fix(tray): vastly improve rendering performance

src/modules/tray/diff.rs

@@ -0,0 +1,104 @@
+use system_tray::message::menu::{MenuItem as MenuItemInfo, ToggleState};
+
+/// Diff change type and associated info.
+#[derive(Debug, Clone)]
+pub enum Diff {
+    Add(MenuItemInfo),
+    Update(i32, MenuItemDiff),
+    Remove(i32),
+}
+
+/// Diff info to be applied to an existing menu item as an update.
+#[derive(Debug, Clone)]
+pub struct MenuItemDiff {
+    /// Text of the item,
+    pub label: Option<String>,
+    /// Whether the item can be activated or not.
+    pub enabled: Option<bool>,
+    /// True if the item is visible in the menu.
+    pub visible: Option<bool>,
+    /// Icon name of the item, following the freedesktop.org icon spec.
+    // pub icon_name: Option<Option<String>>,
+    /// Describe the current state of a "togglable" item. Can be one of:
+    ///   - Some(true): on
+    ///   - Some(false): off
+    ///   - None: indeterminate
+    pub toggle_state: Option<ToggleState>,
+    /// A submenu for this item, typically this would ve revealed to the user by hovering the current item
+    pub submenu: Vec<Diff>,
+}
+
+impl MenuItemDiff {
+    fn new(old: &MenuItemInfo, new: &MenuItemInfo) -> Self {
+        macro_rules! diff {
+            ($field:ident) => {
+                if old.$field == new.$field {
+                    None
+                } else {
+                    Some(new.$field)
+                }
+            };
+
+            (&$field:ident) => {
+                if &old.$field == &new.$field {
+                    None
+                } else {
+                    Some(new.$field.clone())
+                }
+            };
+        }
+
+        Self {
+            label: diff!(&label),
+            enabled: diff!(enabled),
+            visible: diff!(visible),
+            // icon_name: diff!(&icon_name),
+            toggle_state: diff!(toggle_state),
+            submenu: get_diffs(&old.submenu, &new.submenu),
+        }
+    }
+
+    /// Whether this diff contains any changes
+    fn has_diff(&self) -> bool {
+        self.label.is_some()
+            || self.enabled.is_some()
+            || self.visible.is_some()
+            // || self.icon_name.is_some()
+            || self.toggle_state.is_some()
+            || !self.submenu.is_empty()
+    }
+}
+
+/// Gets a diff set between old and new state.
+pub fn get_diffs(old: &[MenuItemInfo], new: &[MenuItemInfo]) -> Vec<Diff> {
+    let mut diffs = vec![];
+
+    for new_item in new {
+        let old_item = old.iter().find(|&item| item.id == new_item.id);
+
+        let diff = match old_item {
+            Some(old_item) => {
+                let item_diff = MenuItemDiff::new(old_item, new_item);
+                if item_diff.has_diff() {
+                    Some(Diff::Update(old_item.id, item_diff))
+                } else {
+                    None
+                }
+            }
+            None => Some(Diff::Add(new_item.clone())),
+        };
+
+        if let Some(diff) = diff {
+            diffs.push(diff);
+        }
+    }
+
+    for old_item in old {
+        let new_item = new.iter().find(|&item| item.id == old_item.id);
+        if new_item.is_none() {
+            diffs.push(Diff::Remove(old_item.id));
+        }
+    }
+
+    diffs
+}