We have gotten feedback that abstracting the coordinate system based on the display scale is unexpected and it is difficult to adapt existing applications to the proposed API.
The new approach is to provide the coordinate systems that people expect, but provide additional information that will help applications properly handle high DPI situations.
The concepts needed for high DPI support are documented in README-highdpi.md. An example of automatically adapting the content to display scale changes can be found in SDL_test_common.c, where auto_scale_content is checked.
Also, the SDL_WINDOW_ALLOW_HIGHDPI window flag has been replaced by the SDL_HINT_VIDEO_ENABLE_HIGH_PIXEL_DENSITY hint.
Fixes https://github.com/libsdl-org/SDL/issues/7709
This fixes rounding errors with coordinate scaling and gives more flexibility in the presentation, as well as making it easy to maintain device independent resolution as windows move between different pixel density displays.
By default when a renderer is created, it will match the window size so window coordinates and render coordinates are 1-1.
Mouse and touch events are no longer filtered to change their coordinates, instead you can call SDL_ConvertEventToRenderCoordinates() to explicitly map event coordinates into the rendering viewport.
SDL_RenderWindowToLogical() and SDL_RenderLogicalToWindow() have been renamed SDL_RenderCoordinatesFromWindow() and SDL_RenderCoordinatesToWindow() and take floating point coordinates in both directions.
The viewport, clipping state, and scale for render targets are now persistent and will remain set whenever they are active.
Rather than iterating over display modes using an index, there is a new function SDL_GetFullscreenDisplayModes() to get the list of available fullscreen modes on a display.
{
SDL_DisplayID display = SDL_GetPrimaryDisplay();
int num_modes = 0;
SDL_DisplayMode **modes = SDL_GetFullscreenDisplayModes(display, &num_modes);
if (modes) {
for (i = 0; i < num_modes; ++i) {
SDL_DisplayMode *mode = modes[i];
SDL_Log("Display %" SDL_PRIu32 " mode %d: %dx%d@%gHz, %d%% scale\n",
display, i, mode->pixel_w, mode->pixel_h, mode->refresh_rate, (int)(mode->display_scale * 100.0f));
}
SDL_free(modes);
}
}
SDL_GetDesktopDisplayMode() and SDL_GetCurrentDisplayMode() return pointers to display modes rather than filling in application memory.
Windows now have an explicit fullscreen mode that is set, using SDL_SetWindowFullscreenMode(). The fullscreen mode for a window can be queried with SDL_GetWindowFullscreenMode(), which returns a pointer to the mode, or NULL if the window will be fullscreen desktop. SDL_SetWindowFullscreen() just takes a boolean value, setting the correct fullscreen state based on the selected mode.
SDL_DisplayMode now includes the pixel size, the screen size and the relationship between the two. For example, a 4K display at 200% scale could have a pixel size of 3840x2160, a screen size of 1920x1080, and a display scale of 2.0.
Sam Lantinga