webp: Skip invalid frames in iterator

Since the iterator cannot return decoding errors and just stops with an invalid frame, just use the next valid frame instead. That should also be more robust for partially corrupted images.
image-rs · Nov 18, 2023 · ad94efe · ad94efe
1 parent ec857a1
commit ad94efe
Showing 1 changed file with 32 additions and 26 deletions.
diff --git a/src/codecs/webp/extended.rs b/src/codecs/webp/extended.rs
@@ -119,33 +119,39 @@ impl ExtendedImage {
                     first_frame,
                 } = &self.image.image
                 {
-                    let frame = frames.get(self.index);
-                    match frame {
-                        Some(anim_frame_data) => {
-                            let anim_frame;
-                            let frame;
-
-                            if self.index == 0 {
-                                // Use already decoded first frame
-                                anim_frame = first_frame;
-                            } else {
-                                frame = read_anim_frame(
-                                    &mut Cursor::new(anim_frame_data),
-                                    self.image.info.canvas_width,
-                                    self.image.info.canvas_height,
-                                )
-                                .ok()?;
-                                anim_frame = &frame;
-                            };
-
-                            self.index += 1;
-                            ExtendedImage::draw_subimage(
-                                &mut self.canvas,
-                                anim_frame,
-                                anim_info.background_color,
-                            )
+                    // Loop until a valid frame is found to skip invalid frames
+                    loop {
+                        let frame = frames.get(self.index);
+                        match frame {
+                            Some(anim_frame_data) => {
+                                self.index += 1;
+                                let anim_frame;
+                                let frame;
+
+                                if self.index == 1 {
+                                    // Use already decoded first frame
+                                    anim_frame = first_frame;
+                                } else {
+                                    frame = read_anim_frame(
+                                        &mut Cursor::new(anim_frame_data),
+                                        self.image.info.canvas_width,
+                                        self.image.info.canvas_height,
+                                    );
+                                    match &frame {
+                                        Ok(frame) => anim_frame = frame,
+                                        // Try next frame
+                                        Err(_) => continue,
+                                    }
+                                };
+
+                                return ExtendedImage::draw_subimage(
+                                    &mut self.canvas,
+                                    anim_frame,
+                                    anim_info.background_color,
+                                );
+                            }
+                            None => return None,
                         }
-                        None => None,
                     }
                 } else {
                     None