Đây là danh mục UII mà tôi sử dụng cho việc này. Nó được dựa trên fastimage. Một cảnh báo chính là NSURLConnectionDelegate được đặt thành chính NSURL và điều này có thể gây ra xung đột trong các tình huống nhất định. Điều này chưa hoàn thành (ví dụ: URL của tệp bị bỏ qua ...) nhưng bạn có thể thấy nó đang đi đâu.
Tiêu đề:
#import <UIKit/UIKit.h>
typedef void (^UIImageSizeRequestCompleted) (NSURL* imgURL, CGSize size);
@interface UIImage (RemoteSize)
+ (void) requestSizeFor: (NSURL*) imgURL completion: (UIImageSizeRequestCompleted) completion;
@end
Nguồn:
#import "UIImage+RemoteSize.h"
#import <objc/runtime.h>
static char *kSizeRequestDataKey = "NSURL.sizeRequestData";
static char *kSizeRequestTypeKey = "NSURL.sizeRequestType";
static char *kSizeRequestCompletionKey = "NSURL.sizeRequestCompletion";
typedef uint32_t dword;
@interface NSURL (RemoteSize)
@property (nonatomic, strong) NSMutableData* sizeRequestData;
@property (nonatomic, strong) NSString* sizeRequestType;
@property (nonatomic, copy) UIImageSizeRequestCompleted sizeRequestCompletion;
@end
@implementation NSURL (RemoteSize)
- (void) setSizeRequestCompletion: (UIImageSizeRequestCompleted) block {
objc_setAssociatedObject(self, &kSizeRequestCompletionKey, block, OBJC_ASSOCIATION_COPY);
}
- (UIImageSizeRequestCompleted) sizeRequestCompletion {
return objc_getAssociatedObject(self, &kSizeRequestCompletionKey);
}
- (void) setSizeRequestData:(NSMutableData *)sizeRequestData {
objc_setAssociatedObject(self, &kSizeRequestDataKey, sizeRequestData, OBJC_ASSOCIATION_RETAIN);
}
- (NSMutableData*) sizeRequestData {
return objc_getAssociatedObject(self, &kSizeRequestDataKey);
}
- (void) setSizeRequestType:(NSString *)sizeRequestType {
objc_setAssociatedObject(self, &kSizeRequestTypeKey, sizeRequestType, OBJC_ASSOCIATION_RETAIN);
}
- (NSString*) sizeRequestType {
return objc_getAssociatedObject(self, &kSizeRequestTypeKey);
}
#pragma mark - NSURLConnectionDelegate
- (void) connection: (NSURLConnection*) connection didReceiveResponse:(NSURLResponse *)response {
[self.sizeRequestData setLength: 0]; //Redirected => reset data
}
- (void) connection: (NSURLConnection*) connection didReceiveData:(NSData *)data {
NSMutableData* receivedData = self.sizeRequestData;
if(!receivedData) {
receivedData = [NSMutableData data];
self.sizeRequestData = receivedData;
}
[receivedData appendData: data];
//Parse metadata
const unsigned char* cString = [receivedData bytes];
const NSInteger length = [receivedData length];
const char pngSignature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
const char bmpSignature[2] = {66, 77};
const char gifSignature[2] = {71, 73};
const char jpgSignature[2] = {255, 216};
if(!self.sizeRequestType) {
if(memcmp(pngSignature, cString, 8) == 0) {
self.sizeRequestType = @"PNG";
}
else if(memcmp(bmpSignature, cString, 2) == 0) {
self.sizeRequestType = @"BMP";
}
else if(memcmp(jpgSignature, cString, 2) == 0) {
self.sizeRequestType = @"JPG";
}
else if(memcmp(gifSignature, cString, 2) == 0) {
self.sizeRequestType = @"GIF";
}
}
if([self.sizeRequestType isEqualToString: @"PNG"]) {
char type[5];
int offset = 8;
dword chunkSize = 0;
int chunkSizeSize = sizeof(chunkSize);
if(offset+chunkSizeSize > length)
return;
memcpy(&chunkSize, cString+offset, chunkSizeSize);
chunkSize = OSSwapInt32(chunkSize);
offset += chunkSizeSize;
if(offset + chunkSize > length)
return;
memcpy(&type, cString+offset, 4); type[4]='\0';
offset += 4;
