This bug report was migrated from our old Bugzilla tracker.

These attachments are available in the static archive:

• Patch to fix loose RESIZED events on SIZE_CHANGED (sizechange.diff, text/plain, 2018-08-13 17:31:45 +0000, 2166 bytes)

Reported in version: HG 2.0
Reported for operating system, platform: All, All

Comments on the original bug report:

On 2018-08-13 17:31:45 +0000, Ethan Lee wrote:

Created attachment 3280
Patch to fix loose RESIZED events on SIZE_CHANGED

At the bottom of this post is a test program that demonstrates what's happening, at least on Windows 10.

I'm finding that Windows REALLY likes to dump lots of resize events when toggling fullscreen; in particular it sends a resize event as it's resizing the window, before SDL is finished changing the window size. The result is this:

• Windows fires RESIZED
• RESIZED fires SIZE_CHANGED, previous SIZE_CHANGED events cleared
• Previous RESIZED events cleared
• SDL sets window size, fires SIZE_CHANGED event, previous SIZE_CHANGED events cleared but RESIZED events are NOT cleared
• Application polls events, conflicting size events!

On Windows you can actually get a good sense of the problem simply by toggling fullscreen a bunch, no clever setup needed. The way I fixed this is by making it so any SIZE_CHANGED event clears out all of the size events, so whatever the latest size event is the only one in the loop. User resizes will still always get exactly 1 SIZE_CHANGED and 1 RESIZED, but programmatic changes will always get exactly 1 SIZE_CHANGED and 0 RESIZED if they end up overriding any resizes between frames.

---

#include <SDL.h>

int main(int argc, char **argv)
{
SDL_DisplayMode mode;
SDL_Window *window;
SDL_Event evt;
SDL_bool ftoggle = SDL_FALSE;
Uint8 run = 1;

SDL_Init(SDL_INIT_VIDEO);
SDL_GetCurrentDisplayMode(0, &mode);
window = SDL_CreateWindow(
"WindowEvent Test",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
800,
480,
SDL_WINDOW_SHOWN
);

while (run)
{
while (SDL_PollEvent(&evt) > 0)
{
if (evt.type == SDL_QUIT)
{
run = 0;
}
else if (evt.type == SDL_KEYDOWN)
{
if (ftoggle)
{
SDL_SetWindowFullscreen(window, 0);
SDL_SetWindowSize(window, 800, 480);
}
else
{
SDL_SetWindowSize(window, mode.w, mode.h);

  			/* Just trying to replicate FNA... */
  			SDL_Delay(1);

  			SDL_SetWindowFullscreen(
  				window,
  				SDL_WINDOW_FULLSCREEN_DESKTOP
  			);
  		}
  		ftoggle = !ftoggle;
  	}
  	else if (evt.type == SDL_WINDOWEVENT)
  	{
  		if (evt.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)
  		{
  			SDL_Log(
  				"%d SIZE CHANGE %d %d",
  				SDL_GetTicks(),
  				evt.window.data1,
  				evt.window.data2
  			);
  		}
  		else if (evt.window.event == SDL_WINDOWEVENT_RESIZED)
  		{
  			SDL_Log(
  				"%d RESIZE %d %d",
  				SDL_GetTicks(),
  				evt.window.data1,
  				evt.window.data2
  			);
  		}
  	}
  }

}

SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}

---

On 2018-10-01 16:42:47 +0000, Sam Lantinga wrote:

Patch added, thanks!
https://hg.libsdl.org/SDL/rev/52dddda6fba7