Fix the issue when WebP is static webp, the SDAnimatedImageCoder protocol implementation still create CGContext, this can reduce RAM usage

SDWebImageWebPCoder/Classes/SDImageWebPCoder.m

@@ -711,6 +711,18 @@ - (BOOL)scanAndCheckFramesValidWithDemuxer:(WebPDemuxer *)demuxer {
  uint32_t loopCount = WebPDemuxGetI(demuxer, WEBP_FF_LOOP_COUNT);
  NSMutableArray<SDWebPCoderFrame *> *frames = [NSMutableArray array];
 
+ _hasAnimation = hasAnimation;
+ _hasAlpha = hasAlpha;
+ _canvasWidth = canvasWidth;
+ _canvasHeight = canvasHeight;
+ _frameCount = frameCount;
+ _loopCount = loopCount;
+
+ // If static WebP, does not need to parse the frame blend index
+ if (frameCount <= 1) {
+ return YES;
+ }
+
  // We should loop all the frames and scan each frames' blendFromIndex for later decoding, this can also ensure all frames is valid
  do {
  SDWebPCoderFrame *frame = [[SDWebPCoderFrame alloc] init];
@@ -748,12 +760,6 @@ - (BOOL)scanAndCheckFramesValidWithDemuxer:(WebPDemuxer *)demuxer {
  return NO;
  }
  _frames = [frames copy];
- _hasAnimation = hasAnimation;
- _hasAlpha = hasAlpha;
- _canvasWidth = canvasWidth;
- _canvasHeight = canvasHeight;
- _frameCount = frameCount;
- _loopCount = loopCount;
 
  return YES;
 }
@@ -774,6 +780,9 @@ - (NSTimeInterval)animatedImageDurationAtIndex:(NSUInteger)index {
  if (index >= _frameCount) {
  return 0;
  }
+ if (_frameCount <= 1) {
+ return 0;
+ }
  return _frames[index].duration;
 }
 
@@ -783,11 +792,40 @@ - (UIImage *)animatedImageFrameAtIndex:(NSUInteger)index {
  return nil;
  }
  SD_LOCK(_lock);
- image = [self safeAnimatedImageFrameAtIndex:index];
+ if (_frameCount <= 1) {
+ image = [self safeStaticImageFrame];
+ } else {
+ image = [self safeAnimatedImageFrameAtIndex:index];
+ }
  SD_UNLOCK(_lock);
  return image;
 }
 
+- (UIImage *)safeStaticImageFrame {
+ UIImage *image;
+ if (!_colorSpace) {
+ _colorSpace = [self sd_colorSpaceWithDemuxer:_demux];
+ }
+ // Static WebP image
+ WebPIterator iter;
+ if (!WebPDemuxGetFrame(_demux, 1, &iter)) {
+ WebPDemuxReleaseIterator(&iter);
+ return nil;
+ }
+ CGImageRef imageRef = [self sd_createWebpImageWithData:iter.fragment colorSpace:_colorSpace];
+ if (!imageRef) {
+ return nil;
+ }
+#if SD_UIKIT || SD_WATCH
+ image = [[UIImage alloc] initWithCGImage:imageRef scale:_scale orientation:UIImageOrientationUp];
+#else
+ image = [[UIImage alloc] initWithCGImage:imageRef scale:_scale orientation:kCGImagePropertyOrientationUp];
+#endif
+ CGImageRelease(imageRef);
+ WebPDemuxReleaseIterator(&iter);
+ return image;
+}
+
 - (UIImage *)safeAnimatedImageFrameAtIndex:(NSUInteger)index {
  if (!_canvas) {
  CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Host;

SDWebImageWebPCoderTests/SDWebImageWebPCoderTests.m

@@ -10,6 +10,7 @@
 @import XCTest;
 #import <SDWebImage/SDWebImage.h>
 #import <SDWebImageWebPCoder/SDWebImageWebPCoder.h>
+#import <objc/runtime.h>
 
 const int64_t kAsyncTestTimeout = 5;
 
@@ -172,6 +173,18 @@ - (void)test33AnimatedImageBlendMethod {
  }
 }
 
+- (void)test34StaticImageNotCreateCGContext {
+ NSURL *staticWebPURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"TestImageStatic" withExtension:@"webp"];
+ NSData *data = [NSData dataWithContentsOfURL:staticWebPURL];
+ SDImageWebPCoder *coder = [[SDImageWebPCoder alloc] initWithAnimatedImageData:data options:nil];
+ XCTAssertTrue(coder.animatedImageFrameCount == 1);
+ UIImage *image = [coder animatedImageFrameAtIndex:0];
+ XCTAssertNotNil(image);
+ Ivar ivar = class_getInstanceVariable(coder.class, "_canvas");
+ CGContextRef canvas = ((CGContextRef (*)(id, Ivar))object_getIvar)(coder, ivar);
+ XCTAssert(canvas == NULL);
+}
+
 @end
 
 @implementation SDWebImageWebPCoderTests (Helpers)