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實例代碼:將iOS中 UIImage根據屏寬調整size

發布時間:2020-07-08 09:53:42 來源:億速云 閱讀:186 作者:Leah 欄目:移動開發

本篇文章為大家展示了實例代碼:將iOS中 UIImage根據屏寬調整size,代碼簡明扼要并且容易理解,絕對能使你眼前一亮,通過這篇文章的詳細介紹希望你能有所收獲。

需求:UIImage根據屏幕寬度按照自己本身比例改變高度

上代碼,為UIImage創建一個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 

在需要使用的地方import然后使用

CGSize size = image.size; 
image = [image imageByScalingToSize:CGSizeMake([UIScreen mainScreen].bounds.size.width,[UIScreen mainScreen].bounds.size.width * (size.height / size.width))]; 
self.imageview.image = image; 

上述內容就是實例代碼:將iOS中 UIImage根據屏寬調整size,你們學到知識或技能了嗎?如果還想學到更多技能或者豐富自己的知識儲備,歡迎關注億速云行業資訊頻道。

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