Add QFont strategy to disable subpixel antialiasing

This patch adds the option to disable subpixel antialiasing on QFont
basis. This can be useful when painting to offscreen surfaces. On OS X
this option disables the aggressive LCD font smoothing, which can be
necessary for certain fonts it may otherwise ruin.

Task-number: QTBUG-40396
Change-Id: I1664b636520ae63ee1503b5df7436748106b9f5c
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qpaintengine_mac.mm b/src/plugins/platforms/cocoa/qpaintengine_mac.mm
index f4cd071ab7..d48cbdfac8 100644
--- a/src/plugins/platforms/cocoa/qpaintengine_mac.mm
+++ b/src/plugins/platforms/cocoa/qpaintengine_mac.mm
@@ -1084,6 +1084,10 @@ void QCoreGraphicsPaintEngine::drawTextItem(const QPointF &pos, const QTextItem
     if (textAA != lineAA)
         CGContextSetShouldAntialias(d->hd, textAA);
 
+    const bool smoothing = textAA && !(fe->fontDef.styleStrategy & QFont::NoSubpixelAntialias);
+    if (d->disabledSmoothFonts == smoothing)
+        CGContextSetShouldSmoothFonts(d->hd, smoothing);
+
     if (ti.glyphs.numGlyphs) {
         switch (fe->type()) {
         case QFontEngine::Mac:
@@ -1100,6 +1104,9 @@ void QCoreGraphicsPaintEngine::drawTextItem(const QPointF &pos, const QTextItem
     if (textAA != lineAA)
         CGContextSetShouldAntialias(d->hd, !textAA);
 
+    if (smoothing == d->disabledSmoothFonts)
+        CGContextSetShouldSmoothFonts(d->hd, !d->disabledSmoothFonts);
+
     updatePen(oldPen);
     updateBrush(oldBrush, oldBrushOrigin);
 }