更改边界或框架时 UIImageView 不调整大小？答案

【问题标题】：UIImageView not resizing when bounds or frame is changed?更改边界或框架时 UIImageView 不调整大小？
【发布时间】：2012-07-31 20:12:07
【问题描述】：

所以我有一个自定义视图（它是一个位于键盘顶部的自定义文本视图）；但是它可以调整大小，所以我希望背景图像（其中包含 UIImage 的 UIImageView）随它缩放。以下代码什么都不做：

//size of entire custom view
CGRect bFrame = self.keyboard.frame;
bFrame.origin.y += heightDifference;
bFrame.size.height += heightDifference;

//lets set frame and bounds for the uiimageview
self.keyboard.background.frame = bFrame;
self.keyboard.background.bounds = bFrame;

//I thought the lines above would work, but they didn't, trying to reset the image and change its content mode as a hack.. .still no beans.
self.keyboard.background.image = [UIImage imageNamed:@"keyboard_backgroundv1_5.png"];
self.keyboard.background.contentMode = UIViewContentModeScaleToFill;

【问题讨论】：

标签： iphone ios uiimageview resize scaling

【解决方案1】：

这个功能可以帮到你

CGSize targetSize = CGSizeMake(self.keyboard.frame.size.width, self.keyboard.frame.size.height);

self.keyboard.background.image = [self imageByScalingProportionallyToSize:targetSize ImageForConvert:[UIImage imageNamed:@"keyboard_backgroundv1_5.png"]];


-(UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize ImageForConvert:(UIImage *)sourceImage
{
    UIImage *newImage = nil;

    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;

    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;

    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;

    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) 
    {

        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor < heightFactor) 
            scaleFactor = widthFactor;
        else
            scaleFactor = heightFactor;

        scaledWidth  = width * scaleFactor*1;
        scaledHeight = height * scaleFactor;

        // center the image

        if (widthFactor < heightFactor)
        {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
        } else if (widthFactor > heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }


    UIGraphicsBeginImageContext(targetSize);

    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage ;
}

【讨论】：