 ><DL | |
85 ><DT | |
86 ><B | |
87 >Table of Contents</B | |
88 ></DT | |
89 ><DT | |
90 ><A | |
91 HREF="sdlcreatethread.html" | |
92 >SDL_CreateThread</A | |
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93 > -- Creates a new thread of execution that shares its parent's properties.</DT |
0 | 94 ><DT |
95 ><A | |
96 HREF="sdlthreadid.html" | |
97 >SDL_ThreadID</A | |
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98 > -- Get the 32-bit thread identifier for the current thread.</DT |
0 | 99 ><DT |
100 ><A | |
101 HREF="sdlgetthreadid.html" | |
102 >SDL_GetThreadID</A | |
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103 > -- Get the SDL thread ID of a SDL_Thread</DT |
0 | 104 ><DT |
105 ><A | |
106 HREF="sdlwaitthread.html" | |
107 >SDL_WaitThread</A | |
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108 > -- Wait for a thread to finish.</DT |
0 | 109 ><DT |
110 ><A | |
111 HREF="sdlkillthread.html" | |
112 >SDL_KillThread</A | |
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113 > -- Gracelessly terminates the thread.</DT |
0 | 114 ><DT |
115 ><A | |
116 HREF="sdlcreatemutex.html" | |
117 >SDL_CreateMutex</A | |
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118 > -- Create a mutex</DT |
0 | 119 ><DT |
120 ><A | |
121 HREF="sdldestroymutex.html" | |
122 >SDL_DestroyMutex</A | |
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123 > -- Destroy a mutex</DT |
0 | 124 ><DT |
125 ><A | |
126 HREF="sdlmutexp.html" | |
127 >SDL_mutexP</A | |
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128 > -- Lock a mutex</DT |
0 | 129 ><DT |
130 ><A | |
131 HREF="sdlmutexv.html" | |
132 >SDL_mutexV</A | |
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133 > -- Unlock a mutex</DT |
0 | 134 ><DT |
135 ><A | |
136 HREF="sdlcreatesemaphore.html" | |
137 >SDL_CreateSemaphore</A | |
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138 > -- Creates a new semaphore and assigns an initial value to it.</DT |
0 | 139 ><DT |
140 ><A | |
141 HREF="sdldestroysemaphore.html" | |
142 >SDL_DestroySemaphore</A | |
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143 > -- Destroys a semaphore that was created by <A |
0 | 144 HREF="sdlcreatesemaphore.html" |
145 >SDL_CreateSemaphore</A | |
146 >.</DT | |
147 ><DT | |
148 ><A | |
149 HREF="sdlsemwait.html" | |
150 >SDL_SemWait</A | |
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151 > -- Lock a semaphore and suspend the thread if the semaphore value is zero.</DT |
0 | 152 ><DT |
153 ><A | |
154 HREF="sdlsemtrywait.html" | |
155 >SDL_SemTryWait</A | |
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156 > -- Attempt to lock a semaphore but don't suspend the thread.</DT |
0 | 157 ><DT |
158 ><A | |
159 HREF="sdlsemwaittimeout.html" | |
160 >SDL_SemWaitTimeout</A | |
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161 > -- Lock a semaphore, but only wait up to a specified maximum time.</DT |
0 | 162 ><DT |
163 ><A | |
164 HREF="sdlsempost.html" | |
165 >SDL_SemPost</A | |
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166 > -- Unlock a semaphore.</DT |
0 | 167 ><DT |
168 ><A | |
169 HREF="sdlsemvalue.html" | |
170 >SDL_SemValue</A | |
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171 > -- Return the current value of a semaphore.</DT |
0 | 172 ><DT |
173 ><A | |
174 HREF="sdlcreatecond.html" | |
175 >SDL_CreateCond</A | |
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176 > -- Create a condition variable</DT |
0 | 177 ><DT |
178 ><A | |
179 HREF="sdldestroycond.html" | |
180 >SDL_DestroyCond</A | |
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181 > -- Destroy a condition variable</DT |
0 | 182 ><DT |
183 ><A | |
