Implemented texture cache for GL paint engine in QtGui.

This is simpler than the existing texture cache in QtOpenGL, as it only
serves the GL paint engine. There's one per context group, to simplify
the design and to prevent performance degradations.

Change-Id: I61e3c9a444d8e246a8b38da019a56f2c0a533c0c
Reviewed-on: http://codereview.qt-project.org/4674
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Kim M. Kalland <kim.kalland@nokia.com>

1 files changed, 215 insertions, 0 deletions

diff --git a/src/gui/opengl/qopengltexturecache.cpp b/src/gui/opengl/qopengltexturecache.cpp
new file mode 100644
index 0000000000..067b7a9e20
--- /dev/null
+++ b/src/gui/opengl/qopengltexturecache.cpp
@@ -0,0 +1,215 @@
+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** 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 1.1, 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.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qopengltexturecache_p.h"
+#include <private/qopenglcontext_p.h>
+#include <private/qimagepixmapcleanuphooks_p.h>
+#include <qplatformpixmap_qpa.h>
+
+QT_BEGIN_NAMESPACE
+
+class QOpenGLTextureCacheWrapper
+{
+public:
+    QOpenGLTextureCacheWrapper()
+    {
+        QImagePixmapCleanupHooks::instance()->addPlatformPixmapModificationHook(cleanupTexturesForPixmapData);
+        QImagePixmapCleanupHooks::instance()->addPlatformPixmapDestructionHook(cleanupTexturesForPixmapData);
+        QImagePixmapCleanupHooks::instance()->addImageHook(cleanupTexturesForCacheKey);
+    }
+
+    ~QOpenGLTextureCacheWrapper()
+    {
+        QImagePixmapCleanupHooks::instance()->removePlatformPixmapModificationHook(cleanupTexturesForPixmapData);
+        QImagePixmapCleanupHooks::instance()->removePlatformPixmapDestructionHook(cleanupTexturesForPixmapData);
+        QImagePixmapCleanupHooks::instance()->removeImageHook(cleanupTexturesForCacheKey);
+    }
+
+    QOpenGLTextureCache *cacheForContext(QOpenGLContext *context) {
+        QMutexLocker lock(&m_mutex);
+        return m_resource.value<QOpenGLTextureCache>(context);
+    }
+
+    static void cleanupTexturesForCacheKey(qint64 key);
+    static void cleanupTexturesForPixmapData(QPlatformPixmap *pmd);
+
+private:
+    QOpenGLMultiGroupSharedResource m_resource;
+    QMutex m_mutex;
+};
+
+Q_GLOBAL_STATIC(QOpenGLTextureCacheWrapper, qt_texture_caches)
+
+QOpenGLTextureCache *QOpenGLTextureCache::cacheForContext(QOpenGLContext *context)
+{
+    return qt_texture_caches()->cacheForContext(context);
+}
+
+void QOpenGLTextureCacheWrapper::cleanupTexturesForCacheKey(qint64 key)
+{
+    QList<QOpenGLSharedResource *> resources = qt_texture_caches()->m_resource.resources();
+    for (QList<QOpenGLSharedResource *>::iterator it = resources.begin(); it != resources.end(); ++it)
+        static_cast<QOpenGLTextureCache *>(*it)->invalidate(key);
+}
+
+void QOpenGLTextureCacheWrapper::cleanupTexturesForPixmapData(QPlatformPixmap *pmd)
+{
+    cleanupTexturesForCacheKey(pmd->cacheKey());
+}
+
+QOpenGLTextureCache::QOpenGLTextureCache(QOpenGLContext *ctx)
+    : QOpenGLSharedResource(ctx->shareGroup())
+    , m_cache(64 * 1024) // 64 MB cache
+{
+}
+
+QOpenGLTextureCache::~QOpenGLTextureCache()
+{
+}
+
+GLuint QOpenGLTextureCache::bindTexture(QOpenGLContext *context, const QPixmap &pixmap)
+{
+    QMutexLocker locker(&m_mutex);
+    qint64 key = pixmap.cacheKey();
+
+    // A QPainter is active on the image - take the safe route and replace the texture.
+    if (!pixmap.paintingActive()) {
+        QOpenGLCachedTexture *entry = m_cache.object(key);
+        if (entry) {
+            glBindTexture(GL_TEXTURE_2D, entry->id());
+            return entry->id();
+        }
+    }
+
+    GLuint id = bindTexture(context, key, pixmap.toImage());
+    if (id > 0)
+        QImagePixmapCleanupHooks::enableCleanupHooks(pixmap);
+
+    return id;
+}
+
+GLuint QOpenGLTextureCache::bindTexture(QOpenGLContext *context, const QImage &image)
+{
+    QMutexLocker locker(&m_mutex);
+    qint64 key = image.cacheKey();
+
+    // A QPainter is active on the image - take the safe route and replace the texture.
+    if (!image.paintingActive()) {
+        QOpenGLCachedTexture *entry = m_cache.object(key);
+        if (entry) {
+            glBindTexture(GL_TEXTURE_2D, entry->id());
+            return entry->id();
+        }
+    }
+
+    GLuint id = bindTexture(context, key, image);
+    if (id > 0)
+        QImagePixmapCleanupHooks::enableCleanupHooks(image);
+
+    return id;
+}
+
+static inline void qgl_byteSwapImage(QImage &img)
+{
+    const int width = img.width();
+    const int height = img.height();
+
+    if (QSysInfo::ByteOrder == QSysInfo::LittleEndian)
+    {
+        for (int i = 0; i < height; ++i) {
+            uint *p = (uint *) img.scanLine(i);
+            for (int x = 0; x < width; ++x)
+                p[x] = ((p[x] << 16) & 0xff0000) | ((p[x] >> 16) & 0xff) | (p[x] & 0xff00ff00);
+        }
+    } else {
+        for (int i = 0; i < height; ++i) {
+            uint *p = (uint *) img.scanLine(i);
+            for (int x = 0; x < width; ++x)
+                p[x] = (p[x] << 8) | (p[x] >> 24);
+        }
+    }
+}
+
+GLuint QOpenGLTextureCache::bindTexture(QOpenGLContext *context, qint64 key, const QImage &image)
+{
+    GLuint id;
+    glGenTextures(1, &id);
+    glBindTexture(GL_TEXTURE_2D, id);
+
+    QImage tx = image.convertToFormat(QImage::Format_ARGB32_Premultiplied);
+
+    qgl_byteSwapImage(tx);
+
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tx.width(), tx.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, const_cast<const QImage &>(tx).bits());
+
+    int cost = tx.width() * tx.height() * 4 / 1024;
+    m_cache.insert(key, new QOpenGLCachedTexture(id, context), cost);
+
+    return id;
+}
+
+void QOpenGLTextureCache::invalidate(qint64 key)
+{
+    QMutexLocker locker(&m_mutex);
+    m_cache.remove(key);
+}
+
+void QOpenGLTextureCache::invalidateResource()
+{
+    m_cache.clear();
+}
+
+void QOpenGLTextureCache::freeResource(QOpenGLContext *)
+{
+    Q_ASSERT(false); // the texture cache lives until the context group disappears
+}
+
+static void freeTexture(QOpenGLFunctions *, GLuint id)
+{
+    glDeleteTextures(1, &id);
+}
+
+QOpenGLCachedTexture::QOpenGLCachedTexture(GLuint id, QOpenGLContext *context)
+{
+    m_resource = new QOpenGLSharedResourceGuard(context, id, freeTexture);
+}
+
+QT_END_NAMESPACE