Add support for multisampling in QQuickWidget

Use a multisampled fbo when the requested format has samples > 0.
Resolving happens after each rendering of the scene.

The blit to the temporary non-multisampled fbo could be avoided,
in theory, by sending the fbo instead of the texture id down the
stack and performing a blit directly to fbo #0. This however
involves a number of potential issues, for example due to the
non-sharability of FBOs between contexts. Hence it is left as a
future exercise.

Task-number: QTBUG-39187
Change-Id: Iae98b969bcbc3bb57e6d73288496f5428913c826
Reviewed-by: Paul Olav Tvete <[email protected]>
Reviewed-by: Gunnar Sletta <[email protected]>

1 files changed, 4 insertions, 2 deletions

diff --git a/examples/quick/quickwidgets/quickwidget/main.cpp b/examples/quick/quickwidgets/quickwidget/main.cpp
index 61c54735cf..3850dde157 100644
--- a/examples/quick/quickwidgets/quickwidget/main.cpp
+++ b/examples/quick/quickwidgets/quickwidget/main.cpp
@@ -58,12 +58,14 @@ private:
 MainWindow::MainWindow()
    : m_quickWidget(new QQuickWidget)
 {
+    QSurfaceFormat format;
     if (QCoreApplication::arguments().contains(QStringLiteral("--coreprofile"))) {
-        QSurfaceFormat format;
         format.setVersion(4, 4);
         format.setProfile(QSurfaceFormat::CoreProfile);
-        m_quickWidget->setFormat(format);
     }
+    if (QCoreApplication::arguments().contains(QStringLiteral("--multisample")))
+        format.setSamples(4);
+    m_quickWidget->setFormat(format);
 
     QMdiArea *centralWidget = new QMdiArea;