QSpanData: use isAffine() instead of rolling your own test

QSpanData did not properly check that whether the matrix is an affine
transformation or not. Therefore, qt paint engine chose the wrong
algorithm for drawing in case of a perpective matrix.

Change-Id: If0523bd45e86679a08874713da3fbe33a9852551
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index 46648fe..0e9129f 100644 (file)
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -4588,7 +4588,7 @@ void QSpanData::setupMatrix(const QTransform &matrix, int bilin)
     txop = inv.type();
     bilinear = bilin;
 
-    const bool affine = !m13 && !m23;
+    const bool affine = inv.isAffine();
     fast_matrix = affine
         && m11 * m11 + m21 * m21 < 1e4
         && m12 * m12 + m22 * m22 < 1e4