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Cocoa: make text subpixel rendering check to work for non-Apple displays

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Task-number: QTBUG-27386

Change-Id: I4e12663f80060dfcea6970a705861af388d816ac
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
This commit is contained in:
Teemu Katajisto 2012-10-29 12:54:17 +02:00 committed by The Qt Project
parent e5ac4fb9b2
commit efc9b77a6e
1 changed files with 35 additions and 13 deletions
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48
src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm
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@ -137,22 +137,44 @@ QCoreTextFontDatabase::QCoreTextFontDatabase()
if (appleValue.isValid()) {
font_smoothing = appleValue.toInt();
} else {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
// non-Apple displays do not provide enough information about subpixel rendering so
// draw text with cocoa and compare pixel colors to see if subpixel rendering is enabled
int w = 10;
int h = 10;
NSRect rect = NSMakeRect(0.0, 0.0, w, h);
NSImage *fontImage = [[NSImage alloc] initWithSize:NSMakeSize(w, h)];
// 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);
[fontImage lockFocus];
// 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];
[d release];
font_smoothing = (displaySubpixelLayout == kDisplaySubPixelLayoutUndefined ? 0 : 1);
[[NSColor whiteColor] setFill];
NSRectFill(rect);
[pool release];
NSString *str = @"X\\";
NSFont *font = [NSFont fontWithName:@"Helvetica" size:10.0];
NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
[attrs setObject:font forKey:NSFontAttributeName];
[attrs setObject:[NSColor blackColor] forKey:NSForegroundColorAttributeName];
[str drawInRect:rect withAttributes:attrs];
NSBitmapImageRep *nsBitmapImage = [[NSBitmapImageRep alloc] initWithFocusedViewRect:rect];
[fontImage unlockFocus];
float red, green, blue;
for (int x = 0; x < w; x++) {
for (int y = 0; y < h; y++) {
NSColor *pixelColor = [nsBitmapImage colorAtX:x y:y];
red = [pixelColor redComponent];
green = [pixelColor greenComponent];
blue = [pixelColor blueComponent];
if (red != green || red != blue)
font_smoothing = 1;
}
}
[nsBitmapImage release];
[fontImage release];
}
QCoreTextFontEngine::defaultGlyphFormat = (font_smoothing > 0
? QFontEngineGlyphCache::Raster_RGBMask