objective-c - 构建具有多个可拉伸(stretch)图像的 UIImage

Question

我有 3 张图片，左边的大写字母，右边的大写字母，中间的。也许使用 CGImageRefs (?)，有没有一种方法可以基于 CGRect 构建位图，将中心部分置于某个容器的中心，拉伸(stretch)左端盖直到它到达中间部分和右侧相同然后生成 UIImage？

Answer 1

好的，我按照 promise 进行了查找。这是一个解决方案:

基本思想

• 取左帽并制作一个右侧拉伸(stretch)的 UIImage
• 用箭头UIImage“粘合”它
• 现在用右边的盖子粘住它，左边有拉伸(stretch)的一面

这是一张小图，我认为它可以表达

  ______ ........    ________      .........___________
 {______|........|  | arrow  |    |.........|__________)
left cap|lc flex     --------      rc flex  | right cap

代码

// get the images from disk
UIImage *leftCap = [UIImage imageNamed:@"leftCap.png"];
UIImage *arrow = [UIImage imageNamed:@"arrow.png"];
UIImage *rightCap = [UIImage imageNamed:@"rightCap"];

// stretch left and right cap
// calculate the edge insets beforehand !

UIImage *leftCapStretched = [leftCap resizableImageWithCapInsets:UIEdgeInsetsMake(topInset, leftInset, bottomInset, rightInset)];
UIImage *rightCapStretched = [rightCap resizableImageWithCapInsets:UIEdgeInsetsMake(topInset, leftInset, bottomInset, rightInset)];

CGFloat widthOfAllImages = leftCapStretched.size.width + arrow.size.width + rightCapStretched.size.width;

// build the actual glued image

UIGraphicsBeginImageContextWithOptions(CGSizeMake(widthOfAllImages, arrow.size.height), NO, 0);
[leftCapStretched drawAtPoint:CGPointMake(0, 0)];
[arrow drawAtPoint:CGPointMake(leftCap.size.width, 0)];
[rightCapStretched drawAtPoint:CGPointMake(leftCap.size.width + arrow.size.width, 0)];
UIImage* im = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext();

// now you should have a ready to use UIImage ;)

替代方案

受 Jonathan Plakets 的启发，仅使用 UIImageViews 并按上述方式拉伸(stretch) UIImages 就可以回答同样的问题。