objective-c - 边框不适应 Aspect Fit？

Question

我正在以编程方式设置带边框的 ImageView 。我将 imageView 的内容模式设置为 Aspect Fit，这有效，但边框仍然是原来的正方形。

代码:

CGRect imageViewRect = CGRectMake(left, top, 158, 119); 
        UIImageView *imageView = [[UIImageView alloc] initWithFrame:imageViewRect];
        [imageView setContentMode:UIViewContentModeScaleAspectFit];
        [imageView setImage:image];
        [imageView.layer setBorderColor:[[UIColor blackColor] CGColor]];
        [imageView.layer setBorderWidth:3.0];

显然，我希望黑色边框能够根据宽高比进行调整，并从各个方向包围图像。相反，它保留在原始框架中，看起来像这样:

Answer 1

使用 Frank Schmitt 在 this post 中略微修改的方法，您可以添加一种方法来计算显示按比例缩放的图像所需的帧:

- (CGRect)getFrameSizeForImage:(UIImage *)image inImageView:(UIImageView *)imageView {

    float hfactor = image.size.width / imageView.frame.size.width;
    float vfactor = image.size.height / imageView.frame.size.height;

    float factor = fmax(hfactor, vfactor);

    // Divide the size by the greater of the vertical or horizontal shrinkage factor
    float newWidth = image.size.width / factor;
    float newHeight = image.size.height / factor;

    // Then figure out if you need to offset it to center vertically or horizontally
    float leftOffset = (imageView.frame.size.width - newWidth) / 2;
    float topOffset = (imageView.frame.size.height - newHeight) / 2;

    return CGRectMake(leftOffset, topOffset, newWidth, newHeight);
}

然后您可以在设置 UIImageView 图像后调用它:

CGRect frame = [self getFrameSizeForImage:imageView.image inImageView:imageView]; 

最后，使用此框架设置 UIImageView 的框架，偏移位置以适应宽度/高度的任何变化:

CGRect imageViewFrame = CGRectMake(imageView.frame.origin.x + frame.origin.x, imageView.frame.origin.y + frame.origin.y, frame.size.width, frame.size.height);
imageView.frame = imageViewFrame;