Enablers for shared graphics cache in raster paint engine

Required changes for using shared graphics cache for distance field
raster glyph rendering. Most of the logic is in platform plugins.

Platform plugins should implement
QPlatformIntegration::createImagePaintEngine() to create a subclass
of QRasterEngine.

Change-Id: Icf0a396e722e43b4caa2c1849aae38753cde38f1
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>

4 files changed, 59 insertions, 20 deletions

diff --git a/src/gui/text/qdistancefield.cpp b/src/gui/text/qdistancefield.cpp
index fb06a26c8f..a1deb47175 100644
--- a/src/gui/text/qdistancefield.cpp
+++ b/src/gui/text/qdistancefield.cpp
@@ -692,17 +692,8 @@ static QImage makeDistanceField(int imgSize, const QPainterPath &path, int dfSca
     return image;
 }
 
-bool qt_fontHasNarrowOutlines(const QRawFont &f)
+static bool imageHasNarrowOutlines(const QImage &im)
 {
-    QRawFont font = f;
-    font.setPixelSize(QT_DISTANCEFIELD_DEFAULT_BASEFONTSIZE);
-    Q_ASSERT(font.isValid());
-
-    QVector<quint32> glyphIndices = font.glyphIndexesForString(QLatin1String("O"));
-    if (glyphIndices.size() < 1)
-        return false;
-
-    QImage im = font.alphaMapForGlyph(glyphIndices.at(0), QRawFont::PixelAntialiasing);
     if (im.isNull())
         return false;
 
@@ -742,6 +733,56 @@ bool qt_fontHasNarrowOutlines(const QRawFont &f)
     return minHThick == 1 || minVThick == 1;
 }
 
+bool qt_fontHasNarrowOutlines(QFontEngine *fontEngine)
+{
+    QFontEngine *fe = fontEngine->cloneWithSize(QT_DISTANCEFIELD_DEFAULT_BASEFONTSIZE);
+
+    QGlyphLayout glyphs;
+    glyph_t glyph;
+    glyphs.glyphs = &glyph;
+    int numGlyphs;
+    QChar *chars = QString(QLatin1String("O")).data();
+    fe->stringToCMap(chars, 1, &glyphs, &numGlyphs, QTextEngine::GlyphIndicesOnly);
+    QImage im = fe->alphaMapForGlyph(glyph, QFixed(), QTransform());
+    delete fe;
+
+    return imageHasNarrowOutlines(im);
+}
+
+bool qt_fontHasNarrowOutlines(const QRawFont &f)
+{
+    QRawFont font = f;
+    font.setPixelSize(QT_DISTANCEFIELD_DEFAULT_BASEFONTSIZE);
+    Q_ASSERT(font.isValid());
+
+    QVector<quint32> glyphIndices = font.glyphIndexesForString(QLatin1String("O"));
+    if (glyphIndices.size() < 1)
+        return false;
+
+    return imageHasNarrowOutlines(font.alphaMapForGlyph(glyphIndices.at(0),
+                                                        QRawFont::PixelAntialiasing));
+}
+
+static QImage renderDistanceFieldPath(const QPainterPath &path, bool doubleResolution)
+{
+    QImage im = makeDistanceField(QT_DISTANCEFIELD_TILESIZE(doubleResolution),
+                                  path,
+                                  QT_DISTANCEFIELD_SCALE(doubleResolution),
+                                  QT_DISTANCEFIELD_RADIUS(doubleResolution) / QT_DISTANCEFIELD_SCALE(doubleResolution));
+    return im;
+}
+
+QImage qt_renderDistanceFieldGlyph(QFontEngine *fe, glyph_t glyph, bool doubleResolution)
+{
+    QFixedPoint position;
+    QPainterPath path;
+    fe->addGlyphsToPath(&glyph, &position, 1, &path, 0);
+    path.translate(-path.boundingRect().topLeft());
+    path.setFillRule(Qt::WindingFill);
+
+    return renderDistanceFieldPath(path, doubleResolution);
+}
+
 QImage qt_renderDistanceFieldGlyph(const QRawFont &font, glyph_t glyph, bool doubleResolution)
 {
     QRawFont renderFont = font;
@@ -751,11 +792,7 @@ QImage qt_renderDistanceFieldGlyph(const QRawFont &font, glyph_t glyph, bool dou
     path.translate(-path.boundingRect().topLeft());
     path.setFillRule(Qt::WindingFill);
 
