Commit 4d1905c9b60489b58c486cee350356e156ce6856
2022-03-29T13:34:14
video: wayland: Use viewports for non-fullscreen windows with fractional scaling 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.
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diff --git a/src/video/wayland/SDL_waylandwindow.c b/src/video/wayland/SDL_waylandwindow.c
index 055f14a..036c3a4 100644
--- a/src/video/wayland/SDL_waylandwindow.c
+++ b/src/video/wayland/SDL_waylandwindow.c
@@ -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;
+ } else {
+ if (NeedWindowedViewport(window)) {
+ int src_width, src_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);
+ GetWindowBufferSize(window, &src_width, &src_height);
+ SetViewport(window, src_width, src_height, window->w, window->h);
+ } else {
+ UnsetViewport(window);
}
- } 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);
+ }
}
}