Basic working compressed texture atlas

This adds experimental automatic atlasing of ETC-compressed textures
(to be expanded to additional formats), similar to existing atlas
support of QImages. It is off by default, and can be enabled with
QSG_ENABLE_COMPRESSED_ATLAS=1.

[ChangeLog] Add experimental automatic atlasing of ETC-compressed
textures (can be enabled with QSG_ENABLE_COMPRESSED_ATLAS=1)

Change-Id: Ia66971f51299d082a569bdfaadb662a3e522bd79
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

11 files changed, 591 insertions, 154 deletions

diff --git a/src/quick/scenegraph/compressedtexture/qsgcompressedatlastexture.cpp b/src/quick/scenegraph/compressedtexture/qsgcompressedatlastexture.cpp
new file mode 100644
index 0000000000..301f2826dc
--- /dev/null
+++ b/src/quick/scenegraph/compressedtexture/qsgcompressedatlastexture.cpp
@@ -0,0 +1,174 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsgcompressedatlastexture_p.h"
+
+#include <QtCore/QVarLengthArray>
+#include <QtCore/QElapsedTimer>
+#include <QtCore/QtMath>
+
+#include <QtGui/QOpenGLContext>
+#include <QtGui/QGuiApplication>
+#include <QtGui/QScreen>
+#include <QtGui/QSurface>
+#include <QtGui/QWindow>
+#include <QtGui/QOpenGLFunctions>
+#include <QtGui/QOpenGLTexture>
+#include <QDebug>
+
+#include <private/qqmlglobal_p.h>
+#include <private/qquickprofiler_p.h>
+#include <private/qsgtexture_p.h>
+#include <private/qsgcompressedtexture_p.h>
+#include <private/qsgpkmhandler_p.h>
+
+QT_BEGIN_NAMESPACE
+
+static QElapsedTimer qsg_renderer_timer;
+
+namespace QSGCompressedAtlasTexture
+{
+
+Atlas::Atlas(const QSize &size, uint format)
+    : QSGAtlasTexture::AtlasBase(size)
+    , m_format(format)
+{
+}
+
+Atlas::~Atlas()
+{
+}
+
+Texture *Atlas::create(const QByteArray &data, int dataLength, int dataOffset, const QSize &size, const QSize &paddedSize)
+{
+    // No need to lock, as manager already locked it.
+    QRect rect = m_allocator.allocate(paddedSize);
+    if (rect.width() > 0 && rect.height() > 0) {
+        Texture *t = new Texture(this, rect, data, dataLength, dataOffset, size);
+        m_pending_uploads << t;
+        return t;
+    }
+    return 0;
+}
+
+void Atlas::generateTexture()
+{
+    QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
+    funcs->glCompressedTexImage2D(GL_TEXTURE_2D, 0, m_format,
+                                  m_size.width(), m_size.height(), 0,
+                                  (m_size.width() * m_size.height()) / 2,
+                                  0);
+}
+
+void Atlas::uploadPendingTexture(int i)
+{
+    Texture *texture = static_cast<Texture*>(m_pending_uploads.at(i));
+
+    const QRect &r = texture->atlasSubRect();
+
+    QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
+    funcs->glCompressedTexSubImage2D(GL_TEXTURE_2D, 0,
+                                     r.x(), r.y(), r.width(), r.height(), m_format,
+                                     texture->sizeInBytes(),
+                                     texture->data().constData() + texture->dataOffset());
+
+    qCDebug(QSG_LOG_TIME_TEXTURE).nospace() << "compressed atlastexture uploaded in: " << qsg_renderer_timer.elapsed()
+                                       << "ms (" << texture->textureSize().width() << "x"
+                                       << texture->textureSize().height() << ")";
+
+    // TODO: consider releasing the data (as is done in the regular atlas)?
+    // The advantage of keeping this data around is that it makes it much easier
+    // to remove the texture from the atlas
+}
+
+Texture::Texture(Atlas *atlas, const QRect &textureRect, const QByteArray &data, int dataLength, int dataOffset, const QSize &size)
+    : QSGAtlasTexture::TextureBase(atlas, textureRect)
+    , m_nonatlas_texture(0)
+    , m_data(data)
+    , m_size(size)
+    , m_dataLength(dataLength)
+    , m_dataOffset(dataOffset)
+{
+    float w = atlas->size().width();
+    float h = atlas->size().height();
+    QRect nopad = atlasSubRect();
+    // offset by half-pixel to prevent bleeding when scaling
+    m_texture_coords_rect = QRectF((nopad.x() + .5) / w,
+                                   (nopad.y() + .5) / h,
