如何以编程方式将图像裁剪成碎片

Question

我需要以编程方式将图像分成 9 块。关于如何做到这一点的任何建议？

Answer 1

下面的代码也是一种检测被点击的图片的解决方案。这个想法是获取 UIImage 并使用 CGImageCreateWithImageInRect 裁剪出碎片。从裁剪后的部分创建一个新的 UIImage 并将其放置在 UIImageView 中。为了让点击手势起作用，我必须将 UIImageView 放在 UIView 中。最后，提供手势和唯一标签，以便在点击时可以识别该作品。

- (void)loadView {
    UIView* root = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
    UIImage* whole = [UIImage imageNamed:@"whole.jpg"]; //I know this image is 300x300

    int partId = 0;
    for (int x=0; x<=200; x+=100) {
        for(int y=0; y<=200; y+=100) {
            CGImageRef cgImg = CGImageCreateWithImageInRect(whole.CGImage, CGRectMake(x, y, 100, 100));
            UIImage* part = [UIImage imageWithCGImage:cgImg];
            UIImageView* iv = [[UIImageView alloc] initWithImage:part];

            UIView* sView = [[UIView alloc] initWithFrame:CGRectMake(200-x, 200-y, 100, 100)];
            [sView addSubview:iv];
            [iv release];

            UITapGestureRecognizer* tap = [[UITapGestureRecognizer alloc] initWithTarget:self
                                                                                  action:@selector(tap:)];
            tap.numberOfTapsRequired = 1;
            [sView addGestureRecognizer:tap];
            [tap release];

            sView.tag = partId;

            [root addSubview:sView];
            [sView release];
            partId++;
            CGImageRelease(cgImg);
        }
    }

    self.view = root;
}

- (void)tap:(UITapGestureRecognizer*)gesture
{
    NSLog(@"image tap=%d", gesture.view.tag);
}

Answer 2

有很多方法可以对图像进行切片和切块，但这里有一种。它使用 Quartz 将图像切割成 9 个大小相等的部分。请注意，它不处理旋转图像（我的意思是具有 imageOrientation!=0 的图像），但它应该可以帮助您入门：

+(NSArray *)splitImageInTo9:(UIImage *)im{
    CGSize size = [im size];
    NSMutableArray *arr = [[NSMutableArray alloc] initWithCapacity:9];
    for (int i=0;i<3;i++){
        for (int j=0;j<3;j++){
            CGRect portion = CGRectMake(i * size.width/3.0, j * size.height/3.0, size.width/3.0, size.height/3.0);
            UIGraphicsBeginImageContext(portion.size);
            CGContextRef context = UIGraphicsGetCurrentContext();
            CGContextScaleCTM(context, 1.0, -1.0);
            CGContextTranslateCTM(context, 0, -portion.size.height);
            CGContextTranslateCTM(context, -portion.origin.x, -portion.origin.y);
            CGContextDrawImage(context,CGRectMake(0.0, 0.0,size.width,  size.height), im.CGImage);
            [arr addObject:UIGraphicsGetImageFromCurrentImageContext()];
            UIGraphicsEndImageContext();


        }
    }
    return [arr autorelease];

}

输出将是一个包含 9 个图像的数组，每个图像的大小（with/3, height/3）

Answer 3

以下代码切片图片基于参数，添加边框和显示：

-(NSMutableArray *)getImagesFromImage:(UIImage *)image withRow:(NSInteger)rows           withColumn:(NSInteger)columns{
  NSMutableArray *images = [NSMutableArray array];
  CGSize imageSize = image.size;
  CGFloat xPos = 0.0, yPos = 0.0;
  CGFloat width = imageSize.width/rows;
  CGFloat height = imageSize.height/columns;
  for (int y = 0; y < columns; y++) {
    xPos = 0.0;
    for (int x = 0; x < rows; x++) {

        CGRect rect = CGRectMake(xPos, yPos, width, height);
        CGImageRef cImage = CGImageCreateWithImageInRect([image CGImage],  rect);

        UIImage *dImage = [[UIImage alloc] initWithCGImage:cImage];
        UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(x*width, y*height, width, height)];
        [imageView setImage:dImage];
        [imageView.layer setBorderColor:[[UIColor blackColor] CGColor]];
        [imageView.layer setBorderWidth:1.0];
        [self.view addSubview:imageView];
        [images addObject:dImage];
        xPos += width;
    }
    yPos += height;
}
return images;
}

项目下载链接：https://github.com/bpolat/Image-Slicer

示例用法和结果：

[self getImagesFromImage:[UIImage imageNamed:@"1.png"] withRow:4 withColumn:4];