author Sam Lantinga <>
Thu, 17 Apr 2014 22:36:14 -0700
changeset 8716 0aade9c0203f
parent 1484 b2b476a4a73c
child 1946 103760c3a5dc
permissions -rw-r--r--
Fixed bug 2325 - SDL_EnableUNICODE sometimes drops keyboard events completely

Rafał Mużyło

The most annoying part of this bug is that though I've found it in two separate apps, I don't have a trivial testcase for it.

The problem seems to be a condition race, as it's triggered quite randomly (therefore it will be hard to tell whether it really gets fixed, if a probable fix is found).

While it's specific to SDL 1.2, it seems quite similar to the problem described and fixed in

Now, I should start describing the problem.

A game uses Escape to open menu (the exact key might not be important). Upon opening, it calls SDL_EnableUNICODE(1). Upon closing it calls SDL_EnableUNICODE(0).

I have an IME running.

Game uses SDL_PollEvent to get the events.

If Escape is pressed repeatedly, menu is opened and closed, till it eventually freezes in open state.
"freezes" in this context means "app itself still runs, but no keyboard events are getting delivered (though - for example - mouse events still are)". "getting delivered" should mean "SDL_PollEvent is not receiving any".
If it matters, the last delivered keyboard event is a keypress, the release never arrives.

It seems (no guarantees, due to random nature of the freeze) that unsetting XMODIFIERS (which - AFAIU - will disable IME as far as SDL is concerned) prevents the freeze, therefore the reference to that SDL2 thread.
     2 * Porting To A New Platform
     4   The first thing you have to do when porting to a new platform, is look at
     5 include/SDL_platform.h and create an entry there for your operating system.
     6 The standard format is __PLATFORM__, where PLATFORM is the name of the OS.
     7 Ideally SDL_platform.h will be able to auto-detect the system it's building
     8 on based on C preprocessor symbols.
    10 There are two basic ways of building SDL at the moment:
    12 1. The "UNIX" way:  ./configure; make; make install
    14    If you have a GNUish system, then you might try this.  Edit,
    15    take a look at the large section labelled:
    16 	"Set up the configuration based on the target platform!"
    17    Add a section for your platform, and then re-run and build!
    19 2. Using an IDE:
    21    If you're using an IDE or other non-configure build system, you'll probably
    22    want to create a custom SDL_config.h for your platform.  Edit SDL_config.h,
    23    add a section for your platform, and create a custom SDL_config_{platform}.h,
    24    based on SDL_config.h.minimal and
    26    Add the top level include directory to the header search path, and then add
    27    the following sources to the project:
    28 	src/*.c
    29 	src/audio/*.c
    30 	src/cdrom/*.c
    31 	src/cpuinfo/*.c
    32 	src/events/*.c
    33 	src/file/*.c
    34 	src/joystick/*.c
    35 	src/stdlib/*.c
    36 	src/thread/*.c
    37 	src/timer/*.c
    38 	src/video/*.c
    39 	src/audio/disk/*.c
    40 	src/video/dummy/*.c
    41 	src/joystick/dummy/*.c
    42 	src/cdrom/dummy/*.c
    43 	src/thread/generic/*.c
    44 	src/timer/dummy/*.c
    45 	src/loadso/dummy/*.c
    48 Once you have a working library without any drivers, you can go back to each
    49 of the major subsystems and start implementing drivers for your platform.
    51 If you have any questions, don't hesitate to ask on the SDL mailing list:
    54 Enjoy!
    55 	Sam Lantinga				(