editing: Decide editable based on true mime type

Previously it was decided on the early unreliable mime type.

Fixes #449

news.d/48.rc/fixed-editable-based-on-reliable-mime-type

@@ -0,0 +1 @@
+Decide if an image has a format that supports editing based on the reliable mime-type. That way a wrong file extension will not impact the detection of the format being editable.

src/metadata.rs

@@ -105,17 +105,28 @@ impl Metadata {
     }
 
     pub fn mime_type(&self) -> Option<String> {
-        self.file_info
-            .as_ref()
-            .and_then(|x| x.mime_type.as_ref())
-            .map(|x| x.to_string())
+        self.mime_type.clone()
+    }
+
+    /// Unreliable mime type
+    ///
+    /// Before the image is successfully loaded, this mime type might be wrong
+    /// since it is not yet based on the more complex mime type detection used
+    /// by glyin.
+    pub fn unreliable_mime_type(&self) -> Option<String> {
+        self.mime_type().or_else(|| {
+            self.file_info
+                .as_ref()
+                .and_then(|x| x.mime_type.as_ref())
+                .map(|x| x.to_string())
+        })
     }
 
     pub fn format_name(&self) -> Option<String> {
         self.image_info
             .as_ref()
             .and_then(|x| x.format_name.clone())
-            .or_else(|| self.mime_type())
+            .or_else(|| self.unreliable_mime_type())
     }
 
     pub fn alpha_channel(&self) -> Option<bool> {

src/widgets/image/loading.rs

@@ -34,14 +34,14 @@ impl imp::LpImage {
     /// Set filename after filename changed
     async fn set_file_changed(&self, file: &gio::File) {
         let obj = self.obj();
-        let prev_mime_type = obj.metadata().mime_type();
+        let prev_mime_type = obj.metadata().unreliable_mime_type();
 
         self.file.replace(Some(file.clone()));
         self.reload_file_info().await;
 
         // Reload if mime type changed since other decoding path might be responsible
         // now
-        if obj.metadata().mime_type() != prev_mime_type {
+        if obj.metadata().unreliable_mime_type() != prev_mime_type {
             obj.load(file).await;
             return;
         }
@@ -80,6 +80,11 @@ impl imp::LpImage {
                 self.emmit_metadata_changed();
 
                 obj.reset_rotation();
+                glib::spawn_future_local(glib::clone!(
+                    #[weak(rename_to=obj)]
+                    self,
+                    async move { obj.check_editable().await },
+                ));
             }
             DecoderUpdate::Dimensions => {
                 log::debug!("Received dimensions: {:?}", self.untransformed_dimensions());
@@ -360,8 +365,12 @@ impl LpImage {
         // Reset background color for reloads
         imp.set_background_color(None);
 
-        let (decoder, decoder_update) =
-            Decoder::new(file.clone(), self.metadata().mime_type(), tiles.clone()).await;
+        let (decoder, decoder_update) = Decoder::new(
+            file.clone(),
+            self.metadata().unreliable_mime_type(),
+            tiles.clone(),
+        )
+        .await;
 
         let weak_obj = self.downgrade();
         glib::spawn_future_local(async move {
@@ -374,7 +383,5 @@ impl LpImage {
         });
 
         imp.decoder.replace(Some(Arc::new(decoder)));
-
-        imp.check_editable().await;
     }
 }

src/widgets/image_page.rs

@@ -231,7 +231,7 @@ impl LpImagePage {
             imp.stack.set_visible_child(&*imp.error_page);
             imp.error_more_info.set_visible(false);
         } else if image.specific_error() == DecoderError::UnsupportedFormat {
-            let mime_type = image.metadata().mime_type().unwrap_or_default();
+            let mime_type = image.metadata().unreliable_mime_type().unwrap_or_default();
             let content_type = gio::content_type_from_mime_type(&mime_type).unwrap_or_default();
             let description = gio::content_type_get_description(&content_type).to_string();