video: wayland: Use wp-viewporter for fullscreen with non-native reso…

…lutions

Wayland doesn't support mode switching, however Wayland compositors can support the wp_viewporter protocol, which allows for the mapping of arbitrarily sized buffer regions to output surfaces.  Use this functionality, when available, for fullscreen output when using non-native display modes and/or when dealing with scaled desktops, which can incur significant overdraw without this extension.

This also allows for the exposure of arbitrarily sized, emulated display modes, which can be useful for legacy compatability.

src/video/SDL_sysvideo.h

@@ -345,6 +345,7 @@ struct SDL_VideoDevice
     Uint32 next_object_id;
     char *clipboard_text;
     SDL_bool setting_display_mode;
+    SDL_bool disable_display_mode_switching;
 
     /* * * */
     /* Data used by the GL drivers */

src/video/SDL_video.c

@@ -1339,14 +1339,17 @@ SDL_UpdateFullscreenMode(SDL_Window * window, SDL_bool fullscreen)
                     resized = SDL_FALSE;
                 }
 
-                /* only do the mode change if we want exclusive fullscreen */
-                if ((window->flags & SDL_WINDOW_FULLSCREEN_DESKTOP) != SDL_WINDOW_FULLSCREEN_DESKTOP) {
-                    if (SDL_SetDisplayModeForDisplay(display, &fullscreen_mode) < 0) {
-                        return -1;
-                    }
-                } else {
-                    if (SDL_SetDisplayModeForDisplay(display, NULL) < 0) {
-                        return -1;
+                /* Don't try to change the display mode if the driver doesn't want it. */
+                if (_this->disable_display_mode_switching == SDL_FALSE) {
+                    /* only do the mode change if we want exclusive fullscreen */
+                    if ((window->flags & SDL_WINDOW_FULLSCREEN_DESKTOP) != SDL_WINDOW_FULLSCREEN_DESKTOP) {
+                        if (SDL_SetDisplayModeForDisplay(display, &fullscreen_mode) < 0) {
+                            return -1;
+                        }
+                    } else {
+                        if (SDL_SetDisplayModeForDisplay(display, NULL) < 0) {
+                            return -1;
+                        }
                     }
                 }
 

src/video/wayland/SDL_waylandevents.c

@@ -389,8 +389,10 @@ pointer_handle_motion(void *data, struct wl_pointer *pointer,
     input->sx_w = sx_w;
     input->sy_w = sy_w;
     if (input->pointer_focus) {
-        const int sx = wl_fixed_to_int(sx_w);
-        const int sy = wl_fixed_to_int(sy_w);
+        const float sx_f = (float)wl_fixed_to_double(sx_w);
+        const float sy_f = (float)wl_fixed_to_double(sy_w);
+        const int   sx   = (int)SDL_lroundf(sx_f * window->pointer_scale);
+        const int   sy   = (int)SDL_lroundf(sy_f * window->pointer_scale);
         SDL_SendMouseMotion(window->sdlwindow, 0, 0, sx, sy);
     }
 }
@@ -717,8 +719,8 @@ touch_handler_down(void *data, struct wl_touch *touch, unsigned int serial,
                    int id, wl_fixed_t fx, wl_fixed_t fy)
 {
     SDL_WindowData *window_data = (SDL_WindowData *)wl_surface_get_user_data(surface);
-    const double dblx = wl_fixed_to_double(fx);
-    const double dbly = wl_fixed_to_double(fy);
+    const double dblx = wl_fixed_to_double(fx) * window_data->pointer_scale;
+    const double dbly = wl_fixed_to_double(fy) * window_data->pointer_scale;
     const float x = dblx / window_data->sdlwindow->w;
     const float y = dbly / window_data->sdlwindow->h;
 
@@ -750,8 +752,8 @@ touch_handler_motion(void *data, struct wl_touch *touch, unsigned int timestamp,
                      int id, wl_fixed_t fx, wl_fixed_t fy)
 {
     SDL_WindowData *window_data = (SDL_WindowData *)wl_surface_get_user_data(touch_surface(id));
-    const double dblx = wl_fixed_to_double(fx);
-    const double dbly = wl_fixed_to_double(fy);
+    const double dblx = wl_fixed_to_double(fx) * window_data->pointer_scale;
+    const double dbly = wl_fixed_to_double(fy) * window_data->pointer_scale;
     const float x = dblx / window_data->sdlwindow->w;
     const float y = dbly / window_data->sdlwindow->h;
 
@@ -1817,8 +1819,10 @@ tablet_tool_handle_motion(void* data, struct zwp_tablet_tool_v2* tool, wl_fixed_
     input->sx_w = sx_w;
     input->sy_w = sy_w;
     if (input->tool_focus) {
-        const int sx = wl_fixed_to_int(sx_w);
-        const int sy = wl_fixed_to_int(sy_w);
+        const float sx_f = (float)wl_fixed_to_double(sx_w);
+        const float sy_f = (float)wl_fixed_to_double(sy_w);
+        const int   sx   = (int)SDL_lroundf(sx_f * window->pointer_scale);
+        const int   sy   = (int)SDL_lroundf(sy_f * window->pointer_scale);
         SDL_SendMouseMotion(window->sdlwindow, 0, 0, sx, sy);
     }
 }
@@ -2345,12 +2349,19 @@ int Wayland_input_confine_pointer(struct SDL_WaylandInput *input, SDL_Window *wi
     if (SDL_RectEmpty(&window->mouse_rect)) {
         confine_rect = NULL;
     } else {
+        SDL_Rect scaled_mouse_rect;
+
+        scaled_mouse_rect.x = (int)SDL_floorf((float)window->mouse_rect.x / w->pointer_scale);
+        scaled_mouse_rect.y = (int)SDL_floorf((float)window->mouse_rect.y / w->pointer_scale);
+        scaled_mouse_rect.w = (int)SDL_ceilf((float)window->mouse_rect.w / w->pointer_scale);
+        scaled_mouse_rect.h = (int)SDL_ceilf((float)window->mouse_rect.h / w->pointer_scale);
+
         confine_rect = wl_compositor_create_region(d->compositor);
         wl_region_add(confine_rect,
-                      window->mouse_rect.x,
-                      window->mouse_rect.y,
-                      window->mouse_rect.w,
-                      window->mouse_rect.h);
+                      scaled_mouse_rect.x,
+                      scaled_mouse_rect.y,
+                      scaled_mouse_rect.w,
+                      scaled_mouse_rect.h);
     }
 
     confined_pointer =

src/video/wayland/SDL_waylandopengles.c

@@ -205,11 +205,11 @@ Wayland_GLES_GetDrawableSize(_THIS, SDL_Window * window, int * w, int * h)
         data = (SDL_WindowData *) window->driverdata;
 
         if (w) {
-            *w = window->w * data->scale_factor;
+            *w = data->drawable_width;
         }
 
         if (h) {
-            *h = window->h * data->scale_factor;
+            *h = data->drawable_height;
         }
     }
 }