Fix to 'QImage convertToFormat doesn't work correctly'

OpenVG paint engine tries to use vgWritePixels shortcut
whenever possible to optimize rendering performance. The
check 'canVgWritePixels' failed to map formats correctly
and resulted to incorrect return value.

Task-number: QTBUG-18682
Reviewed-by: Jason Barron

1 files changed, 15 insertions, 0 deletions

diff --git a/src/openvg/qpaintengine_vg.cpp b/src/openvg/qpaintengine_vg.cpp
index 570adfd..ebdfa5f 100644
--- a/src/openvg/qpaintengine_vg.cpp
+++ b/src/openvg/qpaintengine_vg.cpp
@@ -1024,9 +1024,11 @@ static VGImage toVGImage
     switch (img.format()) {
     case QImage::Format_Mono:
         img = image.convertToFormat(QImage::Format_MonoLSB, flags);
+        img.invertPixels();
         format = VG_BW_1;
         break;
     case QImage::Format_MonoLSB:
+        img.invertPixels();
         format = VG_BW_1;
         break;
     case QImage::Format_RGB32:
@@ -3189,6 +3191,19 @@ void qt_vg_drawVGImageStencil
 bool QVGPaintEngine::canVgWritePixels(const QImage &image) const
 {
     Q_D(const QVGPaintEngine);
+
+    // qt_vg_image_to_vg_format returns VG_sARGB_8888 as
+    // fallback case if no matching VG format is found.
+    // If given image format is not Format_ARGB32 and returned
+    // format is VG_sARGB_8888, it means that no match was
+    // found. In that case vgWritePixels cannot be used.
+    // Also 1-bit formats cannot be used directly either.
+    if ((image.format() != QImage::Format_ARGB32
+           && qt_vg_image_to_vg_format(image.format()) == VG_sARGB_8888)
+           || image.depth() == 1) {
+        return false;
+    }
+
     // vgWritePixels ignores masking, blending and xforms so we can only use it if
     // ALL of the following conditions are true:
     // - It is a simple translate, or a scale of -1 on the y-axis (inverted)