Avoid many unnecessary allocations, so so that paint engines attached to pixmaps

do not consume excessive amounts of memory, and so can still be reasonably kept
cached with the pixmap.
Saves 8K for every pixmaps drawn to on raster paint engine. Saves about 2K for other graphicssystems.

Task-number: QTBUG-10215
Reviewed-by: Gunnar

1 files changed, 7 insertions, 1 deletions

diff --git a/src/gui/painting/qrasterizer.cpp b/src/gui/painting/qrasterizer.cpp
index 51d01c9..f8f8afb 100644
--- a/src/gui/painting/qrasterizer.cpp
+++ b/src/gui/painting/qrasterizer.cpp
@@ -198,9 +198,11 @@ public:
 };
 
 QScanConverter::QScanConverter()
-   : m_alloc(0)
+   : m_lines(0)
+   , m_alloc(0)
    , m_size(0)
    , m_intersections(0)
+   , m_active(0)
 {
 }
 
@@ -310,6 +312,10 @@ struct QBoolToType
 template <typename T>
 void qScanConvert(QScanConverter &d, T allVertical)
 {
+    if (!d.m_lines.size()) {
+        d.m_active.reset();
+        return;
+    }
     qSort(d.m_lines.data(), d.m_lines.data() + d.m_lines.size(), QT_PREPEND_NAMESPACE(topOrder));
     int line = 0;
     for (int y = d.m_lines.first().top; y <= d.m_bottom; ++y) {