+                                   (nopad.width() - 1.) / w,
+                                   (nopad.height() - 1.) / h);
+}
+
+Texture::~Texture()
+{
+    delete m_nonatlas_texture;
+}
+
+bool Texture::hasAlphaChannel() const
+{
+    return QSGCompressedTexture::formatIsOpaque(static_cast<Atlas*>(m_atlas)->format());
+}
+
+QSGTexture *Texture::removedFromAtlas() const
+{
+    if (m_nonatlas_texture) {
+        m_nonatlas_texture->setMipmapFiltering(mipmapFiltering());
+        m_nonatlas_texture->setFiltering(filtering());
+        return m_nonatlas_texture;
+    }
+
+    if (!m_data.isEmpty()) {
+        QSGCompressedTexture::DataPtr texData(QSGCompressedTexture::DataPtr::create());
+        texData->data = m_data;
+        texData->size = m_size;
+        texData->format = static_cast<Atlas*>(m_atlas)->format();
+        texData->hasAlpha = hasAlphaChannel();
+        texData->dataLength = m_dataLength;
+        texData->dataOffset = m_dataOffset;
+        m_nonatlas_texture = new QSGCompressedTexture(texData);
+        m_nonatlas_texture->setMipmapFiltering(mipmapFiltering());
+        m_nonatlas_texture->setFiltering(filtering());
+    }
+
+    return m_nonatlas_texture;
+}
+
+}
+
+QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/compressedtexture/qsgcompressedatlastexture_p.h b/src/quick/scenegraph/compressedtexture/qsgcompressedatlastexture_p.h
new file mode 100644
index 0000000000..59e935b623
--- /dev/null
+++ b/src/quick/scenegraph/compressedtexture/qsgcompressedatlastexture_p.h
@@ -0,0 +1,119 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QSGCOMPRESSEDATLASTEXTURE_P_H
+#define QSGCOMPRESSEDATLASTEXTURE_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/QSize>
+
+#include <QtGui/qopengl.h>
+
+#include <QtQuick/QSGTexture>
+#include <QtQuick/private/qsgareaallocator_p.h>
+#include <QtQuick/private/qsgatlastexture_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class QSGCompressedTextureFactory;
+
+namespace QSGCompressedAtlasTexture {
+
+class Texture;
+
+class Atlas : public QSGAtlasTexture::AtlasBase
+{
+public:
+    Atlas(const QSize &size, uint format);
+    ~Atlas();
+
+    void generateTexture() override;
+    void uploadPendingTexture(int i) override;
+
+    Texture *create(const QByteArray &data, int dataLength, int dataOffset, const QSize &size, const QSize &paddedSize);
+
+    uint format() const { return m_format; }
+
+private:
+    uint m_format;
+};
+
+class Texture : public QSGAtlasTexture::TextureBase
+{
+    Q_OBJECT
+public:
+    Texture(Atlas *atlas, const QRect &textureRect, const QByteArray &data, int dataLength, int dataOffset, const QSize &size);
+    ~Texture();
+
+    QSize textureSize() const override { return m_size; }
+    bool hasAlphaChannel() const override;
+    bool hasMipmaps() const override { return false; }
+
+    QRectF normalizedTextureSubRect() const override { return m_texture_coords_rect; }
+
+    QSGTexture *removedFromAtlas() const override;
+
+    const QByteArray &data() const { return m_data; }
+    int sizeInBytes() const { return m_dataLength; }
+    int dataOffset() const { return m_dataOffset; }
+
+private:
+    QRectF m_texture_coords_rect;
+    mutable QSGTexture *m_nonatlas_texture;
+    QByteArray m_data;
+    QSize m_size;
+    int m_dataLength;
+    int m_dataOffset;
+};
+
+}
+
+QT_END_NAMESPACE
+
+#endif
diff --git a/src/quick/scenegraph/compressedtexture/qsgcompressedtexture.cpp b/src/quick/scenegraph/compressedtexture/qsgcompressedtexture.cpp
index 6d51ed9d61..839c562989 100644
--- a/src/quick/scenegraph/compressedtexture/qsgcompressedtexture.cpp
+++ b/src/quick/scenegraph/compressedtexture/qsgcompressedtexture.cpp
@@ -43,6 +43,7 @@
 #include <QOpenGLTexture>
 #include <QOpenGLFunctions>
 #include <QDebug>
+#include <QtQuick/private/qquickwindow_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -215,11 +216,17 @@ QSGCompressedTextureFactory::QSGCompressedTextureFactory(const QSGCompressedText
 {
 }
 
-QSGTexture *QSGCompressedTextureFactory::createTexture(QQuickWindow *) const
+QSGTexture *QSGCompressedTextureFactory::createTexture(QQuickWindow *window) const
 {
     if (!m_textureData || !m_textureData->isValid())
         return nullptr;
 
