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个部分.有关如何做到这一点的任何建议？

Answer 1

下面的代码也是一个解决方案,可以检测被轻拍的图片.我们的想法是采用UIImage并使用CGImageCreateWithImageInRect来裁剪碎片.从裁剪的部分创建一个新的UIImage并将其放在UIImageView中.为了使轻敲手势起作用,我必须将UIImageView放在UIView中.最后,提供手势和唯一标记,以便在点击时识别该片段.

- (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,但这里有一个.它使用Quartz将图像切割成9个相等大小的分数.请注意,它不处理旋转的图像(我指的是带有imageOrientation!= 0的图像),但它应该让你开始:

+(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9个图像的数组,每个图像的大小(/ 3,高度/ 3)