Enable accelerated composition with QtWidgets view for testing.

Only enable it when the --force-compositing-mode switch is
used. The purpose of this is only to allow testing pinch-zooming
until we are able to use the delegated renderer in the QtQuick view.

Change-Id: I2ca265c84c8fe6a74299f1b2757ad525f33fae17
Reviewed-by: Pierre Rossi <pierre.rossi@gmail.com>
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>

5 files changed, 32 insertions, 7 deletions

diff --git a/lib/quick/render_widget_host_view_qt_delegate_quick.cpp b/lib/quick/render_widget_host_view_qt_delegate_quick.cpp
index d15bac21f..0c67f6e2f 100644
--- a/lib/quick/render_widget_host_view_qt_delegate_quick.cpp
+++ b/lib/quick/render_widget_host_view_qt_delegate_quick.cpp
@@ -83,7 +83,10 @@ bool RenderWidgetHostViewQtDelegateQuick::isVisible() const
 
 QWindow* RenderWidgetHostViewQtDelegateQuick::window() const
 {
-    return QQuickPaintedItem::window();
+    // Only used to enable accelerated compositing by the compositor
+    // directly on our native window, which we want to eventually do
+    // through the delegated renderer instead.
+    return 0;
 }
 
 void RenderWidgetHostViewQtDelegateQuick::update(const QRect& rect)
diff --git a/lib/render_widget_host_view_qt.cpp b/lib/render_widget_host_view_qt.cpp
index ed648f8ec..82ec9ea83 100644
--- a/lib/render_widget_host_view_qt.cpp
+++ b/lib/render_widget_host_view_qt.cpp
@@ -181,10 +181,7 @@ gfx::NativeView RenderWidgetHostViewQt::GetNativeView() const
 
 gfx::NativeViewId RenderWidgetHostViewQt::GetNativeViewId() const
 {
-    // This function is used in IPC in place of GetNativeView
-    // and we can possibly avoid calls for now.
-    QT_NOT_USED
-    return m_delegate->window()->winId();
+    return m_delegate->window() ? m_delegate->window()->winId() : 0;
 }
 
 gfx::NativeViewAccessible RenderWidgetHostViewQt::GetNativeViewAccessible()
@@ -430,8 +427,8 @@ gfx::Rect RenderWidgetHostViewQt::GetBoundsInRootWindow()
 
 gfx::GLSurfaceHandle RenderWidgetHostViewQt::GetCompositingSurface()
 {
-    QT_NOT_YET_IMPLEMENTED
-    return gfx::GLSurfaceHandle();
+    gfx::NativeViewId nativeViewId = GetNativeViewId();
+    return nativeViewId ? gfx::GLSurfaceHandle(nativeViewId, gfx::NATIVE_TRANSPORT) : gfx::GLSurfaceHandle();
 }
 
 void RenderWidgetHostViewQt::SetHasHorizontalScrollbar(bool) { }
diff --git a/lib/render_widget_host_view_qt_delegate.cpp b/lib/render_widget_host_view_qt_delegate.cpp
index b6ae928bc..3c68ac968 100644
--- a/lib/render_widget_host_view_qt_delegate.cpp
+++ b/lib/render_widget_host_view_qt_delegate.cpp
@@ -44,9 +44,16 @@
 #include "backing_store_qt.h"
 #include "render_widget_host_view_qt.h"
 
+#include "base/command_line.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
+#include "content/public/common/content_switches.h"
 #include <QPainter>
 
+bool RenderWidgetHostViewQtDelegate::isCompositingModeForced()
+{
+    return CommandLine::ForCurrentProcess()->HasSwitch(switches::kForceCompositingMode);
+}
+
 RenderWidgetHostViewQtDelegate::RenderWidgetHostViewQtDelegate()
     : m_view(0), m_backingStore(0)
 {
diff --git a/lib/render_widget_host_view_qt_delegate.h b/lib/render_widget_host_view_qt_delegate.h
index b58fefcce..f23bad376 100644
--- a/lib/render_widget_host_view_qt_delegate.h
+++ b/lib/render_widget_host_view_qt_delegate.h
@@ -68,6 +68,8 @@ public:
     void resetView(RenderWidgetHostViewQt*);
 
 protected:
+    static bool isCompositingModeForced();
+
     RenderWidgetHostViewQtDelegate();
     void paint(QPainter*, const QRectF& boundingRect);
     void fetchBackingStore();
diff --git a/lib/widgets/render_widget_host_view_qt_delegate_widget.cpp b/lib/widgets/render_widget_host_view_qt_delegate_widget.cpp
index d90190edb..ee6d553c9 100644
--- a/lib/widgets/render_widget_host_view_qt_delegate_widget.cpp
+++ b/lib/widgets/render_widget_host_view_qt_delegate_widget.cpp
@@ -41,6 +41,7 @@
 
 #include "render_widget_host_view_qt_delegate_widget.h"
 
+#include <QtGlobal>
 #include <QResizeEvent>
 #include <QPainter>
 #include <QPaintEvent>
@@ -51,6 +52,21 @@ RenderWidgetHostViewQtDelegateWidget::RenderWidgetHostViewQtDelegateWidget(QWidg
     setFocusPolicy(Qt::ClickFocus);
     setAttribute(Qt::WA_AcceptTouchEvents);
     setAttribute(Qt::WA_OpaquePaintEvent);
+
+#if defined(Q_OS_LINUX)
+    // FOR TESTING ONLY, use at your own risks.
+    // Supporting this properly on all platforms would require duplicating
+    // many tricks done by RenderWidgetHostView[Win|Mac].
+    if (isCompositingModeForced()) {
+        // This sets Qt::WA_NativeWindow and force a native window creation
+        // that we can give to the GPU process for it to render directly
+        // on through windowHandle().
+        winId();
+        // This makes sure that we won't try to paint the regular backing store
+        // on the window at the same time as the compositor.
+        setUpdatesEnabled(false);
+    }
+#endif
 }
 
 QRectF RenderWidgetHostViewQtDelegateWidget::screenRect() const