Mercurial > sdl-ios-xcode
view README @ 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 | 61b7f5eed0e8 |
| children | ca3718c215af |
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Simple DirectMedia Layer (SDL) Version 1.2 --- http://www.libsdl.org/ This is the Simple DirectMedia Layer, a general API that provides low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D framebuffer across multiple platforms. SDL is written in C, but works with C++ natively, and has bindings to several other languages, including Ada, C#, Eiffel, Java, Lua, ML, Objective C, Perl, PHP, Pike, Python, and Ruby. The current version supports Linux, Windows, BeOS, MacOS, MacOS X, FreeBSD, OpenBSD, BSD/OS, Solaris, IRIX, and QNX. The code contains support for Windows CE, AmigaOS, Dreamcast, Atari, NetBSD, AIX, OSF/Tru64, RISC OS, and SymbianOS, but these are not officially supported. This library is distributed under GNU LGPL version 2, which can be found in the file "COPYING". This license allows you to use SDL freely in commercial programs as long as you link with the dynamic library. The best way to learn how to use SDL is to check out the header files in the "include" subdirectory and the programs in the "test" subdirectory. The header files and test programs are well commented and always up to date. More documentation is available in HTML format in "./docs/index.html" The test programs in the "test" subdirectory are in the public domain. Frequently asked questions are answered online: http://www.libsdl.org/faq.php If you need help with the library, or just want to discuss SDL related issues, you can join the developers mailing list: http://www.libsdl.org/mailing-list.php Enjoy! Sam Lantinga (slouken@libsdl.org)