Add the graphics api independent scenegraph port

Opt in via environment variables:
QSG_RHI=1 -> enable using QRhi instead of GL
QSG_RHI_BACKEND -> set to vulkan, metal, d3d11, gl to override the default
(the default is d3d11 on Windows, metal on Mac, gl elsewhere)

Or force a given rhi backend via the existing
QQuickWindow::setSceneGraphBackend().

Otherwise the default behavior is the same as before, the rhi code path
is never active by default.

-no-opengl builds are supported in the sense that they work and default
to the software backend. However, the rhi code path cannot currently be
used in such builds, even though QRhi from qtbase is fully functional
with Vulkan, D3D, or Metal even when qtbase was configured with
-no-opengl. This cannot be utilized by Quick atm due to OpenGL usage
being all over the place in the sources corresponding to the default
backend, and those host the rhi code path as well. This will be cleaned up
hopefully in Qt 6, with the removal all direct OpenGL usage.

Other env.vars.:
QSG_RHI_DEBUG_LAYER=1 -> enable D3D debug or Vulkan validation layer
(assuming the system is set up for this)
QSG_RHI_SHADEREFFECT_DEBUG=1 -> print stuff from ShaderEffect
QSG_SAMPLES=1,2,4,... -> MSAA sample count (but QSurfaceFormat works too)
QT_D3D_ADAPTER_INDEX=0,1,... -> D3D adapter index
QT_VK_PHYSICAL_DEVICE_INDEX=0,1,... -> Vulkan physical device index
QSG_RHI_UINT32_INDEX=1 -> always use uint index data (both
merged/unmerged, convert when needed - with some rhi backends this is
implicit)
QSG_RENDER_LOOP -> to override the render loop as usual. The default
with RHI is threaded for Metal, threaded for Vulkan on Windows, basic
for Vulkan on Linux and Android (to be checked later), while the existing
rules apply for OpenGL.

Not supported when running with QRhi:
  - particles
  - compressed atlases (though this is transparent to the apps)
  - QSGRenderNode
  - QQuickRenderControl
  - QQuickFramebufferObject
  - certain QQuickWindow functionality that depends directly on OpenGL
  - anisotropic filtering for textures
  - native text may lack some gamma correction
  - QSGEngine applicability unclear
  - some QML profiler logs may be incorrect or irrelevant

Change-Id: I7822e99ad79e342e4166275da6e9e66498d76521
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 568 insertions, 0 deletions

diff --git a/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp b/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp
new file mode 100644
index 0000000000..28fc10e413
--- /dev/null
+++ b/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp
@@ -0,0 +1,568 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 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 "qsgrhidistancefieldglyphcache_p.h"
+#include "qsgcontext_p.h"
+#include <QtGui/private/qdistancefield_p.h>
+#include <QtCore/qelapsedtimer.h>
+#include <QtQml/private/qqmlglobal_p.h>
+#include <qmath.h>
+#include <qendian.h>
+
+QT_BEGIN_NAMESPACE
+
+DEFINE_BOOL_CONFIG_OPTION(qmlUseGlyphCacheWorkaround, QML_USE_GLYPHCACHE_WORKAROUND)
+DEFINE_BOOL_CONFIG_OPTION(qsgPreferFullSizeGlyphCacheTextures, QSG_PREFER_FULLSIZE_GLYPHCACHE_TEXTURES)
+
+#if !defined(QSG_RHI_DISTANCEFIELD_GLYPH_CACHE_PADDING)
+#  define QSG_RHI_DISTANCEFIELD_GLYPH_CACHE_PADDING 2
+#endif
+
+QSGRhiDistanceFieldGlyphCache::QSGRhiDistanceFieldGlyphCache(QRhi *rhi, const QRawFont &font)
+    : QSGDistanceFieldGlyphCache(font)
+    , m_rhi(rhi)
+{
+    // Load a pregenerated cache if the font contains one
+    loadPregeneratedCache(font);
+}
+
+QSGRhiDistanceFieldGlyphCache::~QSGRhiDistanceFieldGlyphCache()
+{
+    for (int i = 0; i < m_textures.count(); ++i)
+        delete m_textures[i].texture;
+
+    delete m_areaAllocator;
+
+    // should be empty, but just in case
+    qDeleteAll(m_pendingDispose);
+}
+
+void QSGRhiDistanceFieldGlyphCache::requestGlyphs(const QSet<glyph_t> &glyphs)
+{
+    QList<GlyphPosition> glyphPositions;
