From a1776ff29fa6ddc0721b43a1f7b0d2a1666ef03e Mon Sep 17 00:00:00 2001
From: Dominic Yu <gobbledegook@users.noreply.github.com>
Date: Thu, 18 Jan 2024 14:49:10 -0800
Subject: [PATCH] animated webp support

---
 DYImageView.h     |  1 +
 DYImageView.m     | 43 +++++++++++++++++++++++++++++++++++++++++--
 SlideshowWindow.m | 10 ++++++++++
 3 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/DYImageView.h b/DYImageView.h
index 1aa7f44..6e1c742 100644
--- a/DYImageView.h
+++ b/DYImageView.h
@@ -26,6 +26,7 @@ typedef NS_ENUM(char, DYImageViewZoomMode) {
 
 @interface DYImageView : NSView
 @property (nonatomic) NSImage *image;
+@property (nonatomic) id webpImageSource; // CGImageSourceRef
 @property (nonatomic) int rotation;
 @property (nonatomic) BOOL scalesUp;
 @property (nonatomic) BOOL showActualSize;
diff --git a/DYImageView.m b/DYImageView.m
index 0c15485..4543e2c 100644
--- a/DYImageView.m
+++ b/DYImageView.m
@@ -17,6 +17,7 @@ @implementation DYImageView
 {
 	NSImage *image;
 	NSTimer *gifTimer;
+	NSArray *_webpFrameInfo; int _webpCurrentFrame; NSUInteger _webpFrameCount;
 	int rotation;
 	BOOL scalesUp, showActualSize, isImageFlipped;
 	NSRect sourceRect;
@@ -122,12 +123,28 @@ - (void)drawRect:(NSRect)rect {
 	}
 	NSGraphicsContext *cg = NSGraphicsContext.currentContext;
 	NSImageInterpolation oldInterp = cg.imageInterpolation;
-	cg.imageInterpolation = zoom > 1 ? NSImageInterpolationNone : NSImageInterpolationHigh;
-	[image drawInRect:destinationRect fromRect:srcRect operation:NSCompositingOperationSourceOver fraction:1.0];
+	cg.imageInterpolation = zoom >= 4 ? NSImageInterpolationNone : NSImageInterpolationHigh;
+	NSImage *toDraw = image;
+	if (_webpImageSource) {
+		CGImageRef webpFrame = CGImageSourceCreateImageAtIndex((CGImageSourceRef)_webpImageSource, _webpCurrentFrame, NULL);
+		if (webpFrame) {
+			toDraw = [[NSImage alloc] initWithCGImage:webpFrame size:NSZeroSize];
+			if (!gifTimer || gifTimer.userInfo != _webpImageSource) {
+				float frameDuration = [_webpFrameInfo[_webpCurrentFrame][@"DelayTime"] floatValue];
+				if (frameDuration < .01) frameDuration = .01; // minimum of 10ms is apparently standard
+				gifTimer = [NSTimer scheduledTimerWithTimeInterval:frameDuration target:self selector:@selector(animateWebp:) userInfo:_webpImageSource repeats:NO];
+				gifTimer.tolerance = frameDuration*0.1;
+			}
+		}
+		CFRelease(webpFrame);
+	}
+	[toDraw drawInRect:destinationRect fromRect:srcRect operation:NSCompositingOperationSourceOver fraction:1.0];
 	cg.imageInterpolation = oldInterp;
 	
 	[transform invert];
 	[transform concat];
+
+	if (image != toDraw) return; // animating webp, so no need to check if animating gif
 	id rep = image.representations[0];
 	if ([rep isKindOfClass:[NSBitmapImageRep class]]
 		&& [rep valueForProperty:NSImageFrameCount]) {
@@ -153,9 +170,31 @@ - (void)animateGIF:(NSTimer *)t {
 	[self setNeedsDisplay:YES];
 }
 
+- (void)setWebpImageSource:(id)src {
+	_webpImageSource = nil;
+	CFDictionaryRef props = CGImageSourceCopyProperties((CGImageSourceRef)src, NULL);
+	if (props) {
+		NSArray *frameInfo = ((__bridge NSDictionary *)props)[@"{WebP}"][@"FrameInfo"];
+		if (frameInfo && (_webpFrameCount = frameInfo.count) > 1) {
+			_webpImageSource = src;
+			_webpFrameInfo = frameInfo;
+		}
+		CFRelease(props);
+	}
+}
+
+- (void)animateWebp:(NSTimer *)t {
+	gifTimer = nil;
+	if (_webpImageSource != t.userInfo) return;
+	if (++_webpCurrentFrame == _webpFrameCount) _webpCurrentFrame = 0;
+	[self setNeedsDisplay:YES];
+}
+
 - (void)setImage:(NSImage *)anImage {
 	if (anImage != image) {
 		image = anImage;
+		_webpImageSource = nil;
+		_webpCurrentFrame = 0;
 	}
 	zoomF = 0;
 	rotation = 0;
diff --git a/SlideshowWindow.m b/SlideshowWindow.m
index 74c689c..d76c955 100644
--- a/SlideshowWindow.m
+++ b/SlideshowWindow.m
@@ -596,6 +596,16 @@ - (void)displayImage {
 		
 		if (hideInfoFld) infoFld.hidden = YES; // this must happen before setImage, for redraw purposes
 		imgView.image = img;
+		if ([theFile.pathExtension.lowercaseString isEqualToString:@"webp"]) {
+			// check for animated webp
+			CGImageSourceRef src = CGImageSourceCreateWithURL((__bridge CFURLRef)[NSURL fileURLWithPath:theFile isDirectory:NO], NULL);
+			if (src) {
+				if (CGImageSourceGetCount(src) > 1)
+					imgView.webpImageSource = CFBridgingRelease(src);
+				else
+					CFRelease(src);
+			}
+		}
 		if (r) imgView.rotation = r;
 		if (imgFlipped) imgView.imageFlipped = YES;
 		// ** see keyDown for specifics