move exif_metadata to Decoder trait - way better user API this way

src/codecs/jpeg/decoder.rs

@@ -52,14 +52,6 @@ impl<R: BufRead + Seek> JpegDecoder<R> {
             phantom: PhantomData,
         })
     }
-
-    /// Returns the raw [Exif](https://en.wikipedia.org/wiki/Exif) chunk, if it is present.
-    /// A third-party crate such as [`kamadak-exif`](https://docs.rs/kamadak-exif/) is required to actually parse it.
-    pub fn exif_metadata(&mut self) -> ImageResult<Option<Vec<u8>>> {
-        let mut decoder = zune_jpeg::JpegDecoder::new(&self.input);
-        decoder.decode_headers().map_err(ImageError::from_jpeg)?;
-        Ok(decoder.exif().cloned())
-    }
 }
 
 impl<R: BufRead + Seek> ImageDecoder for JpegDecoder<R> {
@@ -108,6 +100,12 @@ impl<R: BufRead + Seek> ImageDecoder for JpegDecoder<R> {
     fn read_image_boxed(self: Box<Self>, buf: &mut [u8]) -> ImageResult<()> {
         (*self).read_image(buf)
     }
+
+    fn exif_metadata(&mut self) -> ImageResult<Option<Vec<u8>>> {
+        let mut decoder = zune_jpeg::JpegDecoder::new(&self.input);
+        decoder.decode_headers().map_err(ImageError::from_jpeg)?;
+        Ok(decoder.exif().cloned())
+    }
 }
 
 impl ColorType {

src/image.rs

@@ -628,6 +628,14 @@ pub trait ImageDecoder {
         Ok(None)
     }
 
+    /// Returns the raw [Exif](https://en.wikipedia.org/wiki/Exif) chunk, if it is present.
+    /// A third-party crate such as [`kamadak-exif`](https://docs.rs/kamadak-exif/) is required to actually parse it.
+    ///
+    /// For formats that don't support embedded profiles this function should always return `Ok(None)`.
+    fn exif_metadata(&mut self) -> ImageResult<Option<Vec<u8>>> {
+        Ok(None)
+    }
+
     /// Returns the total number of bytes in the decoded image.
     ///
     /// This is the size of the buffer that must be passed to `read_image` or