Bug 1668805: Enable opaque region if new GDK API is availabe, r=stransky

From GTK 3.24.25 on we have a new API that allows us to savely apply
opaque regions to our own surfaces without risking to freeze GDK.

Differential Revision: https://phabricator.services.mozilla.com/D102835

modules/libpref/init/StaticPrefList.yaml

@@ -10561,6 +10561,12 @@
   type: RelaxedAtomicBool
   value: true
   mirror: always
+
+# Use opaque region for MozContainer wl_surface
+- name: widget.wayland.opaque-region.enabled
+  type: RelaxedAtomicBool
+  value: true
+  mirror: always
 #endif
 
 # Enable the RemoteLookAndFeel in content processes, which will cause all

modules/libpref/init/all.js

@@ -3785,7 +3785,6 @@ pref("network.psl.onUpdate_notify", false);
 #endif
 #ifdef MOZ_WAYLAND
   pref("widget.wayland_vsync.enabled", true);
-  pref("widget.wayland.use-opaque-region", false);
   pref("widget.use-xdg-desktop-portal", false);
 #endif
 

widget/gtk/MozContainerWayland.cpp

@@ -50,14 +50,14 @@
 
 #include "MozContainer.h"
 
-#include <glib.h>
-#include <gtk/gtk.h>
-#include <gdk/gdkx.h>
-#include "nsWaylandDisplay.h"
-#include "gfxPlatformGtk.h"
-#include <wayland-egl.h>
-#include <stdio.h>
 #include <dlfcn.h>
+#include <glib.h>
+#include <stdio.h>
+#include <wayland-egl.h>
+
+#include "gfxPlatformGtk.h"
+#include "nsGtkUtils.h"
+#include "nsWaylandDisplay.h"
 
 #undef LOG
 #ifdef MOZ_LOGGING
@@ -167,8 +167,9 @@ void moz_container_wayland_init(MozContainerWayland* container) {
   container->eglwindow = nullptr;
   container->frame_callback_handler = nullptr;
   container->ready_to_draw = false;
-  container->opaque_region_updates = false;
+  container->opaque_region_needs_updates = false;
   container->opaque_region_subtract_corners = false;
+  container->opaque_region_used = false;
   container->surface_needs_clear = true;
   container->subsurface_dx = 0;
   container->subsurface_dy = 0;
@@ -213,10 +214,65 @@ static void moz_container_wayland_frame_callback_handler(
 static const struct wl_callback_listener moz_container_frame_listener = {
     moz_container_wayland_frame_callback_handler};
 
+static void after_frame_clock_after_paint(GdkFrameClock* clock,
+                                          MozContainer* container) {
+  struct wl_surface* surface = moz_container_wayland_surface_lock(container);
+  if (surface) {
+    wl_surface_commit(surface);
+    moz_container_wayland_surface_unlock(container, &surface);
+  }
+}
+
+static bool moz_gdk_wayland_window_add_frame_callback_surface_locked(
+    MozContainer* container) {
+  static auto sGdkWaylandWindowAddCallbackSurface =
+      (void (*)(GdkWindow*, struct wl_surface*))dlsym(
+          RTLD_DEFAULT, "gdk_wayland_window_add_frame_callback_surface");
+
+  if (!StaticPrefs::widget_wayland_opaque_region_enabled() ||
+      !sGdkWaylandWindowAddCallbackSurface) {
+    return false;
+  }
+
+  GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(container));
+  MozContainerWayland* wl_container = &container->wl_container;
+
+  sGdkWaylandWindowAddCallbackSurface(window, wl_container->surface);
+
+  GdkFrameClock* frame_clock = gdk_window_get_frame_clock(window);
+  g_signal_connect_after(frame_clock, "after-paint",
+                         G_CALLBACK(after_frame_clock_after_paint), container);
+  return true;
+}
+
+static void moz_gdk_wayland_window_remove_frame_callback_surface_locked(
+    MozContainer* container) {
+  static auto sGdkWaylandWindowRemoveCallbackSurface =
+      (void (*)(GdkWindow*, struct wl_surface*))dlsym(
+          RTLD_DEFAULT, "gdk_wayland_window_remove_frame_callback_surface");
+
+  if (!sGdkWaylandWindowRemoveCallbackSurface) {
+    return;
+  }
+
+  GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(container));
+  MozContainerWayland* wl_container = &container->wl_container;
+
+  sGdkWaylandWindowRemoveCallbackSurface(window, wl_container->surface);
+
+  GdkFrameClock* frame_clock = gdk_window_get_frame_clock(window);
+  g_signal_handlers_disconnect_by_func(
+      frame_clock, FuncToGpointer(after_frame_clock_after_paint), container);
+}
+
 static void moz_container_wayland_unmap_internal(MozContainer* container) {
   MozContainerWayland* wl_container = &container->wl_container;
   MutexAutoLock lock(*wl_container->container_lock);
 
