利用UIImageJPEGRepresentation与UIGraphicsBeginImageContext进行图片压缩的简单比较

比较UIImageJPEGRepresentation与UIGraphicsBeginImageContext的图片压缩方法

最新推荐文章于 2020-12-23 17:00:06 发布

转载最新推荐文章于 2020-12-23 17:00:06 发布 · 2.3k 阅读

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本文对比了使用UIImageJPEGRepresentation和UIGraphicsBeginImageContext进行图片压缩的不同方法，并展示了手动实现图片压缩的过程。通过代码实例，详细介绍了如何压缩图片以减少文件大小并保持原始图片质量，同时提供了图片压缩后的实际效果展示。

转自：http://www.it165.net/pro/html/201405/14050.html

利用UIImageJPEGRepresentation与UIGraphicsBeginImageContext进行图片压缩的简单比较

 
   01.
   UIImage *image01 = [UIImage imageNamed:@"002.png"];//原图
  
   02.
    
   03.
   NSData *dataOf02 =UIImageJPEGRepresentation(image01, 0.5);//压缩图片内容，不影响图片的size，得到一个原大小，但更模糊的图片。
  
   04.
   UIImage *image02 = [UIImage imageWithData:dataOf02];//压缩图02
  
   05.
    
   06.
   UIImage *image03 = [self makeThumbnailFromImage:image01 scale:0.5];//压缩图03
  
   07.
   NSLog(@"001===%@",NSStringFromCGSize(image01.size));
  
   08.
   NSLog(@"002===%@",NSStringFromCGSize(image02.size));
  
   09.
   NSLog(@"003===%@",NSStringFromCGSize(image03.size));
  
   10.
    
   11.
   NSData *data001 = UIImageJPEGRepresentation(image01, 1.0);
  
   12.
   NSData *data002 = UIImageJPEGRepresentation(image02, 1.0);
  
   13.
   NSData *data003 = UIImageJPEGRepresentation(image03, 1.0);
  
   14.
    
   15.
   NSLog(@"002.lenght===%d",data001.length);
  
   16.
   NSLog(@"002.lenght===%d",data002.length);
  
   17.
   NSLog(@"003.lenght===%d",data003.length);
  
   18.
    
   19.
   //看一下效果
  
   20.
   UIImageView *imageView01 = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, image01.size.width, image01.size.height)];
  
   21.
   imageView01.image = image01;
  
   22.
   [self.view addSubview:imageView01];
  
   23.
    
   24.
   UIImageView *imageView02 = [[UIImageView alloc] initWithFrame:CGRectMake(0, 100, image02.size.width, image02.size.height)];
  
   25.
   imageView02.image = image02;
  
   26.
   [self.view addSubview:imageView02];
  
   27.
    
   28.
   UIImageView *imageView03 = [[UIImageView alloc] initWithFrame:CGRectMake(0, 200, image03.size.width, image03.size.height)];
  
   29.
   imageView03.image = image03;
  
   30.
   [self.view addSubview:imageView03];

 
   01.
   //手动实现图片压缩，可以写到分类里，封装成常用方法。按照大小进行比例压缩，改变了图片的size。
  
   02.
   - (UIImage *)makeThumbnailFromImage:(UIImage *)srcImage scale:(double)imageScale {
  
   03.
   UIImage *thumbnail = nil;
  
   04.
   CGSize imageSize = CGSizeMake(srcImage.size.width * imageScale, srcImage.size.height * imageScale);
  
   05.
   if (srcImage.size.width != imageSize.width || srcImage.size.height != imageSize.height)
  
   06.
   {
  
   07.
   UIGraphicsBeginImageContext(imageSize);
  
   08.
   CGRect imageRect = CGRectMake(0.0, 0.0, imageSize.width, imageSize.height);
  
   09.
   [srcImage drawInRect:imageRect];
  
   10.
   thumbnail = UIGraphicsGetImageFromCurrentImageContext();
  
   11.
   UIGraphicsEndImageContext();
  
   12.
   }
  
   13.
   else
  
   14.
   {
  
   15.
   thumbnail = srcImage;
  
   16.
   }
  
   17.
   return thumbnail;
  
   18.
   }