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实例代码:将iOS中 UIImage根据屏宽调整size

发布时间:2022-09-27 11:08:55

本篇文章为大家展示了实例代码:将iOS中 UIImage根据屏宽调整size,代码简明扼要并且容易理解,绝对能使你眼前一亮,通过这篇文章的详细介绍希望你能有所收获。

需求:UIImage根据屏幕宽度按照自己本身比例改变高度

上代码,为UIImage创建一个Category

#import "UIImage+UIImageExtras.h" 
@implementation UIImage (UIImageExtras) 
- (UIImage *)imageByScalingToSize:(CGSize)targetSize 
{ 
 UIImage *sourceImage = self; 
 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; 
 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; 
 } 
 } 
 // this is actually the interesting part: 
 UIGraphicsBeginImageContext(targetSize); 
 CGRect thumbnailRect = CGRectZero; 
 thumbnailRect.origin = thumbnailPoint; 
 thumbnailRect.size.width = scaledWidth; 
 thumbnailRect.size.height = scaledHeight; 
 [sourceImage drawInRect:thumbnailRect]; 
 newImage =UIGraphicsGetImageFromCurrentImageContext(); 
 UIGraphicsEndImageContext(); 
 if(newImage == nil) 
 NSLog(@"could not scale image"); 
 return newImage ; 
} 
@end 

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