그라디언트를 시뮬레이트하기 위해 필자가 생각할 수있는 유일한 "쉬운"해결책은 패스를 여러 번 선 획하고 획 폭을 줄이며 매번 약간의 색상을 변경하는 것입니다.
분명히 복잡한 경로에서는 값 비싼 연산이므로 가능한 경우 결과를 캐시해야합니다.
#define RKRandom(x) (arc4random() % ((NSUInteger)(x) + 1))
@implementation StrokeView
- (void)drawRect:(NSRect)rect
{
NSRect bounds = self.bounds;
//first draw using Core Graphics calls
CGContextRef c = [[NSGraphicsContext currentContext] graphicsPort];
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, NULL, NSMidX(bounds), NSMidY(bounds));
CGContextSetMiterLimit(c,90.0);
CGContextSetLineJoin(c, kCGLineJoinRound);
CGContextSetLineCap(c, kCGLineCapRound);
for(NSUInteger f = 0; f < 20; f++)
{
CGPathAddCurveToPoint(
path,
NULL,
(CGFloat)RKRandom((NSInteger)NSWidth(bounds)) + NSMinX(bounds),
(CGFloat)RKRandom((NSInteger)NSHeight(bounds)) + NSMinY(bounds),
(CGFloat)RKRandom((NSInteger)NSWidth(bounds)) + NSMinX(bounds),
(CGFloat)RKRandom((NSInteger)NSHeight(bounds)) + NSMinY(bounds),
(CGFloat)RKRandom((NSInteger)NSWidth(bounds)) + NSMinX(bounds),
(CGFloat)RKRandom((NSInteger)NSHeight(bounds)) + NSMinY(bounds)
);
}
for(NSInteger i = 0; i < 8; i+=2)
{
CGContextSetLineWidth(c, 8.0 - (CGFloat)i);
CGFloat tint = (CGFloat)i * 0.15;
CGContextSetRGBStrokeColor (
c,
1.0,
tint,
tint,
1.0
);
CGContextAddPath(c, path);
CGContextStrokePath(c);
}
CGPathRelease(path);
//now draw using Cocoa drawing
NSBezierPath* cocoaPath = [NSBezierPath bezierPathWithRoundedRect:NSInsetRect(self.bounds, 20.0, 20.0) xRadius:10.0 yRadius:10.0];
for(NSInteger i = 0; i < 8; i+=2)
{
[cocoaPath setLineWidth:8.0 - (CGFloat)i];
CGFloat tint = (CGFloat)i * 0.15;
NSColor* color = [NSColor colorWithCalibratedRed:tint green:tint blue:1.0 alpha:1.0];
[color set];
[cocoaPath stroke];
}
}
@end