+    // attempt to atlas the texture
+    QSGRenderContext *context = QQuickWindowPrivate::get(window)->context;
+    QSGTexture *t = context->compressedTextureForFactory(this);
+    if (t)
+        return t;
+
     return new QSGCompressedTexture(m_textureData);
 }
 
diff --git a/src/quick/scenegraph/compressedtexture/qsgcompressedtexture_p.h b/src/quick/scenegraph/compressedtexture/qsgcompressedtexture_p.h
index dfedac5558..aa87316809 100644
--- a/src/quick/scenegraph/compressedtexture/qsgcompressedtexture_p.h
+++ b/src/quick/scenegraph/compressedtexture/qsgcompressedtexture_p.h
@@ -103,6 +103,9 @@ protected:
     bool m_uploaded = false;
 };
 
+namespace QSGAtlasTexture {
+    class Manager;
+}
 
 class Q_QUICK_PRIVATE_EXPORT QSGCompressedTextureFactory : public QQuickTextureFactory
 {
@@ -114,6 +117,8 @@ public:
 
 protected:
     QSGCompressedTexture::DataPtr m_textureData;
+private:
+    friend class QSGAtlasTexture::Manager;
 };
 
 QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/qsgcontext.cpp b/src/quick/scenegraph/qsgcontext.cpp
index fb66a6ebb1..e5334d59e1 100644
--- a/src/quick/scenegraph/qsgcontext.cpp
+++ b/src/quick/scenegraph/qsgcontext.cpp
@@ -404,6 +404,20 @@ void QSGRenderContext::textureFactoryDestroyed(QObject *o)
     m_mutex.unlock();
 }
 
+/*!
+    Return the texture corresponding to a texture factory.
+
+    This may optionally manipulate the texture in some way; for example by returning
+    an atlased texture.
+
+    This function is not a replacement for textureForFactory; both should be used
+    for a single texture (this might atlas, while the other might cache).
+*/
+QSGTexture *QSGRenderContext::compressedTextureForFactory(const QSGCompressedTextureFactory *) const
+{
+    return nullptr;
+}
+
 #include "qsgcontext.moc"
 #include "moc_qsgcontext_p.cpp"
 
diff --git a/src/quick/scenegraph/qsgcontext_p.h b/src/quick/scenegraph/qsgcontext_p.h
index 84a2523f26..da0adcd5d7 100644
--- a/src/quick/scenegraph/qsgcontext_p.h
+++ b/src/quick/scenegraph/qsgcontext_p.h
@@ -78,6 +78,7 @@ class QSGMaterial;
 class QSGRenderLoop;
 class QSGLayer;
 class QQuickTextureFactory;
+class QSGCompressedTextureFactory;
 class QSGContext;
 class QQuickPaintedItem;
 class QSGRendererInterface;
@@ -173,6 +174,7 @@ public:
 
     virtual QSGTexture *createTexture(const QImage &image, uint flags = CreateTexture_Alpha) const = 0;
     virtual QSGRenderer *createRenderer() = 0;
+    virtual QSGTexture *compressedTextureForFactory(const QSGCompressedTextureFactory *) const;
 
     virtual void setAttachToGraphicsContext(bool attach) { Q_UNUSED(attach); }
 
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext.cpp b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
index 95f3555994..12357f12c7 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext.cpp
+++ b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
@@ -44,6 +44,7 @@
 #include <QtQuick/private/qsgbatchrenderer_p.h>
 #include <QtQuick/private/qsgrenderer_p.h>
 #include <QtQuick/private/qsgatlastexture_p.h>
+#include <QtQuick/private/qsgcompressedtexture_p.h>
 #include <QtQuick/private/qsgdefaultdistancefieldglyphcache_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -243,6 +244,14 @@ QSGRenderer *QSGDefaultRenderContext::createRenderer()
     return new QSGBatchRenderer::Renderer(this);
 }
 
+QSGTexture *QSGDefaultRenderContext::compressedTextureForFactory(const QSGCompressedTextureFactory *factory) const
+{
+    // The atlas implementation is only supported from the render thread
+    if (openglContext() && QThread::currentThread() == openglContext()->thread())
+        return m_atlasManager->create(factory);
+    return nullptr;
+}
+
 /*!
     Compile \a shader, optionally using \a vertexCode and \a fragmentCode as
     replacement for the source code supplied by \a shader.
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext_p.h b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
index 2537a06988..68329256f1 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext_p.h
+++ b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
@@ -84,6 +84,7 @@ public:
 
     QSGTexture *createTexture(const QImage &image, uint flags) const override;
     QSGRenderer *createRenderer() override;
+    QSGTexture *compressedTextureForFactory(const QSGCompressedTextureFactory *factory) const override;
 
     virtual void compileShader(QSGMaterialShader *shader, QSGMaterial *material, const char *vertexCode = 0, const char *fragmentCode = 0);
     virtual void initializeShader(QSGMaterialShader *shader);
diff --git a/src/quick/scenegraph/scenegraph.pri b/src/quick/scenegraph/scenegraph.pri
index 377a4647da..bdd694f95e 100644
--- a/src/quick/scenegraph/scenegraph.pri
+++ b/src/quick/scenegraph/scenegraph.pri
@@ -230,11 +230,13 @@ SOURCES += \
 
 qtConfig(opengl(es1|es2)?) {
     HEADERS += \
+        $$PWD/compressedtexture/qsgcompressedatlastexture_p.h \
         $$PWD/compressedtexture/qsgcompressedtexture_p.h \
         $$PWD/compressedtexture/qsgtexturefilehandler_p.h \
         $$PWD/compressedtexture/qsgpkmhandler_p.h
 