184 HREF="sdlcondsignal.html" | |
185 >SDL_CondSignal</A | |
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186 > -- Restart a thread wait on a condition variable</DT |
0 | 187 ><DT |
188 ><A | |
189 HREF="sdlcondbroadcast.html" | |
190 >SDL_CondBroadcast</A | |
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191 > -- Restart all threads waiting on a condition variable</DT |
0 | 192 ><DT |
193 ><A | |
194 HREF="sdlcondwait.html" | |
195 >SDL_CondWait</A | |
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196 > -- Wait on a condition variable</DT |
0 | 197 ><DT |
198 ><A | |
199 HREF="sdlcondwaittimeout.html" | |
200 >SDL_CondWaitTimeout</A | |
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201 > -- Wait on a condition variable, with timeout</DT |
0 | 202 ></DL |
203 ></DIV | |
204 ><P | |
205 >SDL provides functions for creating threads, mutexes, semphores and condition variables.</P | |
206 ><P | |
207 >In general, you must be very aware of concurrency and data integrity issues | |
208 when writing multi-threaded programs. Some good guidelines include: | |
209 <P | |
210 ></P | |
211 ><UL | |
212 ><LI | |
213 ><P | |
214 >Don't call SDL video/event functions from separate threads</P | |
215 ></LI | |
216 ><LI | |
217 ><P | |
218 >Don't use any library functions in separate threads</P | |
219 ></LI | |
220 ><LI | |
221 ><P | |
222 >Don't perform any memory management in separate threads</P | |
223 ></LI | |
224 ><LI | |
225 ><P | |
226 >Lock global variables which may be accessed by multiple threads</P | |
227 ></LI | |
228 ><LI | |
229 ><P | |
230 >Never terminate threads, always set a flag and wait for them to quit</P | |
231 ></LI | |
232 ><LI | |
233 ><P | |
234 >Think very carefully about all possible ways your code may interact</P | |
235 ></LI | |
236 ></UL | |
237 ></P | |
238 ><DIV | |
239 CLASS="NOTE" | |
240 ><BLOCKQUOTE | |
241 CLASS="NOTE" | |
242 ><P | |
243 ><B | |
244 >Note: </B | |
181
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245 >SDL's threading is not implemented on MacOS, due to that lack of preemptive thread support (MacOS X dos nt suffer from this problem)</P |
0 | 246 ></BLOCKQUOTE |
247 ></DIV | |
248 ></DIV | |
249 ><DIV | |
250 CLASS="NAVFOOTER" | |
251 ><HR | |
252 ALIGN="LEFT" | |
253 WIDTH="100%"><TABLE | |
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254 SUMMARY="Footer navigation table" |
0 | 255 WIDTH="100%" |
256 BORDER="0" | |
257 CELLPADDING="0" | |
258 CELLSPACING="0" | |
259 ><TR | |
260 ><TD | |
261 WIDTH="33%" | |
262 ALIGN="left" | |
263 VALIGN="top" | |
264 ><A | |
265 HREF="sdlcdtrack.html" | |
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266 ACCESSKEY="P" |
0 | 267 >Prev</A |
268 ></TD | |
269 ><TD | |
270 WIDTH="34%" | |
271 ALIGN="center" | |
272 VALIGN="top" | |
273 ><A | |
274 HREF="index.html" | |
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275 ACCESSKEY="H" |
0 | 276 >Home</A |
277 ></TD | |
278 ><TD | |
279 WIDTH="33%" | |
280 ALIGN="right" | |
281 VALIGN="top" | |
282 ><A | |
283 HREF="sdlcreatethread.html" | |
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284 ACCESSKEY="N" |
0 | 285 >Next</A |
286 ></TD | |
287 ></TR | |
288 ><TR | |
289 ><TD | |
290 WIDTH="33%" | |
291 ALIGN="left" | |
292 VALIGN="top" | |
293 >SDL_CDtrack</TD | |
294 ><TD | |
295 WIDTH="34%" | |
296 ALIGN="center" | |
297 VALIGN="top" | |
298 ><A | |
299 HREF="reference.html" | |
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300 ACCESSKEY="U" |
0 | 301 >Up</A |
302 ></TD | |
303 ><TD | |
304 WIDTH="33%" | |
305 ALIGN="right" | |
306 VALIGN="top" | |
307 >SDL_CreateThread</TD | |
308 ></TR | |
309 ></TABLE | |
310 ></DIV | |
311 ></BODY | |
312 ></HTML | |
313 > |