1 files changed, 185 insertions, 0 deletions
diff --git a/src/opengl/gl2paintengineex/qglgradientcache.cpp b/src/opengl/gl2paintengineex/qglgradientcache.cpp
new file mode 100644
index 0000000000..b4591b27fe
--- /dev/null
+++ b/src/opengl/gl2paintengineex/qglgradientcache.cpp
@@ -0,0 +1,185 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtOpenGL module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <private/qdrawhelper_p.h>
+#include <private/qgl_p.h>
+
+#include "qglgradientcache_p.h"
+
+void QGLGradientCache::cleanCache() {
+    QGLGradientColorTableHash::const_iterator it = cache.constBegin();
+    for (; it != cache.constEnd(); ++it) {
+        const CacheInfo &cache_info = it.value();
+        glDeleteTextures(1, &cache_info.texId);
+    }
+    cache.clear();
+}
+
+GLuint QGLGradientCache::getBuffer(const QGradient &gradient, qreal opacity, const QGLContext *ctx)
+{
+    if (buffer_ctx && !qgl_share_reg()->checkSharing(buffer_ctx, ctx))
+        cleanCache();
+
+    buffer_ctx = ctx;
+
+    quint64 hash_val = 0;
+
+    QGradientStops stops = gradient.stops();
+    for (int i = 0; i < stops.size() && i <= 2; i++)
+        hash_val += stops[i].second.rgba();
+
+    QGLGradientColorTableHash::const_iterator it = cache.constFind(hash_val);
+
+    if (it == cache.constEnd())
+        return addCacheElement(hash_val, gradient, opacity);
+    else {
+        do {
+            const CacheInfo &cache_info = it.value();
+            if (cache_info.stops == stops && cache_info.opacity == opacity && cache_info.interpolationMode == gradient.interpolationMode()) {
+                return cache_info.texId;
+            }
+            ++it;
+        } while (it != cache.constEnd() && it.key() == hash_val);
+        // an exact match for these stops and opacity was not found, create new cache
+        return addCacheElement(hash_val, gradient, opacity);
+    }
+}
+
+
+GLuint QGLGradientCache::addCacheElement(quint64 hash_val, const QGradient &gradient, qreal opacity)
+{
+    if (cache.size() == maxCacheSize()) {
+        int elem_to_remove = qrand() % maxCacheSize();
+        quint64 key = cache.keys()[elem_to_remove];
+
+        // need to call glDeleteTextures on each removed cache entry:
+        QGLGradientColorTableHash::const_iterator it = cache.constFind(key);
+        do {
+            glDeleteTextures(1, &it.value().texId);
+        } while (++it != cache.constEnd() && it.key() == key);
+        cache.remove(key); // may remove more than 1, but OK
+    }
+
+    CacheInfo cache_entry(gradient.stops(), opacity, gradient.interpolationMode());
+    uint buffer[1024];
+    generateGradientColorTable(gradient, buffer, paletteSize(), opacity);
+    glGenTextures(1, &cache_entry.texId);
+    glBindTexture(GL_TEXTURE_2D, cache_entry.texId);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, paletteSize(), 1,
+                    0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
+    return cache.insert(hash_val, cache_entry).value().texId;
+}
+
+
+// GL's expects pixels in RGBA, bin-endian (ABGR on x86).
+// Qt stores in ARGB using whatever byte-order the mancine uses.
+static inline uint qtToGlColor(uint c)
+{
+    uint o;
+#if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
+    o = c & 0xFF00FF00; // alpha & green already in the right place
+    o |= (c >> 16) & 0x000000FF; // red
+    o |= (c << 16) & 0x00FF0000; // blue
+
+#else //Q_BIG_ENDIAN
+    o = c & 0x00FF00FF; // alpha & green already in the right place
+    o |= (c << 16) & 0xFF000000; // red
+    o |= (c >> 16) & 0x0000FF00; // blue
+#error big endian not tested with QGLGraphicsContext
+#endif // Q_BYTE_ORDER
+    return o;
+}
+
+//TODO: Let GL generate the texture using an FBO
+void QGLGradientCache::generateGradientColorTable(const QGradient& gradient, uint *colorTable, int size, qreal opacity) const
+{
+    int pos = 0;
+    QGradientStops s = gradient.stops();
+    QVector<uint> colors(s.size());
+
+    for (int i = 0; i < s.size(); ++i)
+        colors[i] = s[i].second.rgba(); // Qt LIES! It returns ARGB
+
+    bool colorInterpolation = (gradient.interpolationMode() == QGradient::ColorInterpolation);
+
+    uint alpha = qRound(opacity * 256);
+    uint current_color = ARGB_COMBINE_ALPHA(colors[0], alpha);
+    qreal incr = 1.0 / qreal(size);
+    qreal fpos = 1.5 * incr;
+    colorTable[pos++] = qtToGlColor(PREMUL(current_color));
+
+    while (fpos <= s.first().first) {
+        colorTable[pos] = colorTable[pos - 1];
+        pos++;
+        fpos += incr;
+    }
+
+    if (colorInterpolation)
+        current_color = PREMUL(current_color);
+
+    for (int i = 0; i < s.size() - 1; ++i) {
+        qreal delta = 1/(s[i+1].first - s[i].first);
+        uint next_color = ARGB_COMBINE_ALPHA(colors[i+1], alpha);
+        if (colorInterpolation)
+            next_color = PREMUL(next_color);
+
+        while (fpos < s[i+1].first && pos < size) {
+            int dist = int(256 * ((fpos - s[i].first) * delta));
+            int idist = 256 - dist;
+            if (colorInterpolation)
+                colorTable[pos] = qtToGlColor(INTERPOLATE_PIXEL_256(current_color, idist, next_color, dist));
+            else
+                colorTable[pos] = qtToGlColor(PREMUL(INTERPOLATE_PIXEL_256(current_color, idist, next_color, dist)));
+            ++pos;
+            fpos += incr;
+        }
+        current_color = next_color;
+    }
+
+    Q_ASSERT(s.size() > 0);
+
+    uint last_color = qtToGlColor(PREMUL(ARGB_COMBINE_ALPHA(colors[s.size() - 1], alpha)));
+    for (;pos < size; ++pos)
+        colorTable[pos] = last_color;
+
+    // Make sure the last color stop is represented at the end of the table
+    colorTable[size-1] = last_color;
+}