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

11 files changed, 88 insertions, 44 deletions

diff --git a/src/gui/painting/qdatabuffer_p.h b/src/gui/painting/qdatabuffer_p.h
index bc5f1ef..8f8544f 100644
--- a/src/gui/painting/qdatabuffer_p.h
+++ b/src/gui/painting/qdatabuffer_p.h
@@ -60,16 +60,20 @@ QT_BEGIN_NAMESPACE
 template <typename Type> class QDataBuffer
 {
 public:
-    QDataBuffer(int res = 64)
+    QDataBuffer(int res)
     {
         capacity = res;
-        buffer = (Type*) qMalloc(capacity * sizeof(Type));
+        if (res)
+            buffer = (Type*) qMalloc(capacity * sizeof(Type));
+        else
+            buffer = 0;
         siz = 0;
     }
 
     ~QDataBuffer()
     {
-        qFree(buffer);
+        if (buffer)
+            qFree(buffer);
     }
 
     inline void reset() { siz = 0; }
@@ -104,6 +108,8 @@ public:
 
     inline void reserve(int size) {
         if (size > capacity) {
+            if (capacity == 0)
+                capacity = 1;
             while (capacity < size)
                 capacity *= 2;
             buffer = (Type*) qRealloc(buffer, capacity * sizeof(Type));
@@ -112,7 +118,12 @@ public:
 
     inline void shrink(int size) {
         capacity = size;
-        buffer = (Type*) qRealloc(buffer, capacity * sizeof(Type));
+        if (size)
+            buffer = (Type*) qRealloc(buffer, capacity * sizeof(Type));
+        else {
+            qFree(buffer);
+            buffer = 0;
+        }
     }
 
     inline void swap(QDataBuffer<Type> &other) {
diff --git a/src/gui/painting/qoutlinemapper.cpp b/src/gui/painting/qoutlinemapper.cpp
index ad0c2eb..1b01960 100644
--- a/src/gui/painting/qoutlinemapper.cpp
+++ b/src/gui/painting/qoutlinemapper.cpp
@@ -154,7 +154,8 @@ QT_FT_Outline *QOutlineMapper::convertPath(const QVectorPath &path)
         // ### We can kill this copying and just use the buffer straight...
 
         m_elements.resize(count);
-        memcpy(m_elements.data(), path.points(), count* sizeof(QPointF));
+        if (count)
+            memcpy(m_elements.data(), path.points(), count* sizeof(QPointF));
 
         m_element_types.resize(0);
     }
diff --git a/src/gui/painting/qoutlinemapper_p.h b/src/gui/painting/qoutlinemapper_p.h
index d0ce1a9..39b7593 100644
--- a/src/gui/painting/qoutlinemapper_p.h
+++ b/src/gui/painting/qoutlinemapper_p.h
@@ -87,8 +87,15 @@ const int QT_RASTER_COORD_LIMIT = 32767;
 class QOutlineMapper
 {
 public:
-    QOutlineMapper()
-        : m_round_coords(false)
+    QOutlineMapper() :
+        m_element_types(0),
+        m_elements(0),
+        m_elements_dev(0),
+        m_points(0),
+        m_tags(0),
+        m_contours(0),
+        m_polygon_dev(0),
+        m_round_coords(false)
     {
     }
 
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()
diff --git a/src/gui/painting/qpaintengine_raster_p.h b/src/gui/painting/qpaintengine_raster_p.h
index 55eb82e..0a0b0b2 100644
--- a/src/gui/painting/qpaintengine_raster_p.h
+++ b/src/gui/painting/qpaintengine_raster_p.h
@@ -300,6 +300,10 @@ QRasterPaintEnginePrivate : public QPaintEngineExPrivate
 {
     Q_DECLARE_PUBLIC(QRasterPaintEngine)
 public:
+    QRasterPaintEnginePrivate() : QPaintEngineExPrivate(),
+        cachedLines(0)
+    {
+    }
 
     void rasterizeLine_dashed(QLineF line, qreal width,
                               int *dashIndex, qreal *dashOffset, bool *inDash);
@@ -354,8 +358,6 @@ public:
     QScopedPointer<QDashStroker> dashStroker;
 
     QScopedPointer<QT_FT_Raster> grayRaster;
-    unsigned long rasterPoolSize;
-    unsigned char *rasterPoolBase;
 
     QDataBuffer<QLineF> cachedLines;
     QSpanData image_filler;
diff --git a/src/gui/painting/qpaintengineex.cpp b/src/gui/painting/qpaintengineex.cpp
index a78cafb..fda937e 100644
--- a/src/gui/painting/qpaintengineex.cpp
+++ b/src/gui/painting/qpaintengineex.cpp
@@ -149,6 +149,7 @@ QDebug Q_GUI_EXPORT &operator<<(QDebug &s, const QVectorPath &path)
 
 
 struct StrokeHandler {
+    StrokeHandler(int reserve) : pts(reserve), types(reserve) {}
     QDataBuffer<qreal> pts;
     QDataBuffer<QPainterPath::ElementType> types;
 };
@@ -394,7 +395,7 @@ void QPaintEngineEx::stroke(const QVectorPath &path, const QPen &pen)
         return;
 
