Merge lp:~fboucault/unity-2d/opengl_plus_composite_fix into lp:unity-2d/3.0

[Florian Boucault]

[dash] Fix use of opengl rendering backend: artifacts were displayed, even more so with transparency enabled.

The cause of the issue was that the QGLWidget viewport was set on the QDeclarativeView
before having setup the QGLWidget's flags.
Implementation of Unity2dDeclarativeView is much clarified as a result and this change
impacts all the components using it:
- launcher
- dash
- spread

Synchronization to VBlank has also been activated.
Set viewport update mode to QGraphicsView::FullViewportUpdate when using OpenGL.

[lp:~fboucault/unity-2d/opengl_plus_composite_fix]

618. By Florian Boucault on 2011-07-05

Set viewport update mode to QGraphicsView::FullViewportUpdate when using OpenGL.

[Ricardo Salveti (rsalveti)]

The code seems fine, but I'm unable to reproduce the original problem at least when using with the OpenGLES QT backend.

Did you only see this issue when using with normal OpenGL? I'll reproduce this on my host machine tomorrow to see if I'm at least able to reproduce the issue.

[Ricardo Salveti (rsalveti)]

When using OpenGL at my desktop I'm able to reproduce the issue this patch fixes. After applying the patch the transparency is now working same way when using without -opengl.

review: Approve

=== modified file 'libunity-2d-private/src/unity2ddeclarativeview.cpp'
--- libunity-2d-private/src/unity2ddeclarativeview.cpp	2011-06-13 00:31:52 +0000
+++ libunity-2d-private/src/unity2ddeclarativeview.cpp	2011-07-05 18:52:39 +0000
@@ -2,10 +2,9 @@
 #include <QGLWidget>
 
 Unity2DDeclarativeView::Unity2DDeclarativeView(QWidget *parent) :
-    QDeclarativeView(parent), m_useOpenGL(false)
+    QDeclarativeView(parent), m_useOpenGL(false), m_transparentBackground(false)
 {
-    setAttribute(Qt::WA_NoSystemBackground);
-    setTransparentBackground(false);
+    setupViewport();
 }
 
 bool Unity2DDeclarativeView::useOpenGL() const
@@ -19,36 +18,77 @@
         return;
     }
 
-    if (useOpenGL) {
+    m_useOpenGL = useOpenGL;
+    setupViewport();
+
+    Q_EMIT useOpenGLChanged(useOpenGL);
+}
+
+bool Unity2DDeclarativeView::transparentBackground() const
+{
+    return m_transparentBackground;
+}
+
+void Unity2DDeclarativeView::setTransparentBackground(bool transparentBackground)
+{
+    if (transparentBackground == m_transparentBackground) {
+        return;
+    }
+
+    m_transparentBackground = transparentBackground;
+    setupViewport();
+
+    Q_EMIT transparentBackgroundChanged(transparentBackground);
+}
+
+void Unity2DDeclarativeView::setupViewport()
+{
+    if (m_useOpenGL) {
         QGLFormat format = QGLFormat::defaultFormat();
         format.setSampleBuffers(false);
+        /* Synchronise rendering with vblank */
+        format.setSwapInterval(1);
 
         QGLWidget *glWidget = new QGLWidget(format);
-        /* TODO: possibly faster, to be tested */
+        /* TODO: possibly faster, to be tested, only works with non transparent windows */
         //glWidget->setAutoFillBackground(false);
 
+        if (m_transparentBackground) {
+            glWidget->setAttribute(Qt::WA_TranslucentBackground, true);
+            setAttribute(Qt::WA_TranslucentBackground, true);
+            /* automatically set by setting WA_TranslucentBackground */
+            setAttribute(Qt::WA_NoSystemBackground, true);
+            setAttribute(Qt::WA_OpaquePaintEvent, true);
+        } else {
+            glWidget->setAttribute(Qt::WA_TranslucentBackground, false);
+            setAttribute(Qt::WA_TranslucentBackground, false);
+            setAttribute(Qt::WA_NoSystemBackground, true);
+            setAttribute(Qt::WA_OpaquePaintEvent, true);
+        }
+
         setViewport(glWidget);
+        /* According to Qt's documentation: "This is the preferred update mode
+           for viewports that do not support partial updates, such as QGLWidget [...]"
+        */
+        setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
     } else {
         setViewport(0);
+        /* This is the default update mode */
+        setViewportUpdateMode(QGraphicsView::MinimalViewportUpdate);
+
+        if (m_transparentBackground) {
+            viewport()->setAttribute(Qt::WA_TranslucentBackground, true);
+            setAttribute(Qt::WA_TranslucentBackground, true);
+            /* automatically set by setting WA_TranslucentBackground */
+            setAttribute(Qt::WA_NoSystemBackground, true);
+            setAttribute(Qt::WA_OpaquePaintEvent, false);
+        } else {
+            viewport()->setAttribute(Qt::WA_TranslucentBackground, false);
+            setAttribute(Qt::WA_TranslucentBackground, false);
+            setAttribute(Qt::WA_NoSystemBackground, true);
+            setAttribute(Qt::WA_OpaquePaintEvent, true);
+        }
     }
-
-    m_useOpenGL = useOpenGL;
-    Q_EMIT useOpenGLChanged(useOpenGL);
-}
-
-bool Unity2DDeclarativeView::transparentBackground() const
-{
-    return m_transparentBackground;
-}
-
-void Unity2DDeclarativeView::setTransparentBackground(bool transparentBackground)
-{
-    setAttribute(Qt::WA_TranslucentBackground, transparentBackground);
-    viewport()->setAttribute(Qt::WA_TranslucentBackground, transparentBackground);
-    setAttribute(Qt::WA_OpaquePaintEvent, !transparentBackground);
-
-    m_transparentBackground = transparentBackground;
-    Q_EMIT transparentBackgroundChanged(transparentBackground);
 }
 
 #include <unity2ddeclarativeview.moc>

=== modified file 'libunity-2d-private/src/unity2ddeclarativeview.h'
--- libunity-2d-private/src/unity2ddeclarativeview.h	2011-06-13 00:31:52 +0000
+++ libunity-2d-private/src/unity2ddeclarativeview.h	2011-07-05 18:52:39 +0000
@@ -25,6 +25,9 @@
     void useOpenGLChanged(bool);
     void transparentBackgroundChanged(bool);
 
+protected:
+    void setupViewport();
+
 private:
     bool m_useOpenGL;
     bool m_transparentBackground;