if(strcmp(type, "IHDR") == 0) { //Should always be first
dword width = 0, height = 0;
memcpy(&width, cString+offset, 4);
offset += 4;
width = OSSwapInt32(width);
memcpy(&height, cString+offset, 4);
offset += 4;
height = OSSwapInt32(height);
if(self.sizeRequestCompletion) {
self.sizeRequestCompletion(self, CGSizeMake(width, height));
}
self.sizeRequestCompletion = nil;
[connection cancel];
}
}
else if([self.sizeRequestType isEqualToString: @"BMP"]) {
int offset = 18;
dword width = 0, height = 0;
memcpy(&width, cString+offset, 4);
offset += 4;
memcpy(&height, cString+offset, 4);
offset += 4;
if(self.sizeRequestCompletion) {
self.sizeRequestCompletion(self, CGSizeMake(width, height));
}
self.sizeRequestCompletion = nil;
[connection cancel];
}
else if([self.sizeRequestType isEqualToString: @"JPG"]) {
int offset = 4;
dword block_length = cString[offset]*256 + cString[offset+1];
while (offset<length) {
offset += block_length;
if(offset >= length)
break;
if(cString[offset] != 0xFF)
break;
if(cString[offset+1] == 0xC0 ||
cString[offset+1] == 0xC1 ||
cString[offset+1] == 0xC2 ||
cString[offset+1] == 0xC3 ||
cString[offset+1] == 0xC5 ||
cString[offset+1] == 0xC6 ||
cString[offset+1] == 0xC7 ||
cString[offset+1] == 0xC9 ||
cString[offset+1] == 0xCA ||
cString[offset+1] == 0xCB ||
cString[offset+1] == 0xCD ||
cString[offset+1] == 0xCE ||
cString[offset+1] == 0xCF) {
dword width = 0, height = 0;
height = cString[offset+5]*256 + cString[offset+6];
width = cString[offset+7]*256 + cString[offset+8];
if(self.sizeRequestCompletion) {
self.sizeRequestCompletion(self, CGSizeMake(width, height));
}
self.sizeRequestCompletion = nil;
[connection cancel];
}
else {
offset += 2;
block_length = cString[offset]*256 + cString[offset+1];
}
}
}
else if([self.sizeRequestType isEqualToString: @"GIF"]) {
int offset = 6;
dword width = 0, height = 0;
memcpy(&width, cString+offset, 2);
offset += 2;
memcpy(&height, cString+offset, 2);
offset += 2;
if(self.sizeRequestCompletion) {
self.sizeRequestCompletion(self, CGSizeMake(width, height));
}
self.sizeRequestCompletion = nil;
[connection cancel];
}
}
- (void) connection: (NSURLConnection*) connection didFailWithError:(NSError *)error {
if(self.sizeRequestCompletion)
self.sizeRequestCompletion(self, CGSizeZero);
}
- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {
return cachedResponse;
}
- (void) connectionDidFinishLoading: (NSURLConnection *)connection {
// Basically, we failed to obtain the image size using metadata and the
// entire image was downloaded...
if(!self.sizeRequestData.length) {
self.sizeRequestData = nil;
}
else {
//Try parse to UIImage
UIImage* image = [UIImage imageWithData: self.sizeRequestData];
if(self.sizeRequestCompletion && image) {
self.sizeRequestCompletion(self, [image size]);
return;
}
}
self.sizeRequestCompletion(self, CGSizeZero);
}
@end
@implementation UIImage (RemoteSize)
+ (void) requestSizeFor: (NSURL*) imgURL completion: (UIImageSizeRequestCompleted) completion {
if([imgURL isFileURL]) {
//Load from file stream
}
else {
imgURL.sizeRequestCompletion = completion;
NSURLRequest* request = [NSURLRequest requestWithURL: imgURL];
NSURLConnection* conn = [NSURLConnection connectionWithRequest: request delegate: imgURL];
[conn scheduleInRunLoop: [NSRunLoop mainRunLoop] forMode: NSDefaultRunLoopMode];
[conn start];
}
}
@end
kích thước hình ảnh (chiều rộng/chiều cao)? hoặc kích thước tệp hình ảnh? – progrmr
Kích thước hình ảnh – jonzz