imageView: Skip unsupported formats when sliding

If an image with unsupported format is opened directly,
the error is shown.

Closes #92

Part-of: <https://gitlab.gnome.org/Incubator/loupe/-/merge_requests/212>

src/widgets/image.rs

@@ -109,6 +109,7 @@ mod imp {
     pub struct LpImage {
         pub(super) file: RefCell<Option<gio::File>>,
         pub(super) is_deleted: Cell<bool>,
+        pub(super) is_unsupported: Cell<bool>,
         /// Track changes to this image
         pub(super) file_monitor: RefCell<Option<gio::FileMonitor>>,
         pub(super) frame_buffer: Arc<ArcSwap<tiling::FrameBuffer>>,
@@ -200,6 +201,9 @@ mod imp {
                     glib::ParamSpecBoolean::builder("is-loaded")
                         .read_only()
                         .build(),
+                    glib::ParamSpecBoolean::builder("is-unsupported")
+                        .read_only()
+                        .build(),
                     glib::ParamSpecString::builder("error").read_only().build(),
                     glib::ParamSpecObject::builder::<LpImageMetadata>("metadata")
                         .read_only()
@@ -241,6 +245,7 @@ mod imp {
                 "file" => obj.file().to_value(),
                 "is-deleted" => obj.is_deleted().to_value(),
                 "is-loaded" => obj.is_loaded().to_value(),
+                "is-unsupported" => obj.is_unsupported().to_value(),
                 "error" => obj.error().to_value(),
                 "metadata" => obj.metadata().to_value(),
                 "format-name" => obj.format_name().to_value(),
@@ -759,13 +764,7 @@ impl LpImage {
         // Reset background color for reloads
         self.set_background_color(None);
 
-        let (decoder, mut decoder_update) = match Decoder::new(file.clone(), tiles.clone()).await {
-            Ok(x) => x,
-            Err(err) => {
-                self.set_error(err);
-                return;
-            }
-        };
+        let (decoder_res, mut decoder_update) = Decoder::new(file.clone(), tiles.clone()).await;
 
         let weak_obj = self.downgrade();
         spawn(async move {
@@ -777,8 +776,10 @@ impl LpImage {
             log::debug!("Stopped listening to decoder since sender is gone");
         });
 
-        let decoder = Arc::new(decoder);
-        self.imp().decoder.replace(Some(decoder));
+        if let Ok(decoder) = decoder_res {
+            let decoder = Arc::new(decoder);
+            self.imp().decoder.replace(Some(decoder));
+        }
     }
 
     /// Called when decoder sends update
@@ -837,6 +838,12 @@ impl LpImage {
                     imp.tick_callback.replace(Some(callback_id));
                 }
             }
+            DecoderUpdate::UnsupportedFormat => {
+                if !self.is_unsupported() {
+                    imp.is_unsupported.set(true);
+                    self.notify("is-unsupported");
+                }
+            }
         }
     }
 
@@ -874,6 +881,10 @@ impl LpImage {
         self.imp().is_deleted.get()
     }
 
+    pub fn is_unsupported(&self) -> bool {
+        self.imp().is_unsupported.get()
+    }
+
     /// Zoom level that makes the image fit in widget
     ///
     /// During image rotation the image does not actually fit into widget.

src/widgets/image_view.rs

@@ -256,7 +256,7 @@ impl LpImageView {
         if let Some(first) = files.first().cloned() {
             let model = LpFileModel::from_files(files);
             self.set_model(model);
-            let page = LpImagePage::from_file(&first);
+            let page = self.new_image_page(&first);
 
             sliding_view.clear();
             sliding_view.append(&page);
@@ -356,7 +356,7 @@ impl LpImageView {
         let page = if let Some(page) = sliding_view.get(new_file) {
             page
         } else {
-            let page = LpImagePage::from_file(new_file);
+            let page = self.new_image_page(new_file);
 
             if new_index > current_index {
                 sliding_view.append(&page);
@@ -397,7 +397,7 @@ impl LpImageView {
             if let Some(page) = existing.get(&file.uri()) {
                 sliding_view.move_to(page, position);
             } else {
-                sliding_view.insert(&LpImagePage::from_file(file), position);
+                sliding_view.insert(&self.new_image_page(file), position);
             }
         }
 
@@ -438,6 +438,32 @@ impl LpImageView {
         self.imp().model.borrow().clone()
     }
 
+    /// Create new image that communicates updates to file model
+    fn new_image_page(&self, file: &gio::File) -> LpImagePage {
+        let page = LpImagePage::from_file(file);
+
+        page.image().connect_notify_local(
+            Some("is-unsupported"),
+            glib::clone!(@weak self as obj => move |image, _| {
+                if image.is_unsupported() {
+                    if obj.current_image().as_ref() == Some(image) {
+                        log::debug!(
+                            "Image format unsupported but not removing since current image"
+                        );
+                        return;
+                    }
+
+                    if let Some(file) = image.file() {
+                        log::debug!("Removing image with unsupported format {:?}", file.uri());
+                        obj.model().remove(&file);
+                    }
+                }
+            }),
+        );
+
+        page
+    }
+
     fn set_model(&self, model: LpFileModel) {
         model.connect_changed(
             glib::clone!(@weak self as obj => move || obj.model_content_changed_cb()),