     SOURCES += \
+        $$PWD/compressedtexture/qsgcompressedatlastexture.cpp \
         $$PWD/compressedtexture/qsgcompressedtexture.cpp \
         $$PWD/compressedtexture/qsgpkmhandler.cpp
 }
diff --git a/src/quick/scenegraph/util/qsgatlastexture.cpp b/src/quick/scenegraph/util/qsgatlastexture.cpp
index 22f0b13f46..9d37746fff 100644
--- a/src/quick/scenegraph/util/qsgatlastexture.cpp
+++ b/src/quick/scenegraph/util/qsgatlastexture.cpp
@@ -44,6 +44,7 @@
 #include <QtCore/QtMath>
 
 #include <QtGui/QOpenGLContext>
+#include <QtGui/QOpenGLTexture>
 #include <QtGui/QOpenGLFunctions>
 #include <QtGui/QGuiApplication>
 #include <QtGui/QScreen>
@@ -52,6 +53,8 @@
 #include <QtGui/qpa/qplatformnativeinterface.h>
 
 #include <private/qsgtexture_p.h>
+#include <private/qsgcompressedtexture_p.h>
+#include <private/qsgcompressedatlastexture_p.h>
 
 #include <private/qquickprofiler_p.h>
 
@@ -65,6 +68,8 @@ int qt_sg_envInt(const char *name, int defaultValue);
 
 static QElapsedTimer qsg_renderer_timer;
 
+DEFINE_BOOL_CONFIG_OPTION(qsgEnableCompressedAtlas, QSG_ENABLE_COMPRESSED_ATLAS)
+
 namespace QSGAtlasTexture
 {
 
@@ -100,6 +105,7 @@ Manager::Manager()
 Manager::~Manager()
 {
     Q_ASSERT(m_atlas == 0);
+    Q_ASSERT(m_atlases.isEmpty());
 }
 
 void Manager::invalidate()
@@ -109,6 +115,14 @@ void Manager::invalidate()
         m_atlas->deleteLater();
         m_atlas = 0;
     }
+
+    QHash<unsigned int, QSGCompressedAtlasTexture::Atlas*>::iterator i = m_atlases.begin();
+    while (i != m_atlases.end()) {
+        i.value()->invalidate();
+        i.value()->deleteLater();
+        ++i;
+    }
+    m_atlases.clear();
 }
 
 QSGTexture *Manager::create(const QImage &image, bool hasAlphaChannel)
@@ -125,13 +139,147 @@ QSGTexture *Manager::create(const QImage &image, bool hasAlphaChannel)
     return t;
 }
 