+  if (wl_container->opaque_region_used) {
+    moz_gdk_wayland_window_remove_frame_callback_surface_locked(container);
+  }
+
   g_clear_pointer(&wl_container->eglwindow, wl_egl_window_destroy);
   g_clear_pointer(&wl_container->subsurface, wl_subsurface_destroy);
   g_clear_pointer(&wl_container->surface, wl_surface_destroy);
@@ -336,7 +392,12 @@ static void moz_container_wayland_set_opaque_region_locked(
     MozContainer* container) {
   MozContainerWayland* wl_container = &container->wl_container;
 
-  if (!wl_container->opaque_region_updates) {
+  if (!wl_container->opaque_region_needs_updates) {
+    return;
+  }
+
+  if (!wl_container->opaque_region_used) {
+    wl_container->opaque_region_needs_updates = false;
     return;
   }
 
@@ -348,6 +409,7 @@ static void moz_container_wayland_set_opaque_region_locked(
       wl_container->opaque_region_subtract_corners);
   wl_surface_set_opaque_region(wl_container->surface, region);
   wl_region_destroy(region);
+  wl_container->opaque_region_needs_updates = false;
 }
 
 static void moz_container_wayland_set_opaque_region(MozContainer* container) {
@@ -437,6 +499,9 @@ static bool moz_container_wayland_surface_create_locked(
   wl_surface_commit(wl_container->surface);
   wl_display_flush(WaylandDisplayGet()->GetDisplay());
 
+  wl_container->opaque_region_used =
+      moz_gdk_wayland_window_add_frame_callback_surface_locked(container);
+
   LOGWAYLAND(("    created surface %p ID %d\n", (void*)wl_container->surface,
               wl_proxy_get_id((struct wl_proxy*)wl_container->surface)));
   return true;
@@ -504,7 +569,7 @@ gboolean moz_container_wayland_surface_needs_clear(MozContainer* container) {
 void moz_container_wayland_update_opaque_region(MozContainer* container,
                                                 bool aSubtractCorners) {
   MozContainerWayland* wl_container = &container->wl_container;
-  wl_container->opaque_region_updates = true;
+  wl_container->opaque_region_needs_updates = true;
   wl_container->opaque_region_subtract_corners = aSubtractCorners;
 
   // When GL compositor / WebRender is used,

widget/gtk/MozContainerWayland.h

@@ -37,9 +37,9 @@ struct MozContainerWayland {
   int subsurface_dx, subsurface_dy;
   struct wl_egl_window* eglwindow;
   struct wl_callback* frame_callback_handler;
-  gboolean opaque_region_updates;
+  gboolean opaque_region_needs_updates;
   gboolean opaque_region_subtract_corners;
-  gboolean opaque_region_fullscreen;
+  gboolean opaque_region_used;
   gboolean surface_needs_clear;
   gboolean ready_to_draw;
   gboolean before_first_size_alloc;

widget/gtk/mozgtk/mozgtk.c

@@ -550,6 +550,7 @@ STUB(gdk_display_manager_open_display)
 STUB(gdk_error_trap_pop_ignored)
 STUB(gdk_event_get_source_device)
 STUB(gdk_screen_get_monitor_workarea)
+STUB(gdk_window_get_frame_clock)
 STUB(gdk_window_get_type)
 STUB(gdk_window_set_opaque_region)
 STUB(gdk_x11_window_get_xid)

widget/gtk/nsWindow.cpp

@@ -379,7 +379,6 @@ static bool gBlockActivateEvent = false;
 static bool gGlobalsInitialized = false;
 static bool gRaiseWindows = true;
 static bool gUseWaylandVsync = true;
-static bool gUseWaylandUseOpaqueRegion = true;
 static bool gUseAspectRatio = true;
 static GList* gVisibleWaylandPopupWindows = nullptr;
 static uint32_t gLastTouchID = 0;
@@ -5662,8 +5661,7 @@ void nsWindow::UpdateTopLevelOpaqueRegion(void) {
   cairo_region_destroy(region);
 
 #ifdef MOZ_WAYLAND
-  // We don't set opaque region to mozContainer by default due to Bug 1615098.
-  if (!mIsX11Display && gUseWaylandUseOpaqueRegion) {
+  if (!mIsX11Display) {
     moz_container_wayland_update_opaque_region(mContainer, subtractCorners);
   }
 #endif
@@ -7345,8 +7343,6 @@ static nsresult initialize_prefs(void) {
       Preferences::GetBool("mozilla.widget.raise-on-setfocus", true);
   gUseWaylandVsync =
       Preferences::GetBool("widget.wayland_vsync.enabled", false);
-  gUseWaylandUseOpaqueRegion =
-      Preferences::GetBool("widget.wayland.use-opaque-region", false);
 
   if (Preferences::HasUserValue("widget.use-aspect-ratio")) {
     gUseAspectRatio = Preferences::GetBool("widget.use-aspect-ratio", true);