Fix loading animated images with a huge number of frames

CHANGELOG.md

@@ -14,6 +14,7 @@
 - (pro) If the `step` argument of the `video_thumbnail_tile` is negative, calculate `step` automatically.
 
 ### Fix
+- Fix loading animated images with a huge number of frames.
 - (pro) Fix `video_thumbnail_tile` option behavior when the video has a single keyframe.
 - (pro) Fix the `trim` argument of the `video_thumbnail_tile` processing option.
 - (pro) Fix `video_thumbnail_tile` behavior when the `step` argument value is less than frame duration.

processing/processing.go

@@ -102,21 +102,19 @@ func transformAnimated(ctx context.Context, img *vips.Image, po *options.Process
 	}
 
 	imgWidth := img.Width()
+	framesCount := imath.Min(img.Pages(), po.SecurityOptions.MaxAnimationFrames)
 
 	frameHeight, err := img.GetInt("page-height")
 	if err != nil {
 		return err
 	}
 
-	framesCount := imath.Min(img.Height()/frameHeight, po.SecurityOptions.MaxAnimationFrames)
-
 	// Double check dimensions because animated image has many frames
 	if err = security.CheckDimensions(imgWidth, frameHeight, framesCount, po.SecurityOptions); err != nil {
 		return err
 	}
 
-	// Vips 8.8+ supports n-pages and doesn't load the whole animated image on header access
-	if nPages, _ := img.GetIntDefault("n-pages", 1); nPages > framesCount {
+	if img.Pages() > framesCount {
 		// Load only the needed frames
 		if err = img.Load(imgdata, 1, 1.0, framesCount); err != nil {
 			return err
@@ -197,7 +195,7 @@ func transformAnimated(ctx context.Context, img *vips.Image, po *options.Process
 	img.SetInt("page-height", frames[0].Height())
 	img.SetIntSlice("delay", delay)
 	img.SetInt("loop", loop)
-	img.SetInt("n-pages", framesCount)
+	img.SetInt("n-pages", img.Height()/frames[0].Height())
 
 	return nil
 }

vips/vips.go

@@ -292,6 +292,14 @@ func (img *Image) Height() int {
 	return int(img.VipsImage.Ysize)
 }
 
+func (img *Image) Pages() int {
+	p, err := img.GetIntDefault("n-pages", 1)
+	if err != nil {
+		return 1
+	}
+	return p
+}
+
 func (img *Image) Load(imgdata *imagedata.ImageData, shrink int, scale float64, pages int) error {
 	if imgdata.Type == imagetype.ICO {
 		return img.loadIco(imgdata.Data, shrink, scale, pages)