对于任何其他想知道如何根据Costique建议使用Core Graphics绘制内部阴影的人,这就是如何:(在iOS上根据需要进行调整)
在您的drawRect:方法中...
CGRect bounds = [self bounds];
CGContextRef context = UIGraphicsGetCurrentContext();
CGFloat radius = 0.5f * CGRectGetHeight(bounds);
// Create the "visible" path, which will be the shape that gets the inner shadow
// In this case it's just a rounded rect, but could be as complex as your want
CGMutablePathRef visiblePath = CGPathCreateMutable();
CGRect innerRect = CGRectInset(bounds, radius, radius);
CGPathMoveToPoint(visiblePath, NULL, innerRect.origin.x, bounds.origin.y);
CGPathAddLineToPoint(visiblePath, NULL, innerRect.origin.x + innerRect.size.width, bounds.origin.y);
CGPathAddArcToPoint(visiblePath, NULL, bounds.origin.x + bounds.size.width, bounds.origin.y, bounds.origin.x + bounds.size.width, innerRect.origin.y, radius);
CGPathAddLineToPoint(visiblePath, NULL, bounds.origin.x + bounds.size.width, innerRect.origin.y + innerRect.size.height);
CGPathAddArcToPoint(visiblePath, NULL, bounds.origin.x + bounds.size.width, bounds.origin.y + bounds.size.height, innerRect.origin.x + innerRect.size.width, bounds.origin.y + bounds.size.height, radius);
CGPathAddLineToPoint(visiblePath, NULL, innerRect.origin.x, bounds.origin.y + bounds.size.height);
CGPathAddArcToPoint(visiblePath, NULL, bounds.origin.x, bounds.origin.y + bounds.size.height, bounds.origin.x, innerRect.origin.y + innerRect.size.height, radius);
CGPathAddLineToPoint(visiblePath, NULL, bounds.origin.x, innerRect.origin.y);
CGPathAddArcToPoint(visiblePath, NULL, bounds.origin.x, bounds.origin.y, innerRect.origin.x, bounds.origin.y, radius);
CGPathCloseSubpath(visiblePath);
// Fill this path
UIColor *aColor = [UIColor redColor];
[aColor setFill];
CGContextAddPath(context, visiblePath);
CGContextFillPath(context);
// Now create a larger rectangle, which we're going to subtract the visible path from
// and apply a shadow
CGMutablePathRef path = CGPathCreateMutable();
//(when drawing the shadow for a path whichs bounding box is not known pass "CGPathGetPathBoundingBox(visiblePath)" instead of "bounds" in the following line:)
//-42 cuould just be any offset > 0
CGPathAddRect(path, NULL, CGRectInset(bounds, -42, -42));
// Add the visible path (so that it gets subtracted for the shadow)
CGPathAddPath(path, NULL, visiblePath);
CGPathCloseSubpath(path);
// Add the visible paths as the clipping path to the context
CGContextAddPath(context, visiblePath);
CGContextClip(context);
// Now setup the shadow properties on the context
aColor = [UIColor colorWithRed:0.0f green:0.0f blue:0.0f alpha:0.5f];
CGContextSaveGState(context);
CGContextSetShadowWithColor(context, CGSizeMake(0.0f, 1.0f), 3.0f, [aColor CGColor]);
// Now fill the rectangle, so the shadow gets drawn
[aColor setFill];
CGContextSaveGState(context);
CGContextAddPath(context, path);
CGContextEOFillPath(context);
// Release the paths
CGPathRelease(path);
CGPathRelease(visiblePath);
因此,基本上有以下步骤:
- 创建你的道路
- 设置所需的填充颜色,将此路径添加到上下文中,然后填充上下文
- 现在创建一个更大的矩形,该矩形可以绑定可见路径。在关闭此路径之前,请添加可见路径。然后关闭路径,以便创建一个形状,并从其中减去可见路径。您可能要研究填充方法(偶数/奇数的非零缠绕),具体取决于创建这些路径的方式。本质上,要将子路径添加到一起时要使其“减去”,您需要沿相反的方向(一个顺时针方向,另一个逆时针方向)绘制(或构造)它们。
- 然后,您需要将可见路径设置为上下文中的剪切路径,以免在屏幕之外绘制任何内容。
- 然后在上下文上设置阴影,包括阴影,模糊和颜色。
- 然后在大形状中填充孔。颜色无关紧要,因为如果您正确完成所有操作,就不会看到此颜色,而只会看到阴影。