获取图片的宽高

Posted 2023-02-04 成成先生

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1、获取本地图片宽高

    /**
     *  本地图片宽高的获取
     */
    UIImage *img = [UIImage imageNamed:@"test.jpg"];
    UIImageView *imgView = [[UIImageView alloc]initWithImage:img];
    imgView.frame = CGRectMake(0, 0, img.size.width, img.size.height);
    [self.view addSubview:imgView];
    NSLog(@"===%f===%f",img.size.width,img.size.width);

2、加载互联网图片

SDWebImage下载图片,图片被缓存到本地获取本地图片的宽高。

/**
   *  sdwebimage获取图片宽高
   */
  UIImageView * sdImgView = [UIImageView new];
  [self.view addSubview:sdImgView];
  NSURL * url = [NSURL URLWithString:@"http://appceshi.ywsoftware.com/OneCarAPI/rechargeCard/logo/C9100.jpg"];
  [sdImgView sd_setImageWithURL:url completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) 
      NSLog(@"%f==%f",image.size.height,image.size.width);
      sdImgView.frame = CGRectMake(0, CGRectGetMaxY(imgView.frame)+20, image.size.width, image.size.height);
  ];

网络框架加载:先通过文件头获取图片大小(没什么卵用)，如果获取失败，则下载完整的图片data，然后计算大小

-(CGSize)getImageSizeWithURL:(id)imageURL

  NSURL* URL = nil;
  if([imageURL isKindOfClass:[NSURL class]])
      URL = imageURL;
  
  if([imageURL isKindOfClass:[NSString class]])
      URL = [NSURL URLWithString:imageURL];
  
  if(URL == nil)
      return CGSizeZero;                  // url不正确返回CGSizeZero

  NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:URL];
  NSString* pathExtendsion = [URL.pathExtension lowercaseString];

  CGSize size = CGSizeZero;
  if([pathExtendsion isEqualToString:@"png"])
      size =  [self getPNGImageSizeWithRequest:request];
  
  else if([pathExtendsion isEqual:@"gif"])
  
      size =  [self getGIFImageSizeWithRequest:request];
  
  else
      size = [self getJPGImageSizeWithRequest:request];
  
  if(CGSizeEqualToSize(CGSizeZero, size))                    // 如果获取文件头信息失败,发送异步请求请求原图
  

      NSData* data = [NSURLConnection sendSynchronousRequest:[NSURLRequest requestWithURL:URL] returningResponse:nil error:nil];

      UIImage* image = [UIImage imageWithData:data];
      if(image)
      
          size = image.size;
      
  
  return size;

//  获取PNG图片的大小
-(CGSize)getPNGImageSizeWithRequest:(NSMutableURLRequest*)request

  [request setValue:@"bytes=16-23" forHTTPHeaderField:@"Range"];
  NSData* data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
  if(data.length == 8)
  
      int w1 = 0, w2 = 0, w3 = 0, w4 = 0;
      [data getBytes:&w1 range:NSMakeRange(0, 1)];
      [data getBytes:&w2 range:NSMakeRange(1, 1)];
      [data getBytes:&w3 range:NSMakeRange(2, 1)];
      [data getBytes:&w4 range:NSMakeRange(3, 1)];
      int w = (w1 << 24) + (w2 << 16) + (w3 << 8) + w4;
      int h1 = 0, h2 = 0, h3 = 0, h4 = 0;
      [data getBytes:&h1 range:NSMakeRange(4, 1)];
      [data getBytes:&h2 range:NSMakeRange(5, 1)];
      [data getBytes:&h3 range:NSMakeRange(6, 1)];
      [data getBytes:&h4 range:NSMakeRange(7, 1)];
      int h = (h1 << 24) + (h2 << 16) + (h3 << 8) + h4;
      return CGSizeMake(w, h);
  
  return CGSizeZero;

//  获取gif图片的大小
-(CGSize)getGIFImageSizeWithRequest:(NSMutableURLRequest*)request

  [request setValue:@"bytes=6-9" forHTTPHeaderField:@"Range"];
  NSData* data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
  if(data.length == 4)
  
      short w1 = 0, w2 = 0;
      [data getBytes:&w1 range:NSMakeRange(0, 1)];
      [data getBytes:&w2 range:NSMakeRange(1, 1)];
      short w = w1 + (w2 << 8);
      short h1 = 0, h2 = 0;
      [data getBytes:&h1 range:NSMakeRange(2, 1)];
      [data getBytes:&h2 range:NSMakeRange(3, 1)];
      short h = h1 + (h2 << 8);
      return CGSizeMake(w, h);
  
  return CGSizeZero;

//  获取jpg图片的大小
-(CGSize)getJPGImageSizeWithRequest:(NSMutableURLRequest*)request

  [request setValue:@"bytes=0-209" forHTTPHeaderField:@"Range"];
  NSData* data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];

  if ([data length] <= 0x58) 
      return CGSizeZero;
  

  if ([data length] < 210) // 肯定只有一个DQT字段
      short w1 = 0, w2 = 0;
      [data getBytes:&w1 range:NSMakeRange(0x60, 0x1)];
      [data getBytes:&w2 range:NSMakeRange(0x61, 0x1)];
      short w = (w1 << 8) + w2;
      short h1 = 0, h2 = 0;
      [data getBytes:&h1 range:NSMakeRange(0x5e, 0x1)];
      [data getBytes:&h2 range:NSMakeRange(0x5f, 0x1)];
      short h = (h1 << 8) + h2;
      return CGSizeMake(w, h);
   else 
      short word = 0x0;
      [data getBytes:&word range:NSMakeRange(0x15, 0x1)];
      if (word == 0xdb) 
          [data getBytes:&word range:NSMakeRange(0x5a, 0x1)];
          if (word == 0xdb) // 两个DQT字段
              short w1 = 0, w2 = 0;
              [data getBytes:&w1 range:NSMakeRange(0xa5, 0x1)];
              [data getBytes:&w2 range:NSMakeRange(0xa6, 0x1)];
              short w = (w1 << 8) + w2;
              short h1 = 0, h2 = 0;
              [data getBytes:&h1 range:NSMakeRange(0xa3, 0x1)];
              [data getBytes:&h2 range:NSMakeRange(0xa4, 0x1)];
              short h = (h1 << 8) + h2;
              return CGSizeMake(w, h);
           else // 一个DQT字段
              short w1 = 0, w2 = 0;
              [data getBytes:&w1 range:NSMakeRange(0x60, 0x1)];
              [data getBytes:&w2 range:NSMakeRange(0x61, 0x1)];
              short w = (w1 << 8) + w2;
              short h1 = 0, h2 = 0;
              [data getBytes:&h1 range:NSMakeRange(0x5e, 0x1)];
              [data getBytes:&h2 range:NSMakeRange(0x5f, 0x1)];
              short h = (h1 << 8) + h2;
              return CGSizeMake(w, h);
          
       else 
          return CGSizeZero;

推荐拓展阅读

文／DeepWater（简书作者）
原文链接：http://www.jianshu.com/p/6bed68e996dc
著作权归作者所有，转载请联系作者获得授权，并标注“简书作者”。

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