[GTK] Web view background colors don't work in accelerated compositing mode

https://bugs.webkit.org/show_bug.cgi?id=159455

Reviewed by Michael Catanzaro.

Source/WebKit2:

In non AC mode it's the drawing area backing store the one drawing the background, and the web process just
renders into a transparent bitmap. In AC mode we need to make the redirected window pixmap transparent for the
web process to render there, and let the web view fill the background color before rendering the redirected
window pixmap on top. To be able to make the redirected window surface transparent, we need to ensure the parent
window has an RGBA visual, even when setting a fully opaque background, because we still need the web process
to render on the transparent xwindow.

* UIProcess/API/gtk/WebKitWebView.cpp: Update documentation of webkit_web_view_set_background_color() since now
it's required to set the RGBA visual even for opaque colors in case AC mode is enabled.
* UIProcess/API/gtk/WebKitWebViewBase.cpp:
(webkitWebViewRenderAcceleratedCompositingResults): When a background color has been set, fill it before
rendering the redirected window surface.
* UIProcess/gtk/RedirectedXCompositeWindow.cpp:
(WebKit::RedirectedXCompositeWindow::RedirectedXCompositeWindow): Mark the surface as dirty after every damage
event, since the web process has modified it.
(WebKit::RedirectedXCompositeWindow::surface): Initialize the surface after creating it, to avoid flickering and
rendering artifacts when waiting for the first damage event from the web process.
* WebProcess/WebPage/gtk/LayerTreeHostGtk.cpp:
(WebKit::LayerTreeHostGtk::compositeLayersToContext): Use a fully transparent color to clear the context when the page
is resized or when a view background color has been set.

Tools:

Set always RGBA visual to the view widget when setting a background color.

* MiniBrowser/gtk/BrowserWindow.c:
(browser_window_set_background_color):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@203496 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Author: [email protected]

Source/WebKit2/ChangeLog

@@ -1,3 +1,31 @@
+2016-07-21  Carlos Garcia Campos  <[email protected]>
+
+        [GTK] Web view background colors don't work in accelerated compositing mode
+        https://bugs.webkit.org/show_bug.cgi?id=159455
+
+        Reviewed by Michael Catanzaro.
+
+        In non AC mode it's the drawing area backing store the one drawing the background, and the web process just
+        renders into a transparent bitmap. In AC mode we need to make the redirected window pixmap transparent for the
+        web process to render there, and let the web view fill the background color before rendering the redirected
+        window pixmap on top. To be able to make the redirected window surface transparent, we need to ensure the parent
+        window has an RGBA visual, even when setting a fully opaque background, because we still need the web process
+        to render on the transparent xwindow.
+
+        * UIProcess/API/gtk/WebKitWebView.cpp: Update documentation of webkit_web_view_set_background_color() since now
+        it's required to set the RGBA visual even for opaque colors in case AC mode is enabled.
+        * UIProcess/API/gtk/WebKitWebViewBase.cpp:
+        (webkitWebViewRenderAcceleratedCompositingResults): When a background color has been set, fill it before
+        rendering the redirected window surface.
+        * UIProcess/gtk/RedirectedXCompositeWindow.cpp:
+        (WebKit::RedirectedXCompositeWindow::RedirectedXCompositeWindow): Mark the surface as dirty after every damage
+        event, since the web process has modified it.
+        (WebKit::RedirectedXCompositeWindow::surface): Initialize the surface after creating it, to avoid flickering and
+        rendering artifacts when waiting for the first damage event from the web process.
+        * WebProcess/WebPage/gtk/LayerTreeHostGtk.cpp:
+        (WebKit::LayerTreeHostGtk::compositeLayersToContext): Use a fully transparent color to clear the context when the page
+        is resized or when a view background color has been set.
+
 2016-07-20  Carlos Garcia Campos  <[email protected]>
 
