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, 26 insertions, 21 deletions

diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index 9148ac2..483bc0c 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -336,17 +336,6 @@ void QRasterPaintEngine::init()
     d->hdc = 0;
 #endif
 
-    d->rasterPoolSize = 8192;
-    d->rasterPoolBase =
-#if defined(Q_WS_WIN64)
-        // We make use of setjmp and longjmp in qgrayraster.c which requires
-        // 16-byte alignment, hence we hardcode this requirement here..
-        (unsigned char *) _aligned_malloc(d->rasterPoolSize, sizeof(void*) * 2);
-#else
-        (unsigned char *) malloc(d->rasterPoolSize);
-#endif
-    Q_CHECK_PTR(d->rasterPoolBase);
-
     // The antialiasing raster.
     d->grayRaster.reset(new QT_FT_Raster);
     Q_CHECK_PTR(d->grayRaster.data());
@@ -354,8 +343,6 @@ void QRasterPaintEngine::init()
         QT_THROW(std::bad_alloc()); // an error creating the raster is caused by a bad malloc
 
 
-    qt_ft_grays_raster.raster_reset(*d->grayRaster.data(), d->rasterPoolBase, d->rasterPoolSize);
-
     d->rasterizer.reset(new QRasterizer);
     d->rasterBuffer.reset(new QRasterBuffer());
     d->outlineMapper.reset(new QOutlineMapper);
@@ -437,12 +424,6 @@ QRasterPaintEngine::~QRasterPaintEngine()
 {
     Q_D(QRasterPaintEngine);
 
-#if defined(Q_WS_WIN64)
-    _aligned_free(d->rasterPoolBase);
-#else
-    free(d->rasterPoolBase);
-#endif
-
     qt_ft_grays_raster.raster_done(*d->grayRaster.data());
 }
 
@@ -4090,6 +4071,22 @@ void QRasterPaintEnginePrivate::rasterize(QT_FT_Outline *outline,
         return;
     }
 
+    const int rasterPoolInitialSize = 8192;
+    int rasterPoolSize = rasterPoolInitialSize;
+    unsigned char *rasterPoolBase;
+#if defined(Q_WS_WIN64)
+    rasterPoolBase =
+        // We make use of setjmp and longjmp in qgrayraster.c which requires
+        // 16-byte alignment, hence we hardcode this requirement here..
+        (unsigned char *) _aligned_malloc(rasterPoolSize, sizeof(void*) * 2);
+#else
+    unsigned char rasterPoolOnStack[rasterPoolInitialSize];
+    rasterPoolBase = rasterPoolOnStack;
+#endif
+    Q_CHECK_PTR(rasterPoolBase);
+
+    qt_ft_grays_raster.raster_reset(*grayRaster.data(), rasterPoolBase, rasterPoolSize);
+
     void *data = userData;
 
     QT_FT_BBox clip_box = { deviceRect.x(),
@@ -4122,13 +4119,14 @@ void QRasterPaintEnginePrivate::rasterize(QT_FT_Outline *outline,
             int new_size = rasterPoolSize * 2;
             if (new_size > 1024 * 1024) {
                 qWarning("QPainter: Rasterization of primitive failed");
-                return;
+                break;
             }
 
 #if defined(Q_WS_WIN64)
             _aligned_free(rasterPoolBase);
 #else
-            free(rasterPoolBase);
+            if (rasterPoolBase != rasterPoolOnStack) // initially on the stack
+                free(rasterPoolBase);
 #endif
 
             rasterPoolSize = new_size;
@@ -4149,6 +4147,13 @@ void QRasterPaintEnginePrivate::rasterize(QT_FT_Outline *outline,
             done = true;
         }
     }
+
+#if defined(Q_WS_WIN64)
+    _aligned_free(rasterPoolBase);
+#else
+    if (rasterPoolBase != rasterPoolOnStack) // initially on the stack
+        free(rasterPoolBase);
+#endif
 }
 
 void QRasterPaintEnginePrivate::recalculateFastImages()