Cocoa：使用NSGradient作为掩码在其下面绘制
我试图用Cocoa绘制一个形状的反射。我已经应用了NSAffineTransform并成功重新绘制了形状，但现在我无法弄清楚如何在其上绘制alpha蒙版。我正在使用
NSCompositeDestinationOut
- (void)fadeOutRect:(NSRect)rect {
[NSGraphicsContext saveGraphicsState];
[[NSGraphicsContext currentContext] setCompositingOperation:NSCompositeDestinationOut];
NSGradient *gradient = [[NSGradient alloc] initWithColorsAndLocations:
[[NSColor blackColor] colorWithAlphaComponent:0.5], 0.0,
[[NSColor blackColor] colorWithAlphaComponent:1.0], 0.8, nil];
[gradient drawInRect:NSMakeRect(rect.origin.x, rect.origin.y + rect.size.height - ( PILL_HEIGHT * 2 ),
rect.size.width, PILL_HEIGHT) angle:270];
[NSGraphicsContext restoreGraphicsState];
}
没有找到相关结果
已邀请:
1 个回复
锑寝粒
// Draw our mask into the image NSGradient* fade = [[NSGradient alloc] initWithStartingColor:[NSColor colorWithCalibratedWhite:1.0 alpha:0.5] endingColor:[NSColor clearColor]]; [fade drawFromPoint:NSMakePoint(0.0, size.height) toPoint:NSMakePoint(0.0, 0.0) options:0]; // Composite the original image, upside-down NSAffineTransform* flipper = [NSAffineTransform transform]; [flipper scaleXBy:1.0 yBy:-1.0]; [flipper concat]; [self drawInRect:NSMakeRect(0.0, -1.0*size.height, size.width, size.height) fromRect:NSMakeRect(0.0, 0.0, self.size.width, size.height / scaleFactor) operation:NSCompositeSourceIn fraction:1.0];