如何从 UIView/UIScrollView 创建图像

问题描述

我在 UIScrollView 中有一张图片，可以滚动和缩放.

I have an image in an UIScrollView, that can be scrolled and zoomed.

当用户按下按钮时，我希望代码从我用 CGRect 指定的区域内的 UIScrollView 的任何部分创建图像.

When the user presses a button, I want the code to create an image from whatever part of the UIScrollView is inside an area I specify with a CGRect.

我见过裁剪 UIImages 的代码，但我无法调整它来为视图做同样的事情，因为它使用 CGContextDrawImage.

I've seen code to crop UIImages, but I can't adapt it to do the same for a view, because it uses CGContextDrawImage.

有什么想法吗?

干杯，安德烈

推荐答案

我已经搞定了.

这是我的解决方案，基于网络上的几个不同的解决方案:

Here's my solution, based on a few different ones from the web:

- (UIImage *)imageByCropping:(UIScrollView *)imageToCrop toRect:(CGRect)rect
{
    CGSize pageSize = rect.size;
    UIGraphicsBeginImageContext(pageSize);

    CGContextRef resizedContext = UIGraphicsGetCurrentContext();
    CGContextTranslateCTM(resizedContext, -imageToCrop.contentOffset.x, -imageToCrop.contentOffset.y);
    [imageToCrop.layer renderInContext:resizedContext];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return image;
}

您使用以下方式调用:

CGRect clippedRect = CGRectMake(0, 0, 320, 300);
picture.image = [self imageByCropping:myScrollView toRect:clippedRect];