         [GTK] Avoid the redirected window resize when the view is realized in AC mode

Source/WebKit2/UIProcess/API/gtk/WebKitWebView.cpp

@@ -3515,25 +3515,22 @@ void webkitWebViewWebProcessCrashed(WebKitWebView* webView)
  * the actual contents are rendered. Note that if the web page loaded in @web_view
  * specifies a background color, it will take precedence over the @rgba color.
  * By default the @web_view background color is opaque white.
- * If the @rgba color is not fully opaque, the parent window must have a RGBA visual and
- * #GtkWidget:app-paintable property set to %TRUE, for the transparencies to work.
+ * Note that the parent window must have a RGBA visual and
+ * #GtkWidget:app-paintable property set to %TRUE for backgrounds colors to work.
  *
  * <informalexample><programlisting>
  * static void browser_window_set_background_color (BrowserWindow *window,
  *                                                  const GdkRGBA *rgba)
  * {
  *     WebKitWebView *web_view;
+ *     GdkScreen *screen = gtk_window_get_screen (GTK_WINDOW (window));
+ *     GdkVisual *rgba_visual = gdk_screen_get_rgba_visual (screen);
  *
- *     if (rgba->alpha < 1) {
- *         GdkScreen *screen = gtk_window_get_screen (GTK_WINDOW (window));
- *         GdkVisual *rgba_visual = gdk_screen_get_rgba_visual (screen);
+ *     if (!rgba_visual)
+ *          return;
  *
- *         if (!rgba_visual)
- *              return;
- *
- *         gtk_widget_set_visual (GTK_WIDGET (window), rgba_visual);
- *         gtk_widget_set_app_paintable (GTK_WIDGET (window), TRUE);
- *     }
+ *     gtk_widget_set_visual (GTK_WIDGET (window), rgba_visual);
+ *     gtk_widget_set_app_paintable (GTK_WIDGET (window), TRUE);
  *
  *     web_view = browser_window_get_web_view (window);
  *     webkit_web_view_set_background_color (web_view, rgba);

Source/WebKit2/UIProcess/API/gtk/WebKitWebViewBase.cpp

@@ -592,10 +592,28 @@ static bool webkitWebViewRenderAcceleratedCompositingResults(WebKitWebViewBase*
     webkitWebViewBaseResizeRedirectedWindow(webViewBase);
     if (cairo_surface_t* surface = priv->redirectedWindow->surface()) {
         cairo_save(cr);
+
+        if (!priv->pageProxy->drawsBackground()) {
+            const WebCore::Color& color = priv->pageProxy->backgroundColor();
+            if (color.hasAlpha()) {
+                cairo_rectangle(cr, clipRect->x, clipRect->y, clipRect->width, clipRect->height);
+                cairo_set_operator(cr, CAIRO_OPERATOR_CLEAR);
+                cairo_fill(cr);
+            }
+
+            if (color.alpha() > 0) {
+                setSourceRGBAFromColor(cr, color);
+                cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+                cairo_rectangle(cr, clipRect->x, clipRect->y, clipRect->width, clipRect->height);
+                cairo_fill(cr);
+            }
+        }
+
         cairo_rectangle(cr, clipRect->x, clipRect->y, clipRect->width, clipRect->height);
         cairo_set_source_surface(cr, surface, 0, 0);
-        cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+        cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
         cairo_fill(cr);
+
         cairo_restore(cr);
     }
 

Source/WebKit2/UIProcess/gtk/RedirectedXCompositeWindow.cpp

@@ -189,7 +189,12 @@ RedirectedXCompositeWindow::RedirectedXCompositeWindow(WebPageProxy& webPage, co
         &windowAttributes);
     XMapWindow(m_display, m_window.get());
 
