performance(rendering): improve rendering performance (#1960)

* refactor(plugins): plugins now need to explicitly ask to be rendered

* performance(render): remove various needless renders

* performance(render): cache boundaries

* performance(render): adjust tests and cache cursor location/shape

* style(comment): remove outdated

* style(fmt): rustfmt

1 files changed, 29 insertions, 3 deletions

diff --git a/default-plugins/strider/src/main.rs b/default-plugins/strider/src/main.rs
index fcac6ec6..6868c670 100644
--- a/default-plugins/strider/src/main.rs
+++ b/default-plugins/strider/src/main.rs
@@ -13,7 +13,8 @@ impl ZellijPlugin for State {
         subscribe(&[EventType::Key, EventType::Mouse]);
     }
 
-    fn update(&mut self, event: Event) {
+    fn update(&mut self, event: Event) -> bool {
+        let mut should_render = false;
         let prev_event = if self.ev_history.len() == 2 {
             self.ev_history.pop_front()
         } else {
@@ -23,13 +24,22 @@ impl ZellijPlugin for State {
         match event {
             Event::Key(key) => match key {
                 Key::Up | Key::Char('k') => {
+                    let currently_selected = self.selected();
                     *self.selected_mut() = self.selected().saturating_sub(1);
+                    if currently_selected != self.selected() {
+                        should_render = true;
+                    }
                 },
                 Key::Down | Key::Char('j') => {
+                    let currently_selected = self.selected();
                     let next = self.selected().saturating_add(1);
                     *self.selected_mut() = min(self.files.len().saturating_sub(1), next);
+                    if currently_selected != self.selected() {
+                        should_render = true;
+                    }
                 },
                 Key::Right | Key::Char('\n') | Key::Char('l') if !self.files.is_empty() => {
+                    should_render = true;
                     self.traverse_dir_or_open_file();
                     self.ev_history.clear();
                 },
@@ -39,11 +49,13 @@ impl ZellijPlugin for State {
                         // the reason this is a hard-coded number (2) and not "== ROOT"
                         // or some such is that there are certain cases in which self.path
                         // is empty and this will work then too
+                        should_render = true;
                         self.path.pop();
                         refresh_directory(self);
                     }
                 },
                 Key::Char('.') => {
+                    should_render = true;
                     self.toggle_hidden_files();
                     refresh_directory(self);
                 },
@@ -52,15 +64,23 @@ impl ZellijPlugin for State {
             },
             Event::Mouse(mouse_event) => match mouse_event {
                 Mouse::ScrollDown(_) => {
+                    let currently_selected = self.selected();
                     let next = self.selected().saturating_add(1);
                     *self.selected_mut() = min(self.files.len().saturating_sub(1), next);
+                    if currently_selected != self.selected() {
+                        should_render = true;
+                    }
                 },
                 Mouse::ScrollUp(_) => {
+                    let currently_selected = self.selected();
                     *self.selected_mut() = self.selected().saturating_sub(1);
+                    if currently_selected != self.selected() {
+                        should_render = true;
+                    }
                 },
                 Mouse::Release(line, _) => {
                     if line < 0 {
-                        return;
+                        return should_render;
                     }
                     let mut should_select = true;
                     if let Some((Event::Mouse(Mouse::Release(prev_line, _)), t)) = prev_event {
@@ -70,10 +90,15 @@ impl ZellijPlugin for State {
                             self.traverse_dir_or_open_file();
                             self.ev_history.clear();
                             should_select = false;
+                            should_render = true;
                         }
                     }
                     if should_select && self.scroll() + (line as usize) < self.files.len() {
+                        let currently_selected = self.selected();
                         *self.selected_mut() = self.scroll() + (line as usize);
+                        if currently_selected != self.selected() {
+                            should_render = true;
+                        }
                     }
                 },
                 _ => {},
@@ -81,7 +106,8 @@ impl ZellijPlugin for State {
             _ => {
                 dbg!("Unknown event {:?}", event);
             },
-        }
+        };
+        should_render
     }
 
     fn render(&mut self, rows: usize, cols: usize) {