[GTK] Rendering artifacts when resizing the window in X11 with AC mod…

…e enabled

https://bugs.webkit.org/show_bug.cgi?id=168728

Reviewed by Žan Doberšek.

This happens because the pixmap we create from the redirected window is uninitialized until the threaded
compositor renders into it. We should always initialize the pixmap right after it's created.

* WebProcess/WebPage/gtk/AcceleratedSurfaceX11.cpp:
(WebKit::defaultVisual): Helper static method to get the default GdkVisual.
(WebKit::AcceleratedSurfaceX11::AcceleratedSurfaceX11): Use createPixmap().
(WebKit::AcceleratedSurfaceX11::createPixmap): Create and initialize the pixmap.
(WebKit::AcceleratedSurfaceX11::resize): Use createPixmap().
* WebProcess/WebPage/gtk/AcceleratedSurfaceX11.h:

Canonical link: https://commits.webkit.org/185899@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@213061 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebKit2/ChangeLog

@@ -1,3 +1,20 @@
+2017-02-27  Carlos Garcia Campos  <cgarcia@igalia.com>
+
+        [GTK] Rendering artifacts when resizing the window in X11 with AC mode enabled
+        https://bugs.webkit.org/show_bug.cgi?id=168728
+
+        Reviewed by Žan Doberšek.
+
+        This happens because the pixmap we create from the redirected window is uninitialized until the threaded
+        compositor renders into it. We should always initialize the pixmap right after it's created.
+
+        * WebProcess/WebPage/gtk/AcceleratedSurfaceX11.cpp:
+        (WebKit::defaultVisual): Helper static method to get the default GdkVisual.
+        (WebKit::AcceleratedSurfaceX11::AcceleratedSurfaceX11): Use createPixmap().
+        (WebKit::AcceleratedSurfaceX11::createPixmap): Create and initialize the pixmap.
+        (WebKit::AcceleratedSurfaceX11::resize): Use createPixmap().
+        * WebProcess/WebPage/gtk/AcceleratedSurfaceX11.h:
+
 2017-02-27  Carlos Garcia Campos  <cgarcia@igalia.com>
 
         [GTK] Flickering when leaving accelerated compositing mode

Source/WebKit2/WebProcess/WebPage/gtk/AcceleratedSurfaceX11.cpp

@@ -30,8 +30,10 @@
 
 #include "WebPage.h"
 #include <WebCore/PlatformDisplayX11.h>
+#include <WebCore/RefPtrCairo.h>
 #include <X11/Xlib.h>
 #include <X11/extensions/Xcomposite.h>
+#include <cairo-xlib.h>
 #include <gdk/gdkx.h>
 #include <wtf/RunLoop.h>
 
@@ -46,17 +48,22 @@ std::unique_ptr<AcceleratedSurfaceX11> AcceleratedSurfaceX11::create(WebPage& we
     return std::unique_ptr<AcceleratedSurfaceX11>(new AcceleratedSurfaceX11(webPage));
 }
 
+static GdkVisual* defaultVisual()
+{
+    if (GdkVisual* visual = gdk_screen_get_rgba_visual(gdk_screen_get_default()))
+        return visual;
+    return gdk_screen_get_system_visual(gdk_screen_get_default());
+}
+
 AcceleratedSurfaceX11::AcceleratedSurfaceX11(WebPage& webPage)
     : AcceleratedSurface(webPage)
     , m_display(downcast<PlatformDisplayX11>(PlatformDisplay::sharedDisplay()).native())
 {
     Screen* screen = DefaultScreenOfDisplay(m_display);
 
     ASSERT(downcast<PlatformDisplayX11>(PlatformDisplay::sharedDisplay()).native() == m_display);
-    GdkVisual* visual = gdk_screen_get_rgba_visual(gdk_screen_get_default());
-    if (!visual)
-        visual = gdk_screen_get_system_visual(gdk_screen_get_default());
 
+    GdkVisual* visual = defaultVisual();
     XUniqueColormap colormap(XCreateColormap(m_display, RootWindowOfScreen(screen), GDK_VISUAL_XVISUAL(visual), AllocNone));
 
     XSetWindowAttributes windowAttributes;
@@ -103,8 +110,7 @@ AcceleratedSurfaceX11::AcceleratedSurfaceX11(WebPage& webPage)
     }
     XSelectInput(m_display, m_window.get(), NoEventMask);
     XCompositeRedirectWindow(m_display, m_window.get(), CompositeRedirectManual);
-    m_pixmap = XCompositeNameWindowPixmap(m_display, m_window.get());
-    XSync(m_display, False);
+    createPixmap();
 }
 
 AcceleratedSurfaceX11::~AcceleratedSurfaceX11()
@@ -118,6 +124,16 @@ AcceleratedSurfaceX11::~AcceleratedSurfaceX11()
     m_parentWindow.reset();
 }
 
+void AcceleratedSurfaceX11::createPixmap()
+{
+    m_pixmap = XCompositeNameWindowPixmap(m_display, m_window.get());
+    RefPtr<cairo_surface_t> surface = adoptRef(cairo_xlib_surface_create(m_display, m_pixmap.get(), GDK_VISUAL_XVISUAL(defaultVisual()), m_size.width(), m_size.height()));
+    RefPtr<cairo_t> cr = adoptRef(cairo_create(surface.get()));
+    cairo_set_operator(cr.get(), CAIRO_OPERATOR_CLEAR);
+    cairo_paint(cr.get());
+    XSync(m_display, False);
+}
+
 bool AcceleratedSurfaceX11::resize(const IntSize& size)
 {
     if (!AcceleratedSurface::resize(size))
@@ -129,8 +145,7 @@ bool AcceleratedSurfaceX11::resize(const IntSize& size)
 
     // Release the previous pixmap later to give some time to the UI process to update.
     RunLoop::main().dispatchAfter(std::chrono::seconds(5), [pixmap = WTFMove(m_pixmap)] { });
-    m_pixmap = XCompositeNameWindowPixmap(m_display, m_window.get());
-    XSync(m_display, False);
+    createPixmap();
     return true;
 }
 

Source/WebKit2/WebProcess/WebPage/gtk/AcceleratedSurfaceX11.h

@@ -52,6 +52,8 @@ class AcceleratedSurfaceX11 final : public AcceleratedSurface {
 private:
     AcceleratedSurfaceX11(WebPage&);
 
+    void createPixmap();
+
     Display* m_display { nullptr };
     WebCore::XUniqueWindow m_window;
     WebCore::XUniqueWindow m_parentWindow;