-Atlas::Atlas(const QSize &size)
+QSGTexture *Manager::create(const QSGCompressedTextureFactory *factory)
+{
+    QSGTexture *t = 0;
+    if (!qsgEnableCompressedAtlas() || !factory->m_textureData || !factory->m_textureData->isValid())
+        return t;
+
+    // TODO: further abstract the atlas and remove this restriction
+    unsigned int format = factory->m_textureData->format;
+    switch (format) {
+    case QOpenGLTexture::RGB8_ETC1:
+    case QOpenGLTexture::RGB8_ETC2:
+    case QOpenGLTexture::RGBA8_ETC2_EAC:
+    case QOpenGLTexture::RGB8_PunchThrough_Alpha1_ETC2:
+        break;
+    default:
+        return t;
+    }
+
+    QSize size = factory->m_textureData->size;
+    if (size.width() < m_atlas_size_limit && size.height() < m_atlas_size_limit) {
+        QHash<unsigned int, QSGCompressedAtlasTexture::Atlas*>::iterator i = m_atlases.find(format);
+        if (i == m_atlases.end())
+            i = m_atlases.insert(format, new QSGCompressedAtlasTexture::Atlas(m_atlas_size, format));
+        // must be multiple of 4
+        QSize paddedSize(((size.width() + 3) / 4) * 4, ((size.height() + 3) / 4) * 4);
+        QByteArray data = factory->m_textureData->data;
+        t = i.value()->create(data, factory->m_textureData->sizeInBytes(), factory->m_textureData->dataOffset, size, paddedSize);
+    }
+    return t;
+}
+
+AtlasBase::AtlasBase(const QSize &size)
     : m_allocator(size)
     , m_texture_id(0)
     , m_size(size)
-    , m_atlas_transient_image_threshold(0)
     , m_allocated(false)
 {
+}
+
+AtlasBase::~AtlasBase()
+{
+    Q_ASSERT(!m_texture_id);
+}
+
+void AtlasBase::invalidate()
+{
+    if (m_texture_id && QOpenGLContext::currentContext())
+        QOpenGLContext::currentContext()->functions()->glDeleteTextures(1, &m_texture_id);
+    m_texture_id = 0;
+}
+
+int AtlasBase::textureId() const
+{
+    if (!m_texture_id) {
+        Q_ASSERT(QOpenGLContext::currentContext());
+        QOpenGLContext::currentContext()->functions()->glGenTextures(1, &const_cast<AtlasBase *>(this)->m_texture_id);
+    }
+
+    return m_texture_id;
+}
+
+void AtlasBase::bind(QSGTexture::Filtering filtering)
+{
+    QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
+    if (!m_allocated) {
+        m_allocated = true;
+
+        while (funcs->glGetError() != GL_NO_ERROR) ;
+
+        funcs->glGenTextures(1, &m_texture_id);
+        funcs->glBindTexture(GL_TEXTURE_2D, m_texture_id);
+        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+#if !defined(QT_OPENGL_ES_2)
+        if (!QOpenGLContext::currentContext()->isOpenGLES())
+            funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
+#endif
+        generateTexture();
+
+        GLenum errorCode = funcs->glGetError();
+        if (errorCode == GL_OUT_OF_MEMORY) {
+            qDebug("QSGTextureAtlas: texture atlas allocation failed, out of memory");
+            funcs->glDeleteTextures(1, &m_texture_id);
+            m_texture_id = 0;
+        } else if (errorCode != GL_NO_ERROR) {
+            qDebug("QSGTextureAtlas: texture atlas allocation failed, code=%x", errorCode);
+            funcs->glDeleteTextures(1, &m_texture_id);
+            m_texture_id = 0;
+        }
+    } else {
+        funcs->glBindTexture(GL_TEXTURE_2D, m_texture_id);
+    }
+
+    if (m_texture_id == 0)
+        return;
+
+    // Upload all pending images..
+    for (int i=0; i<m_pending_uploads.size(); ++i) {
+
+        bool profileFrames = QSG_LOG_TIME_TEXTURE().isDebugEnabled();
+        if (profileFrames)
+            qsg_renderer_timer.start();
+
+        Q_QUICK_SG_PROFILE_START(QQuickProfiler::SceneGraphTexturePrepare);
+
+        // Skip bind, convert, swizzle; they're irrelevant
+        Q_QUICK_SG_PROFILE_SKIP(QQuickProfiler::SceneGraphTexturePrepare,
+                                QQuickProfiler::SceneGraphTexturePrepareStart, 3);
+
+        uploadPendingTexture(i);
+
+        Q_QUICK_SG_PROFILE_RECORD(QQuickProfiler::SceneGraphTexturePrepare,
+                                  QQuickProfiler::SceneGraphTexturePrepareUpload);
+
+        // Skip mipmap; unused
+        Q_QUICK_SG_PROFILE_SKIP(QQuickProfiler::SceneGraphTexturePrepare,
+                                QQuickProfiler::SceneGraphTexturePrepareUpload, 1);
+        Q_QUICK_SG_PROFILE_REPORT(QQuickProfiler::SceneGraphTexturePrepare,
+                                  QQuickProfiler::SceneGraphTexturePrepareMipmap);
+    }
+
+    GLenum f = filtering == QSGTexture::Nearest ? GL_NEAREST : GL_LINEAR;
+    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, f);
+    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, f);
+
+    m_pending_uploads.clear();
+}
+
+void AtlasBase::remove(TextureBase *t)
+{
+    QRect atlasRect = t->atlasSubRect();
+    m_allocator.deallocate(atlasRect);
+    m_pending_uploads.removeOne(t);
+}
+
+Atlas::Atlas(const QSize &size)
+    : AtlasBase(size)
+    , m_atlas_transient_image_threshold(0)
+{
 
     m_internalFormat = GL_RGBA;
     m_externalFormat = GL_BGRA;
@@ -188,14 +336,6 @@ Atlas::Atlas(const QSize &size)
 
 Atlas::~Atlas()
 {
-    Q_ASSERT(!m_texture_id);
-}
-
-void Atlas::invalidate()
-{
-    if (m_texture_id && QOpenGLContext::currentContext())
-        QOpenGLContext::currentContext()->functions()->glDeleteTextures(1, &m_texture_id);
-    m_texture_id = 0;
 }
 
 Texture *Atlas::create(const QImage &image)
@@ -210,17 +350,6 @@ Texture *Atlas::create(const QImage &image)
     return 0;
 }
 
