SDL: wayland: Add dedupe logic to window geometry configuration

From a8cb7bbe2fd7ab230c7fdb9d98a7af6c1f9f6c4a Mon Sep 17 00:00:00 2001
From: Frank Praznik <[EMAIL REDACTED]>
Date: Sat, 1 Oct 2022 11:31:26 -0400
Subject: [PATCH] wayland: Add dedupe logic to window geometry configuration

Adds deduplication logic to ConfigureWindowGeometry() to avoid setting redundant backbuffer, viewport and surface opaque region dimensions. State is now only set when the window and/or backbuffer dimensions change.

This repurposes the viewport rect to always hold the actual size of the window, which can differ from the SDL size if things are being scaled. The SDL_Rect was removed in favor of two ints, as the x/y members of the struct were never used, so they just wasted space.

Since the internal variables always have the true window size, the width/height getter functions are no longer required and can be removed.
---
 src/video/wayland/SDL_waylandwindow.c | 131 +++++++++++---------------
 src/video/wayland/SDL_waylandwindow.h |   2 +-
 2 files changed, 58 insertions(+), 75 deletions(-)

diff --git a/src/video/wayland/SDL_waylandwindow.c b/src/video/wayland/SDL_waylandwindow.c
index 4f015b03ba2e..2abb2d54e689 100644
--- a/src/video/wayland/SDL_waylandwindow.c
+++ b/src/video/wayland/SDL_waylandwindow.c
@@ -164,21 +164,6 @@ NeedViewport(SDL_Window *window)
     return SDL_FALSE;
 }
 
-/* If a viewport is active, use the width and height for the window dimensions. */
-SDL_FORCE_INLINE int
-GetWindowWidth(SDL_Window *window)
-{
-    SDL_WindowData *data = (SDL_WindowData *)window->driverdata;
-    return SDL_RectEmpty(&data->viewport_rect) ? window->w : data->viewport_rect.w;
-}
-
-SDL_FORCE_INLINE int
-GetWindowHeight(SDL_Window *window)
-{
-    SDL_WindowData *data = (SDL_WindowData *)window->driverdata;
-    return SDL_RectEmpty(&data->viewport_rect) ? window->h : data->viewport_rect.h;
-}
-
 static void
 GetBufferSize(SDL_Window *window, int *width, int *height)
 {
@@ -247,11 +232,16 @@ ConfigureWindowGeometry(SDL_Window *window)
     SDL_VideoData         *viddata = data->waylandData;
     SDL_WaylandOutputData *output  = (SDL_WaylandOutputData *)SDL_GetDisplayForWindow(window)->driverdata;
     struct wl_region      *region;
+    const int              old_dw = data->drawable_width;
+    const int              old_dh = data->drawable_height;
+    SDL_bool               window_size_changed;
+    SDL_bool               drawable_size_changed;
 
     /* Set the drawable backbuffer size. */
     GetBufferSize(window, &data->drawable_width, &data->drawable_height);
+    drawable_size_changed = data->drawable_width != old_dw || data->drawable_height != old_dh;
 
-    if (data->egl_window) {
+    if (data->egl_window && drawable_size_changed) {
         WAYLAND_wl_egl_window_resize(data->egl_window,
                                      data->drawable_width,
                                      data->drawable_height,
@@ -260,58 +250,63 @@ ConfigureWindowGeometry(SDL_Window *window)
 
     if (FullscreenModeEmulation(window) && NeedViewport(window)) {
         int fs_width, fs_height;
-        int src_width, src_height;
         const int output_width  = data->fs_output_width ? data->fs_output_width : output->width;
         const int output_height = data->fs_output_height ? data->fs_output_height : output->height;
 
-        GetFullScreenDimensions(window, &fs_width, &fs_height, &src_width, &src_height);
+        window_size_changed = data->window_width != output_width || data->window_height != output_height;
 
-        /* Set the buffer scale to 1 since a viewport will be used. */
-        wl_surface_set_buffer_scale(data->surface, 1);
-        SetDrawSurfaceViewport(window, src_width, src_height, output_width, output_height);
+        if (window_size_changed || drawable_size_changed) {
+            GetFullScreenDimensions(window, &fs_width, &fs_height, NULL, NULL);
 
-        data->viewport_rect.x = 0;
-        data->viewport_rect.y = 0;
-        data->viewport_rect.w = output_width;
-        data->viewport_rect.h = output_height;
+            /* Set the buffer scale to 1 since a viewport will be used. */
+            wl_surface_set_buffer_scale(data->surface, 1);
+            SetDrawSurfaceViewport(window, data->drawable_width, data->drawable_height,
+                                   output_width, output_height);
 
-        data->pointer_scale_x = (float)fs_width / (float)output_width;
-        data->pointer_scale_y = (float)fs_height / (float)output_height;
+            data->window_width  = output_width;
+            data->window_height = output_height;
 
