Ensure same glyph cache is used for same font at different sizes

This was fixed in Qt 5.9.0 by 9921b48c83490b450241d6c172f1375ab4efb6b1,
but refactoring caused this change to be lost.

This is just porting the fix to the refactored class hierarchy.

Task-number: QTBUG-60696
Change-Id: I4f95cc7bdd49580ae623a03a7f9cc5242599b6c2
Reviewed-by: Robin Burchell <robin.burchell@crimson.no>

3 files changed, 26 insertions, 3 deletions

diff --git a/src/quick/scenegraph/qsgcontext_p.h b/src/quick/scenegraph/qsgcontext_p.h
index 6ff8f4a76e..84a2523f26 100644
--- a/src/quick/scenegraph/qsgcontext_p.h
+++ b/src/quick/scenegraph/qsgcontext_p.h
@@ -194,7 +194,7 @@ protected:
     QMutex m_mutex;
     QHash<QQuickTextureFactory *, QSGTexture *> m_textures;
     QSet<QSGTexture *> m_texturesToDelete;
-    QHash<QRawFont, QSGDistanceFieldGlyphCache*> m_glyphCaches;
+    QHash<QString, QSGDistanceFieldGlyphCache *> m_glyphCaches;
 
     QSet<QFontEngine *> m_fontEnginesToClean;
 };
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext.cpp b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
index 29600ef0ca..34bb554db6 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext.cpp
+++ b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
@@ -271,6 +271,26 @@ void QSGDefaultRenderContext::compileShader(QSGMaterialShader *shader, QSGMateri
     }
 }
 
+QString QSGDefaultRenderContext::fontKey(const QRawFont &font)
+{
+    QFontEngine *fe = QRawFontPrivate::get(font)->fontEngine;
+    if (!fe->faceId().filename.isEmpty()) {
+        QByteArray keyName = fe->faceId().filename;
+        if (font.style() != QFont::StyleNormal)
+            keyName += QByteArray(" I");
+        if (font.weight() != QFont::Normal)
+            keyName += ' ' + QByteArray::number(font.weight());
+        keyName += QByteArray(" DF");
+        return QString::fromUtf8(keyName);
+    } else {
+        return QString::fromLatin1("%1_%2_%3_%4")
+            .arg(font.familyName())
+            .arg(font.styleName())
+            .arg(font.weight())
+            .arg(font.style());
+    }
+}
+
 void QSGDefaultRenderContext::initializeShader(QSGMaterialShader *shader)
 {
     shader->program()->bind();
@@ -293,10 +313,11 @@ QT_END_NAMESPACE
 
 QSGDistanceFieldGlyphCache *QSGDefaultRenderContext::distanceFieldGlyphCache(const QRawFont &font)
 {
-    QSGDistanceFieldGlyphCache *cache = m_glyphCaches.value(font, 0);
+    QString key = fontKey(font);
+    QSGDistanceFieldGlyphCache *cache = m_glyphCaches.value(key, 0);
     if (!cache) {
         cache = new QSGDefaultDistanceFieldGlyphCache(openglContext(), font);
-        m_glyphCaches.insert(font, cache);
+        m_glyphCaches.insert(key, cache);
     }
 
     return cache;
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext_p.h b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
index 0aed46b658..2537a06988 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext_p.h
+++ b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
@@ -96,6 +96,8 @@ public:
     int maxTextureSize() const override { return m_maxTextureSize; }
 
 protected:
+    static QString fontKey(const QRawFont &font);
+
     QOpenGLContext *m_gl;
     QSGDepthStencilBufferManager *m_depthStencilManager;
     int m_maxTextureSize;