From 8dc55367ca3993f465f270ef79c2cb212d821d0c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C5=82a=C5=BCej=20Szczygie=C5=82?= <spaz16@wp.pl>
Date: Mon, 8 Feb 2016 15:02:17 +0100
Subject: QtGui: Avoid rgba64->rgba32 conversion on every pixel in gradient

Convert rgba64 color table to a new rgb32 color table only once. Use
this cache when required.

This patch can 2x speed up gradient painting using 32bit color format.

Task-number: QTBUG-50930
Change-Id: I9212e01e397c2e0127cdf3070cc49880a2d8df88
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
---
 src/gui/painting/qpaintengine_raster.cpp | 38 ++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 9 deletions(-)

(limited to 'src/gui/painting/qpaintengine_raster.cpp')

diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index 05ccff5de0..fb44a7aeb1 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -4138,7 +4138,8 @@ class QGradientCache
     {
         inline CacheInfo(QGradientStops s, int op, QGradient::InterpolationMode mode) :
             stops(qMove(s)), opacity(op), interpolationMode(mode) {}
-        QRgba64 buffer[GRADIENT_STOPTABLE_SIZE];
+        QRgba64 buffer64[GRADIENT_STOPTABLE_SIZE];
+        QRgb buffer32[GRADIENT_STOPTABLE_SIZE];
         QGradientStops stops;
         int opacity;
         QGradient::InterpolationMode interpolationMode;
@@ -4147,7 +4148,9 @@ class QGradientCache
     typedef QMultiHash<quint64, CacheInfo> QGradientColorTableHash;
 
 public:
-    inline const QRgba64 *getBuffer(const QGradient &gradient, int opacity) {
+    typedef QPair<const QRgb *, const QRgba64 *> ColorBufferPair;
+
+    inline ColorBufferPair getBuffer(const QGradient &gradient, int opacity) {
         quint64 hash_val = 0;
 
         const QGradientStops stops = gradient.stops();
@@ -4163,7 +4166,8 @@ public:
             do {
                 const CacheInfo &cache_info = it.value();
                 if (cache_info.stops == stops && cache_info.opacity == opacity && cache_info.interpolationMode == gradient.interpolationMode())
-                    return cache_info.buffer;
+                    return qMakePair(reinterpret_cast<const QRgb *>(cache_info.buffer32),
+                                     reinterpret_cast<const QRgba64 *>(cache_info.buffer64));
                 ++it;
             } while (it != cache.constEnd() && it.key() == hash_val);
             // an exact match for these stops and opacity was not found, create new cache
@@ -4177,14 +4181,18 @@ protected:
     inline void generateGradientColorTable(const QGradient& g,
                                            QRgba64 *colorTable,
                                            int size, int opacity) const;
-    QRgba64 *addCacheElement(quint64 hash_val, const QGradient &gradient, int opacity) {
+    ColorBufferPair addCacheElement(quint64 hash_val, const QGradient &gradient, int opacity) {
         if (cache.size() == maxCacheSize()) {
             // may remove more than 1, but OK
             cache.erase(cache.begin() + (qrand() % maxCacheSize()));
         }
         CacheInfo cache_entry(gradient.stops(), opacity, gradient.interpolationMode());
-        generateGradientColorTable(gradient, cache_entry.buffer, paletteSize(), opacity);
-        return cache.insert(hash_val, cache_entry).value().buffer;
+        generateGradientColorTable(gradient, cache_entry.buffer64, paletteSize(), opacity);
+        for (int i = 0; i < GRADIENT_STOPTABLE_SIZE; ++i)
+            cache_entry.buffer32[i] = cache_entry.buffer64[i].toArgb32();
+        CacheInfo &cache_value = cache.insert(hash_val, cache_entry).value();
+        return qMakePair(reinterpret_cast<const QRgb *>(cache_value.buffer32),
+                         reinterpret_cast<const QRgba64 *>(cache_value.buffer64));
     }
 
     QGradientColorTableHash cache;
@@ -4418,7 +4426,11 @@ void QSpanData::setup(const QBrush &brush, int alpha, QPainter::CompositionMode
             type = LinearGradient;
             const QLinearGradient *g = static_cast<const QLinearGradient *>(brush.gradient());
             gradient.alphaColor = !brush.isOpaque() || alpha != 256;
-            gradient.colorTable = const_cast<QRgba64*>(qt_gradient_cache()->getBuffer(*g, alpha));
+
+            QGradientCache::ColorBufferPair colorBuffers = qt_gradient_cache()->getBuffer(*g, alpha);
+            gradient.colorTable64 = colorBuffers.second;
+            gradient.colorTable32 = colorBuffers.first;
+
             gradient.spread = g->spread();
 
             QLinearGradientData &linearData = gradient.linear;
@@ -4435,7 +4447,11 @@ void QSpanData::setup(const QBrush &brush, int alpha, QPainter::CompositionMode
             type = RadialGradient;
             const QRadialGradient *g = static_cast<const QRadialGradient *>(brush.gradient());
             gradient.alphaColor = !brush.isOpaque() || alpha != 256;
-            gradient.colorTable = const_cast<QRgba64*>(qt_gradient_cache()->getBuffer(*g, alpha));
+
+            QGradientCache::ColorBufferPair colorBuffers = qt_gradient_cache()->getBuffer(*g, alpha);
+            gradient.colorTable64 = colorBuffers.second;
+            gradient.colorTable32 = colorBuffers.first;
+
             gradient.spread = g->spread();
 
             QRadialGradientData &radialData = gradient.radial;
@@ -4456,7 +4472,11 @@ void QSpanData::setup(const QBrush &brush, int alpha, QPainter::CompositionMode
             type = ConicalGradient;
             const QConicalGradient *g = static_cast<const QConicalGradient *>(brush.gradient());
             gradient.alphaColor = !brush.isOpaque() || alpha != 256;
-            gradient.colorTable = const_cast<QRgba64*>(qt_gradient_cache()->getBuffer(*g, alpha));
+
+            QGradientCache::ColorBufferPair colorBuffers = qt_gradient_cache()->getBuffer(*g, alpha);
+            gradient.colorTable64 = colorBuffers.second;
+            gradient.colorTable32 = colorBuffers.first;
+
             gradient.spread = QGradient::RepeatSpread;
 
             QConicalGradientData &conicalData = gradient.conical;
-- 
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