-
-int Atlas::textureId() const
-{
-    if (!m_texture_id) {
-        Q_ASSERT(QOpenGLContext::currentContext());
-        QOpenGLContext::currentContext()->functions()->glGenTextures(1, &const_cast<Atlas *>(this)->m_texture_id);
-    }
-
-    return m_texture_id;
-}
-
 static void swizzleBGRAToRGBA(QImage *image)
 {
     const int width = image->width();
@@ -334,121 +463,68 @@ void Atlas::uploadBgra(Texture *texture)
     }
 }
 
-void Atlas::bind(QSGTexture::Filtering filtering)
+void Atlas::generateTexture()
 {
     QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
-    if (!m_allocated) {
-        m_allocated = true;
-
-        while (funcs->glGetError() != GL_NO_ERROR) ;
-
-        funcs->glGenTextures(1, &m_texture_id);
-        funcs->glBindTexture(GL_TEXTURE_2D, m_texture_id);
-        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-#if !defined(QT_OPENGL_ES_2)
-        if (!QOpenGLContext::currentContext()->isOpenGLES())
-            funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
-#endif
-        funcs->glTexImage2D(GL_TEXTURE_2D, 0, m_internalFormat, m_size.width(), m_size.height(), 0, m_externalFormat, GL_UNSIGNED_BYTE, 0);
+    funcs->glTexImage2D(GL_TEXTURE_2D, 0, m_internalFormat, m_size.width(), m_size.height(), 0, m_externalFormat, GL_UNSIGNED_BYTE, 0);
 
 #if 0
-        QImage pink(m_size.width(), m_size.height(), QImage::Format_ARGB32_Premultiplied);
-        pink.fill(0);
-        QPainter p(&pink);
-        QLinearGradient redGrad(0, 0, m_size.width(), 0);
-        redGrad.setColorAt(0, Qt::black);
-        redGrad.setColorAt(1, Qt::red);
-        p.fillRect(0, 0, m_size.width(), m_size.height(), redGrad);
-        p.setCompositionMode(QPainter::CompositionMode_Plus);
-        QLinearGradient blueGrad(0, 0, 0, m_size.height());
-        blueGrad.setColorAt(0, Qt::black);
-        blueGrad.setColorAt(1, Qt::blue);
-        p.fillRect(0, 0, m_size.width(), m_size.height(), blueGrad);
-        p.end();
-
-        funcs->glTexImage2D(GL_TEXTURE_2D, 0, m_internalFormat, m_size.width(), m_size.height(), 0, m_externalFormat, GL_UNSIGNED_BYTE, pink.constBits());
+    QImage pink(m_size.width(), m_size.height(), QImage::Format_ARGB32_Premultiplied);
+    pink.fill(0);
+    QPainter p(&pink);
+    QLinearGradient redGrad(0, 0, m_size.width(), 0);
+    redGrad.setColorAt(0, Qt::black);
+    redGrad.setColorAt(1, Qt::red);
+    p.fillRect(0, 0, m_size.width(), m_size.height(), redGrad);
+    p.setCompositionMode(QPainter::CompositionMode_Plus);
+    QLinearGradient blueGrad(0, 0, 0, m_size.height());
+    blueGrad.setColorAt(0, Qt::black);
+    blueGrad.setColorAt(1, Qt::blue);
+    p.fillRect(0, 0, m_size.width(), m_size.height(), blueGrad);
+    p.end();
+
+    funcs->glTexImage2D(GL_TEXTURE_2D, 0, m_internalFormat, m_size.width(), m_size.height(), 0, m_externalFormat, GL_UNSIGNED_BYTE, pink.constBits());
 #endif
+}
 
