Support to encode as new PDF with bitmap image

Example/SDWebImagePDFCoder-Example-macOS/ViewController.m

@@ -40,7 +40,7 @@ - (void)viewDidLoad {
             NSAssert(pdfData.length > 0, @"PDF Data export failed");
         }
     }];
-    [imageView2 sd_setImageWithURL:pdfURL2 placeholderImage:nil options:SDWebImageRetryFailed context:@{SDWebImageContextPDFImageSize : @(imageView2.bounds.size)} progress:nil completed:^(UIImage * _Nullable image, NSError * _Nullable error, SDImageCacheType cacheType, NSURL * _Nullable imageURL) {
+    [imageView2 sd_setImageWithURL:pdfURL2 placeholderImage:nil options:SDWebImageRetryFailed context:@{SDWebImageContextImageThumbnailPixelSize : @(imageView2.bounds.size)} progress:nil completed:^(UIImage * _Nullable image, NSError * _Nullable error, SDImageCacheType cacheType, NSURL * _Nullable imageURL) {
         if (image) {
             NSLog(@"PDF load animation success");
             [NSAnimationContext runAnimationGroup:^(NSAnimationContext * _Nonnull context) {

README.md

@@ -22,7 +22,7 @@ You can modify the code or use some other PDF files to check the compatibility.
 + tvOS 9+
 + macOS 10.11+
 + watchOS 2+
-+ Xcode 11+
++ Xcode 13+
 
 ## Installation
 
@@ -50,7 +50,7 @@ SDWebImagePDFCoder is available through [Swift Package Manager](https://swift.or
 ```swift
 let package = Package(
     dependencies: [
-        .package(url: "https://github.com/SDWebImage/SDWebImagePDFCoder.git", from: "0.6")
+        .package(url: "https://github.com/SDWebImage/SDWebImagePDFCoder.git", from: "1.0")
     ]
 )
 ```
@@ -115,24 +115,21 @@ imageView.sd_setImage(with: url, placeholderImage: nil, options: [], context: [.
 
 `SDWebImagePDFCoder` provide an easy way to export the PDF image generated from framework, to the original PDF data.
 
-Note: For firmware which is below iOS/tvOS 11+, UIImage does not support PDF vector image as well as exporting. The bitmap form of PDF does not support PDF data export as well.
+If the input image is already vector PDF based, will export that instead (fast).
+Else we will create an empty PDF page with the bitmap image drawn on (slow).
 
 + Objective-C
 
 ```objectivec
 UIImage *pdfImage; // UIImage with vector image, or NSImage contains `NSPDFImageRep`
-if (pdfImage.sd_isVector) { // This API available in SDWebImage 5.6.0
-    NSData *pdfData = [pdfImage sd_imageDataAsFormat:SDImageFormatPDF];
-}
+NSData *pdfData = [pdfImage sd_imageDataAsFormat:SDImageFormatPDF]; // May return the vector data, or create new PDF with current image drawn on
 ```
 
 + Swift
 
 ```swift
 let pdfImage: UIImage // UIImage with vector image, or NSImage contains `NSPDFImageRep`
-if pdfImage.sd_isVector { // This API available in SDWebImage 5.6.0
-    let pdfData = pdfImage.sd_imageData(as: .PDF)
-}
+let pdfData = pdfImage.sd_imageData(as: .PDF) // May return the vector data, or create new PDF with current image drawn on
 ```
 
 ## Screenshot

SDWebImagePDFCoder/Classes/SDImagePDFCoder.m

@@ -62,7 +62,7 @@ - (UIImage *)decodedImageWithData:(NSData *)data options:(SDImageCoderOptions *)
     BOOL prefersBitmap = NO;
     CGSize imageSize = CGSizeZero;
     BOOL preserveAspectRatio = YES;
-
+    
     // Parse args
     if (options[SDImageCoderDecodePDFPageNumber]) {
         pageNumber = [options[SDImageCoderDecodePDFPageNumber] unsignedIntegerValue];
@@ -101,20 +101,20 @@ - (BOOL)canEncodeToFormat:(SDImageFormat)format {
 
 - (NSData *)encodedDataWithImage:(UIImage *)image format:(SDImageFormat)format options:(SDImageCoderOptions *)options {
     if (![self.class supportsVectorPDFImage]) {
-        return nil;
+        return [self.class createPDFDataWithBitmapImage:image];
     }
 #if SD_MAC
     // Pixel size use `NSImageRepMatchesDevice` to avoid CGImage bitmap format
     NSRect imageRect = NSMakeRect(0, 0, NSImageRepMatchesDevice, NSImageRepMatchesDevice);
     NSImageRep *imageRep = [image bestRepresentationForRect:imageRect context:nil hints:nil];
     if (![imageRep isKindOfClass:NSPDFImageRep.class]) {
-        return nil;
+        return [self.class createPDFDataWithBitmapImage:image];
     }
     return ((NSPDFImageRep *)imageRep).PDFRepresentation;
 #else
     CGPDFPageRef page = ((CGPDFPageRef (*)(id,SEL))[image methodForSelector:SDCGPDFPageSEL])(image, SDCGPDFPageSEL);
     if (!page) {
-        return nil;
+        return [self.class createPDFDataWithBitmapImage:image];
     }
 
     // Draw the PDF page using PDFContextToData
@@ -175,6 +175,26 @@ - (UIImage *)createVectorPDFWithData:(nonnull NSData *)data pageNumber:(NSUInteg
     return image;
 }
 
+#pragma mark - Bitmap PDF creation
++ (NSData *)createPDFDataWithBitmapImage:(UIImage *)image {
+    CGImageRef imageRef = image.CGImage;
+    if (!imageRef) {
+        return nil;
+    }
+    NSMutableData *pdfData = [NSMutableData data];
+    CGDataConsumerRef pdfConsumer = CGDataConsumerCreateWithCFData((__bridge CFMutableDataRef)pdfData);
+
+    CGSize imageSize = CGSizeMake(CGImageGetWidth(imageRef), CGImageGetHeight(imageRef));
+    CGRect mediaBox = CGRectMake(0, 0, imageSize.width, imageSize.height);
+    CGContextRef context = CGPDFContextCreate(pdfConsumer, &mediaBox, NULL);
+
+    CGContextBeginPage(context, &mediaBox);
+    CGContextDrawImage(context, mediaBox, imageRef);
+    CGContextEndPage(context);
+
+    return [pdfData copy];
+}
+
 + (BOOL)supportsVectorPDFImage {
 #if SD_MAC
     // macOS's `NSImage` supports PDF built-in rendering