fix: Don't return inputBuf if input is of type PDF (#377)

CHANGELOG.md

@@ -5,7 +5,7 @@
 - Breaking: Go version 1.17 is now the minimum required version to build this. (#292)
 - Breaking: Thumbnail generation now requires libvips. See [docs/build.md](./docs/build.md) for prerequisite instructions. (#366, #369)
 - Breaking: Resolver caches are now stored in PostgreSQL. See [docs/build.md](./docs/build.md) for prerequisite instructions. (#271)
-- PDF: Generate customized tooltips for PDF files. (#374)
+- PDF: Generate customized tooltips for PDF files. (#374, #377)
 - Twitter: Generate thumbnails with all images of a tweet. (#373)
 - YouTube: Added support for 'YouTube shorts' URLs. (#299)
 - Fix: SevenTV emotes now resolve correctly. (#281, #288, #307)

pkg/thumbnail/thumbnail.go

@@ -47,21 +47,22 @@ func Shutdown() {
 func BuildStaticThumbnail(inputBuf []byte, resp *http.Response) ([]byte, error) {
 	image, err := vips.NewImageFromBuffer(inputBuf)
 
+	if err != nil {
+		return []byte{}, fmt.Errorf("could not load image from url: %s", resp.Request.URL)
+	}
+
 	// govips has the height & width values in int, which means we're converting uint to int.
 	maxThumbnailSize := int(cfg.MaxThumbnailSize)
+	format := image.Format()
 
 	// Only resize if the original image has bigger dimensions than maxThumbnailSize
-	if image.Width() <= maxThumbnailSize && image.Height() <= maxThumbnailSize {
+	if image.Width() <= maxThumbnailSize && image.Height() <= maxThumbnailSize && format != vips.ImageTypePDF {
 		// We don't need to resize image nor does it need to be passed through govips.
 		return inputBuf, nil
 	}
 
 	importParams := vips.NewImportParams()
 
-	if err != nil {
-		return []byte{}, fmt.Errorf("could not load image from url: %s", resp.Request.URL)
-	}
-
 	image, err = vips.LoadThumbnailFromBuffer(inputBuf, maxThumbnailSize, maxThumbnailSize, vips.InterestingNone, vips.SizeDown, importParams)
 
 	if err != nil {
@@ -70,7 +71,7 @@ func BuildStaticThumbnail(inputBuf []byte, resp *http.Response) ([]byte, error)
 	}
 
 	var outputBuf []byte
-	if image.Format() == vips.ImageTypePDF {
+	if format == vips.ImageTypePDF {
 		// Export thumbnails for PDF as PNG
 		outputBuf, _, err = image.ExportPng(vips.NewPngExportParams())
 	} else {