+    QVector<glyph_t> glyphsToRender;
+
+    if (m_areaAllocator == nullptr)
+        m_areaAllocator = new QSGAreaAllocator(QSize(maxTextureSize(), m_maxTextureCount * maxTextureSize()));
+
+    for (QSet<glyph_t>::const_iterator it = glyphs.constBegin(); it != glyphs.constEnd() ; ++it) {
+        glyph_t glyphIndex = *it;
+
+        int padding = QSG_RHI_DISTANCEFIELD_GLYPH_CACHE_PADDING;
+        QRectF boundingRect = glyphData(glyphIndex).boundingRect;
+        int glyphWidth = qCeil(boundingRect.width()) + distanceFieldRadius() * 2;
+        int glyphHeight = qCeil(boundingRect.height()) + distanceFieldRadius() * 2;
+        QSize glyphSize(glyphWidth + padding * 2, glyphHeight + padding * 2);
+        QRect alloc = m_areaAllocator->allocate(glyphSize);
+
+        if (alloc.isNull()) {
+            // Unallocate unused glyphs until we can allocated the new glyph
+            while (alloc.isNull() && !m_unusedGlyphs.isEmpty()) {
+                glyph_t unusedGlyph = *m_unusedGlyphs.constBegin();
+
+                TexCoord unusedCoord = glyphTexCoord(unusedGlyph);
+                QRectF unusedGlyphBoundingRect = glyphData(unusedGlyph).boundingRect;
+                int unusedGlyphWidth = qCeil(unusedGlyphBoundingRect.width()) + distanceFieldRadius() * 2;
+                int unusedGlyphHeight = qCeil(unusedGlyphBoundingRect.height())  + distanceFieldRadius() * 2;
+                m_areaAllocator->deallocate(QRect(unusedCoord.x - padding,
+                                                  unusedCoord.y - padding,
+                                                  padding * 2 + unusedGlyphWidth,
+                                                  padding * 2 + unusedGlyphHeight));
+
+                m_unusedGlyphs.remove(unusedGlyph);
+                m_glyphsTexture.remove(unusedGlyph);
+                removeGlyph(unusedGlyph);
+
+                alloc = m_areaAllocator->allocate(glyphSize);
+            }
+
+            // Not enough space left for this glyph... skip to the next one
+            if (alloc.isNull())
+                continue;
+        }
+
+        TextureInfo *tex = textureInfo(alloc.y() / maxTextureSize());
+        alloc = QRect(alloc.x(), alloc.y() % maxTextureSize(), alloc.width(), alloc.height());
+
+        tex->allocatedArea |= alloc;
+        Q_ASSERT(tex->padding == padding || tex->padding < 0);
+        tex->padding = padding;
+
+        GlyphPosition p;
+        p.glyph = glyphIndex;
+        p.position = alloc.topLeft() + QPoint(padding, padding);
+
+        glyphPositions.append(p);
+        glyphsToRender.append(glyphIndex);
+        m_glyphsTexture.insert(glyphIndex, tex);
+    }
+
+    setGlyphsPosition(glyphPositions);
+    markGlyphsToRender(glyphsToRender);
+}
+
+void QSGRhiDistanceFieldGlyphCache::storeGlyphs(const QList<QDistanceField> &glyphs)
+{
+    typedef QHash<TextureInfo *, QVector<glyph_t> > GlyphTextureHash;
+    typedef GlyphTextureHash::const_iterator GlyphTextureHashConstIt;
+
+    GlyphTextureHash glyphTextures;
+
+    QVarLengthArray<QRhiTextureUploadEntry, 32> uploads;
+    for (int i = 0; i < glyphs.size(); ++i) {
+        QDistanceField glyph = glyphs.at(i);
+        glyph_t glyphIndex = glyph.glyph();
+        TexCoord c = glyphTexCoord(glyphIndex);
+        TextureInfo *texInfo = m_glyphsTexture.value(glyphIndex);
+
+        resizeTexture(texInfo, texInfo->allocatedArea.width(), texInfo->allocatedArea.height());
+
+        glyphTextures[texInfo].append(glyphIndex);
+
+        int padding = texInfo->padding;
+        int expectedWidth = qCeil(c.width + c.xMargin * 2);
+        glyph = glyph.copy(-padding, -padding,
+                           expectedWidth + padding  * 2, glyph.height() + padding * 2);
+
+        if (useTextureResizeWorkaround()) {
+            uchar *inBits = glyph.scanLine(0);
+            uchar *outBits = texInfo->image.scanLine(int(c.y) - padding) + int(c.x) - padding;
