Provide a way to cheaply flip your painted FBO

After recent changes the painted images are upside down from previous
and there is no way to get at the texture coordinates to flip them back
without reimplementing QSGPainterNode and QSGPaintedItem.

This change adds only an enum and has minimal impact, while providing
useful functionality that also fixes this problem.

Change-Id: I6884da884d9303f6e08a984d4560cc7f7728d918
Reviewed-by: Sarah Jane Smith <sarah.j.smith@nokia.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/declarative/scenegraph/util/qsgpainternode.cpp b/src/declarative/scenegraph/util/qsgpainternode.cpp
index 3f07f20695..1f44750f98 100644
--- a/src/declarative/scenegraph/util/qsgpainternode.cpp
+++ b/src/declarative/scenegraph/util/qsgpainternode.cpp
@@ -238,8 +238,11 @@ void QSGPainterNode::updateGeometry()
         source = QRectF(0, 0, 1, 1);
     else
         source = QRectF(0, 0, qreal(m_size.width()) / m_fboSize.width(), qreal(m_size.height()) / m_fboSize.height());
+    QRectF dest(0, 0, m_size.width(), m_size.height());
+    if (m_actualRenderTarget == QQuickPaintedItem::InvertedYFramebufferObject)
+        dest = QRectF(QPointF(0, m_size.height()), QPointF(m_size.width(), 0));
     QSGGeometry::updateTexturedRectGeometry(&m_geometry,
-                                            QRectF(0, 0, m_size.width(), m_size.height()),
+                                            dest,
                                             source);
     markDirty(DirtyGeometry);
 }
@@ -262,7 +265,7 @@ void QSGPainterNode::updateRenderTarget()
         if (!m_multisamplingSupported && m_smoothPainting)
             m_actualRenderTarget = QQuickPaintedItem::Image;
         else
-            m_actualRenderTarget = QQuickPaintedItem::FramebufferObject;
+            m_actualRenderTarget = m_preferredRenderTarget;
     }
     if (oldTarget != m_actualRenderTarget) {
         m_image = QImage();
@@ -271,7 +274,8 @@ void QSGPainterNode::updateRenderTarget()
         m_fbo = m_multisampledFbo = 0;
     }
 
-    if (m_actualRenderTarget == QQuickPaintedItem::FramebufferObject) {
+    if (m_actualRenderTarget == QQuickPaintedItem::FramebufferObject ||
+            m_actualRenderTarget == QQuickPaintedItem::InvertedYFramebufferObject) {
         const QOpenGLContext *ctx = m_context->glContext();
         if (m_fbo && !m_dirtyGeometry && (!ctx->format().samples() || !m_multisamplingSupported))
             return;