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video: wayland: Use viewports for non-fullscreen windows with fractional scaling

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Use viewports for non-fullscreen windows when the desktop uses fractional scaling and the window is flagged as DPI-aware to provide a backbuffer mapped as close to 1:1 output as possible.  In the cases of odd window sizes the backbuffer may be a pixel off of scaling perfectly into the window size due to its scaled size being rounded off, but a minute amount of scaling during output is likely preferable to the large amounts of overdraw needed with integer scaled buffers.
This commit is contained in:
Frank Praznik 2022-03-29 13:34:14 -04:00 committed by Ethan Lee
parent fa4c51989d
commit 4d1905c9b6
1 changed files with 65 additions and 21 deletions
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86
src/video/wayland/SDL_waylandwindow.c
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@ -115,8 +115,8 @@ DesktopIsFractionalScaled(SDL_Window *window)
SDL_WindowData *data = window->driverdata;
SDL_WaylandOutputData *output = (SDL_WaylandOutputData *)SDL_GetDisplayForWindow(window)->driverdata;
if ((output->native_width != (output->width * data->scale_factor) ||
output->native_height != (output->height * data->scale_factor))) {
if ((output->native_width != (int)(output->width * data->scale_factor) ||
output->native_height != (int)(output->height * data->scale_factor))) {
return SDL_TRUE;
}
@ -163,6 +163,43 @@ NeedFullscreenViewport(SDL_Window *window)
return SDL_FALSE;
}
static inline SDL_bool
NeedWindowedViewport(SDL_Window *window)
{
SDL_WindowData *data = window->driverdata;
SDL_VideoData *video = data->waylandData;
return !(window->flags & SDL_WINDOW_FULLSCREEN) && (video->viewporter != NULL) &&
DesktopIsFractionalScaled(window) && (window->flags & SDL_WINDOW_ALLOW_HIGHDPI);
}
static void
GetWindowBufferSize(SDL_Window *window, int *width, int *height)
{
SDL_WindowData *data = window->driverdata;
SDL_WaylandOutputData *output = (SDL_WaylandOutputData *)SDL_GetDisplayForWindow(window)->driverdata;
int buf_width;
int buf_height;
if (NeedWindowedViewport(window)) {
const float frac_scale_x = (float)output->native_width / (float)output->width;
const float frac_scale_y = (float)output->native_height / (float)output->height;
buf_width = (int)SDL_lroundf(window->w * frac_scale_x);
buf_height = (int)SDL_lroundf(window->h * frac_scale_y);
} else { /* Windowed or fullscreen with no viewport */
buf_width = window->w * data->scale_factor;
buf_height = window->h * data->scale_factor;
}
if (width) {
*width = buf_width;
}
if (height) {
*height = buf_height;
}
}
static void
SetViewport(SDL_Window *window, int src_width, int src_height, int dst_width, int dst_height)
{
@ -197,7 +234,7 @@ ConfigureViewport(SDL_Window *window)
SDL_VideoData *viddata = data->waylandData;
SDL_WaylandOutputData *output = (SDL_WaylandOutputData *)SDL_GetDisplayForWindow(window)->driverdata;
if ((window->flags & SDL_WINDOW_FULLSCREEN) && NeedFullscreenViewport(window)) {
if (NeedFullscreenViewport(window)) {
int fs_width, fs_height;
int src_width, src_height;
@ -206,24 +243,27 @@ ConfigureViewport(SDL_Window *window)
data->pointer_scale_x = (float)fs_width / (float)output->width;
data->pointer_scale_y = (float)fs_height / (float)output->height;
/*
* If mouse_rect is not empty, re-create the confinement region with the new scale value.
* If the pointer is locked to the general surface with unspecified coordinates, it will
* be confined to the viewport region, so no update is required.
*/
if (!SDL_RectEmpty(&window->mouse_rect)) {
Wayland_input_confine_pointer(viddata->input, window);
}
} else {
UnsetViewport(window);
if (NeedWindowedViewport(window)) {
int src_width, src_height;
GetWindowBufferSize(window, &src_width, &src_height);
SetViewport(window, src_width, src_height, window->w, window->h);
} else {
UnsetViewport(window);
}
data->pointer_scale_x = 1.0f;
data->pointer_scale_y = 1.0f;
}
/* Re-scale the pointer confinement region */
if (!SDL_RectEmpty(&window->mouse_rect)) {
Wayland_input_confine_pointer(viddata->input, window);
}
/*
* If mouse_rect is not empty, re-create the confinement region with the new scale value.
* If the pointer is locked to the general surface with unspecified coordinates, it will
* be confined to the viewport region, so no update is required.
*/
if (!SDL_RectEmpty(&window->mouse_rect)) {
Wayland_input_confine_pointer(viddata->input, window);
}
}
@ -232,7 +272,7 @@ SetDrawScale(SDL_Window *window)
{
SDL_WindowData *data = window->driverdata;
if ((window->flags & SDL_WINDOW_FULLSCREEN) && NeedFullscreenViewport(window)) {
if (NeedFullscreenViewport(window)) {
int fs_width, fs_height;
GetFullScreenDimensions(window, &fs_width, &fs_height, &data->drawable_width, &data->drawable_height);
@ -240,10 +280,14 @@ SetDrawScale(SDL_Window *window)
/* Set the buffer scale to 1 since a viewport will be used. */
wl_surface_set_buffer_scale(data->surface, 1);
} else {
data->drawable_width = window->w * data->scale_factor;
data->drawable_height = window->h * data->scale_factor;
GetWindowBufferSize(window, &data->drawable_width, &data->drawable_height);
wl_surface_set_buffer_scale(data->surface, (int32_t)data->scale_factor);
if (NeedWindowedViewport(window)) {
/* Set the buffer scale to 1 since a viewport will be used. */
wl_surface_set_buffer_scale(data->surface, 1);
} else {
wl_surface_set_buffer_scale(data->surface, (int32_t)data->scale_factor);
}
}
}