UILabel的内阴影 [英] Inner Shadow in UILabel

问题描述

是否可以创建具有内部和外部阴影的UILabel？

is it possible to create such a UILabel with inner and outer shadow?

alt text http://dl.getdropbox.com/u/80699/Bildschirmfoto%202010-07-12%20um%2021.28.57.png

我只知道 shadowColor 和 shadowOffset

缩放：

alt text http://dl.getdropbox.com/u/80699/Bildschirmfoto%202010-07-12%20um%2021.39.56.png

谢谢！

推荐答案

dmaclach的答案是仅适用于易于倒置的形状。我的解决方案是一个自定义视图，适用于任何形状和文本。它需要iOS 4并且与分辨率无关。

The answer by dmaclach is only suitable for shapes that can easily be inverted. My solution is a custom view that works with any shape and also text. It requires iOS 4 and is resolution independent.

首先，代码所做的图解说明。这里的形状是一个圆圈。

First, a graphical explanation of what the code does. The shape here is a circle.

代码绘制带有白色阴影的文本。如果不需要，可以进一步重构代码，因为需要以不同方式屏蔽阴影。如果你需要在旧版本的iOS上使用它，你必须更换块并使用（恼人的）CGBitmapContext。

The code draws text with a white dropshadow. If it's not required, the code could be refactored further, because the dropshadow needs to be masked differently. If you need it on an older version of iOS, you would have to replace the block and use an (annoying) CGBitmapContext.

- (UIImage*)blackSquareOfSize:(CGSize)size {
  UIGraphicsBeginImageContextWithOptions(size, NO, 0);  
  [[UIColor blackColor] setFill];
  CGContextFillRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, size.width, size.height));
  UIImage *blackSquare = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return blackSquare;
}


- (CGImageRef)createMaskWithSize:(CGSize)size shape:(void (^)(void))block {
  UIGraphicsBeginImageContextWithOptions(size, NO, 0);  
  block();
  CGImageRef shape = [UIGraphicsGetImageFromCurrentImageContext() CGImage];
  UIGraphicsEndImageContext();  
    CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(shape),
                                      CGImageGetHeight(shape),
                                      CGImageGetBitsPerComponent(shape),
                                      CGImageGetBitsPerPixel(shape),
                                      CGImageGetBytesPerRow(shape),
                                      CGImageGetDataProvider(shape), NULL, false);
  return mask;
}


- (void)drawRect:(CGRect)rect {
  UIFont *font = [UIFont fontWithName:@"HelveticaNeue-Bold" size:40.0f];
  CGSize fontSize = [text_ sizeWithFont:font];

  CGImageRef mask = [self createMaskWithSize:rect.size shape:^{
    [[UIColor blackColor] setFill];
    CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
    [[UIColor whiteColor] setFill];
    // custom shape goes here
    [text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), 0) withFont:font];
    [text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -1) withFont:font];
  }];

  CGImageRef cutoutRef = CGImageCreateWithMask([self blackSquareOfSize:rect.size].CGImage, mask);
  CGImageRelease(mask);
  UIImage *cutout = [UIImage imageWithCGImage:cutoutRef scale:[[UIScreen mainScreen] scale] orientation:UIImageOrientationUp];
  CGImageRelease(cutoutRef);  

  CGImageRef shadedMask = [self createMaskWithSize:rect.size shape:^{
    [[UIColor whiteColor] setFill];
    CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
    CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(0, 1), 1.0f, [[UIColor colorWithWhite:0.0 alpha:0.5] CGColor]);
    [cutout drawAtPoint:CGPointZero];
  }];

  // create negative image
  UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
  [[UIColor blackColor] setFill];
  // custom shape goes here
  [text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -1) withFont:font];
  UIImage *negative = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext(); 

  CGImageRef innerShadowRef = CGImageCreateWithMask(negative.CGImage, shadedMask);
  CGImageRelease(shadedMask);
  UIImage *innerShadow = [UIImage imageWithCGImage:innerShadowRef scale:[[UIScreen mainScreen] scale] orientation:UIImageOrientationUp];
  CGImageRelease(innerShadowRef);

  // draw actual image
  [[UIColor whiteColor] setFill];
  [text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -0.5) withFont:font];
  [[UIColor colorWithWhite:0.76 alpha:1.0] setFill];
  [text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -1) withFont:font];  

  // finally apply shadow
  [innerShadow drawAtPoint:CGPointZero];
}

这篇关于UILabel的内阴影的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！