+            for (int y = 0; y < glyph.height(); ++y) {
+                memcpy(outBits, inBits, glyph.width());
+                inBits += glyph.width();
+                outBits += texInfo->image.width();
+            }
+        }
+
+        QRhiTextureSubresourceUploadDescription subresDesc(glyph.constBits(), glyph.width() * glyph.height());
+        subresDesc.setSourceSize(QSize(glyph.width(), glyph.height()));
+        subresDesc.setDestinationTopLeft(QPoint(c.x - padding, c.y - padding));
+        texInfo->uploads.append(QRhiTextureUploadEntry(0, 0, subresDesc));
+    }
+
+    if (!m_resourceUpdates)
+        m_resourceUpdates = m_rhi->nextResourceUpdateBatch();
+
+    for (int i = 0; i < glyphs.size(); ++i) {
+        TextureInfo *texInfo = m_glyphsTexture.value(glyphs.at(i).glyph());
+        if (!texInfo->uploads.isEmpty()) {
+            m_resourceUpdates->uploadTexture(texInfo->texture, texInfo->uploads);
+            texInfo->uploads.clear();
+        }
+    }
+
+    for (GlyphTextureHashConstIt i = glyphTextures.constBegin(), cend = glyphTextures.constEnd(); i != cend; ++i) {
+        Texture t;
+        t.texture = i.key()->texture;
+        t.size = i.key()->size;
+        t.rhiBased = true;
+        setGlyphsTexture(i.value(), t);
+    }
+}
+
+void QSGRhiDistanceFieldGlyphCache::referenceGlyphs(const QSet<glyph_t> &glyphs)
+{
+    m_unusedGlyphs -= glyphs;
+}
+
+void QSGRhiDistanceFieldGlyphCache::releaseGlyphs(const QSet<glyph_t> &glyphs)
+{
+    m_unusedGlyphs += glyphs;
+}
+
+void QSGRhiDistanceFieldGlyphCache::createTexture(TextureInfo *texInfo,
+                                                      int width,
+                                                      int height)
+{
+    QByteArray zeroBuf(width * height, 0);
+    createTexture(texInfo, width, height, zeroBuf.constData());
+}
+
+void QSGRhiDistanceFieldGlyphCache::createTexture(TextureInfo *texInfo,
+                                                  int width,
+                                                  int height,
+                                                  const void *pixels)
+{
+    if (useTextureResizeWorkaround() && texInfo->image.isNull()) {
+        texInfo->image = QDistanceField(width, height);
+        memcpy(texInfo->image.bits(), pixels, width * height);
+    }
+
+    texInfo->texture = m_rhi->newTexture(QRhiTexture::RED_OR_ALPHA8, QSize(width, height), 1, QRhiTexture::UsedAsTransferSource);
+    if (texInfo->texture->build()) {
+        if (!m_resourceUpdates)
+            m_resourceUpdates = m_rhi->nextResourceUpdateBatch();
+
+        QRhiTextureSubresourceUploadDescription subresDesc(pixels, width * height);
+        subresDesc.setSourceSize(QSize(width, height));
+        m_resourceUpdates->uploadTexture(texInfo->texture, QRhiTextureUploadEntry(0, 0, subresDesc));
+    } else {
+        qWarning("Failed to create distance field glyph cache");
+    }
+
+    texInfo->size = QSize(width, height);
+}
+
+void QSGRhiDistanceFieldGlyphCache::resizeTexture(TextureInfo *texInfo, int width, int height)
+{
+    int oldWidth = texInfo->size.width();
+    int oldHeight = texInfo->size.height();
+    if (width == oldWidth && height == oldHeight)
+        return;
+
+    QRhiTexture *oldTexture = texInfo->texture;
+    createTexture(texInfo, width, height);
+
+    if (!oldTexture)
+        return;
+
+    updateRhiTexture(oldTexture, texInfo->texture, texInfo->size);
+
+    if (!m_resourceUpdates)
+        m_resourceUpdates = m_rhi->nextResourceUpdateBatch();
+
+    if (useTextureResizeWorkaround()) {
+        QRhiTextureSubresourceUploadDescription subresDesc(texInfo->image.constBits(),
+                                                           oldWidth * oldHeight);
+        subresDesc.setSourceSize(QSize(oldWidth, oldHeight));
+        m_resourceUpdates->uploadTexture(texInfo->texture, QRhiTextureUploadEntry(0, 0, subresDesc));
+        texInfo->image = texInfo->image.copy(0, 0, width, height);
+    } else {
+        m_resourceUpdates->copyTexture(texInfo->texture, oldTexture);
+    }
+
+    m_pendingDispose.insert(oldTexture);
+}
+
+bool QSGRhiDistanceFieldGlyphCache::useTextureResizeWorkaround() const
+{
+    static bool set = false;
+    static bool useWorkaround = false;
+    if (!set) {
+        useWorkaround = m_rhi->backend() == QRhi::OpenGLES2 || qmlUseGlyphCacheWorkaround();
+        set = true;
+    }
+    return useWorkaround;
+}
+
+bool QSGRhiDistanceFieldGlyphCache::createFullSizeTextures() const
+{
+    return qsgPreferFullSizeGlyphCacheTextures() && glyphCount() > QT_DISTANCEFIELD_HIGHGLYPHCOUNT();
+}
+
+int QSGRhiDistanceFieldGlyphCache::maxTextureSize() const
+{
+    if (!m_maxTextureSize)
+        m_maxTextureSize = m_rhi->resourceLimit(QRhi::TextureSizeMax);
+    return m_maxTextureSize;
+}
+
+namespace {
+    struct Qtdf {
+        // We need these structs to be tightly packed, but some compilers we use do not
+        // support #pragma pack(1), so we need to hardcode the offsets/sizes in the
+        // file format
+        enum TableSize {
+            HeaderSize = 14,
+            GlyphRecordSize = 46,
+            TextureRecordSize = 17
+        };
+
+        enum Offset {
+            // Header
+            majorVersion        = 0,
+            minorVersion        = 1,
+            pixelSize           = 2,
+            textureSize         = 4,
+            flags               = 8,
+            headerPadding       = 9,
+            numGlyphs           = 10,
+
+            // Glyph record
+            glyphIndex          = 0,
+            textureOffsetX      = 4,
+            textureOffsetY      = 8,
+            textureWidth        = 12,
+            textureHeight       = 16,
+            xMargin             = 20,
+            yMargin             = 24,
+            boundingRectX       = 28,
+            boundingRectY       = 32,
+            boundingRectWidth   = 36,
+            boundingRectHeight  = 40,
+            textureIndex        = 44,
+
+            // Texture record
+            allocatedX          = 0,
+            allocatedY          = 4,
+            allocatedWidth      = 8,
+            allocatedHeight     = 12,
+            texturePadding      = 16
+
+        };
+
+        template <typename T>
+        static inline T fetch(const char *data, Offset offset)
+        {
+            return qFromBigEndian<T>(data + int(offset));
+        }
+    };
+}
+
+bool QSGRhiDistanceFieldGlyphCache::loadPregeneratedCache(const QRawFont &font)
+{
+    // The pregenerated data must be loaded first, otherwise the area allocator
+    // will be wrong
+    if (m_areaAllocator != nullptr) {
+        qWarning("Font cache must be loaded before cache is used");
+        return false;
+    }
+
+    static QElapsedTimer timer;
+
+    bool profile = QSG_LOG_TIME_GLYPH().isDebugEnabled();
+    if (profile)
+        timer.start();
+
+    QByteArray qtdfTable = font.fontTable("qtdf");
+    if (qtdfTable.isEmpty())
+        return false;
+
+    typedef QHash<TextureInfo *, QVector<glyph_t> > GlyphTextureHash;
+
+    GlyphTextureHash glyphTextures;
+
+    if (uint(qtdfTable.size()) < Qtdf::HeaderSize) {
+        qWarning("Invalid qtdf table in font '%s'",
+                 qPrintable(font.familyName()));
+        return false;
+    }
+
+    const char *qtdfTableStart = qtdfTable.constData();
+    const char *qtdfTableEnd = qtdfTableStart + qtdfTable.size();
+
+    int padding = 0;
+    int textureCount = 0;
+    {
+        quint8 majorVersion = Qtdf::fetch<quint8>(qtdfTableStart, Qtdf::majorVersion);
+        quint8 minorVersion = Qtdf::fetch<quint8>(qtdfTableStart, Qtdf::minorVersion);
+        if (majorVersion != 5 || minorVersion != 12) {
+            qWarning("Invalid version of qtdf table %d.%d in font '%s'",
+                     majorVersion,
+                     minorVersion,
+                     qPrintable(font.familyName()));
+            return false;
+        }
+
+        qreal pixelSize = qreal(Qtdf::fetch<quint16>(qtdfTableStart, Qtdf::pixelSize));
+        m_maxTextureSize = Qtdf::fetch<quint32>(qtdfTableStart, Qtdf::textureSize);
+        m_doubleGlyphResolution = Qtdf::fetch<quint8>(qtdfTableStart, Qtdf::flags) == 1;
+        padding = Qtdf::fetch<quint8>(qtdfTableStart, Qtdf::headerPadding);
+
+        if (pixelSize <= 0.0) {
+            qWarning("Invalid pixel size in '%s'", qPrintable(font.familyName()));
+            return false;
+        }
+
+        if (m_maxTextureSize <= 0) {
+            qWarning("Invalid texture size in '%s'", qPrintable(font.familyName()));
+            return false;
+        }
+
+        int systemMaxTextureSize = m_rhi->resourceLimit(QRhi::TextureSizeMax);
+
+        if (m_maxTextureSize > systemMaxTextureSize) {
+            qWarning("System maximum texture size is %d. This is lower than the value in '%s', which is %d",
+                     systemMaxTextureSize,
+                     qPrintable(font.familyName()),
+                     m_maxTextureSize);
+        }
+
+        if (padding != QSG_RHI_DISTANCEFIELD_GLYPH_CACHE_PADDING) {
+            qWarning("Padding mismatch in '%s'. Font requires %d, but Qt is compiled with %d.",
+                     qPrintable(font.familyName()),
+                     padding,
+                     QSG_RHI_DISTANCEFIELD_GLYPH_CACHE_PADDING);
+        }
+
+        m_referenceFont.setPixelSize(pixelSize);
+
+        quint32 glyphCount = Qtdf::fetch<quint32>(qtdfTableStart, Qtdf::numGlyphs);
+        m_unusedGlyphs.reserve(glyphCount);
+
+        const char *allocatorData = qtdfTableStart + Qtdf::HeaderSize;
+        {
+            m_areaAllocator = new QSGAreaAllocator(QSize(0, 0));
+            allocatorData = m_areaAllocator->deserialize(allocatorData, qtdfTableEnd - allocatorData);
+            if (allocatorData == nullptr)
+                return false;
+        }
+
+        if (m_areaAllocator->size().height() % m_maxTextureSize != 0) {
+            qWarning("Area allocator size mismatch in '%s'", qPrintable(font.familyName()));
+            return false;
+        }
+
+        textureCount = m_areaAllocator->size().height() / m_maxTextureSize;
+        m_maxTextureCount = qMax(m_maxTextureCount, textureCount);
+
+        const char *textureRecord = allocatorData;
+        for (int i = 0; i < textureCount; ++i, textureRecord += Qtdf::TextureRecordSize) {
+            if (textureRecord + Qtdf::TextureRecordSize > qtdfTableEnd) {
+                qWarning("qtdf table too small in font '%s'.",
+                         qPrintable(font.familyName()));
+                return false;
+            }
+
+            TextureInfo *tex = textureInfo(i);
+            tex->allocatedArea.setX(Qtdf::fetch<quint32>(textureRecord, Qtdf::allocatedX));
+            tex->allocatedArea.setY(Qtdf::fetch<quint32>(textureRecord, Qtdf::allocatedY));
+            tex->allocatedArea.setWidth(Qtdf::fetch<quint32>(textureRecord, Qtdf::allocatedWidth));
+            tex->allocatedArea.setHeight(Qtdf::fetch<quint32>(textureRecord, Qtdf::allocatedHeight));
+            tex->padding = Qtdf::fetch<quint8>(textureRecord, Qtdf::texturePadding);
+        }
+
+        const char *glyphRecord = textureRecord;
+        for (quint32 i = 0; i < glyphCount; ++i, glyphRecord += Qtdf::GlyphRecordSize) {
+            if (glyphRecord + Qtdf::GlyphRecordSize > qtdfTableEnd) {
+                qWarning("qtdf table too small in font '%s'.",
+                         qPrintable(font.familyName()));
+                return false;
+            }
+
+            glyph_t glyph = Qtdf::fetch<quint32>(glyphRecord, Qtdf::glyphIndex);
+            m_unusedGlyphs.insert(glyph);
+
+            GlyphData &glyphData = emptyData(glyph);
+
+#define FROM_FIXED_POINT(value) \
+(((qreal)value)/(qreal)65536)
+
+            glyphData.texCoord.x = FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::textureOffsetX));
+            glyphData.texCoord.y = FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::textureOffsetY));
+            glyphData.texCoord.width = FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::textureWidth));
+            glyphData.texCoord.height = FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::textureHeight));
+            glyphData.texCoord.xMargin = FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::xMargin));
+            glyphData.texCoord.yMargin = FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::yMargin));
+            glyphData.boundingRect.setX(FROM_FIXED_POINT(Qtdf::fetch<qint32>(glyphRecord, Qtdf::boundingRectX)));
+            glyphData.boundingRect.setY(FROM_FIXED_POINT(Qtdf::fetch<qint32>(glyphRecord, Qtdf::boundingRectY)));
+            glyphData.boundingRect.setWidth(FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::boundingRectWidth)));
+            glyphData.boundingRect.setHeight(FROM_FIXED_POINT(Qtdf::fetch<quint32>(glyphRecord, Qtdf::boundingRectHeight)));
+
+#undef FROM_FIXED_POINT
+
+            int textureIndex = Qtdf::fetch<quint16>(glyphRecord, Qtdf::textureIndex);
+            if (textureIndex < 0 || textureIndex >= textureCount) {
+                qWarning("Invalid texture index %d (texture count == %d) in '%s'",
+                         textureIndex,
+                         textureCount,
+                         qPrintable(font.familyName()));
+                return false;
+            }
+
+
+            TextureInfo *texInfo = textureInfo(textureIndex);
+            m_glyphsTexture.insert(glyph, texInfo);
+
+            glyphTextures[texInfo].append(glyph);
+        }
+
+        const uchar *textureData = reinterpret_cast<const uchar *>(glyphRecord);
+        for (int i = 0; i < textureCount; ++i) {
+
+            TextureInfo *texInfo = textureInfo(i);
+
+            int width = texInfo->allocatedArea.width();
+            int height = texInfo->allocatedArea.height();
+            qint64 size = width * height;
+            if (reinterpret_cast<const char *>(textureData + size) > qtdfTableEnd) {
+                qWarning("qtdf table too small in font '%s'.",
+                         qPrintable(font.familyName()));
+                return false;
+            }
+
+            createTexture(texInfo, width, height, textureData);
+
+            QVector<glyph_t> glyphs = glyphTextures.value(texInfo);
+
+            Texture t;
+            t.texture = texInfo->texture;
+            t.size = texInfo->size;
+            t.rhiBased = true;
+
+            setGlyphsTexture(glyphs, t);
+
+            textureData += size;
+        }
+    }
+
+    if (profile) {
+        quint64 now = timer.elapsed();
+        qCDebug(QSG_LOG_TIME_GLYPH,
+                "distancefield: %d pre-generated glyphs loaded in %dms",
+                m_unusedGlyphs.size(),
+                (int) now);
+    }
+
+    return true;
+}
+
+void QSGRhiDistanceFieldGlyphCache::commitResourceUpdates(QRhiResourceUpdateBatch *mergeInto)
+{
+    if (m_resourceUpdates) {
+        mergeInto->merge(m_resourceUpdates);
+        m_resourceUpdates->release();
+        m_resourceUpdates = nullptr;
+    }
+
+    // now let's assume the resource updates will be committed in this frame
+    for (QRhiTexture *t : m_pendingDispose)
+        t->releaseAndDestroyLater(); // will be releaseAndDestroyed after the frame is submitted -> safe
+
+    m_pendingDispose.clear();
+}
+
+bool QSGRhiDistanceFieldGlyphCache::eightBitFormatIsAlphaSwizzled() const
+{
+    // return true when the shaders for 8-bit formats need .a instead of .r
+    // when sampling the texture
+    return !m_rhi->isFeatureSupported(QRhi::RedOrAlpha8IsRed);
+}
+
+QT_END_NAMESPACE