refactor: map only used keybinds in subscription

this should improve efficiency

this is also largely motivated by all the `path.clone()` calls in view,
which concern me a lot.

reducing the number of used subscriptions should trigger view less,
but it's very far from a perfect solution

src/app/mod.rs

@@ -33,9 +33,20 @@ enum Message {
 
     OpenImage(PathBuf),
 
+    PickPath,
     OpenPath(Option<PathBuf>),
 
-    KeyPressed(keyboard::Key, keyboard::Modifiers),
+    FocusNext,
+    FocusPrevious,
+
+    ScrollBy(f32),
+
+    CycleFilter,
+
+    IncreaseColumns,
+    DecreaseColumns,
+
+    Quit,
 }
 
 #[derive(Default)]
@@ -129,67 +140,36 @@ impl State {
                 }
             }
 
-            Message::KeyPressed(key, modifiers) => match key.as_ref() {
+            Message::FocusNext => return widget::operation::focus_next(),
-                // input field cycling
+            Message::FocusPrevious => return widget::operation::focus_next(),
-                keyboard::Key::Named(keyboard::key::Named::Tab) => {
-                    return if modifiers.shift() {
-                        widget::operation::focus_previous()
-                    } else {
-                        widget::operation::focus_next()
-                    };
-                }
 
-                keyboard::Key::Character("o") => {
+            Message::PickPath => {
                 return Task::perform(
                     async { AsyncFileDialog::new().pick_folder().await.map(Into::into) },
                     Message::OpenPath,
                 );
             }
 
-                keyboard::Key::Character("j")
+            Message::ScrollBy(offset) => {
-                | keyboard::Key::Named(
-                    keyboard::key::Named::ArrowDown | keyboard::key::Named::PageDown,
-                ) => {
                 return widget::operation::scroll_by(
                     "main",
-                        widget::operation::AbsoluteOffset {
+                    widget::operation::AbsoluteOffset { x: 0., y: offset },
-                            x: 0.,
-                            y: if modifiers.shift() { 500. } else { 100. },
-                        },
-                    );
-                }
-                keyboard::Key::Character("k")
-                | keyboard::Key::Named(
-                    keyboard::key::Named::ArrowUp | keyboard::key::Named::PageUp,
-                ) => {
-                    return widget::operation::scroll_by(
-                        "main",
-                        widget::operation::AbsoluteOffset {
-                            x: 0.,
-                            y: if modifiers.shift() { -500. } else { -100. },
-                        },
                 );
             }
 
-                keyboard::Key::Character("=" | "+") => {
+            Message::IncreaseColumns => self.columns = (self.columns + 1).clamp(1, 10),
-                    self.columns = (self.columns + 1).clamp(1, 10)
+            Message::DecreaseColumns => self.columns = (self.columns - 1).clamp(1, 10),
-                }
-                keyboard::Key::Character("-" | "_") => {
-                    self.columns = (self.columns - 1).clamp(1, 10)
-                }
 
-                keyboard::Key::Character("f") => {
+            Message::CycleFilter => {
                 self.filter = match self.filter {
                     widget::image::FilterMethod::Linear => widget::image::FilterMethod::Nearest,
                     widget::image::FilterMethod::Nearest => widget::image::FilterMethod::Linear,
                 }
             }
 
-                keyboard::Key::Character("q") => {
+            Message::Quit => {
                 return window::latest().and_then(window::close);
             }
-                _ => {}
-            },
         }
 
         Task::none()
@@ -240,7 +220,40 @@ impl State {
     fn subscription(&self) -> Subscription<Message> {
         event::listen().filter_map(|event| match event {
             Event::Keyboard(keyboard::Event::KeyPressed { key, modifiers, .. }) => {
-                Some(Message::KeyPressed(key, modifiers))
+                match key.as_ref() {
+                    // input field cycling
+                    keyboard::Key::Named(keyboard::key::Named::Tab) => Some(if modifiers.shift() {
+                        Message::FocusPrevious
+                    } else {
+                        Message::FocusNext
+                    }),
+
+                    keyboard::Key::Character("o") => Some(Message::PickPath),
+
+                    keyboard::Key::Character("j")
+                    | keyboard::Key::Named(
+                        keyboard::key::Named::ArrowDown | keyboard::key::Named::PageDown,
+                    ) => Some(Message::ScrollBy(match modifiers.shift() {
+                        false => 100.,
+                        true => 500.,
+                    })),
+                    keyboard::Key::Character("k")
+                    | keyboard::Key::Named(
+                        keyboard::key::Named::ArrowUp | keyboard::key::Named::PageUp,
+                    ) => Some(Message::ScrollBy(match modifiers.shift() {
+                        false => -100.,
+                        true => -500.,
+                    })),
+
+                    keyboard::Key::Character("=" | "+") => Some(Message::IncreaseColumns),
+                    keyboard::Key::Character("-" | "_") => Some(Message::DecreaseColumns),
+
+                    keyboard::Key::Character("f") => Some(Message::CycleFilter),
+
+                    keyboard::Key::Character("q") => Some(Message::Quit),
+
+                    _ => None,
+                }
             }
             _ => None,
         })