// 根据图片url获取图片尺寸
+(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;
}
}
}
摘自: https://blog.csdn.net/chenyong05314/article/details/52585492
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