Add a small utility converter.

Author: richard-uk1

crates/file/src/file_reader.rs

@@ -142,6 +142,19 @@ pub mod callbacks {
         }
     }
 
+    /// Read the contents of `blob` into a `Vec<u8>`, and then run the callback.
+    ///
+    /// If the returned `FileReader` is dropped before the callback is invoked, the read will be
+    /// cancelled.
+    pub fn read_as_bytes<F>(blob: &Blob, callback: F) -> FileReader
+    where
+        F: FnOnce(Result<Vec<u8>, FileReadError>) + 'static,
+    {
+        read_as_array_buffer(blob, move |result| {
+            callback(result.map(|buffer| js_sys::Uint8Array::new(&buffer).to_vec()));
+        })
+    }
+
     /// Get the event from the reader target, doing necessary casting.
     fn reader_from_event(event: &web_sys::Event) -> web_sys::FileReader {
         let target = event.target().unwrap_throw();
@@ -192,6 +205,15 @@ pub mod futures {
         });
         receiver.await.unwrap_throw()
     }
+
+    /// Read the contents of `blob` into a Vec<u8>.
+    pub async fn read_as_bytes(blob: &Blob) -> Result<Vec<u8>, FileReadError> {
+        let (sender, receiver) = futures_channel::oneshot::channel();
+        let _reader = super::callbacks::read_as_bytes(blob, |result| {
+            sender.send(result).unwrap_throw();
+        });
+        receiver.await.unwrap_throw()
+    }
 }
 
 enum ReadyState {

crates/file/tests/web.rs

@@ -63,6 +63,16 @@ async fn data_url_future() {
     );
 }
 
+#[cfg(feature = "futures")]
+#[wasm_bindgen_test]
+async fn bytes_future() {
+    let blob = Blob::new_with_options(PNG_FILE, Some("image/png"));
+    assert_eq!(
+        gloo_file::futures::read_as_bytes(&blob).await.unwrap(),
+        PNG_FILE
+    );
+}
+
 const PNG_FILE: &'static [u8] = &[
     0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00, 0x0d, 0x49, 0x48, 0x44, 0x52,
     0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x01, 0x03, 0x00, 0x00, 0x00, 0x25, 0xdb, 0x56,