ios - 从矩形缩放 UIView 的正确转换？

Question

我想在 View 上模仿“放大”。较大的 View 将作为 subview 添加到较小的 View 的父 View 中，较大的 View 应该看起来像是从较小的 View 放大。给定较小 View 的矩形 fromRect 和放大 View 的最终帧 finalRect，什么是正确的变换？

我想方法签名会像下面这样，view 是父 View 。我写这篇文章是为了帮助自己，但还无法弄明白。

-(CGAffineTransform) translatedAndScaledTransformUsingViewRect:(CGRect)viewRect fromRect:(CGRect)fromRect inView:(UIView*) view
{
//calculate the scaling based on the final frame of viewToBeStretched (viewRect) vs the "fromRect"
CGFloat scaleX = ?, scaleY = ?;
CGAffineTransform scaleTransform = CGAffineTransformMakeScale(scaleX, scaleY);

//use translation instead of modifying the view's center, since frame changes with transforms are no good
CGFloat translationX = ?, translationY =?;
CGAffineTransform translationTransform = CGAffineTransformMakeTranslation(translationX, translationY);

CGAffineTransform final = CGAffineTransformConcat(scaleTransform, translationTransform);

return final;
}

Answer 1

所以实际实现起来很简单:

- (CGAffineTransform)translatedAndScaledTransformUsingViewRect:(CGRect)viewRect fromRect:(CGRect)fromRect {

    CGSize scales = CGSizeMake(viewRect.size.width/fromRect.size.width, viewRect.size.height/fromRect.size.height);
    CGPoint offset = CGPointMake(CGRectGetMidX(viewRect) - CGRectGetMidX(fromRect), CGRectGetMidY(viewRect) - CGRectGetMidY(fromRect));
    return CGAffineTransformMake(scales.width, 0, 0, scales.height, offset.x, offset.y);

}

您可以在此处查看完整示例:https://github.com/vGubriienko/TransformTest

(我仍然需要更新它以使用身份作为完整图像)