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annotate docs/html/sdlsemvalue.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 |
parents | 355632dca928 |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_SemValue</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_SemPost" | |
17 HREF="sdlsempost.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_CreateCond" | |
20 HREF="sdlcreatecond.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="sdlsempost.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="sdlcreatecond.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="SDLSEMVALUE" | |
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74 ></A |
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75 >SDL_SemValue</H1 |
0 | 76 ><DIV |
77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN8218" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_SemValue -- Return the current value of a semaphore.</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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87 NAME="AEN8221" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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94 NAME="AEN8222" |
0 | 95 ></A |
96 ><P | |
97 ></P | |
98 ><PRE | |
99 CLASS="FUNCSYNOPSISINFO" | |
100 >#include "SDL.h" | |
101 #include "SDL/SDL_thread.h"</PRE | |
102 ><P | |
103 ><CODE | |
104 ><CODE | |
105 CLASS="FUNCDEF" | |
106 >Uint32 <B | |
107 CLASS="FSFUNC" | |
108 >SDL_SemValue</B | |
109 ></CODE | |
110 >(SDL_sem *sem);</CODE | |
111 ></P | |
112 ><P | |
113 ></P | |
114 ></DIV | |
115 ></DIV | |
116 ><DIV | |
117 CLASS="REFSECT1" | |
118 ><A | |
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119 NAME="AEN8228" |
0 | 120 ></A |
121 ><H2 | |
122 >Description</H2 | |
123 ><P | |
124 ><TT | |
125 CLASS="FUNCTION" | |
126 >SDL_SemValue()</TT | |
127 > returns the current semaphore value from | |
128 the semaphore pointed to by <TT | |
129 CLASS="PARAMETER" | |
130 ><I | |
131 >sem</I | |
132 ></TT | |
133 >.</P | |
134 ></DIV | |
135 ><DIV | |
136 CLASS="REFSECT1" | |
137 ><A | |
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138 NAME="AEN8233" |
0 | 139 ></A |
140 ><H2 | |
141 >Return Value</H2 | |
142 ><P | |
143 >Returns current value of the semaphore.</P | |
144 ></DIV | |
145 ><DIV | |
146 CLASS="REFSECT1" | |
147 ><A | |
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148 NAME="AEN8236" |
0 | 149 ></A |
150 ><H2 | |
151 >Examples</H2 | |
152 ><P | |
153 ><PRE | |
154 CLASS="PROGRAMLISTING" | |
155 > sem_value = SDL_SemValue(my_sem);</PRE | |
156 ></P | |
157 ></DIV | |
158 ><DIV | |
159 CLASS="REFSECT1" | |
160 ><A | |
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161 NAME="AEN8240" |
0 | 162 ></A |
163 ><H2 | |
164 >See Also</H2 | |
165 ><P | |
166 ><A | |
167 HREF="sdlcreatesemaphore.html" | |
168 ><TT | |
169 CLASS="FUNCTION" | |
170 >SDL_CreateSemaphore</TT | |
171 ></A | |
172 >, | |
173 <A | |
174 HREF="sdldestroysemaphore.html" | |
175 ><TT | |
176 CLASS="FUNCTION" | |
177 >SDL_DestroySemaphore</TT | |
178 ></A | |
179 >, | |
180 <A | |
181 HREF="sdlsemwait.html" | |
182 ><TT | |
183 CLASS="FUNCTION" | |
184 >SDL_SemWait</TT | |
185 ></A | |
186 >, | |
187 <A | |
188 HREF="sdlsemtrywait.html" | |
189 ><TT | |
190 CLASS="FUNCTION" | |
191 >SDL_SemTryWait</TT | |
192 ></A | |
193 >, | |
194 <A | |
195 HREF="sdlsemwaittimeout.html" | |
196 ><TT | |
197 CLASS="FUNCTION" | |
198 >SDL_SemWaitTimeout</TT | |
199 ></A | |
200 >, | |
201 <A | |
202 HREF="sdlsempost.html" | |
203 ><TT | |
204 CLASS="FUNCTION" | |
205 >SDL_SemPost</TT | |
206 ></A | |
207 ></P | |
208 ></DIV | |
209 ><DIV | |
210 CLASS="NAVFOOTER" | |
211 ><HR | |
212 ALIGN="LEFT" | |
213 WIDTH="100%"><TABLE | |
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214 SUMMARY="Footer navigation table" |
0 | 215 WIDTH="100%" |
216 BORDER="0" | |
217 CELLPADDING="0" | |
218 CELLSPACING="0" | |
219 ><TR | |
220 ><TD | |
221 WIDTH="33%" | |
222 ALIGN="left" | |
223 VALIGN="top" | |
224 ><A | |
225 HREF="sdlsempost.html" | |
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226 ACCESSKEY="P" |
0 | 227 >Prev</A |
228 ></TD | |
229 ><TD | |
230 WIDTH="34%" | |
231 ALIGN="center" | |
232 VALIGN="top" | |
233 ><A | |
234 HREF="index.html" | |
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235 ACCESSKEY="H" |
0 | 236 >Home</A |
237 ></TD | |
238 ><TD | |
239 WIDTH="33%" | |
240 ALIGN="right" | |
241 VALIGN="top" | |
242 ><A | |
243 HREF="sdlcreatecond.html" | |
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244 ACCESSKEY="N" |
0 | 245 >Next</A |
246 ></TD | |
247 ></TR | |
248 ><TR | |
249 ><TD | |
250 WIDTH="33%" | |
251 ALIGN="left" | |
252 VALIGN="top" | |
253 >SDL_SemPost</TD | |
254 ><TD | |
255 WIDTH="34%" | |
256 ALIGN="center" | |
257 VALIGN="top" | |
258 ><A | |
259 HREF="thread.html" | |
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260 ACCESSKEY="U" |
0 | 261 >Up</A |
262 ></TD | |
263 ><TD | |
264 WIDTH="33%" | |
265 ALIGN="right" | |
266 VALIGN="top" | |
267 >SDL_CreateCond</TD | |
268 ></TR | |
269 ></TABLE | |
270 ></DIV | |
271 ></BODY | |
272 ></HTML | |
273 > |