QSGSoftwarePixmapRenderer: Fix incorrect background coordinates

The pixmap renderer sets up QPainter's window coordinates system but still
positions the background node in device coordinates. If the window rectangle is
QRect(x, y, w, h) then the background rectangle will be set to QRect(0, 0, w,
h). As the rendering output is clipped to the background rectangle, this means
that the image will be left with transparent bands of x pixels on the right and
y pixels on the bottom.

Task-number: QTBUG-62867
Change-Id: I3b2c18dafda4381b0daa64f849330f51bcc743b2
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

4 files changed, 10 insertions, 9 deletions

diff --git a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
index 30088846a6..4cec84646e 100644
--- a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
@@ -233,11 +233,11 @@ void QSGAbstractSoftwareRenderer::setBackgroundColor(const QColor &color)
     renderableNode(m_background)->markMaterialDirty();
 }
 
-void QSGAbstractSoftwareRenderer::setBackgroundSize(const QSize &size)
+void QSGAbstractSoftwareRenderer::setBackgroundRect(const QRect &rect)
 {
-    if (m_background->rect().size().toSize() == size)
+    if (m_background->rect().toRect() == rect)
         return;
-    m_background->setRect(0.0f, 0.0f, size.width(), size.height());
+    m_background->setRect(rect);
     renderableNode(m_background)->markGeometryDirty();
     // Invalidate the whole scene when the background is resized
     markDirty();
@@ -248,9 +248,9 @@ QColor QSGAbstractSoftwareRenderer::backgroundColor()
     return m_background->color();
 }
 
-QSize QSGAbstractSoftwareRenderer::backgroundSize()
+QRect QSGAbstractSoftwareRenderer::backgroundRect()
 {
-    return m_background->rect().size().toSize();
+    return m_background->rect().toRect();
 }
 
 void QSGAbstractSoftwareRenderer::nodeAdded(QSGNode *node)
diff --git a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h
index f20c2cf977..f6594d931a 100644
--- a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h
+++ b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h
@@ -83,9 +83,9 @@ protected:
     QRegion optimizeRenderList();
 
     void setBackgroundColor(const QColor &color);
-    void setBackgroundSize(const QSize &size);
+    void setBackgroundRect(const QRect &rect);
     QColor backgroundColor();
-    QSize backgroundSize();
+    QRect backgroundRect();
     // only known after calling optimizeRenderList()
     bool isOpaque() const { return m_isOpaque; }
 
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp
index 7824e53622..a56c126541 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
-    setBackgroundSize(QSize(target->width(), target->height()));
+    setBackgroundRect(m_projectionRect);
     setBackgroundColor(clearColor());
 
     renderTimer.start();
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
index cad826fb27..ddc7ec5d4c 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
@@ -112,7 +112,8 @@ void QSGSoftwareRenderer::render()
     QElapsedTimer renderTimer;
 
     setBackgroundColor(clearColor());
-    setBackgroundSize(QSize(m_paintDevice->width() / m_paintDevice->devicePixelRatio(),
+    setBackgroundRect(QRect(0, 0,
+                            m_paintDevice->width() / m_paintDevice->devicePixelRatio(),
                             m_paintDevice->height() / m_paintDevice->devicePixelRatio()));
 
     // Build Renderlist