Simple Directmedia Layer
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Sam Lantinga 195b8bd8ee Fixed bug 3249 - keysym.mod is incorrect when mod keys are pressed for SDL_KEYDOWN events
Adam M.

The keysym.mod field does not reflect the state of the modified keys when processing key down events for the modifier keys themselves. The documentation says that it returns the current key modifiers, but they are not current for key down events involving modifier keys. I interpret "current" to mean "equal to SDL_GetModState() at the instant the event is processed/enqueued".

For example, if you depress the Shift key you get a key down event with .mod == 0. However, .mod should not be 0 because a shift key is down. If you then release the Shift key, you get a key up event with .mod == 0. Neither event reports the modifier key.

If you press Shift and then A, .mod is incorrect (== 0) when Shift is pressed, but is correct later when A is pressed (== KMOD_LSHIFT).

You might say this behavior is deliberate, i.e. keysym.mod is the value /before/ the event, not the current value as documented, but that explanation is incorrect because only key down events behave that way. Key up events correctly give the current value, not the value before the event.

Not only is it inconsistent with itself, I think it makes keyboard processing harder.

The problem is near line 740 in SDL_keyboard.c:

if (SDL_KEYDOWN == type) {
    modstate = keyboard->modstate; // SHOULD THIS BE MOVED DOWN?
    switch (keycode) {
    case SDLK_NUMLOCKCLEAR:
        keyboard->modstate ^= KMOD_NUM;
        break;
    case SDLK_CAPSLOCK:
        keyboard->modstate ^= KMOD_CAPS;
        break;
    default:
        keyboard->modstate |= modifier;
        break;
    }
} else {
    keyboard->modstate &= ~modifier;
    modstate = keyboard->modstate;
}

In the key down path, modstate (and thus keysym.mod) ends up being the modifier state /before/ the event, but in the key up path modstate ends up being the modifier state /after/ the event. Personally I think the "modstate = keyboard->modstate" line should just be moved after the entire if/else statement, so that keysym.mod always reflects the current state.
2017-08-12 12:34:09 -07:00
VisualC Updated Visual Studio 2008 project 2017-07-10 15:55:13 -07:00
VisualC-WinRT WinRT: removed Windows 8.0 from build-bot + NuGet package creation scripts 2017-02-25 21:23:12 -05:00
Xcode Updated copyright for 2017 2017-01-01 18:33:28 -08:00
Xcode-iOS ios: Fixed math include in demos. 2017-05-25 23:01:59 +02:00
acinclude Fixed bug 3481 - Configure fails to detect dynamic library support on powerpc64le 2016-11-06 20:26:48 -08:00
android-project Fixed bug 3191 - haptic system on android? 2017-08-12 08:15:09 -07:00
build-scripts Disable static builds for static analysis. 2017-07-30 14:36:01 -04:00
cmake cmake: whoops, Sam and I both fixed this bug at the same time. :) 2017-08-09 22:34:45 -04:00
debian We don't actually build with the Xt library 2017-01-10 23:23:32 -08:00
docs README-linux.md: added libsndio-dev to the package list. 2017-08-07 00:36:45 -04:00
include Fixed bug 3191 - haptic system on android? 2017-08-12 08:15:09 -07:00
src Fixed bug 3249 - keysym.mod is incorrect when mod keys are pressed for SDL_KEYDOWN events 2017-08-12 12:34:09 -07:00
test Fixed bug 3639 - SDL_GetPrefPath returns a path with two consecutive slashes on Unix if org is omitted 2017-08-11 11:32:00 -07:00
visualtest Updated copyright for 2017 2017-01-01 18:33:28 -08:00
.hgignore audio: Initial bits to enable audio capture support. 2016-08-01 00:18:56 -04:00
Android.mk Fixed bug 3191 - haptic system on android? 2017-08-12 08:15:09 -07:00
BUGS.txt BUGS.txt: Changed mailing list link to discourse.libsdl.org. 2017-04-01 00:05:25 -04:00
CMakeLists.txt Forgot to add function check for fopen64 to CMake build 2017-08-11 21:17:10 -07:00
COPYING.txt Updated copyright for 2017 2017-01-01 18:33:28 -08:00
CREDITS.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
INSTALL.txt More HTTPS doc tweaks. 2017-02-16 16:59:07 -05:00
Makefile.in Fixed bug 3651 - CMake build does not install CMake package configuration 2017-08-09 19:03:10 -07:00
Makefile.minimal Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
Makefile.pandora pandora: Fixed compiler warning about redefining SDL_REVISION. 2017-06-18 23:00:27 +02:00
Makefile.psp PSP: Added missing object for generic TLS to Makefile. 2016-02-13 17:34:14 +01:00
Makefile.wiz Pandora: Updated SDL version in Makefile. 2016-07-19 21:01:30 +02:00
README-SDL.txt More HTTPS changes in the documentation. 2017-02-16 16:52:03 -05:00
README.txt readme: correct webpage URL to use HTTPS. 2017-02-16 13:30:34 -05:00
SDL2.spec.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
SDL2Config.cmake Fixed bug 3651 - CMake build does not install CMake package configuration 2017-08-09 19:03:10 -07:00
TODO.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
VisualC.html Fixed two typos in documentation. 2016-01-12 22:23:53 +01:00
WhatsNew.txt Added note for David Carlier's work on OpenBSD 2016-10-12 18:57:12 -07:00
autogen.sh Don't use pushd/popd in autogen.sh; Ubuntu's /bin/sh doesn't support it. 2016-12-26 22:58:58 -05:00
cmake_uninstall.cmake.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
configure Fixed bug 3292 - SDL_rwops and 64-bit file I/O 2017-08-11 21:16:33 -07:00
configure.in Fixed bug 3292 - SDL_rwops and 64-bit file I/O 2017-08-11 21:16:33 -07:00
sdl2-config.cmake.in Applied Ubuntu patch bug_822210_fix_sdl2-config.cmake_whitespace.patch 2016-10-07 15:08:37 -07:00
sdl2-config.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
sdl2.m4 Fixed bug 3429 - Update AM_PATH_SDL2() to also check for SDL2.framework 2016-09-29 16:37:08 -07:00
sdl2.pc.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00

README.txt

                         Simple DirectMedia Layer

                                  (SDL)

                                Version 2.0

---
https://www.libsdl.org/

Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.

More extensive documentation is available in the docs directory, starting
with README.md

Enjoy!
	Sam Lantinga				(slouken@libsdl.org)