-    QImage im = makeDistanceField(QT_DISTANCEFIELD_TILESIZE(doubleResolution),
-                                  path,
-                                  QT_DISTANCEFIELD_SCALE(doubleResolution),
-                                  QT_DISTANCEFIELD_RADIUS(doubleResolution) / QT_DISTANCEFIELD_SCALE(doubleResolution));
-    return im;
+    return renderDistanceFieldPath(path, doubleResolution);
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/text/qdistancefield_p.h b/src/gui/text/qdistancefield_p.h
index 486d291b78..bf87e7d3cb 100644
--- a/src/gui/text/qdistancefield_p.h
+++ b/src/gui/text/qdistancefield_p.h
@@ -79,6 +79,8 @@ QT_BEGIN_NAMESPACE
 
 bool Q_GUI_EXPORT qt_fontHasNarrowOutlines(const QRawFont &f);
 QImage Q_GUI_EXPORT qt_renderDistanceFieldGlyph(const QRawFont &font, glyph_t glyph, bool doubleResolution);
+bool Q_GUI_EXPORT qt_fontHasNarrowOutlines(QFontEngine *fontEngine);
+QImage Q_GUI_EXPORT qt_renderDistanceFieldGlyph(QFontEngine *fontEngine, glyph_t glyph, bool doubleResolution);
 
 QT_END_NAMESPACE
 
diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index 53c5f9fc31..364a356b96 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -775,7 +775,7 @@ QByteArray QFontEngine::getSfntTable(uint tag) const
     return table;
 }
 
-void QFontEngine::setGlyphCache(void *key, QFontEngineGlyphCache *data)
+void QFontEngine::setGlyphCache(const void *key, QFontEngineGlyphCache *data)
 {
     Q_ASSERT(data);
 
@@ -794,7 +794,7 @@ void QFontEngine::setGlyphCache(void *key, QFontEngineGlyphCache *data)
 
 }
 
-QFontEngineGlyphCache *QFontEngine::glyphCache(void *key, QFontEngineGlyphCache::Type type, const QTransform &transform) const
+QFontEngineGlyphCache *QFontEngine::glyphCache(const void *key, QFontEngineGlyphCache::Type type, const QTransform &transform) const
 {
     for (QLinkedList<GlyphCacheEntry>::const_iterator it = m_glyphCaches.constBegin(), end = m_glyphCaches.constEnd(); it != end; ++it) {
         QFontEngineGlyphCache *c = it->cache.data();
diff --git a/src/gui/text/qfontengine_p.h b/src/gui/text/qfontengine_p.h
index b4436426b2..1114cdf12c 100644
--- a/src/gui/text/qfontengine_p.h
+++ b/src/gui/text/qfontengine_p.h
@@ -239,8 +239,8 @@ public:
 
     virtual HB_Error getPointInOutline(HB_Glyph glyph, int flags, hb_uint32 point, HB_Fixed *xpos, HB_Fixed *ypos, hb_uint32 *nPoints);
 
-    void setGlyphCache(void *key, QFontEngineGlyphCache *data);
-    QFontEngineGlyphCache *glyphCache(void *key, QFontEngineGlyphCache::Type type, const QTransform &transform) const;
+    void setGlyphCache(const void *key, QFontEngineGlyphCache *data);
+    QFontEngineGlyphCache *glyphCache(const void *key, QFontEngineGlyphCache::Type type, const QTransform &transform) const;
 
     static const uchar *getCMap(const uchar *table, uint tableSize, bool *isSymbolFont, int *cmapSize);
     static quint32 getTrueTypeGlyphIndex(const uchar *cmap, uint unicode);
@@ -284,7 +284,7 @@ protected:
 
 private:
     struct GlyphCacheEntry {
-        void *context;
+        const void *context;
         QExplicitlySharedDataPointer<QFontEngineGlyphCache> cache;
         bool operator==(const GlyphCacheEntry &other) const { return context == other.context && cache == other.cache; }
     };