If SHM pixmaps support is available, for example, Intel drivers now support t...

webkit/glue/plugins/webplugin_delegate_impl_gtk.cc

Index: webkit/glue/plugins/webplugin_delegate_impl_gtk.cc
===================================================================
--- webkit/glue/plugins/webplugin_delegate_impl_gtk.cc	(revision 54851)
+++ webkit/glue/plugins/webplugin_delegate_impl_gtk.cc	(working copy)
@@ -44,6 +44,7 @@
       windowless_(false),
       plugin_(NULL),
       instance_(instance),
+      windowless_shm_pixmap_(None),
       pixmap_(NULL),
       first_event_time_(-1.0),
       plug_(NULL),
@@ -399,47 +400,99 @@
                         pixmap_draw_rect.right(),
                         pixmap_draw_rect.bottom());
 
-  EnsurePixmapAtLeastSize(pixmap_rect.width(), pixmap_rect.height());
-
-  // Copy the current image into the pixmap, so the plugin can draw over
-  // this background.
-  cairo_t* cairo = gdk_cairo_create(pixmap_);
-  BlitContextToContext(cairo, pixmap_draw_rect, context, draw_rect.origin());
-  cairo_destroy(cairo);
-
   // Construct the paint message, targeting the pixmap.
   NPEvent np_event = {0};
   XGraphicsExposeEvent &event = np_event.xgraphicsexpose;
   event.type = GraphicsExpose;
-  event.display = GDK_DISPLAY();
-  event.drawable = GDK_PIXMAP_XID(pixmap_);
   event.x = pixmap_draw_rect.x();
   event.y = pixmap_draw_rect.y();
   event.width = pixmap_draw_rect.width();
   event.height = pixmap_draw_rect.height();
+  event.display = GDK_DISPLAY();
 
-  // Tell the plugin to paint into the pixmap.
-  static StatsRate plugin_paint("Plugin.Paint");
-  StatsScope<StatsRate> scope(plugin_paint);
-  NPError err = instance()->NPP_HandleEvent(&np_event);
-  DCHECK_EQ(err, NPERR_NO_ERROR);
+  if (windowless_shm_pixmap_ != None) {
+    Pixmap pixmap = None;
+    GC xgc = NULL;
+    Display* display = event.display;
+    gfx::Rect plugin_draw_rect = draw_rect;
 
-  cairo_save(context);
-  // Now copy the rendered image pixmap back into the drawing buffer.
-  gdk_cairo_set_source_pixmap(context, pixmap_, -offset_x, -offset_y);
-  cairo_rectangle(context, draw_rect.x(), draw_rect.y(),
-                  draw_rect.width(), draw_rect.height());
-  cairo_clip(context);
-  cairo_paint(context);
+    // Make plugin_draw_rect relative to the plugin window.
+    plugin_draw_rect.Offset(-window_rect_.x(), -window_rect_.y());
 
+    // In case the drawing area does not start with the plugin window origin,
+    // we can not let the plugin directly draw over the shared memory pixmap.
+    if (plugin_draw_rect.x() != pixmap_draw_rect.x() ||
+        plugin_draw_rect.y() != pixmap_draw_rect.y()) {
+      pixmap = XCreatePixmap(display, windowless_shm_pixmap_,
+                             std::max(1, pixmap_rect.width()),
+                             std::max(1, pixmap_rect.height()),
+                             DefaultDepth(display, 0));
+      xgc = XCreateGC(display, windowless_shm_pixmap_, 0, NULL);
+      // Copy the current image into the pixmap, so the plugin can draw over it.
+      XCopyArea(display, windowless_shm_pixmap_, pixmap, xgc,
+                plugin_draw_rect.x(), plugin_draw_rect.y(),
+                pixmap_draw_rect.width(), pixmap_draw_rect.height(),
+                pixmap_draw_rect.x(), pixmap_draw_rect.y());
+
+      event.drawable = pixmap;
+    } else {
+      event.drawable = windowless_shm_pixmap_;
+    }
+
+    // Tell the plugin to paint into the pixmap.
+    static StatsRate plugin_paint("Plugin.Paint");
+    StatsScope<StatsRate> scope(plugin_paint);
+    NPError err = instance()->NPP_HandleEvent(&np_event);
+    DCHECK_EQ(err, NPERR_NO_ERROR);
+
+    if (pixmap != None) {
+      // Copy the rendered image pixmap back into the shm pixmap
+      // and thus the drawing buffer.
+      XCopyArea(display, pixmap, windowless_shm_pixmap_, xgc,
+                pixmap_draw_rect.x(), pixmap_draw_rect.y(),
+                pixmap_draw_rect.width(), pixmap_draw_rect.height(),
+                plugin_draw_rect.x(), plugin_draw_rect.y());
+      XSync(display, FALSE);
+      if (xgc)
+        XFreeGC(display, xgc);
+      XFreePixmap(display, pixmap);
+    } else {
+      XSync(display, FALSE);
+    }
+  } else {
+    EnsurePixmapAtLeastSize(pixmap_rect.width(), pixmap_rect.height());
+
+    // Copy the current image into the pixmap, so the plugin can draw over
+    // this background.
+    cairo_t* cairo = gdk_cairo_create(pixmap_);
+    BlitContextToContext(cairo, pixmap_draw_rect, context, draw_rect.origin());
+    cairo_destroy(cairo);
+
+    event.drawable = GDK_PIXMAP_XID(pixmap_);
+
+    // Tell the plugin to paint into the pixmap.
+    static StatsRate plugin_paint("Plugin.Paint");
+    StatsScope<StatsRate> scope(plugin_paint);
+    NPError err = instance()->NPP_HandleEvent(&np_event);
+    DCHECK_EQ(err, NPERR_NO_ERROR);
+
+    cairo_save(context);
+    // Now copy the rendered image pixmap back into the drawing buffer.
+    gdk_cairo_set_source_pixmap(context, pixmap_, -offset_x, -offset_y);
+    cairo_rectangle(context, draw_rect.x(), draw_rect.y(),
+                    draw_rect.width(), draw_rect.height());
+    cairo_clip(context);
+    cairo_paint(context);
+
 #ifdef DEBUG_RECTANGLES
-  // Draw some debugging rectangles.
-  // Pixmap rect = blue.
-  DrawDebugRectangle(context, pixmap_rect, 0, 0, 1);
-  // Drawing rect = red.
-  DrawDebugRectangle(context, draw_rect, 1, 0, 0);
+    // Draw some debugging rectangles.
+    // Pixmap rect = blue.
+    DrawDebugRectangle(context, pixmap_rect, 0, 0, 1);
+    // Drawing rect = red.
+    DrawDebugRectangle(context, draw_rect, 1, 0, 0);
 #endif
-  cairo_restore(context);
+    cairo_restore(context);
+  }
 }
 
 void WebPluginDelegateImpl::WindowlessSetWindow() {