ios - 如何根据设备大小和比例调整 UIImage 的大小？
<p><p>我有一个尺寸为 (1008, 669) 的 UIImage 如何根据我的设备尺寸调整它的大小(例如，如果我在 iPhone4s 中查看它，它的宽度将为 640 x 960 ((320 *retina_scale) x (480 *retina_scale))。我正在使用下面的方法，但我的图像只是在 <code>UIImageView</code> 中拉伸(stretch)。如何处理这个？如何使其动态以便它可以工作各种图片？</p>
<pre><code>- (UIImage *) hResizeImage:(UIImage *)image withTargetSize:(CGSize)targetSize {
CGSize size = image.size;
CGFloat widthRatio = targetSize.width / image.size.width;
CGFloat heightRatio = targetSize.height / image.size.height;
// Figure out what our orientation is, and use that to form the rectangle
CGSize newSize;
if(widthRatio > heightRatio) {
newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio);
} else {
newSize = CGSizeMake(size.width * widthRatio,size.height * widthRatio);
}
// This is the rect that we've calculated out and this is what is actually used below
CGRect scaledRect = CGRectMake(0, 0, newSize.width * .scale, newSize.height * .scale);
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(scaledRect.size, false, .scale);
;
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
</code></pre></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>由于在 UIGraphicsBeginImageContextWithOptions 中指定了缩放因子，因此在计算 scaledRect 时不需要将宽高乘以屏幕比例。</p>
<p>如果你在 UIGraphicsBeginImageContextWithOptions 中指定 0.0 的值，缩放因子会自动设置为设备主屏幕的缩放因子。</p>
<pre><code>- (UIImage *)hResizeImage:(UIImage *)image withTargetSize:(CGSize)targetSize {
CGSize size = image.size;
CGFloat widthRatio = targetSize.width / image.size.width;
CGFloat heightRatio = targetSize.height / image.size.height;
// Figure out what our orientation is, and use that to form the rectangle
CGSize newSize;
if(widthRatio > heightRatio) {
newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio);
} else {
newSize = CGSizeMake(size.width * widthRatio,size.height * widthRatio);
}
// This is the rect that we've calculated out and this is what is actually used below
CGRect scaledRect = CGRectMake(0, 0, newSize.width, newSize.height);
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(scaledRect.size, false, 0.0f);
;
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
</code></pre></p>
<p style="font-size: 20px;">关于ios - 如何根据设备大小和比例调整 UIImage 的大小？，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/29642587/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/29642587/
</a>
</p>
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