Support pen color with color fonts

Color fonts may also contain regular alphabet characters that
should be rendered with the current pen. In Qt, however, these
characters were drawn into the cache with a default pen color
of black.

Since all characters in a font is currently backed by the same cache,
and it would require a lot of plumbing to get around this, a step
in the right direction is to include the current pen color in the
cache as long as it is an RGB cache. This means that drawing
text with the color font with different pen colors will create
different caches.

There is no API to select font color on Freetype currently, but
this problem has also not been observed there, as the fonts
in question, with both regular and color glyphs, are not being
detected as color fonts (so the text color will be correct).
So Freetype will be left out for now.

[ChangeLog][QtGui][Text] Fixed bug where regular text rendered
with a color font would always display in black.

Task-number: QTBUG-55096
Task-number: QTBUG-74761
Change-Id: Icc7dbf73241db1e7cc6a0de18c2de927aeecf713
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 6 insertions, 4 deletions

diff --git a/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm b/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
index 25e7c6df72..072dd1a28a 100644
--- a/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
+++ b/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
@@ -747,7 +747,7 @@ qreal QCoreTextFontEngine::fontSmoothingGamma()
     return 2.0;
 }
 
-QImage QCoreTextFontEngine::imageForGlyph(glyph_t glyph, QFixed subPixelPosition, const QTransform &matrix)
+QImage QCoreTextFontEngine::imageForGlyph(glyph_t glyph, QFixed subPixelPosition, const QTransform &matrix, const QColor &color)
 {
     glyph_metrics_t br = alphaMapBoundingBox(glyph, subPixelPosition, matrix, glyphFormat);
 
@@ -827,6 +827,8 @@ QImage QCoreTextFontEngine::imageForGlyph(glyph_t glyph, QFixed subPixelPosition
             CTFontDrawGlyphs(ctfont, &cgGlyph, &CGPointZero, 1, ctx);
         }
     } else {
+        CGContextSetRGBFillColor(ctx, color.redF(), color.greenF(), color.blueF(), color.alphaF());
+
         // CGContextSetTextMatrix does not work with color glyphs, so we use
         // the CTM instead. This means we must translate the CTM as well, to
         // set the glyph position, instead of using CGContextSetTextPosition.
@@ -884,12 +886,12 @@ QImage QCoreTextFontEngine::alphaRGBMapForGlyph(glyph_t glyph, QFixed subPixelPo
     return imageForGlyph(glyph, subPixelPosition, x);
 }
 
-QImage QCoreTextFontEngine::bitmapForGlyph(glyph_t glyph, QFixed subPixelPosition, const QTransform &t)
+QImage QCoreTextFontEngine::bitmapForGlyph(glyph_t glyph, QFixed subPixelPosition, const QTransform &t, const QColor &color)
 {
     if (t.type() > QTransform::TxScale)
-        return QFontEngine::bitmapForGlyph(glyph, subPixelPosition, t);
+        return QFontEngine::bitmapForGlyph(glyph, subPixelPosition, t, color);
 
-    return imageForGlyph(glyph, subPixelPosition, t);
+    return imageForGlyph(glyph, subPixelPosition, t, color);
 }
 
 void QCoreTextFontEngine::recalcAdvances(QGlyphLayout *glyphs, QFontEngine::ShaperFlags flags) const