Merge pull request #2080 from dreampiggy/feature_heif_image_format

Add image format detect of HEIC (One type of HEIF which use HEVC codec). This is supported natively in iOS 11 & macOS 10.13

SDWebImage/NSData+ImageContentType.h

@@ -16,7 +16,8 @@ typedef NS_ENUM(NSInteger, SDImageFormat) {
     SDImageFormatPNG,
     SDImageFormatGIF,
     SDImageFormatTIFF,
-    SDImageFormatWebP
+    SDImageFormatWebP,
+    SDImageFormatHEIC
 };
 
 @interface NSData (ImageContentType)

SDWebImage/NSData+ImageContentType.m

@@ -14,6 +14,11 @@
 #import <MobileCoreServices/MobileCoreServices.h>
 #endif
 
+// Currently Image/IO does not support WebP
+#define kSDUTTypeWebP ((__bridge CFStringRef)@"public.webp")
+// AVFileTypeHEIC is defined in AVFoundation via iOS 11, we use this without import AVFoundation
+#define kSDUTTypeHEIC ((__bridge CFStringRef)@"public.heic")
+
 @implementation NSData (ImageContentType)
 
 + (SDImageFormat)sd_imageFormatForImageData:(nullable NSData *)data {
@@ -21,6 +26,7 @@
         return SDImageFormatUndefined;
     }
     
+    // File signatures table: http://www.garykessler.net/library/file_sigs.html
     uint8_t c;
     [data getBytes:&c length:1];
     switch (c) {
@@ -33,16 +39,26 @@
         case 0x49:
         case 0x4D:
             return SDImageFormatTIFF;
-        case 0x52:
-            // R as RIFF for WEBP
-            if (data.length < 12) {
-                return SDImageFormatUndefined;
+        case 0x52: {
+            if (data.length >= 12) {
+                //RIFF....WEBP
+                NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(0, 12)] encoding:NSASCIIStringEncoding];
+                if ([testString hasPrefix:@"RIFF"] && [testString hasSuffix:@"WEBP"]) {
+                    return SDImageFormatWebP;
+                }
             }
-            
-            NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(0, 12)] encoding:NSASCIIStringEncoding];
-            if ([testString hasPrefix:@"RIFF"] && [testString hasSuffix:@"WEBP"]) {
-                return SDImageFormatWebP;
+            break;
+        }
+        case 0x00: {
+            if (data.length >= 12) {
+                //....ftypheic
+                NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(4, 8)] encoding:NSASCIIStringEncoding];
+                if ([testString isEqualToString:@"ftypheic"]) {
+                    return SDImageFormatHEIC;
+                }
             }
+            break;
+        }
     }
     return SDImageFormatUndefined;
 }
@@ -62,6 +78,12 @@
         case SDImageFormatTIFF:
             UTType = kUTTypeTIFF;
             break;
+        case SDImageFormatWebP:
+            UTType = kSDUTTypeWebP;
+            break;
+        case SDImageFormatHEIC:
+            UTType = kSDUTTypeHEIC;
+            break;
         default:
             // default is kUTTypePNG
             UTType = kUTTypePNG;

SDWebImage/SDWebImageCoder.h

@@ -33,10 +33,12 @@ CG_EXTERN BOOL SDCGImageRefContainsAlpha(_Nullable CGImageRef imageRef);
 
 /**
  This is the image coder protocol to provide custom image decoding/encoding.
+ These methods are all required to implement.
  @note Pay attention that these methods are not called from main queue.
  */
 @protocol SDWebImageCoder <NSObject>
 
+@required
 #pragma mark - Decoding
 /**
  Returns YES if this coder can decode some data. Otherwise, the data should be passed to another coder.
@@ -90,10 +92,12 @@ CG_EXTERN BOOL SDCGImageRefContainsAlpha(_Nullable CGImageRef imageRef);
 
 /**
  This is the image coder protocol to provide custom progressive image decoding.
+ These methods are all required to implement.
  @note Pay attention that these methods are not called from main queue.
  */
 @protocol SDWebImageProgressiveCoder <SDWebImageCoder>
 
+@required
 /**
  Returns YES if this coder can incremental decode some data. Otherwise, it should be passed to another coder.
  

SDWebImage/SDWebImageImageIOCoder.m

@@ -66,8 +66,8 @@ static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to over
 #pragma mark - Decode
 - (BOOL)canDecodeFromData:(nullable NSData *)data {
     switch ([NSData sd_imageFormatForImageData:data]) {
-        // Do not support WebP decoding
         case SDImageFormatWebP:
+            // Do not support WebP decoding
             return NO;
         default:
             return YES;
@@ -76,8 +76,8 @@ static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to over
 
 - (BOOL)canIncrementallyDecodeFromData:(NSData *)data {
     switch ([NSData sd_imageFormatForImageData:data]) {
-        // Support static GIF progressive decoding
         case SDImageFormatWebP:
+            // Do not support WebP progressive decoding
             return NO;
         default:
             return YES;
@@ -394,9 +394,12 @@ static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to over
 #pragma mark - Encode
 - (BOOL)canEncodeToFormat:(SDImageFormat)format {
     switch (format) {
-        // Do not support WebP encoding
         case SDImageFormatWebP:
+            // Do not support WebP encoding
             return NO;
+        case SDImageFormatHEIC:
+            // Check HEIC encoding compatibility
+            return [[self class] canEncodeToHEICFormat];
         default:
             return YES;
     }
@@ -469,6 +472,28 @@ static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to over
     return YES;
 }
 
++ (BOOL)canEncodeToHEICFormat
+{
+    static BOOL canEncode = NO;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        NSMutableData *imageData = [NSMutableData data];
+        CFStringRef imageUTType = [NSData sd_UTTypeFromSDImageFormat:SDImageFormatHEIC];
+        
+        // Create an image destination.
+        CGImageDestinationRef imageDestination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)imageData, imageUTType, 1, NULL);
+        if (!imageDestination) {
+            // Can't encode to HEIC
+            canEncode = NO;
+        } else {
+            // Can encode to HEIC
+            CFRelease(imageDestination);
+            canEncode = YES;
+        }
+    });
+    return canEncode;
+}
+
 #if SD_UIKIT || SD_WATCH
 #pragma mark EXIF orientation tag converter
 + (UIImageOrientation)sd_imageOrientationFromImageData:(nonnull NSData *)imageData {