Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_SetTimer.3 @ 1259:36f24cdfcda7
te: Thu, 17 Apr 2003 11:25:26 -0700
From: "Jim"
Subject: [SDL] Frame buffer patches...
Would seem that GCC 3.2.2 promotes all signed values to unsigned if any single vlaue is unsigned in an expression...
for instance when calculating an elo touch position....evertyhign is an (int) except for cach_vinfo.xres which is unsigned. THerefore if y
ou reverse the SDL_ELO_MIN_X and SDL_ELO_MAX_X values the resulging negative value pegs the expression to it's max. Attached it the accumu
lated patch to typecast the unsigned values to (int)
- *dx = (cache_vinfo.xres - (cache_vinfo.xres * (input_x - ELO_MIN_X)) / width);
+ *dx = ((int)cache_vinfo.xres - ((int)cache_vinfo.xres * (input_x - ELO_MIN_X)) / width);
and also to provide quite failure to operations which have the screen currently locked...
The touch screen I'm using the original values were exactly opposite of any position I touched on the screen - evaluating the math the expr
ession SHOULD have handled reversing the min and max values - and after casting the unsigned .xres and .yres to a signed int - worked well.
..
Jim
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 24 Jan 2006 06:36:43 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
| rev | line source |
|---|---|
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e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
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1 .TH "SDL_SetTimer" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
| 3 SDL_SetTimer\- Set a callback to run after the specified number of milliseconds has elapsed\&. | |
| 4 .SH "SYNOPSIS" | |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBint \fBSDL_SetTimer\fP\fR(\fBUint32 interval, SDL_TimerCallback callback\fR); | |
| 9 .SH "CALLBACK" | |
| 10 .PP | |
| 11 /* Function prototype for the timer callback function */ typedef Uint32 (*SDL_TimerCallback)(Uint32 interval); | |
| 12 .SH "DESCRIPTION" | |
| 13 .PP | |
| 14 Set a callback to run after the specified number of milliseconds has elapsed\&. The callback function is passed the current timer interval and returns the next timer interval\&. If the returned value is the same as the one passed in, the periodic alarm continues, otherwise a new alarm is scheduled\&. | |
| 15 .PP | |
| 16 To cancel a currently running timer, call \fBSDL_SetTimer(0, NULL);\fP | |
| 17 .PP | |
| 18 The timer callback function may run in a different thread than your main constant, and so shouldn\&'t call any functions from within itself\&. | |
| 19 .PP | |
| 20 The maximum resolution of this timer is 10 ms, which means that if you request a 16 ms timer, your callback will run approximately 20 ms later on an unloaded system\&. If you wanted to set a flag signaling a frame update at 30 frames per second (every 33 ms), you might set a timer for 30 ms (see example below)\&. | |
| 21 .PP | |
| 22 If you use this function, you need to pass \fBSDL_INIT_TIMER\fP to \fBSDL_Init()\fP\&. | |
| 23 .PP | |
| 24 .RS | |
| 25 \fBNote: | |
| 26 .PP | |
|
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Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
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27 This function is kept for compatibility but has been superseded by the new timer functions \fISDL_AddTimer\fR and \fISDL_RemoveTimer\fR which support multiple timers\&. |
| 0 | 28 .RE |
| 29 .SH "EXAMPLES" | |
| 30 .PP | |
| 31 .PP | |
| 32 .nf | |
| 33 \f(CWSDL_SetTimer((33/10)*10, my_callback);\fR | |
| 34 .fi | |
| 35 .PP | |
| 36 .SH "SEE ALSO" | |
| 37 .PP | |
| 38 \fI\fBSDL_AddTimer\fP\fR | |
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181
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Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
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39 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |