qtextureglyphcache.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include <qmath.h>
 
#include "qtextureglyphcache_p.h"
#include "private/qfontengine_p.h"
#include "private/qnumeric_p.h"
 
#include <QtGui/qpainterpath.h>
 
QT_BEGIN_NAMESPACE
 
// #define CACHE_DEBUG
 
// out-of-line to avoid vtable duplication, breaking e.g. RTTI
QTextureGlyphCache::~QTextureGlyphCache()
{
}
 
int QTextureGlyphCache::calculateSubPixelPositionCount(glyph_t glyph) const
{
    // Test 12 different subpixel positions since it factors into 3*4 so it gives
    // the coverage we need.
 
    const int NumSubpixelPositions = 12;
 
    QImage images[NumSubpixelPositions];
    int numImages = 0;
    for (int i = 0; i < NumSubpixelPositions; ++i) {
        QImage img = textureMapForGlyph(glyph, QFixedPoint(QFixed::fromReal(i / 12.0), 0));
 
        if (numImages == 0) {
            QPainterPath path;
            QFixedPoint point;
            m_current_fontengine->addGlyphsToPath(&glyph, &point, 1, &path, QTextItem::RenderFlags());
 
            // Glyph is space, return 0 to indicate that we need to keep trying
            if (path.isEmpty())
                break;
 
            images[numImages++] = std::move(img);
        } else {
            bool found = false;
            for (int j = 0; j < numImages; ++j) {
                if (images[j] == img) {
                    found = true;
                    break;
                }
            }
            if (!found)
                images[numImages++] = std::move(img);
        }
    }
 
    return numImages;
}
 
bool QTextureGlyphCache::populate(QFontEngine *fontEngine,
                                  qsizetype numGlyphs,
                                  const glyph_t *glyphs,
                                  const QFixedPoint *positions,
                                  QPainter::RenderHints renderHints,
                                  bool includeGlyphCacheScale)
{
#ifdef CACHE_DEBUG
    printf("Populating with %lld glyphs\n", static_cast<long long>(numGlyphs));
    qDebug() << " -> current transformation: " << m_transform;
#endif
 
    m_current_fontengine = fontEngine;
    const int padding = glyphPadding();
    const int paddingDoubled = padding * 2;
 
    bool supportsSubPixelPositions = fontEngine->supportsSubPixelPositions();
    bool verticalSubPixelPositions = fontEngine->supportsVerticalSubPixelPositions()
            && (renderHints & QPainter::VerticalSubpixelPositioning) != 0;
    if (fontEngine->m_subPixelPositionCount == 0) {
        if (!supportsSubPixelPositions) {
            fontEngine->m_subPixelPositionCount = 1;
        } else {
            qsizetype i = 0;
            while (fontEngine->m_subPixelPositionCount == 0 && i < numGlyphs)
                fontEngine->m_subPixelPositionCount = calculateSubPixelPositionCount(glyphs[i++]);
        }
    }
 
    if (m_cx == 0 && m_cy == 0) {
        m_cx = padding;
        m_cy = padding;
    }
 
    qreal glyphCacheScaleX = transform().m11();
    qreal glyphCacheScaleY = transform().m22();
 
    QHash<GlyphAndSubPixelPosition, Coord> listItemCoordinates;
    int rowHeight = 0;
 
    // check each glyph for its metrics and get the required rowHeight.
    for (qsizetype i = 0; i < numGlyphs; ++i) {
        const glyph_t glyph = glyphs[i];
 
        QFixedPoint subPixelPosition;
        if (supportsSubPixelPositions) {
            QFixedPoint pos = positions != nullptr ? positions[i] : QFixedPoint();
            if (includeGlyphCacheScale) {
                pos = QFixedPoint(QFixed::fromReal(pos.x.toReal() * glyphCacheScaleX),
                                  QFixed::fromReal(pos.y.toReal() * glyphCacheScaleY));
            }
            subPixelPosition = fontEngine->subPixelPositionFor(pos);
            if (!verticalSubPixelPositions)
                subPixelPosition.y = 0;
        }
 
        if (coords.contains(GlyphAndSubPixelPosition(glyph, subPixelPosition)))
            continue;
        if (listItemCoordinates.contains(GlyphAndSubPixelPosition(glyph, subPixelPosition)))
            continue;
 
        glyph_metrics_t metrics = fontEngine->alphaMapBoundingBox(glyph, subPixelPosition, m_transform, m_format);
 
#ifdef CACHE_DEBUG
        printf("(%4x): w=%.2f, h=%.2f, xoff=%.2f, yoff=%.2f, x=%.2f, y=%.2f\n",
               glyph,
               metrics.width.toReal(),
               metrics.height.toReal(),
               metrics.xoff.toReal(),
               metrics.yoff.toReal(),
               metrics.x.toReal(),
               metrics.y.toReal());
#endif
        GlyphAndSubPixelPosition key(glyph, subPixelPosition);
        int glyph_width = metrics.width.ceil().toInt();
        int glyph_height = metrics.height.ceil().toInt();
        if (glyph_height == 0 || glyph_width == 0) {
            // Avoid multiple calls to boundingBox() for non-printable characters
            Coord c = { 0, 0, 0, 0, 0, 0 };
            coords.insert(key, c);
            continue;
        }
        // align to 8-bit boundary
        if (m_format == QFontEngine::Format_Mono)
            glyph_width = (glyph_width+7)&~7;
 
        Coord c = { 0, 0, // will be filled in later
                    glyph_width,
                    glyph_height, // texture coords
                    metrics.x.truncate(),
                    -metrics.y.truncate() }; // baseline for horizontal scripts
 
        listItemCoordinates.insert(key, c);
        rowHeight = qMax(rowHeight, glyph_height);
    }
    if (listItemCoordinates.isEmpty())
        return true;
 
    rowHeight += paddingDoubled;
 
    if (m_w == 0) {
        if (fontEngine->maxCharWidth() <= QT_DEFAULT_TEXTURE_GLYPH_CACHE_WIDTH)
            m_w = QT_DEFAULT_TEXTURE_GLYPH_CACHE_WIDTH;
        else
            m_w = qNextPowerOfTwo(qCeil(fontEngine->maxCharWidth()) - 1);
    }
 
    // now actually use the coords and paint the wanted glyps into cache.
    QHash<GlyphAndSubPixelPosition, Coord>::iterator iter = listItemCoordinates.begin();
    int requiredWidth = m_w;
    while (iter != listItemCoordinates.end()) {
        Coord c = iter.value();
 
        m_currentRowHeight = qMax(m_currentRowHeight, c.h);
 
        if (m_cx + c.w + padding > requiredWidth) {
            int new_width = requiredWidth*2;
            while (new_width < m_cx + c.w + padding)
                new_width *= 2;
            if (new_width <= maxTextureWidth()) {
                requiredWidth = new_width;
            } else {
                // no room on the current line, start new glyph strip
                m_cx = padding;
                m_cy += m_currentRowHeight + paddingDoubled;
                m_currentRowHeight = c.h; // New row
            }
        }
 
        if (maxTextureHeight() > 0 && m_cy + c.h + padding > maxTextureHeight()) {
            // We can't make a cache of the required size, so we bail out
            return false;
        }
 
        c.x = m_cx;
        c.y = m_cy;
 
        coords.insert(iter.key(), c);
        m_pendingGlyphs.insert(iter.key(), c);
 
        m_cx += c.w + paddingDoubled;
        ++iter;
    }
    return true;
 
}
 
void QTextureGlyphCache::fillInPendingGlyphs()
{
    if (!hasPendingGlyphs())
        return;
 
    int requiredHeight = m_h;
    int requiredWidth = m_w; // Use a minimum size to avoid a lot of initial reallocations
    {
        QHash<GlyphAndSubPixelPosition, Coord>::iterator iter = m_pendingGlyphs.begin();
        while (iter != m_pendingGlyphs.end()) {
            Coord c = iter.value();
            requiredHeight = qMax(requiredHeight, c.y + c.h);
            requiredWidth = qMax(requiredWidth, c.x + c.w);
            ++iter;
        }
    }
 
    if (isNull() || requiredHeight > m_h || requiredWidth > m_w) {
        if (isNull())
            createCache(qNextPowerOfTwo(requiredWidth - 1), qNextPowerOfTwo(requiredHeight - 1));
        else
            resizeCache(qNextPowerOfTwo(requiredWidth - 1), qNextPowerOfTwo(requiredHeight - 1));
    }
 
    beginFillTexture();
    {
        QHash<GlyphAndSubPixelPosition, Coord>::iterator iter = m_pendingGlyphs.begin();
        while (iter != m_pendingGlyphs.end()) {
            GlyphAndSubPixelPosition key = iter.key();
            fillTexture(iter.value(), key.glyph, key.subPixelPosition);
 
            ++iter;
        }
    }
    endFillTexture();
 
    m_pendingGlyphs.clear();
}
 
QImage QTextureGlyphCache::textureMapForGlyph(glyph_t g, const QFixedPoint &subPixelPosition) const
{
    switch (m_format) {
    case QFontEngine::Format_A32:
        return m_current_fontengine->alphaRGBMapForGlyph(g, subPixelPosition, m_transform);
    case QFontEngine::Format_ARGB:
        return m_current_fontengine->bitmapForGlyph(g, subPixelPosition, m_transform, color());
    default:
        return m_current_fontengine->alphaMapForGlyph(g, subPixelPosition, m_transform);
    }
}
 
/************************************************************************
 * QImageTextureGlyphCache
 */
 
// out-of-line to avoid vtable duplication, breaking e.g. RTTI
QImageTextureGlyphCache::~QImageTextureGlyphCache()
{
}
 
void QImageTextureGlyphCache::resizeTextureData(int width, int height)
{
    m_image = m_image.copy(0, 0, width, height);
    // Regions not part of the copy are initialized to 0, and that is just what
    // we need.
}
 
void QImageTextureGlyphCache::createTextureData(int width, int height)
{
    switch (m_format) {
    case QFontEngine::Format_Mono:
        m_image = QImage(width, height, QImage::Format_Mono);
        break;
    case QFontEngine::Format_A8:
        m_image = QImage(width, height, QImage::Format_Alpha8);
        break;
    case QFontEngine::Format_A32:
        m_image = QImage(width, height, QImage::Format_RGB32);
        break;
    case QFontEngine::Format_ARGB:
        m_image = QImage(width, height, QImage::Format_ARGB32_Premultiplied);
        break;
    default:
        Q_UNREACHABLE();
    }
 
    // Regions not touched by the glyphs must be initialized to 0. (such
    // locations may in fact be sampled with styled (shifted) text materials)
    // When resizing, the QImage copy() does this implicitly but the initial
    // contents must be zeroed out explicitly here.
    m_image.fill(0);
}
 
void QImageTextureGlyphCache::fillTexture(const Coord &c,
                                          glyph_t g,
                                          const QFixedPoint &subPixelPosition)
{
    QImage mask = textureMapForGlyph(g, subPixelPosition);
 
#ifdef CACHE_DEBUG
    printf("fillTexture of %dx%d at %d,%d in the cache of %dx%d\n", c.w, c.h, c.x, c.y, m_image.width(), m_image.height());
    if (mask.width() > c.w || mask.height() > c.h) {
        printf("   ERROR; mask is bigger than reserved space! %dx%d instead of %dx%d\n", mask.width(), mask.height(), c.w,c.h);
        return;
    }
#endif
    Q_ASSERT(mask.width() <= c.w && mask.height() <= c.h);
 
    if (m_format == QFontEngine::Format_A32
        || m_format == QFontEngine::Format_ARGB) {
        QImage ref(m_image.bits() + (c.x * 4 + c.y * m_image.bytesPerLine()),
                   qMin(mask.width(), c.w), qMin(mask.height(), c.h), m_image.bytesPerLine(),
                   m_image.format());
        QPainter p(&ref);
        p.setCompositionMode(QPainter::CompositionMode_Source);
        p.fillRect(0, 0, c.w, c.h, QColor(0,0,0,0)); // TODO optimize this
        p.drawImage(0, 0, mask);
        p.end();
    } else if (m_format == QFontEngine::Format_Mono) {
        if (mask.depth() > 1) {
            // TODO optimize this
            mask.convertTo(QImage::Format_Alpha8);
            mask.reinterpretAsFormat(QImage::Format_Grayscale8);
            mask.invertPixels();
            mask.convertTo(QImage::Format_Mono, Qt::ThresholdDither);
        }
 
        int mw = qMin(mask.width(), c.w);
        int mh = qMin(mask.height(), c.h);
        uchar *d = m_image.bits();
        qsizetype dbpl = m_image.bytesPerLine();
 
        for (int y = 0; y < c.h; ++y) {
            uchar *dest = d + (c.y + y) *dbpl + c.x/8;
 
            if (y < mh) {
                const uchar *src = mask.constScanLine(y);
                for (int x = 0; x < c.w/8; ++x) {
                    if (x < (mw+7)/8)
                        dest[x] = src[x];
                    else
                        dest[x] = 0;
                }
            } else {
                for (int x = 0; x < c.w/8; ++x)
                    dest[x] = 0;
            }
        }
    } else { // A8
        int mw = qMin(mask.width(), c.w);
        int mh = qMin(mask.height(), c.h);
        uchar *d = m_image.bits();
        qsizetype dbpl = m_image.bytesPerLine();
 
        if (mask.depth() == 1) {
            for (int y = 0; y < c.h; ++y) {
                uchar *dest = d + (c.y + y) *dbpl + c.x;
                if (y < mh) {
                    const uchar *src = mask.constScanLine(y);
                    for (int x = 0; x < c.w; ++x) {
                        if (x < mw)
                            dest[x] = (src[x >> 3] & (1 << (7 - (x & 7)))) > 0 ? 255 : 0;
                    }
                }
            }
        } else if (mask.depth() == 8) {
            for (int y = 0; y < c.h; ++y) {
                uchar *dest = d + (c.y + y) *dbpl + c.x;
                if (y < mh) {
                    const uchar *src = mask.constScanLine(y);
                    for (int x = 0; x < c.w; ++x) {
                        if (x < mw)
                            dest[x] = src[x];
                    }
                }
            }
        }
    }
 
#ifdef CACHE_DEBUG
//     QPainter p(&m_image);
//     p.drawLine(
    int margin = m_current_fontengine ? m_current_fontengine->glyphMargin(m_format) : 0;
    QPoint base(c.x + margin, c.y + margin + c.baseLineY-1);
    if (m_image.rect().contains(base))
        m_image.setPixel(base, 255);
    m_image.save(QString::fromLatin1("cache-%1.png").arg(qint64(this)));
#endif
}
 
QT_END_NAMESPACE