Cocoa: set font engine glyph format based on display type

Make the QCoreTextFontEngine::glyphFormat depend on the primary
display's subpixel layout (if any). This change also refactors the
antialiasing threshold setting to live beside the defaultGlyphFormat.

Change-Id: I27f94f775d91d2a68cd647cc24503b31b6ff5e61
Reviewed-by: Morten Johan Sørvig <morten.sorvig@nokia.com>

src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm

@@ -39,10 +39,12 @@
 **
 ****************************************************************************/
 
+#import <Cocoa/Cocoa.h>
+#import <IOKit/graphics/IOGraphicsLib.h>
+
 #include "qcoretextfontdatabase_p.h"
 #include "qfontengine_coretext_p.h"
 #include <QtCore/QSettings>
-#import <Foundation/Foundation.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -86,9 +88,6 @@ static const char *languageForWritingSystem[] = {
 };
 enum { LanguageCount = sizeof(languageForWritingSystem) / sizeof(const char *) };
 
-int qt_antialiasing_threshold = 0;
-bool qt_enable_font_smoothing = true;
-
 QFont::StyleHint styleHintFromNSString(NSString *style)
 {
     if ([style isEqual: @"sans-serif"])
@@ -122,13 +121,37 @@ QCoreTextFontDatabase::QCoreTextFontDatabase()
     QSettings appleSettings(QLatin1String("apple.com"));
     QVariant appleValue = appleSettings.value(QLatin1String("AppleAntiAliasingThreshold"));
     if (appleValue.isValid())
-        qt_antialiasing_threshold = appleValue.toInt();
+        QCoreTextFontEngine::antialiasingThreshold = appleValue.toInt();
 
+    /*
+        font_smoothing = 0 means no smoothing, while 1-3 means subpixel
+        antialiasing with different hinting styles (but we don't care about the
+        exact value, only if subpixel rendering is available or not)
+    */
+    int font_smoothing = 0;
     appleValue = appleSettings.value(QLatin1String("AppleFontSmoothing"));
-    // Only disable font smoothing when AppleFontSmoothing is set to 0,
-    // empty or non-zero means enabled
-    if (appleValue.isValid() && appleValue.toInt() == 0)
-        qt_enable_font_smoothing = false;
+    if (appleValue.isValid()) {
+        font_smoothing = appleValue.toInt();
+    } else {
+        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+        // find the primary display (which is always the first NSScreen
+        // according to the documentation)
+        NSScreen *defaultScreen = [[NSScreen screens] objectAtIndex:0];
+        CGDirectDisplayID displayId = [[[defaultScreen deviceDescription] objectForKey:@"NSScreenNumber"] unsignedIntValue];
+        io_service_t iodisplay = CGDisplayIOServicePort(displayId);
+
+        // determine if font smoothing is available based on the subpixel
+        // layout of the primary display
+        NSDictionary *d = (NSDictionary *) IODisplayCreateInfoDictionary(iodisplay, kIODisplayOnlyPreferredName);
+        uint displaySubpixelLayout = [[d objectForKey:@kDisplaySubPixelLayout] unsignedIntValue];
+        font_smoothing = (displaySubpixelLayout == kDisplaySubPixelLayoutUndefined ? 0 : 1);
+
+        [pool release];
+    }
+    QCoreTextFontEngine::defaultGlyphFormat = (font_smoothing > 0
+                                               ? QFontEngineGlyphCache::Raster_RGBMask
+                                               : QFontEngineGlyphCache::Raster_A8);
 }
 
 QCoreTextFontDatabase::~QCoreTextFontDatabase()

src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm

@@ -77,7 +77,9 @@ static void loadAdvancesForGlyphs(CTFontRef ctfont,
     }
 }
 
-extern int qt_antialiasing_threshold, qt_enable_font_smoothing;
+
+int QCoreTextFontEngine::antialiasingThreshold = 0;
+QFontEngineGlyphCache::Type QCoreTextFontEngine::defaultGlyphFormat = QFontEngineGlyphCache::Raster_RGBMask;
 
 CGAffineTransform qt_transform_from_fontdef(const QFontDef &fontDef)
 {
@@ -147,8 +149,7 @@ void QCoreTextFontEngine::init()
     Q_ASSERT(ctfont != NULL);
     Q_ASSERT(cgFont != NULL);
 
-    glyphFormat = qt_enable_font_smoothing ? QFontEngineGlyphCache::Raster_RGBMask
-                                           : QFontEngineGlyphCache::Raster_A8;
+    glyphFormat = defaultGlyphFormat;
 
     QCFString family = CTFontCopyFamilyName(ctfont);
     fontDef.family = family;
@@ -421,7 +422,7 @@ QImage QCoreTextFontEngine::imageForGlyph(glyph_t glyph, QFixed subPixelPosition
                                              8, im.bytesPerLine(), colorspace,
                                              cgflags);
     CGContextSetFontSize(ctx, fontDef.pixelSize);
-    CGContextSetShouldAntialias(ctx, (aa || fontDef.pointSize > qt_antialiasing_threshold)
+    CGContextSetShouldAntialias(ctx, (aa || fontDef.pointSize > antialiasingThreshold)
                                  && !(fontDef.styleStrategy & QFont::NoAntialias));
     CGContextSetShouldSmoothFonts(ctx, aa);
     CGAffineTransform oldTextMatrix = CGContextGetTextMatrix(ctx);

src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h

@@ -100,6 +100,9 @@ public:
     virtual QFontEngine *cloneWithSize(qreal pixelSize) const;
     virtual int glyphMargin(QFontEngineGlyphCache::Type type) { return 0; }
 
+    static int antialiasingThreshold;
+    static QFontEngineGlyphCache::Type defaultGlyphFormat;
+
 private:
     friend class QRawFontPrivate;
 

src/plugins/platforms/cocoa/cocoa.pro

@@ -73,7 +73,7 @@ HEADERS += qcocoaintegration.h \
 FORMS += $$PWD/../../../widgets/dialogs/qfiledialog.ui
 RESOURCES += qcocoaresources.qrc
 
-LIBS += -framework Cocoa
+LIBS += -framework Cocoa -framework IOKit
 
 QT += core-private gui-private widgets-private platformsupport-private printsupport
 

src/plugins/platforms/cocoa/qpaintengine_mac.mm

@@ -73,8 +73,6 @@
 
 QT_BEGIN_NAMESPACE
 
-extern int qt_antialiasing_threshold; // from qcoretextfontdatabase.mm
-
 /*****************************************************************************
   QCoreGraphicsPaintEngine utility functions
  *****************************************************************************/
@@ -1182,7 +1180,9 @@ void QCoreGraphicsPaintEngine::drawTextItem(const QPointF &pos, const QTextItem
 
     QFontEngine *fe = ti.fontEngine;
 
-    const bool textAA = state->renderHints() & QPainter::TextAntialiasing && fe->fontDef.pointSize > qt_antialiasing_threshold && !(fe->fontDef.styleStrategy & QFont::NoAntialias);
+    const bool textAA = ((state->renderHints() & QPainter::TextAntialiasing)
+                         && (fe->fontDef.pointSize > QCoreTextFontEngine::antialiasingThreshold)
+                         && !(fe->fontDef.styleStrategy & QFont::NoAntialias));
     const bool lineAA = state->renderHints() & QPainter::Antialiasing;
     if (textAA != lineAA)
         CGContextSetShouldAntialias(d->hd, textAA);