iphone - 使用 Core Graphics 在 CGContextClip 之后绘制阴影

Question

更新:我尝试实现 Peter 指定的方法，但得到了不正确的阴影。怎么了？

alt text http://grab.by/2XyP

CGContextSetShadowWithColor(c, CGSizeMake(4, 4), kAudioThumbShadowBlur, [[UAColor blackColor] CGColor]);
    CGContextFillPath(c);

    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, minx, midy);
    CGPathAddArcToPoint(path, NULL, minx, miny, midx, miny, kDefaultMargin);
    CGPathAddArcToPoint(path, NULL, maxx, miny, maxx, midy, kDefaultMargin);
    CGPathAddArcToPoint(path, NULL, maxx, maxy, midx, maxy, kDefaultMargin);
    CGPathAddArcToPoint(path, NULL, minx, maxy, minx, midy, kDefaultMargin);
    CGPathCloseSubpath(path);


    // Fill and stroke the path
    CGContextSaveGState(c);
    CGContextAddPath(c, path);
    CGContextClip(c);


    myGradient = CGGradientCreateWithColorComponents(myColorspace, components, locations, 2);
    CGContextDrawLinearGradient(c, myGradient, CGPointMake(minx,miny), CGPointMake(minx,maxy), 0);

    CGContextAddPath(c, path);
    CGPathRelease(path);
    CGContextStrokePath(c);
    CGContextRestoreGState(c);

原问题:我希望使用以下代码在 CoreGraphics 中制作的自定义圆形单元格项目的底部周围绘制自然的阴影:

...
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, minx, miny);
    CGPathAddArcToPoint(path, NULL, minx, maxy, midx, maxy, kDefaultMargin);
    CGPathAddArcToPoint(path, NULL, maxx, maxy, maxx, miny, kDefaultMargin);
    CGPathAddLineToPoint(path, NULL, maxx, miny);
    CGPathAddLineToPoint(path, NULL, minx, miny);
    CGPathCloseSubpath(path);

    // Fill and stroke the path
    CGContextSaveGState(c);
    CGContextAddPath(c, path);
    CGContextClip(c);

    myGradient = CGGradientCreateWithColorComponents(myColorspace, components, locations, 2);
    CGContextDrawLinearGradient(c, myGradient, CGPointMake(minx,miny), CGPointMake(minx,maxy), 0);

    CGContextAddPath(c, path);
    CGPathRelease(path);
    CGContextStrokePath(c);
    CGContextRestoreGState(c);
...

我想在渐变填充之前或之后在该路径的外部应用阴影。这样做的最佳方法是什么？

Answer 1

渐变绘制不算作填充，因此，首先设置阴影并进行纯色填充。然后，使用渐变和剪切描边在纯色填充上绘制。