-    xDamageNotifier().add(m_window.get(), WTFMove(damageNotify));
+    xDamageNotifier().add(m_window.get(), [this, damageNotify = WTFMove(damageNotify)] {
+        // The surface has been modified by the web process, mark it as dirty.
+        if (m_surface)
+            cairo_surface_mark_dirty(m_surface.get());
+        damageNotify();
+    });
 
     while (1) {
         XEvent event;
@@ -269,14 +274,18 @@ cairo_surface_t* RedirectedXCompositeWindow::surface()
     cairoSurfaceSetDeviceScale(newSurface.get(), m_webPage.deviceScaleFactor(), m_webPage.deviceScaleFactor());
 
     RefPtr<cairo_t> cr = adoptRef(cairo_create(newSurface.get()));
-    cairo_set_source_rgb(cr.get(), 1, 1, 1);
+    if (!m_webPage.drawsBackground())
+        cairo_set_operator(cr.get(), CAIRO_OPERATOR_CLEAR);
+    else
+        setSourceRGBAFromColor(cr.get(), m_webPage.backgroundColor());
     cairo_paint(cr.get());
 
     // Nvidia drivers seem to prepare their redirected window pixmap asynchronously, so for a few fractions
     // of a second after each resize, while doing continuous resizing (which constantly destroys and creates
     // pixmap window-backings), the pixmap memory is uninitialized. To work around this issue, paint the old
     // pixmap to the new one to properly initialize it.
     if (m_surface) {
+        cairo_set_operator(cr.get(), CAIRO_OPERATOR_OVER);
         cairo_set_source_surface(cr.get(), m_surface.get(), 0, 0);
         cairo_paint(cr.get());
     }

Source/WebKit2/WebProcess/WebPage/gtk/LayerTreeHostGtk.cpp

@@ -313,9 +313,8 @@ void LayerTreeHostGtk::compositeLayersToContext(CompositePurpose purpose)
     // we set the viewport parameters directly from the window size.
     IntSize contextSize = m_context->defaultFrameBufferSize();
     glViewport(0, 0, contextSize.width(), contextSize.height());
-
-    if (purpose == ForResize) {
-        glClearColor(1, 1, 1, 0);
+    if (purpose == ForResize || !m_webPage.drawsBackground()) {
+        glClearColor(0, 0, 0, 0);
         glClear(GL_COLOR_BUFFER_BIT);
     }
 

Tools/ChangeLog

@@ -1,3 +1,15 @@
+2016-07-21  Carlos Garcia Campos  <[email protected]>
+
+        [GTK] Web view background colors don't work in accelerated compositing mode
+        https://bugs.webkit.org/show_bug.cgi?id=159455
+
+        Reviewed by Michael Catanzaro.
+
+        Set always RGBA visual to the view widget when setting a background color.
+
+        * MiniBrowser/gtk/BrowserWindow.c:
+        (browser_window_set_background_color):
+
 2016-07-20  Youenn Fablet  <[email protected]>
 
         Bots should run built-ins generator tests

Tools/MiniBrowser/gtk/BrowserWindow.c

@@ -1069,14 +1069,12 @@ void browser_window_set_background_color(BrowserWindow *window, GdkRGBA *rgba)
     if (gdk_rgba_equal(rgba, &viewRGBA))
         return;
 
-    if (rgba->alpha < 1) {
-        GdkVisual *rgbaVisual = gdk_screen_get_rgba_visual(gtk_window_get_screen(GTK_WINDOW(window)));
-        if (!rgbaVisual)
-            return;
+    GdkVisual *rgbaVisual = gdk_screen_get_rgba_visual(gtk_window_get_screen(GTK_WINDOW(window)));
+    if (!rgbaVisual)
+        return;
 
-        gtk_widget_set_visual(GTK_WIDGET(window), rgbaVisual);
-        gtk_widget_set_app_paintable(GTK_WIDGET(window), TRUE);
-    }
+    gtk_widget_set_visual(GTK_WIDGET(window), rgbaVisual);
+    gtk_widget_set_app_paintable(GTK_WIDGET(window), TRUE);
 
     webkit_web_view_set_background_color(webView, rgba);
 }