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Fixed bug 3015 - grab mouse inconsistent state 

Martin Gerhardy

Not sure - but I think there might be a logic flaw in SDL_SetWindowGrab.

The problem here is that this modifies the window flags and e.g. sets
SDL_WINDOW_INPUT_GRABBED - but the _this->grabbed_window pointer is not
yet set.

Then in SDL_UpdateWindowGrab the _this->grabbed_window pointer is only
set if the function pointer _this->SetWindowGrab is not NULL. But if
this is NULL, the _this->grabbed_window pointer is never set, but every
future call to any of the grab functions include an assert for:
SDL_assert(!_this->grabbed_window || ((_this->grabbed_window->flags &
SDL_WINDOW_INPUT_GRABBED) != 0));

That means the first call works, the second always fails and triggers
the assert.
main
Sam Lantinga 2015-06-15 23:44:08 -07:00
parent ccc12a3632
commit 59d34bc35d
1 changed files with 19 additions and 17 deletions
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4
src/video/SDL_video.c
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@ -2122,7 +2122,6 @@ SDL_GetWindowGammaRamp(SDL_Window * window, Uint16 * red,
void void
SDL_UpdateWindowGrab(SDL_Window * window) SDL_UpdateWindowGrab(SDL_Window * window)
{ {
if (_this->SetWindowGrab) {
SDL_Window *grabbed_window; SDL_Window *grabbed_window;
SDL_bool grabbed; SDL_bool grabbed;
if ((SDL_GetMouse()->relative_mode || (window->flags & SDL_WINDOW_INPUT_GRABBED)) && if ((SDL_GetMouse()->relative_mode || (window->flags & SDL_WINDOW_INPUT_GRABBED)) &&
@ -2137,13 +2136,16 @@ SDL_UpdateWindowGrab(SDL_Window * window)
if (grabbed_window && (grabbed_window != window)) { if (grabbed_window && (grabbed_window != window)) {
/* stealing a grab from another window! */ /* stealing a grab from another window! */
grabbed_window->flags &= ~SDL_WINDOW_INPUT_GRABBED; grabbed_window->flags &= ~SDL_WINDOW_INPUT_GRABBED;
if (_this->SetWindowGrab) {
_this->SetWindowGrab(_this, grabbed_window, SDL_FALSE); _this->SetWindowGrab(_this, grabbed_window, SDL_FALSE);
} }
}
_this->grabbed_window = window; _this->grabbed_window = window;
} else if (grabbed_window == window) { } else if (grabbed_window == window) {
_this->grabbed_window = NULL; /* ungrabbing. */ _this->grabbed_window = NULL; /* ungrabbing. */
} }
if (_this->SetWindowGrab) {
_this->SetWindowGrab(_this, window, grabbed); _this->SetWindowGrab(_this, window, grabbed);
} }
} }