如何仅重复图像的一部分？

Question

如何仅重复图像的一部分，

有两个图像。

https://i.sstatic.net/KC0Pm.png

源图片类似于上面的内容 我想将其更改为：

https://i.sstatic.net/t8CwQ.png

这意味着我只想重复图像的一部分？不拉伸源图片， 可以这样做吗？

谢谢 更新：

此处代码：http://www.box.net/shared/cmtz0e48a5urtajxu4yn 还是有问题！！

更新： 我裁剪图像文件并重复该部分，但我仍然有一些问题。

- (UIImage *)imageWithImage:(NSString *)iconName covertToSize:(CGSize)size {
CGRect topLeft,topRight,bottomLeft,bottomRight,top,bottom,left,right;
if ([iconName isEqualToString:@"border_baikuang"]) {
    topLeft = CGRectMake(0, 0, 18, 18);
    topRight = CGRectMake(108-18, 0, 18, 18);
    bottomLeft = CGRectMake(0, 104-18, 18, 18);
    bottomRight = CGRectMake(108-18, 104-18, 18, 18);
    top = CGRectMake(18, 0, 1, 18);
    bottom = CGRectMake(18, 104-18, 1, 18);
    left = CGRectMake(0, 18, 18, 1);
    right = CGRectMake(108-18, 18, 18, 1);
} else if ([iconName isEqualToString:@"border_fuguxiangkuang"]) {
    topLeft = CGRectMake(0, 0, 28, 28);
    topRight = CGRectMake(108-28, 0, 28, 28);
    bottomLeft = CGRectMake(0, 104-28, 28, 28);
    bottomRight = CGRectMake(108-28, 104-28, 28, 28);
    top = CGRectMake(28, 0, 28, 24);
    bottom = CGRectMake(28, 104-28, 28, 24);
    left = CGRectMake(0, 28, 24, 28);
    right = CGRectMake(108-24, 28, 24, 28);
}
float width = size.width;
float height = size.height;
UIGraphicsBeginImageContext(size);
//
UIImage *topLeftPattern = [self fetchImgWithSrc:iconName rect:topLeft];
[topLeftPattern drawInRect:CGRectMake(0, 0, topLeftPattern.size.width, topLeftPattern.size.height)];

UIImage *topRightPattern = [self fetchImgWithSrc:iconName rect:topRight];
[topRightPattern drawInRect:CGRectMake(width-topRightPattern.size.width, 0, topRightPattern.size.width, topRightPattern.size.height)];

UIImage *bottomLeftPattern = [self fetchImgWithSrc:iconName rect:bottomLeft];
[bottomLeftPattern drawInRect:CGRectMake(0, height-bottomLeftPattern.size.height, bottomLeftPattern.size.width, bottomLeftPattern.size.height)];

UIImage *bottomRightPattern = [self fetchImgWithSrc:iconName rect:bottomRight];
[bottomRightPattern drawInRect:CGRectMake(width-bottomRightPattern.size.width, height-bottomRightPattern.size.height, bottomRightPattern.size.width, bottomRightPattern.size.height)];

UIImage *topPattern = [self fetchImgWithSrc:iconName rect:top];
[topPattern drawAsPatternInRect:CGRectMake(topLeftPattern.size.width, 0, width-topRightPattern.size.width-topLeftPattern.size.width, topPattern.size.height)];

UIImage *bottomPattern = [self fetchImgWithSrc:iconName rect:bottom];
[bottomPattern drawAsPatternInRect:CGRectMake(bottomLeftPattern.size.width, height-bottomLeftPattern.size.height, width-bottomRightPattern.size.width-bottomLeftPattern.size.width, bottomPattern.size.height)];

UIImage *leftPattern = [self fetchImgWithSrc:iconName rect:left];
[leftPattern drawAsPatternInRect:CGRectMake(0, topLeftPattern.size.height, leftPattern.size.width, height-bottomLeftPattern.size.height-topLeftPattern.size.height)];

UIImage *rightPattern = [self fetchImgWithSrc:iconName rect:right];
[rightPattern drawAsPatternInRect:CGRectMake(width-topRightPattern.size.width, topRightPattern.size.height, rightPattern.size.width, height-bottomRightPattern.size.height - topRightPattern.size.height)];

UIImage *destImage = UIGraphicsGetImageFromCurrentImageContext();    
UIGraphicsEndImageContext();
return destImage;

结果

- (UIImage*)fetchImgWithSrc:(NSString *)iconName rect:(CGRect)clipRect {

NSString *completeName = [iconName stringByAppendingString:@".png"];
UIImage *src = [UIImage imageFromFileName:completeName];
NSLog(@"src=%@",NSStringFromCGSize(src.size));
UIImage *tmpPattern = [UIImage imageWithCGImage:CGImageCreateWithImageInRect(src.CGImage, clipRect)];
NSLog(@"dest=%@",NSStringFromCGSize(tmpPattern.size));
return tmpPattern;

：

是这样的 https://i.sstatic.net/jO0O5.png

有什么问题吗？

谢谢

Answer 1

iOS 5 中有 stretchableImageWithLeftCapWidth:topCapHeight:（最高 4.3）或 ressizedImageWithCapInsets:

Answer 2

使用 UIImage，您只能重复图像的 1 像素宽部分。您能做的最好的事情就是裁剪图像文件并重复您想要重复的部分。您也可以使用 Core Graphics 来完成此操作，但它比修改文件要复杂得多。

Answer 3

您可以使用NSDrawThreePartImage（仅限 OSX）来提示一种可能的解决方案。

它的声明如下：

void NSDrawThreePartImage(NSRect frame,
   NSImage *startCap,
   NSImage *centerFill,
   NSImage *endCap,
   BOOL vertical,
   NSCompositingOperation op,
   CGFloat alphaFraction,
   BOOL flipped
);

因此，您将需要三个图像来模拟它。

如果您还知道偏移量，您实际上可以使用一张图像和一些奇特的 CoreGraphics 操作来完成此操作。

模拟时首先想到的是使用 CGBitmapContext ，然后使用上下文将图像绘制到位图上，然后将结果作为位图或 >CGImage（您可能想要保存结果，因为计算成本可能很高）。