Add surface format to QQuickWidget.

Change-Id: Id72a042588e37832a0d3757bad935c531ef8275a
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>

examples/quick/quickwidgets/quickwidget/main.cpp

@@ -58,6 +58,13 @@ private:
 MainWindow::MainWindow()
    : m_quickWidget(new QQuickWidget)
 {
+    if (QCoreApplication::arguments().contains(QStringLiteral("--coreprofile"))) {
+        QSurfaceFormat format;
+        format.setVersion(4, 4);
+        format.setProfile(QSurfaceFormat::CoreProfile);
+        m_quickWidget->setFormat(format);
+    }
+
     QMdiArea *centralWidget = new QMdiArea;
 
     QLCDNumber *lcd = new QLCDNumber;

src/quickwidgets/qquickwidget.cpp

@@ -97,6 +97,9 @@ void QQuickWidgetPrivate::handleWindowChange()
 QQuickWidgetPrivate::QQuickWidgetPrivate()
     : root(0)
     , component(0)
+    , offscreenWindow(0)
+    , offscreenSurface(0)
+    , renderControl(0)
     , fbo(0)
     , context(0)
     , resizeMode(QQuickWidget::SizeViewToRootObject)
@@ -110,9 +113,7 @@ QQuickWidgetPrivate::QQuickWidgetPrivate()
     offscreenWindow = new QQuickWindow(renderControl);
     offscreenWindow->setTitle(QString::fromLatin1("Offscreen"));
     // Do not call create() on offscreenWindow.
-    offscreenSurface = new QOffscreenSurface;
-    offscreenSurface->setFormat(offscreenWindow->requestedFormat());
-    offscreenSurface->create();
+    createOffscreenSurface();
 }
 
 QQuickWidgetPrivate::~QQuickWidgetPrivate()
@@ -125,6 +126,15 @@ QQuickWidgetPrivate::~QQuickWidgetPrivate()
     delete fbo;
 }
 
+void QQuickWidgetPrivate::createOffscreenSurface()
+{
+    delete offscreenSurface;
+    offscreenSurface = 0;
+    offscreenSurface = new QOffscreenSurface;
+    offscreenSurface->setFormat(offscreenWindow->requestedFormat());
+    offscreenSurface->create();
+}
+
 void QQuickWidgetPrivate::execute()
 {
     Q_Q(QQuickWidget);
@@ -941,4 +951,42 @@ void QQuickWidget::triggerUpdate()
     }
 }
 
+/*!
+    Sets the surface \a format for the context and offscreen surface used
+    by this widget.
+
+    Call this function when there is a need to request a context for a
+    given OpenGL version or profile. The sizes for depth, stencil and
+    alpha buffers are taken care of automatically and there is no need
+    to request those explicitly.
+
+    \sa QWindow::setFormat(), QWindow::format(), format()
+*/
+void QQuickWidget::setFormat(const QSurfaceFormat &format)
+{
+    Q_D(QQuickWidget);
+    QSurfaceFormat currentFormat = d->offscreenWindow->format();
+    QSurfaceFormat newFormat = format;
+    newFormat.setDepthBufferSize(qMax(newFormat.depthBufferSize(), currentFormat.depthBufferSize()));
+    newFormat.setStencilBufferSize(qMax(newFormat.stencilBufferSize(), currentFormat.stencilBufferSize()));
+    newFormat.setAlphaBufferSize(qMax(newFormat.alphaBufferSize(), currentFormat.alphaBufferSize()));
+    if (currentFormat != newFormat) {
+        d->offscreenWindow->setFormat(newFormat);
+        d->createOffscreenSurface();
+    }
+}
+
+/*!
+    Returns the actual surface format.
+
+    If the widget has not yet been shown, the requested format is returned.
+
+    \sa setFormat()
+*/
+QSurfaceFormat QQuickWidget::format() const
+{
+    Q_D(const QQuickWidget);
+    return d->offscreenWindow->format();
+}
+
 QT_END_NAMESPACE

src/quickwidgets/qquickwidget.h

@@ -89,6 +89,9 @@ public:
     QSize sizeHint() const;
     QSize initialSize() const;
 
+    void setFormat(const QSurfaceFormat &format);
+    QSurfaceFormat format() const;
+
 public Q_SLOTS:
     void setSource(const QUrl&);
     void setContent(const QUrl& url, QQmlComponent *component, QObject *item);

src/quickwidgets/qquickwidget_p.h

@@ -87,6 +87,7 @@ public:
     void createContext();
     void destroyContext();
     void handleContextCreationFailure(const QSurfaceFormat &format, bool isEs);
+    void createOffscreenSurface();
 
     GLuint textureId() const Q_DECL_OVERRIDE;