-        GLenum errorCode = funcs->glGetError();
-        if (errorCode == GL_OUT_OF_MEMORY) {
-            qDebug("QSGTextureAtlas: texture atlas allocation failed, out of memory");
-            funcs->glDeleteTextures(1, &m_texture_id);
-            m_texture_id = 0;
-        } else if (errorCode != GL_NO_ERROR) {
-            qDebug("QSGTextureAtlas: texture atlas allocation failed, code=%x", errorCode);
-            funcs->glDeleteTextures(1, &m_texture_id);
-            m_texture_id = 0;
-        }
+void Atlas::uploadPendingTexture(int i)
+{
+    Texture *t = static_cast<Texture*>(m_pending_uploads.at(i));
+    if (m_externalFormat == GL_BGRA &&
+            !m_use_bgra_fallback) {
+        uploadBgra(t);
     } else {
-        funcs->glBindTexture(GL_TEXTURE_2D, m_texture_id);
+        upload(t);
     }
-
-    if (m_texture_id == 0)
-        return;
-
-    // Upload all pending images..
-    for (int i=0; i<m_pending_uploads.size(); ++i) {
-
-        bool profileFrames = QSG_LOG_TIME_TEXTURE().isDebugEnabled();
-        if (profileFrames)
-            qsg_renderer_timer.start();
-
-        Q_QUICK_SG_PROFILE_START(QQuickProfiler::SceneGraphTexturePrepare);
-
-        // Skip bind, convert, swizzle; they're irrelevant
-        Q_QUICK_SG_PROFILE_SKIP(QQuickProfiler::SceneGraphTexturePrepare,
-                                QQuickProfiler::SceneGraphTexturePrepareStart, 3);
-
-        Texture *t = m_pending_uploads.at(i);
-        if (m_externalFormat == GL_BGRA &&
-                !m_use_bgra_fallback) {
-            uploadBgra(t);
-        } else {
-            upload(t);
-        }
-        const QSize textureSize = t->textureSize();
-        if (textureSize.width() > m_atlas_transient_image_threshold ||
-                textureSize.height() > m_atlas_transient_image_threshold)
-            t->releaseImage();
-
-        qCDebug(QSG_LOG_TIME_TEXTURE).nospace() << "atlastexture uploaded in: " << qsg_renderer_timer.elapsed()
-                                           << "ms (" << t->textureSize().width() << "x"
-                                           << t->textureSize().height() << ")";
-
-        Q_QUICK_SG_PROFILE_RECORD(QQuickProfiler::SceneGraphTexturePrepare,
-                                  QQuickProfiler::SceneGraphTexturePrepareUpload);
-
-        // Skip mipmap; unused
-        Q_QUICK_SG_PROFILE_SKIP(QQuickProfiler::SceneGraphTexturePrepare,
-                                QQuickProfiler::SceneGraphTexturePrepareUpload, 1);
-        Q_QUICK_SG_PROFILE_REPORT(QQuickProfiler::SceneGraphTexturePrepare,
-                                  QQuickProfiler::SceneGraphTexturePrepareMipmap);
-    }
-
-    GLenum f = filtering == QSGTexture::Nearest ? GL_NEAREST : GL_LINEAR;
-    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, f);
-    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, f);
-
-    m_pending_uploads.clear();
+    const QSize textureSize = t->textureSize();
+    if (textureSize.width() > m_atlas_transient_image_threshold ||
+            textureSize.height() > m_atlas_transient_image_threshold)
+        t->releaseImage();
+
+    qCDebug(QSG_LOG_TIME_TEXTURE).nospace() << "atlastexture uploaded in: " << qsg_renderer_timer.elapsed()
+                                            << "ms (" << t->textureSize().width() << "x"
+                                            << t->textureSize().height() << ")";
 }
 
-void Atlas::remove(Texture *t)
+TextureBase::TextureBase(AtlasBase *atlas, const QRect &textureRect)
+    : m_allocated_rect(textureRect)
+    , m_atlas(atlas)
 {
-    QRect atlasRect = t->atlasSubRect();
-    m_allocator.deallocate(atlasRect);
-    m_pending_uploads.removeOne(t);
 }
 
+TextureBase::~TextureBase()
+{
+    m_atlas->remove(this);
+}
 
+void TextureBase::bind()
+{
+    m_atlas->bind(filtering());
+}
 
 Texture::Texture(Atlas *atlas, const QRect &textureRect, const QImage &image)
-    : QSGTexture()
-    , m_allocated_rect(textureRect)
+    : TextureBase(atlas, textureRect)
     , m_image(image)
-    , m_atlas(atlas)
     , m_nonatlas_texture(0)
     , m_has_alpha(image.hasAlphaChannel())
 {
@@ -463,16 +539,10 @@ Texture::Texture(Atlas *atlas, const QRect &textureRect, const QImage &image)
 
 Texture::~Texture()
 {
-    m_atlas->remove(this);
     if (m_nonatlas_texture)
         delete m_nonatlas_texture;
 }
 
-void Texture::bind()
-{
-    m_atlas->bind(filtering());
-}
-
 QSGTexture *Texture::removedFromAtlas() const
 {
     if (m_nonatlas_texture) {
@@ -508,7 +578,7 @@ QSGTexture *Texture::removedFromAtlas() const
         QRect r = atlasSubRectWithoutPadding();
         // and copy atlas into our texture.
         while (f->glGetError() != GL_NO_ERROR) ;
-        f->glCopyTexImage2D(GL_TEXTURE_2D, 0, m_atlas->internalFormat(), r.x(), r.y(), r.width(), r.height(), 0);
+        f->glCopyTexImage2D(GL_TEXTURE_2D, 0, static_cast<Atlas*>(m_atlas)->internalFormat(), r.x(), r.y(), r.width(), r.height(), 0);
         // BGRA may have been rejected by some GLES implementations
         if (f->glGetError() != GL_NO_ERROR)
             f->glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, r.x(), r.y(), r.width(), r.height(), 0);
diff --git a/src/quick/scenegraph/util/qsgatlastexture_p.h b/src/quick/scenegraph/util/qsgatlastexture_p.h
index 3dee539547..14dc8f7958 100644
--- a/src/quick/scenegraph/util/qsgatlastexture_p.h
+++ b/src/quick/scenegraph/util/qsgatlastexture_p.h
@@ -61,10 +61,16 @@
 
