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/****************************************************************************
**
** 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 QGL2GradientCache::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 QGL2GradientCache::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 QGL2GradientCache::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 QGL2GradientCache::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;
}
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