recode animated webp avatars

Reencoding animated WebPs into JPEG loses all frames except the first one.

src/blob.rs

@@ -350,7 +350,24 @@ impl<'a> BlobObject<'a> {
                 *vt = Viewtype::Image;
                 return Ok(name);
             }
-            let mut img = imgreader.decode().context("image decode failure")?;
+
+            let mut img = match fmt {
+                image::ImageFormat::WebP => {
+                    // `with_guessed_format()` restores file position,
+                    // so `buf_reader` is at the beginning of the file.
+                    let buf_reader = imgreader.into_inner();
+                    let webp_decoder = image::codecs::webp::WebPDecoder::new(buf_reader)
+                        .context("Failed to create WebP decoder")?;
+
+                    // If WebP has animation, do not try to recode it.
+                    // Recoding into JPEG will result in losing the animation.
+                    if !is_avatar && webp_decoder.has_animation() {
+                        return Ok(name);
+                    }
+                    DynamicImage::from_decoder(webp_decoder)?
+                }
+                _ => imgreader.decode().context("Failed to decode image")?,
+            };
             let orientation = exif
                 .as_ref()
                 .map(|exif| exif_orientation(exif, context))

src/blob/blob_tests.rs

@@ -4,7 +4,9 @@ use super::*;
 use crate::message::{Message, Viewtype};
 use crate::param::Param;
 use crate::sql;
-use crate::test_utils::{self, AVATAR_64x64_BYTES, AVATAR_64x64_DEDUPLICATED, TestContext};
+use crate::test_utils::{
+    self, AVATAR_64x64_BYTES, AVATAR_64x64_DEDUPLICATED, TestContext, TestContextManager,
+};
 use crate::tools::SystemTime;
 
 fn check_image_size(path: impl AsRef<Path>, width: u32, height: u32) -> image::DynamicImage {
@@ -738,6 +740,66 @@ async fn test_send_gif_as_sticker() -> Result<()> {
     Ok(())
 }
 
+/// Tests that animated WebP is sent without reencoding.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_send_animated_webp_as_image() -> Result<()> {
+    let bytes = include_bytes!("../../test-data/image/animated.webp");
+    let (width, height) = (1280u32, 531u32);
+    let mut tcm = TestContextManager::new();
+    let alice = &tcm.alice().await;
+    let bob = &tcm.bob().await;
+    alice
+        .set_config(
+            Config::MediaQuality,
+            Some(&(MediaQuality::Worse as i32).to_string()),
+        )
+        .await?;
+    let file = alice.get_blobdir().join("file").with_extension("gif");
+    fs::write(&file, &bytes)
+        .await
+        .context("Failed to write file")?;
+    let mut msg = Message::new(Viewtype::Image);
+    msg.set_file_and_deduplicate(alice, &file, Some("file.webp"), None)?;
+
+    let chat = alice.create_chat(bob).await;
+    let sent = alice.send_msg(chat.id, &mut msg).await;
+    let bob_msg = bob.recv_msg(&sent).await;
+    assert_eq!(bob_msg.get_viewtype(), Viewtype::Image);
+    assert_eq!(bob_msg.get_width() as u32, width);
+    assert_eq!(bob_msg.get_height() as u32, height);
+    assert_eq!(
+        bob_msg.get_filebytes(bob).await?.unwrap(),
+        bytes.len() as u64
+    );
+    Ok(())
+}
+
+/// Tests that if user sets animated WebP as an avatar, it may be recoded.
+///
+/// We don't want to recode animated WebPs into JPEG and lose animation,
+/// but for avatars we don't want animation and transparency anyway.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_recode_animated_webp_avatar() -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let t = &tcm.alice().await;
+
+    let avatar_src = t.dir.path().join("avatar.webp");
+    let avatar_bytes = include_bytes!("../../test-data/image/animated.webp");
+    fs::write(&avatar_src, avatar_bytes).await.unwrap();
+
+    t.set_config(Config::Selfavatar, Some(avatar_src.to_str().unwrap()))
+        .await?;
+    let avatar_blob = t.get_config(Config::Selfavatar).await?.unwrap();
+    assert!(avatar_blob.ends_with(".jpg"));
+
+    let scaled_avatar_size = fs::metadata(&avatar_blob).await.unwrap().len();
+    assert!(
+        scaled_avatar_size < avatar_bytes.len() as u64,
+        "Animated WebP avatar must be recoded"
+    );
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn test_create_and_deduplicate() -> Result<()> {
     let t = TestContext::new().await;