Improve QML text rendering when LCD smoothing is enabled for OS X.

Text in QML is always painted into a pixmap, and with sub-pixel
antialiasing enabled this produced incorrect results. This patch is a
temporary fix until QTBUG-12252 and/or QTBUG-7747 can be properly
addressed in a patch release. In the worst case, if using QML and
QPainters are being constructed in a non-GUI thread, this patch could
potentially turn off sub-pixel antialiasing for them.

Task-number: QTBUG-11002
Reviewed-by: Aaron Kennedy
Reviewed-by: Eskil Abrahamsen Blomfeldt

2 files changed, 32 insertions, 0 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativepainteditem.cpp b/src/declarative/graphicsitems/qdeclarativepainteditem.cpp
index 3b9b8df..a6db1fa 100644
--- a/src/declarative/graphicsitems/qdeclarativepainteditem.cpp
+++ b/src/declarative/graphicsitems/qdeclarativepainteditem.cpp
@@ -90,6 +90,8 @@ QT_BEGIN_NAMESPACE
 static int inpaint=0;
 static int inpaint_clearcache=0;
 
+extern Q_GUI_EXPORT bool qt_applefontsmoothing_enabled;
+
 /*!
     Marks areas of the cache that intersect with the given \a rect as dirty and
     in need of being refreshed.
@@ -287,7 +289,14 @@ void QDeclarativePaintedItem::paint(QPainter *p, const QStyleOptionGraphicsItem
             QRectF target(area.x(), area.y(), area.width(), area.height());
             if (!d->cachefrozen) {
                 if (!d->imagecache[i]->dirty.isNull() && topaint.contains(d->imagecache[i]->dirty)) {
+#ifdef Q_WS_MAC
+                    bool oldSmooth = qt_applefontsmoothing_enabled;
+                    qt_applefontsmoothing_enabled = false;
+#endif
                     QPainter qp(&d->imagecache[i]->image);
+#ifdef Q_WS_MAC
+                    qt_applefontsmoothing_enabled = oldSmooth;
+#endif
                     qp.setRenderHints(QPainter::HighQualityAntialiasing | QPainter::TextAntialiasing | QPainter::SmoothPixmapTransform, d->smoothCache);
                     qp.translate(-area.x(), -area.y());
                     qp.scale(d->contentsScale,d->contentsScale);
@@ -349,7 +358,14 @@ void QDeclarativePaintedItem::paint(QPainter *p, const QStyleOptionGraphicsItem
                 if (d->fillColor.isValid())
                     img.fill(d->fillColor);
                 {
+#ifdef Q_WS_MAC
+                    bool oldSmooth = qt_applefontsmoothing_enabled;
+                    qt_applefontsmoothing_enabled = false;
+#endif
                     QPainter qp(&img);
+#ifdef Q_WS_MAC
+                    qt_applefontsmoothing_enabled = oldSmooth;
+#endif
                     qp.setRenderHints(QPainter::HighQualityAntialiasing | QPainter::TextAntialiasing | QPainter::SmoothPixmapTransform, d->smoothCache);
 
                     qp.translate(-r.x(),-r.y());
diff --git a/src/declarative/graphicsitems/qdeclarativetext.cpp b/src/declarative/graphicsitems/qdeclarativetext.cpp
index ba4fa21..d63d633 100644
--- a/src/declarative/graphicsitems/qdeclarativetext.cpp
+++ b/src/declarative/graphicsitems/qdeclarativetext.cpp
@@ -57,6 +57,8 @@
 
 QT_BEGIN_NAMESPACE
 
+extern Q_GUI_EXPORT bool qt_applefontsmoothing_enabled;
+
 class QTextDocumentWithImageResources : public QTextDocument {
     Q_OBJECT
 
@@ -1028,7 +1030,14 @@ QPixmap QDeclarativeTextPrivate::wrappedTextImage(bool drawStyle)
     QPixmap img(size);
     if (!size.isEmpty()) {
         img.fill(Qt::transparent);
+#ifdef Q_WS_MAC
+        bool oldSmooth = qt_applefontsmoothing_enabled;
+        qt_applefontsmoothing_enabled = false;
+#endif
         QPainter p(&img);
+#ifdef Q_WS_MAC
+        qt_applefontsmoothing_enabled = oldSmooth;
+#endif
         drawWrappedText(&p, QPointF(0,0), drawStyle);
     }
     return img;
@@ -1051,7 +1060,14 @@ QPixmap QDeclarativeTextPrivate::richTextImage(bool drawStyle)
     //paint text
     QPixmap img(size);
     img.fill(Qt::transparent);
+#ifdef Q_WS_MAC
+    bool oldSmooth = qt_applefontsmoothing_enabled;
+    qt_applefontsmoothing_enabled = false;
+#endif
     QPainter p(&img);
+#ifdef Q_WS_MAC
+    qt_applefontsmoothing_enabled = oldSmooth;
+#endif
 
     QAbstractTextDocumentLayout::PaintContext context;