ios中图片的绘画和截图

ios中图片的绘画和截图

CGImageCreateWithImageInRect截图和UIGraphicsGetImageFromCurrentImageContext绘画图片

使用CGImageCreateWithImageInRect截图

    UIImage *img1 = [UIImage imageNamed:@"123"];
    //截取图片
        CGImageRef imgSmall = CGImageCreateWithImageInRect(img1.CGImage, CGRectMake(100, 100, 100, 100));
        UIImage *img2 = [UIImage imageWithCGImage:imgSmall];
        UIImageView *imgView = [[UIImageView alloc] initWithImage:img2];
        [imgView setFrame:CGRectMake(0, 100, 100, 100)];
        [self.view addSubview:imgView];

使用UIGraphicsGetImageFromCurrentImageContext绘画图片

UIImage *img1 = [UIImage imageNamed:@"123"];
UIImage *img2 = [UIImage imageNamed:@"123"];

    //开始绘画，设置画布的大小
UIGraphicsBeginImageContext(CGSizeMake(img1.size.width, img1.size.height * 2));
    //将图片画进去
[img1 drawInRect:CGRectMake(0, 0, img1.size.width, img1.size.height)];
[img2 drawInRect:CGRectMake(0,img1.size.height,  img1.size.width,  img1.size.height)];
    //就画布中的内容，放置到图片中
UIImage *img3 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
    //在视图中显示
UIImageView *imgView = [[UIImageView alloc] initWithImage:img3];
[imgView setFrame:CGRectMake(0, 100, 100, 100)];
[self.view addSubview:imgView];