Fix transformed text on Mac OS X

In change 1582407fc782c0befd0760633324dd5c206524a1, the Q_WS_MAC
code path which disabled drawing cached glyphs for any transform
was removed, as was the comment that scaling and rotation wasn't
supported by the Mac font engines. This obviously broke transformed
text on Mac, so we need to put it back.

I put it into the font engine itself where it belongs, and I kept
the somewhat confusing naming convention which is used in the
paint engine to minimize this patch. I'll clean up these function
names in a future commit.

Task-number: QTBUG-27362
Change-Id: I4fc6a503eedd4b1ebaf3ee659d948f997f433338
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>

5 files changed, 15 insertions, 2 deletions

diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index fec01afdee..2841a583d5 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -2992,7 +2992,7 @@ void QRasterPaintEngine::drawStaticTextItem(QStaticTextItem *textItem)
     ensureRasterState();
 
     QFontEngine *fontEngine = textItem->fontEngine();
-    if (shouldDrawCachedGlyphs(fontEngine, state()->matrix)) {
+    if (!supportsTransformations(fontEngine)) {
         drawCachedGlyphs(textItem->numGlyphs, textItem->glyphs, textItem->glyphPositions,
                          fontEngine);
     } else if (state()->matrix.type() < QTransform::TxProject) {
@@ -3291,7 +3291,7 @@ bool QRasterPaintEngine::supportsTransformations(QFontEngine *fontEngine) const
 */
 bool QRasterPaintEngine::supportsTransformations(QFontEngine *fontEngine, const QTransform &m) const
 {
-    if (m.type() >= QTransform::TxProject)
+    if (fontEngine->supportsTransformations(m))
         return true;
 
     return !shouldDrawCachedGlyphs(fontEngine, m);
diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index fa4e7a75bc..400ce8366f 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -268,6 +268,10 @@ QFixed QFontEngine::averageCharWidth() const
     return bb.xoff;
 }
 
+bool QFontEngine::supportsTransformations(const QTransform &transform) const
+{
+    return (transform.type() >= QTransform::TxProject);
+}
 
 void QFontEngine::getGlyphPositions(const QGlyphLayout &glyphs, const QTransform &matrix, QTextItem::RenderFlags flags,
                                     QVarLengthArray<glyph_t> &glyphs_out, QVarLengthArray<QFixedPoint> &positions)
diff --git a/src/gui/text/qfontengine_p.h b/src/gui/text/qfontengine_p.h
index 745e39ecf5..3321ca3b93 100644
--- a/src/gui/text/qfontengine_p.h
+++ b/src/gui/text/qfontengine_p.h
@@ -241,6 +241,8 @@ public:
         return canRender(utf16, utf16len);
     }
 
+    virtual bool supportsTransformations(const QTransform &transform) const;
+
     virtual Type type() const = 0;
 
     virtual int glyphCount() const;
diff --git a/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm b/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
index d413711828..1087d18891 100644
--- a/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
+++ b/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
@@ -600,6 +600,11 @@ QFontEngine *QCoreTextFontEngine::cloneWithSize(qreal pixelSize) const
     return new QCoreTextFontEngine(cgFont, newFontDef);
 }
 
+bool QCoreTextFontEngine::supportsTransformations(const QTransform &transform) const
+{
+    return transform.type() > QTransform::TxTranslate;
+}
+
 QT_END_NAMESPACE
 
 #endif// !defined(Q_WS_MAC) || (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
diff --git a/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h b/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h
index db1ebbaca1..6c5c557b13 100644
--- a/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h
+++ b/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h
@@ -103,6 +103,8 @@ public:
     virtual qreal minLeftBearing() const;
     virtual QFixed emSquareSize() const;
 
+    bool supportsTransformations(const QTransform &transform) const;
+
     virtual QFontEngine *cloneWithSize(qreal pixelSize) const;
     virtual int glyphMargin(QFontEngineGlyphCache::Type type) { Q_UNUSED(type); return 0; }