Fix crash when trying to create paths for color-glyphs (Emoji) on Mac

CoreText segfaults when creating paths for color-glyphs:

  0  0x00007fff8fd41e69 in TFont::FindColourBitmapForGlyph ()
  1  0x00007fff8fd417ac in TFont::CreatePathForGlyph ()
  2  0x000000010567d1af in QCoreTextFontEngine::addGlyphsToPath (...)

So we shortcut the code-path, since we don't support Emoji yet anyways.

Task-number: QTBUG-28615
Change-Id: Ife16ae4959077d9eaaf6ea5cd1f27a4e2e01e7f5
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

src/gui/text/qfontengineglyphcache_p.h

@@ -69,7 +69,8 @@ public:
     enum Type {
         Raster_RGBMask,
         Raster_A8,
-        Raster_Mono
+        Raster_Mono,
+        Raster_ARGB
     };
 
     QFontEngineGlyphCache(const QTransform &matrix, Type type) : m_transform(matrix), m_type(type) { }

src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm

@@ -149,8 +149,6 @@ void QCoreTextFontEngine::init()
     Q_ASSERT(ctfont != NULL);
     Q_ASSERT(cgFont != NULL);
 
-    glyphFormat = defaultGlyphFormat;
-
     QCFString family = CTFontCopyFamilyName(ctfont);
     fontDef.family = family;
 
@@ -159,6 +157,14 @@ void QCoreTextFontEngine::init()
 
     synthesisFlags = 0;
     CTFontSymbolicTraits traits = CTFontGetSymbolicTraits(ctfont);
+
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
+    if (supportsColorGlyphs() && (traits & kCTFontColorGlyphsTrait))
+        glyphFormat = QFontEngineGlyphCache::Raster_ARGB;
+    else
+#endif
+        glyphFormat = defaultGlyphFormat;
+
     if (traits & kCTFontItalicTrait)
         fontDef.style = QFont::StyleItalic;
 
@@ -422,6 +428,9 @@ static void convertCGPathToQPainterPath(void *info, const CGPathElement *element
 void QCoreTextFontEngine::addGlyphsToPath(glyph_t *glyphs, QFixedPoint *positions, int nGlyphs,
                                           QPainterPath *path, QTextItem::RenderFlags)
 {
+    if (glyphFormat == QFontEngineGlyphCache::Raster_ARGB)
+        return; // We can't convert color-glyphs to path
+
     CGAffineTransform cgMatrix = CGAffineTransformIdentity;
     cgMatrix = CGAffineTransformScale(cgMatrix, 1, -1);
 

src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h

@@ -108,6 +108,21 @@ public:
     virtual QFontEngine *cloneWithSize(qreal pixelSize) const;
     virtual int glyphMargin(QFontEngineGlyphCache::Type type) { Q_UNUSED(type); return 0; }
 
+    static bool supportsColorGlyphs()
+    {
+#if defined(Q_OS_IOS)
+        return true;
+#elif MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
+  #if MAC_OS_X_VERSION_MIN_REQUIRED < 1070
+        return &CTFontDrawGlyphs;
+  #else
+        return true;
+  #endif
+#else
+        return false;
+#endif
+    }
+
     static int antialiasingThreshold;
     static QFontEngineGlyphCache::Type defaultGlyphFormat;