Make QSGLayer::grab work correctly in software renderer

Fix three separate issues:
1. It was possible that the QSGSoftwarePixmapRenderer's
   background image's rectangle was set to a non-normalized
   rectangle. That would have led to the damage area detection
   creating an empty QRegion for the damage area and
   QQuickItem::grabToImage would grab an empty image.
2. The QSGSoftwarePixmapRenderer was rendering the image vertically
   mirrored compared to what its equivalent in the OpenGL backend
   was doing. Therefore QSGLayer::grab was vertically mirrored, too,
   so QQuickItem::grabToImage would grab a mirrored image, too.
   Additionally QSGSoftwareInternalImageNode (used by
   QQuickShaderEffectSource) now has to mirror its internal texture
   if that one is a QSGSoftwareLayer.
3. QSGSoftwareInternalImageNode (used by QQuickShaderEffectSource)
   was not updating correctly when mirroring (with the fix for 2
   also in case of a QSGSoftwareLayer as texture).

Related to QTBUG-63185 and QTBUG-65975.

Change-Id: I0d0ead7fb1c839a8ff427ff7881d8a881e538409
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

4 files changed, 15 insertions, 6 deletions

diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode.cpp
index 3b0f3c48ff..aa83709b72 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode.cpp
@@ -320,6 +320,7 @@ QSGSoftwareInternalImageNode::QSGSoftwareInternalImageNode()
     , m_subSourceRect(0, 0, 1, 1)
     , m_texture(nullptr)
     , m_mirror(false)
+    , m_textureIsLayer(false)
     , m_smooth(true)
     , m_tileHorizontal(false)
     , m_tileVertical(false)
@@ -366,6 +367,7 @@ void QSGSoftwareInternalImageNode::setTexture(QSGTexture *texture)
 {
     m_texture = texture;
     m_cachedMirroredPixmapIsDirty = true;
+    m_textureIsLayer = static_cast<bool>(qobject_cast<QSGSoftwareLayer*>(texture));
     markDirty(DirtyMaterial);
 }
 
@@ -415,8 +417,13 @@ void QSGSoftwareInternalImageNode::setVerticalWrapMode(QSGTexture::WrapMode wrap
 void QSGSoftwareInternalImageNode::update()
 {
     if (m_cachedMirroredPixmapIsDirty) {
-        if (m_mirror) {
-            m_cachedMirroredPixmap = pixmap().transformed(QTransform(-1, 0, 0, 1, 0, 0));
+        if (m_mirror || m_textureIsLayer) {
+            QTransform transform(
+                        (m_mirror ? -1 : 1), 0,
+                        0                  , (m_textureIsLayer ? -1 :1),
+                        0                  , 0
+            );
+            m_cachedMirroredPixmap = pixmap().transformed(transform);
         } else {
             //Cleanup cached pixmap if necessary
             if (!m_cachedMirroredPixmap.isNull())
@@ -436,6 +443,7 @@ void QSGSoftwareInternalImageNode::preprocess()
     }
     if (doDirty)
         markDirty(DirtyMaterial);
+    m_cachedMirroredPixmapIsDirty = doDirty;
 }
 
 static Qt::TileRule getTileRule(qreal factor)
@@ -454,7 +462,7 @@ void QSGSoftwareInternalImageNode::paint(QPainter *painter)
 {
     painter->setRenderHint(QPainter::SmoothPixmapTransform, m_smooth);
 
-    const QPixmap &pm = m_mirror ? m_cachedMirroredPixmap : pixmap();
+    const QPixmap &pm = m_mirror || m_textureIsLayer ? m_cachedMirroredPixmap : pixmap();
 
     if (m_innerTargetRect != m_targetRect) {
         // border image
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode_p.h b/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode_p.h
index 5c95eb064a..b80bacbaa0 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode_p.h
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwareinternalimagenode_p.h
@@ -136,6 +136,7 @@ private:
     QPixmap m_cachedMirroredPixmap;
 
     bool m_mirror;
+    bool m_textureIsLayer;
     bool m_smooth;
     bool m_tileHorizontal;
     bool m_tileVertical;
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarelayer.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarelayer.cpp
index b4301451d8..70378d2950 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarelayer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarelayer.cpp
@@ -240,9 +240,9 @@ void QSGSoftwareLayer::grab()
     m_renderer->setDeviceRect(m_size);
     m_renderer->setViewportRect(m_size);
     QRect mirrored(m_mirrorHorizontal ? m_rect.right() * m_device_pixel_ratio : m_rect.left() * m_device_pixel_ratio,
-                   m_mirrorVertical ? m_rect.top() * m_device_pixel_ratio : m_rect.bottom() * m_device_pixel_ratio,
+                   m_mirrorVertical ? m_rect.bottom() * m_device_pixel_ratio : m_rect.top() * m_device_pixel_ratio,
                    m_mirrorHorizontal ? -m_rect.width() * m_device_pixel_ratio : m_rect.width() * m_device_pixel_ratio,
-                   m_mirrorVertical ? m_rect.height() * m_device_pixel_ratio : -m_rect.height() * m_device_pixel_ratio);
+                   m_mirrorVertical ? -m_rect.height() * m_device_pixel_ratio : m_rect.height() * m_device_pixel_ratio);
     m_renderer->setProjectionRect(mirrored);
     m_renderer->setClearColor(Qt::transparent);
 
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp
index 303f98c801..bb4afc8301 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp
@@ -79,7 +79,7 @@ void QSGSoftwarePixmapRenderer::render(QPaintDevice *target)
     QElapsedTimer renderTimer;
 
     // Setup background item
-    setBackgroundRect(m_projectionRect);
+    setBackgroundRect(m_projectionRect.normalized());
     setBackgroundColor(clearColor());
 
     renderTimer.start();