1 獲取網絡圖片的尺寸問題

問題：下面的方法 jpeg圖片獲取不到尺寸，最好服務器能返回圖片的尺寸。

+(CGSize)downloadImageSizeWithURL:(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;NSString* absoluteString = URL.absoluteString;#ifdef dispatch_main_sync_safeif([[SDImageCache sharedImageCache] diskImageExistsWithKey:absoluteString]){UIImage* image = [[SDImageCache sharedImageCache] imageFromMemoryCacheForKey:absoluteString];if(!image){NSData* data = [[SDImageCache sharedImageCache] performSelector:@selector(diskImageDataBySearchingAllPathsForKey:) withObject:URL.absoluteString];image = [UIImage imageWithData:data];}if(!image){return image.size;}} #endifNSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:URL];NSString* pathExtendsion = [URL.pathExtension lowercaseString];CGSize size = CGSizeZero;if([pathExtendsion isEqualToString:@"png"]) {size = [self downloadPNGImageSizeWithRequest:request];} else if([pathExtendsion isEqual:@"gif"]) {size = [self downloadGIFImageSizeWithRequest:request];} else {size = [self downloadJPGImageSizeWithRequest:request];}if(CGSizeEqualToSize(CGSizeZero, size)){NSData* data = [NSURLConnection sendSynchronousRequest:[NSURLRequest requestWithURL:URL] returningResponse:nil error:nil];UIImage* image = [UIImage imageWithData:data];if(image){ #ifdef dispatch_main_sync_safe[[SDImageCache sharedImageCache] storeImage:image recalculateFromImage:YES imageData:data forKey:URL.absoluteString toDisk:YES]; #endif//size = image.size;}}return size; }+(CGSize)downloadPNGImageSizeWithRequest:(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; } +(CGSize)downloadGIFImageSizeWithRequest:(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; } -(id)diskImageDataBySearchingAllPathsForKey:(id)key{return nil; }+(CGSize)downloadJPGImageSizeWithRequest:(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) {// 肯定只有一個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) {// 兩個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 {// 一個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;}} }復制代碼

2 長圖加載和剪切圖片demo

使用第三方SDImageView 處理過
github.com/LiuDao27/cu…

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