-        if (!EGLTransparencyEnabled()) {
-            region = wl_compositor_create_region(viddata->compositor);
-            wl_region_add(region, data->viewport_rect.x, data->viewport_rect.y,
-                          data->viewport_rect.w, data->viewport_rect.h);
-            wl_surface_set_opaque_region(data->surface, region);
-            wl_region_destroy(region);
+            data->pointer_scale_x = (float) fs_width / (float) output_width;
+            data->pointer_scale_y = (float) fs_height / (float) output_height;
         }
     } else {
-        if (NeedViewport(window)) {
-            wl_surface_set_buffer_scale(data->surface, 1);
-            SetDrawSurfaceViewport(window, data->drawable_width, data->drawable_height, window->w, window->h);
-        } else {
-            UnsetDrawSurfaceViewport(window);
+        window_size_changed = data->window_width != window->w || data->window_height != window->h;
 
-            /* Round to the next integer in case of a fractional value. */
-            wl_surface_set_buffer_scale(data->surface, (int32_t)SDL_ceilf(data->scale_factor));
-        }
+        if (window_size_changed || drawable_size_changed) {
+            if (NeedViewport(window)) {
+                wl_surface_set_buffer_scale(data->surface, 1);
+                SetDrawSurfaceViewport(window, data->drawable_width, data->drawable_height, window->w, window->h);
+            } else {
+                UnsetDrawSurfaceViewport(window);
+
+                /* Round to the next integer in case of a fractional value. */
+                wl_surface_set_buffer_scale(data->surface, (int32_t) SDL_ceilf(data->scale_factor));
+            }
 
-        SDL_zero(data->viewport_rect);
+            data->window_width = window->w;
+            data->window_height = window->h;
 
-        data->pointer_scale_x = 1.0f;
-        data->pointer_scale_y = 1.0f;
+            data->pointer_scale_x = 1.0f;
+            data->pointer_scale_y = 1.0f;
+        }
+    }
 
+    /*
+     * The opaque and pointer confinement regions only need to be recalculated
+     * if the output size has changed.
+     */
+    if (window_size_changed) {
         if (!EGLTransparencyEnabled()) {
             region = wl_compositor_create_region(viddata->compositor);
-            wl_region_add(region, 0, 0, window->w, window->h);
+            wl_region_add(region, 0, 0,
+                          data->window_width, data->window_height);
             wl_surface_set_opaque_region(data->surface, region);
             wl_region_destroy(region);
         }
-    }
 
-    /* Recreate the pointer confinement region when the window geometry changes. */
-    if (data->confined_pointer) {
-        Wayland_input_confine_pointer(viddata->input, window);
+        if (data->confined_pointer) {
+            Wayland_input_confine_pointer(viddata->input, window);
+        }
     }
 }
 
@@ -361,7 +356,7 @@ SetMinMaxDimensions(SDL_Window *window, SDL_bool commit)
                                             max_height);
 
         if (commit) {
-            struct libdecor_state *state = libdecor_state_new(GetWindowWidth(window), GetWindowHeight(window));
+            struct libdecor_state *state = libdecor_state_new(wind->window_width, wind->window_height);
             libdecor_frame_commit(wind->shell_surface.libdecor.frame, state, NULL);
             libdecor_state_free(state);
             wl_surface_commit(wind->surface);
@@ -415,7 +410,7 @@ SetFullscreen(SDL_Window *window, struct wl_output *output)
                 libdecor_frame_set_capabilities(wind->shell_surface.libdecor.frame, LIBDECOR_ACTION_RESIZE);
                 wl_surface_commit(wind->surface);
             } else {
-                struct libdecor_state *state = libdecor_state_new(GetWindowWidth(window), GetWindowHeight(window));
+                struct libdecor_state *state = libdecor_state_new(wind->window_width, wind->window_height);
                 libdecor_frame_commit(wind->shell_surface.libdecor.frame, state, NULL);
                 libdecor_state_free(state);
                 wl_surface_commit(wind->surface);
@@ -430,7 +425,7 @@ SetFullscreen(SDL_Window *window, struct wl_output *output)
                 libdecor_frame_unset_capabilities(wind->shell_surface.libdecor.frame, LIBDECOR_ACTION_RESIZE);
                 wl_surface_commit(wind->surface);
             } else {
-                struct libdecor_state *state = libdecor_state_new(GetWindowWidth(window), GetWindowHeight(window));
+                struct libdecor_state *state = libdecor_state_new(wind->window_width, wind->window_height);
                 libdecor_frame_commit(wind->shell_surface.libdecor.frame, state, NULL);
                 libdecor_state_free(state);
                 wl_surface_commit(wind->surface);
@@ -509,14 +504,14 @@ CommitWindowGeometry(SDL_Window *window)
 
 #ifdef HAVE_LIBDECOR_H
     if (WINDOW_IS_LIBDECOR(data, window) && wind->shell_surface.libdecor.frame) {
-        struct libdecor_state *state = libdecor_state_new(GetWindowWidth(window), GetWindowHeight(window));
+        struct libdecor_state *state = libdecor_state_new(wind->window_width, wind->window_height);
         libdecor_frame_commit(wind->shell_surface.libdecor.frame, state, NULL);
         libdecor_state_free(state);
     } else
 #endif
     if (viddata->shell.xdg && wind->shell_surface.xdg.surface) {
         xdg_surface_set_window_geometry(wind->shell_surface.xdg.surface, 0, 0,
-                                        GetWindowWidth(window), GetWindowHeight(window));
+                                        wind->window_width, wind->window_height);
     }
 }
 
