Convenience to locate QRenderSurfaceSelector

This is in fact done at several places nowadays, sometimes with bugs, so
let's provide a single tested implementation for it.

Change-Id: I782ba18a15e5b4a3b320ac6b472173b1f8e417a3
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

2 files changed, 33 insertions, 1 deletions

diff --git a/src/render/framegraph/qrendersurfaceselector.cpp b/src/render/framegraph/qrendersurfaceselector.cpp
index 349ceb827..e76963e72 100644
--- a/src/render/framegraph/qrendersurfaceselector.cpp
+++ b/src/render/framegraph/qrendersurfaceselector.cpp
@@ -43,7 +43,9 @@
 #include <QtGui/QWindow>
 #include <QtGui/QScreen>
 #include <QtGui/QOffscreenSurface>
+#include <Qt3DCore/qentity.h>
 #include <Qt3DCore/qpropertyupdatedchange.h>
+#include <Qt3DRender/qrendersettings.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -104,6 +106,30 @@ QRenderSurfaceSelectorPrivate::~QRenderSurfaceSelectorPrivate()
     QObject::disconnect(m_screenConn);
 }
 
+QRenderSurfaceSelector *QRenderSurfaceSelectorPrivate::find(QObject *rootObject)
+{
+    auto rendererSettings = rootObject->findChild<Qt3DRender::QRenderSettings *>();
+    if (!rendererSettings) {
+        qWarning() << "No renderer settings component found";
+        return nullptr;
+    }
+
+    auto frameGraphRoot = rendererSettings->activeFrameGraph();
+    if (!frameGraphRoot) {
+        qWarning() << "No active frame graph found";
+        return nullptr;
+    }
+
+    auto surfaceSelector = qobject_cast<Qt3DRender::QRenderSurfaceSelector *>(frameGraphRoot);
+    if (!surfaceSelector)
+        surfaceSelector = frameGraphRoot->findChild<Qt3DRender::QRenderSurfaceSelector *>();
+
+    if (!surfaceSelector)
+        qWarning() << "No render surface selector found in frame graph";
+
+    return surfaceSelector;
+}
+
 void QRenderSurfaceSelectorPrivate::setExternalRenderTargetSize(const QSize &size)
 {
     m_externalRenderTargetSize = size;
diff --git a/src/render/framegraph/qrendersurfaceselector_p.h b/src/render/framegraph/qrendersurfaceselector_p.h
index d21bf744c..899387b98 100644
--- a/src/render/framegraph/qrendersurfaceselector_p.h
+++ b/src/render/framegraph/qrendersurfaceselector_p.h
@@ -53,6 +53,7 @@
 
 #include <Qt3DRender/private/qframegraphnode_p.h>
 #include <Qt3DRender/private/platformsurfacefilter_p.h>
+#include <Qt3DRender/private/qt3drender_global_p.h>
 #include <QtGui/qsurface.h>
 #include <QtGui/qwindow.h>
 #include <QtCore/qpointer.h>
@@ -61,12 +62,17 @@ QT_BEGIN_NAMESPACE
 
 namespace Qt3DRender {
 
-class QRenderSurfaceSelectorPrivate : public Qt3DRender::QFrameGraphNodePrivate
+class QRenderSurfaceSelector;
+
+class QT3DRENDERSHARED_PRIVATE_EXPORT QRenderSurfaceSelectorPrivate : public Qt3DRender::QFrameGraphNodePrivate
 {
 public:
     QRenderSurfaceSelectorPrivate();
     ~QRenderSurfaceSelectorPrivate();
 
+    // TODO: Qt 5.8, make it public
+    static QRenderSurfaceSelector *find(QObject *rootObject);
+
     void setExternalRenderTargetSize(const QSize &size);
     QSize externalRenderTargetSize() const { return m_externalRenderTargetSize; }