 QT_BEGIN_NAMESPACE
 
+namespace QSGCompressedAtlasTexture {
+    class Atlas;
+}
+class QSGCompressedTextureFactory;
+
 namespace QSGAtlasTexture
 {
 
 class Texture;
+class TextureBase;
 class Atlas;
 
 class Manager : public QObject
@@ -76,93 +82,121 @@ public:
     ~Manager();
 
     QSGTexture *create(const QImage &image, bool hasAlphaChannel);
+    QSGTexture *create(const QSGCompressedTextureFactory *factory);
     void invalidate();
 
 private:
     Atlas *m_atlas;
+    // set of atlases for different compressed formats
+    QHash<unsigned int, QSGCompressedAtlasTexture::Atlas*> m_atlases;
 
     QSize m_atlas_size;
     int m_atlas_size_limit;
 };
 
-class Atlas : public QObject
+class AtlasBase : public QObject
 {
+    Q_OBJECT
 public:
-    Atlas(const QSize &size);
-    ~Atlas();
+    AtlasBase(const QSize &size);
+    ~AtlasBase();
 
     void invalidate();
 
     int textureId() const;
     void bind(QSGTexture::Filtering filtering);
 
+    void remove(TextureBase *t);
+
+    QSize size() const { return m_size; }
+
+protected:
+    virtual void generateTexture() = 0;
+    virtual void uploadPendingTexture(int i) = 0;
+
+protected:
+    QSGAreaAllocator m_allocator;
+    unsigned int m_texture_id;
+    QSize m_size;
+    QList<TextureBase *> m_pending_uploads;
+
+private:
+    bool m_allocated;
+};
+
+class Atlas : public AtlasBase
+{
+public:
+    Atlas(const QSize &size);
+    ~Atlas();
+
+    void generateTexture() override;
+    void uploadPendingTexture(int i) override;
+
     void upload(Texture *texture);
     void uploadBgra(Texture *texture);
 
     Texture *create(const QImage &image);
-    void remove(Texture *t);
-
-    QSize size() const { return m_size; }
 
     uint internalFormat() const { return m_internalFormat; }
     uint externalFormat() const { return m_externalFormat; }
 
 private:
-    QSGAreaAllocator m_allocator;
-    unsigned int m_texture_id;
-    QSize m_size;
-    QList<Texture *> m_pending_uploads;
-
     uint m_internalFormat;
     uint m_externalFormat;
 
     int m_atlas_transient_image_threshold;
 
-    uint m_allocated : 1;
     uint m_use_bgra_fallback: 1;
-
     uint m_debug_overlay : 1;
 };
 
-class Texture : public QSGTexture
+class TextureBase : public QSGTexture
+{
+    Q_OBJECT
+public:
+    TextureBase(AtlasBase *atlas, const QRect &textureRect);
+    ~TextureBase();
+
+    int textureId() const override { return m_atlas->textureId(); }
+    bool isAtlasTexture() const override { return true; }
+
+    QRect atlasSubRect() const { return m_allocated_rect; }
+
+    void bind() override;
+
+protected:
+    QRect m_allocated_rect;
+    AtlasBase *m_atlas;
+};
+
+class Texture : public TextureBase
 {
     Q_OBJECT
 public:
     Texture(Atlas *atlas, const QRect &textureRect, const QImage &image);
     ~Texture();
 
-    int textureId() const override { return m_atlas->textureId(); }
     QSize textureSize() const override { return atlasSubRectWithoutPadding().size(); }
     void setHasAlphaChannel(bool alpha) { m_has_alpha = alpha; }
     bool hasAlphaChannel() const override { return m_has_alpha; }
     bool hasMipmaps() const override { return false; }
-    bool isAtlasTexture() const override { return true; }
 
     QRectF normalizedTextureSubRect() const override { return m_texture_coords_rect; }
 
     QRect atlasSubRect() const { return m_allocated_rect; }
     QRect atlasSubRectWithoutPadding() const { return m_allocated_rect.adjusted(1, 1, -1, -1); }
 
-    bool isTexture() const { return true; }
-
     QSGTexture *removedFromAtlas() const override;
 
     void releaseImage() { m_image = QImage(); }
     const QImage &image() const { return m_image; }
 
-    void bind() override;
-
 private:
-    QRect m_allocated_rect;
     QRectF m_texture_coords_rect;
-
     QImage m_image;
-
-    Atlas *m_atlas;
-
     mutable QSGPlainTexture *m_nonatlas_texture;
-
-    uint m_has_alpha : 1;
+    bool m_has_alpha;
 };
 
 }