     if (!d->strokeHandler) {
-        d->strokeHandler = new StrokeHandler;
+        d->strokeHandler = new StrokeHandler(path.elementCount()+4);
         d->stroker.setMoveToHook(qpaintengineex_moveTo);
         d->stroker.setLineToHook(qpaintengineex_lineTo);
         d->stroker.setCubicToHook(qpaintengineex_cubicTo);
diff --git a/src/gui/painting/qpathclipper.cpp b/src/gui/painting/qpathclipper.cpp
index c910024..78553c9 100644
--- a/src/gui/painting/qpathclipper.cpp
+++ b/src/gui/painting/qpathclipper.cpp
@@ -278,7 +278,8 @@ private:
 };
 
 SegmentTree::SegmentTree(QPathSegments &segments)
-    : m_segments(segments)
+    : m_segments(segments),
+      m_intersections(0)
 {
     m_bounds.x1 = qt_inf();
     m_bounds.y1 = qt_inf();
@@ -806,7 +807,7 @@ void QWingedEdge::intersectAndAdd()
     for (int i = 0; i < m_segments.points(); ++i)
         addVertex(m_segments.pointAt(i));
 
-    QDataBuffer<QPathSegments::Intersection> intersections;
+    QDataBuffer<QPathSegments::Intersection> intersections(m_segments.segments());
     for (int i = 0; i < m_segments.segments(); ++i) {
         intersections.reset();
 
@@ -857,11 +858,17 @@ void QWingedEdge::intersectAndAdd()
     }
 }
 
-QWingedEdge::QWingedEdge()
+QWingedEdge::QWingedEdge() :
+    m_edges(0),
+    m_vertices(0),
+    m_segments(0)
 {
 }
 
-QWingedEdge::QWingedEdge(const QPainterPath &subject, const QPainterPath &clip)
+QWingedEdge::QWingedEdge(const QPainterPath &subject, const QPainterPath &clip) :
+    m_edges(subject.length()),
+    m_vertices(subject.length()),
+    m_segments(subject.length())
 {
     m_segments.setPath(subject);
     m_segments.addPath(clip);
@@ -1414,9 +1421,9 @@ bool QPathClipper::intersect()
     else if (clipIsRect)
         return subjectPath.intersects(r2);
 
-    QPathSegments a;
+    QPathSegments a(subjectPath.length());
     a.setPath(subjectPath);
-    QPathSegments b;
+    QPathSegments b(clipPath.length());
     b.setPath(clipPath);
 
     QIntersectionFinder finder;
@@ -1459,9 +1466,9 @@ bool QPathClipper::contains()
     if (clipIsRect)
         return subjectPath.contains(r2);
 
-    QPathSegments a;
+    QPathSegments a(subjectPath.length());
     a.setPath(subjectPath);
-    QPathSegments b;
+    QPathSegments b(clipPath.length());
     b.setPath(clipPath);
 
     QIntersectionFinder finder;
diff --git a/src/gui/painting/qpathclipper_p.h b/src/gui/painting/qpathclipper_p.h
index 7962400..fab618d 100644
--- a/src/gui/painting/qpathclipper_p.h
+++ b/src/gui/painting/qpathclipper_p.h
@@ -199,7 +199,7 @@ public:
     };
 
 
-    QPathSegments();
+    QPathSegments(int reserve);
 
     void setPath(const QPainterPath &path);
     void addPath(const QPainterPath &path);
@@ -345,7 +345,10 @@ inline QPathVertex::operator QPointF() const
     return QPointF(x, y);
 }
 
-inline QPathSegments::QPathSegments()
+inline QPathSegments::QPathSegments(int reserve) :
+    m_points(reserve),
+    m_segments(reserve),
+    m_intersections(reserve)
 {
 }
 
diff --git a/src/gui/painting/qpolygonclipper_p.h b/src/gui/painting/qpolygonclipper_p.h
index 1b4cbb3..cdaac1c 100644
--- a/src/gui/painting/qpolygonclipper_p.h
+++ b/src/gui/painting/qpolygonclipper_p.h
@@ -62,7 +62,8 @@ QT_BEGIN_NAMESPACE
 template <typename InType, typename OutType, typename CastType> class QPolygonClipper
 {
 public:
-    QPolygonClipper()
+    QPolygonClipper() :
+        buffer1(0), buffer2(0)
     {
         x1 = y1 = x2 = y2 = 0;
     }
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) {
diff --git a/src/gui/painting/qstroker.cpp b/src/gui/painting/qstroker.cpp
index e43544c..9b8e099 100644
--- a/src/gui/painting/qstroker.cpp
+++ b/src/gui/painting/qstroker.cpp
@@ -187,7 +187,7 @@ static inline qreal adapted_angle_on_x(const QLineF &line)
 }
 
 QStrokerOps::QStrokerOps()
-    : m_customData(0), m_moveTo(0), m_lineTo(0), m_cubicTo(0)
+    : m_elements(0), m_customData(0), m_moveTo(0), m_lineTo(0), m_cubicTo(0)
 {
 }