SDL2/src/video/windows/SDL_windowsmodes.h
Sam Lantinga 6e1b11bae4 Fixed bug 3714 - Windows: SDL_WINDOW_FULLSCREEN_DESKTOP broken on 3 monitor setup w/ DPI scaling
Eric Wasylishen 2017-07-26 18:42:58 UTC
I set up an (admittedly exotic) 3-monitor setup, and when I enter fullscreen-desktop on the middle display (#2), the SDL window is off center. (covers half of monitor #2 and most of monitor #3).

The displays are arranged from left to right:

Display #1 (main): 2880x1800, 200% scaling
Display #2: 1920x1200, 150% scaling
Display #3: 1920x1080, 100% scaling

SDL display bounds:
INFO: Bounds: 1440x900 at 0,0
INFO: Bounds: 1281x801 at 1921,0  (these are incorrect)
INFO: Bounds: 1920x1080 at 4800,0

Correct bounds reported by calling EnumDisplayMonitors and printing the LPRECT param of the callback:
1440x900 at (0, 0)
1280x800 at (2880, 0)
1920x1080 at (4800, 0)

It seems like you need 3 displays to reproduce this, and the left two need DPI scaling, and the 3rd display needs to have a different scale factor than the others.

Related: https://bugzilla.libsdl.org/show_bug.cgi?id=3709

SDL: current hg (11235:6a587b9e0ec8)
Windows 10, Version 10.0.15063 Build 15063
Tested with testdraw2 and testgl2, and pressing alt+enter to enter fullscreen desktop.

This patch reworks SDL_windowsmodes.c to use EnumDisplayMonitors instead of EnumDisplayDevices, so we always have an HMONITOR for each SDL display.

With access to an HMONITOR, we can get the monitor bounds in virtual screen coordinates the proper way, by calling GetMonitorInfo. (whereas the original code was doing some calculations - e.g. "data->DeviceMode.dmPosition.x * data->ScaleX" - to try to get virtual screen coordinates. These worked in simple cases, but failed in more complex cases like this bug)

The one potential problem with my patch is, the ChangeDisplaySettingsEx docs say that you're supposed to get the display name from EnumDisplayDevices, but I'm getting the display name from GetMonitorInfo now.
2017-08-11 10:18:45 -07:00

48 lines
1.7 KiB
C

/*
Simple DirectMedia Layer
Copyright (C) 1997-2017 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "../../SDL_internal.h"
#ifndef _SDL_windowsmodes_h
#define _SDL_windowsmodes_h
typedef struct
{
TCHAR DeviceName[32];
HMONITOR MonitorHandle;
} SDL_DisplayData;
typedef struct
{
DEVMODE DeviceMode;
} SDL_DisplayModeData;
extern int WIN_InitModes(_THIS);
extern int WIN_GetDisplayBounds(_THIS, SDL_VideoDisplay * display, SDL_Rect * rect);
extern int WIN_GetDisplayUsableBounds(_THIS, SDL_VideoDisplay * display, SDL_Rect * rect);
extern int WIN_GetDisplayDPI(_THIS, SDL_VideoDisplay * display, float * ddpi, float * hdpi, float * vdpi);
extern void WIN_GetDisplayModes(_THIS, SDL_VideoDisplay * display);
extern int WIN_SetDisplayMode(_THIS, SDL_VideoDisplay * display, SDL_DisplayMode * mode);
extern void WIN_QuitModes(_THIS);
#endif /* _SDL_windowsmodes_h */
/* vi: set ts=4 sw=4 expandtab: */