Can read image from memory

src/lib.rs

@@ -6,6 +6,7 @@
 use std::path::Path;
 
 use anyhow::anyhow;
+use image::DynamicImage;
 
 /// Embed the image from `image_filename` into `music_filename`, in-place. Any errors reading ID3
 /// tags from the music file or parsing the image get propagated upwards.
@@ -14,10 +15,21 @@ use anyhow::anyhow;
 /// Tags get written as ID3v2.3.
 ///
 pub fn embed_image(music_filename: &Path, image_filename: &Path) -> anyhow::Result<()> {
-    let mut tag = read_tag(music_filename)?;
     let image = image::open(&image_filename).
         map_err(|e| anyhow!("Error reading image {:?}: {}", image_filename, e))?;
 
+    embed_image_from_memory(music_filename, &image)
+}
+
+/// Embed the image `image` into `music_filename`, in-place. Any errors reading ID3
+/// tags from the music file get propagated upwards.
+///
+/// The image is encoded as a JPEG with a 90% quality setting, and embedded as a "Front cover".
+/// Tags get written as ID3v2.3.
+///
+pub fn embed_image_from_memory(music_filename: &Path, image: &image::DynamicImage) -> anyhow::Result<()> {
+    let mut tag = read_tag(music_filename)?;
+
     let mut encoded_image_bytes = Vec::new();
     // Unwrap: Writing to a Vec should always succeed;
     image.write_to(&mut encoded_image_bytes, image::ImageOutputFormat::Jpeg(90)).unwrap();
@@ -42,19 +54,23 @@ pub fn embed_image(music_filename: &Path, image_filename: &Path) -> anyhow::Resu
 /// there's no embedded images in the mp3 file.
 ///
 pub fn extract_first_image(music_filename: &Path, image_filename: &Path) -> anyhow::Result<()> {
+    extract_first_image_as_img(music_filename)?
+        .save(&image_filename).
+        map_err(|e| anyhow!("Couldn't write image file {:?}: {}", image_filename, e))
+}
+
+/// Extract the first found embedded image from `music_filename` and return it as image object
+///
+/// Any errors from parsing id3 tags will be propagated. The function will also return an error if
+/// there's no embedded images in the mp3 file.
+///
+pub fn extract_first_image_as_img(music_filename: &Path) -> anyhow::Result<DynamicImage> {
     let tag = read_tag(music_filename)?;
     let first_picture = tag.pictures().next();
 
     if let Some(p) = first_picture {
-        match image::load_from_memory(&p.data) {
-            Ok(image) => {
-                image.save(&image_filename).
-                    map_err(|e| anyhow!("Couldn't write image file {:?}: {}", image_filename, e))?;
-            },
-            Err(e) => return Err(anyhow!("Couldn't load image: {}", e)),
-        };
-
-        Ok(())
+        return image::load_from_memory(&p.data)
+            .map_err(|e| anyhow!("Couldn't load image: {}", e));
     } else {
         Err(anyhow!("No image found in music file"))
     }