@@ -527,11 +522,9 @@ surface_damage_frame_done(void *data, struct wl_callback *cb, uint32_t time)
 {
     SDL_WindowData *wind = (SDL_WindowData *)data;
 
-    /* Manually set the damage region when using a viewport. */
-    if (!SDL_RectEmpty(&wind->viewport_rect)) {
-        wl_surface_damage(wind->surface, wind->viewport_rect.x, wind->viewport_rect.y,
-                          wind->viewport_rect.w, wind->viewport_rect.h);
-    }
+    /* Set the damage region. */
+    wl_surface_damage(wind->surface, 0, 0,
+                      wind->window_width, wind->window_height);
 
     wl_callback_destroy(cb);
     wind->surface_damage_frame_callback = wl_surface_frame(wind->surface);
@@ -933,7 +926,7 @@ decoration_frame_configure(struct libdecor_frame *frame,
     wind->shell_surface.libdecor.initial_configure_seen = SDL_TRUE;
 
     /* ... then commit the changes on the libdecor side. */
-    state = libdecor_state_new(GetWindowWidth(window), GetWindowHeight(window));
+    state = libdecor_state_new(wind->window_width, wind->window_height);
     libdecor_frame_commit(frame, state, configuration);
     libdecor_state_free(state);
 
@@ -1971,7 +1964,6 @@ int Wayland_CreateWindow(_THIS, SDL_Window *window)
 {
     SDL_WindowData *data;
     SDL_VideoData *c;
-    struct wl_region *region;
 
     data = SDL_calloc(1, sizeof *data);
     if (data == NULL)
@@ -1998,8 +1990,6 @@ int Wayland_CreateWindow(_THIS, SDL_Window *window)
     data->sdlwindow = window;
 
     data->scale_factor = 1.0f;
-    data->pointer_scale_x = 1.0f;
-    data->pointer_scale_y = 1.0f;
 
     if (window->flags & SDL_WINDOW_ALLOW_HIGHDPI) {
         int i;
@@ -2021,6 +2011,9 @@ int Wayland_CreateWindow(_THIS, SDL_Window *window)
 
     SDL_WAYLAND_register_surface(data->surface);
 
+    /* Must be called before EGL configuration to set the drawable backbuffer size. */
+    ConfigureWindowGeometry(window);
+
     /* Fire a callback when the compositor wants a new frame rendered.
      * Right now this only matters for OpenGL; we use this callback to add a
      * wait timeout that avoids getting deadlocked by the compositor when the
@@ -2048,9 +2041,6 @@ int Wayland_CreateWindow(_THIS, SDL_Window *window)
     }
 #endif /* SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH */
 
-    data->drawable_width = SDL_lroundf(window->w * data->scale_factor);
-    data->drawable_height = SDL_lroundf(window->h * data->scale_factor);
-
     if (window->flags & SDL_WINDOW_OPENGL) {
         data->egl_window = WAYLAND_wl_egl_window_create(data->surface, data->drawable_width, data->drawable_height);
 
@@ -2072,13 +2062,6 @@ int Wayland_CreateWindow(_THIS, SDL_Window *window)
     }
 #endif /* SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH */
 
-    if (!EGLTransparencyEnabled()) {
-        region = wl_compositor_create_region(c->compositor);
-        wl_region_add(region, 0, 0, window->w, window->h);
-        wl_surface_set_opaque_region(data->surface, region);
-        wl_region_destroy(region);
-    }
-
     if (c->relative_mouse_mode) {
         Wayland_input_lock_pointer(c->input);
     }
@@ -2149,7 +2132,7 @@ Wayland_HandleResize(SDL_Window *window, int width, int height, float scale)
         viddata->shell.xdg &&
         data->shell_surface.xdg.surface) {
         xdg_surface_set_window_geometry(data->shell_surface.xdg.surface, 0, 0,
-                                        GetWindowWidth(window), GetWindowHeight(window));
+                                        data->window_width, data->window_height);
     }
 }
 
diff --git a/src/video/wayland/SDL_waylandwindow.h b/src/video/wayland/SDL_waylandwindow.h
index 0a37a2781309..a14ba13649e8 100644
--- a/src/video/wayland/SDL_waylandwindow.h
+++ b/src/video/wayland/SDL_waylandwindow.h
@@ -105,7 +105,7 @@ typedef struct {
     float pointer_scale_y;
     int drawable_width, drawable_height;
     int fs_output_width, fs_output_height;
-    SDL_Rect viewport_rect;
+    int window_width, window_height;
     SDL_bool needs_resize_event;
     SDL_bool floating_resize_pending;
     SDL_bool is_fullscreen;