Half-page scroll actions

zellij-server/src/route.rs

@@ -170,6 +170,18 @@ fn route_action(
                 .send_to_screen(ScreenInstruction::PageScrollDown(client_id))
                 .unwrap();
         }
+        Action::HalfPageScrollUp => {
+            session
+                .senders
+                .send_to_screen(ScreenInstruction::HalfPageScrollUp(client_id))
+                .unwrap();
+        }
+        Action::HalfPageScrollDown => {
+            session
+                .senders
+                .send_to_screen(ScreenInstruction::HalfPageScrollDown(client_id))
+                .unwrap();
+        }
         Action::ToggleFocusFullscreen => {
             session
                 .senders

zellij-server/src/screen.rs

@@ -57,6 +57,8 @@ pub(crate) enum ScreenInstruction {
     ScrollToBottom(ClientId),
     PageScrollUp(ClientId),
     PageScrollDown(ClientId),
+    HalfPageScrollUp(ClientId),
+    HalfPageScrollDown(ClientId),
     ClearScroll(ClientId),
     CloseFocusedPane(ClientId),
     ToggleActiveTerminalFullscreen(ClientId),
@@ -118,6 +120,8 @@ impl From<&ScreenInstruction> for ScreenContext {
             ScreenInstruction::ScrollToBottom(..) => ScreenContext::ScrollToBottom,
             ScreenInstruction::PageScrollUp(..) => ScreenContext::PageScrollUp,
             ScreenInstruction::PageScrollDown(..) => ScreenContext::PageScrollDown,
+            ScreenInstruction::HalfPageScrollUp(..) => ScreenContext::HalfPageScrollUp,
+            ScreenInstruction::HalfPageScrollDown(..) => ScreenContext::HalfPageScrollDown,
             ScreenInstruction::ClearScroll(..) => ScreenContext::ClearScroll,
             ScreenInstruction::CloseFocusedPane(..) => ScreenContext::CloseFocusedPane,
             ScreenInstruction::ToggleActiveTerminalFullscreen(..) => {
@@ -826,6 +830,22 @@ pub(crate) fn screen_thread_main(
 
                 screen.render();
             }
+            ScreenInstruction::HalfPageScrollUp(client_id) => {
+                screen
+                    .get_active_tab_mut(client_id)
+                    .unwrap()
+                    .scroll_active_terminal_up_half_page();
+
+                screen.render();
+            }
+            ScreenInstruction::HalfPageScrollDown(client_id) => {
+                screen
+                    .get_active_tab_mut(client_id)
+                    .unwrap()
+                    .scroll_active_terminal_down_half_page();
+
+                screen.render();
+            }
             ScreenInstruction::ClearScroll(client_id) => {
                 screen
                     .get_active_tab_mut(client_id)

zellij-server/src/tab.rs

@@ -2513,6 +2513,31 @@ impl Tab {
             }
         }
     }
+    pub fn scroll_active_terminal_up_half_page(&mut self) {
+        if let Some(active_terminal_id) = self.get_active_terminal_id() {
+            let active_terminal = self
+                .panes
+                .get_mut(&PaneId::Terminal(active_terminal_id))
+                .unwrap();
+            // prevent overflow when row == 0
+            let scroll_columns = (active_terminal.rows().max(1) - 1)/2;
+            active_terminal.scroll_up(scroll_columns);
+        }
+    }
+    pub fn scroll_active_terminal_down_half_page(&mut self) {
+        if let Some(active_terminal_id) = self.get_active_terminal_id() {
+            let active_terminal = self
+                .panes
+                .get_mut(&PaneId::Terminal(active_terminal_id))
+                .unwrap();
+            // prevent overflow when row == 0
+            let scroll_columns = (active_terminal.rows().max(1) - 1)/2;
+            active_terminal.scroll_down(scroll_columns);
+            if !active_terminal.is_scrolled() {
+                self.process_pending_vte_events(active_terminal_id);
+            }
+        }
+    }
     pub fn scroll_active_terminal_to_bottom(&mut self) {
         if let Some(active_terminal_id) = self.get_active_terminal_id() {
             let active_terminal = self

zellij-utils/assets/config/default.yaml

@@ -253,6 +253,10 @@ keybinds:
           key: [Ctrl: 'f', PageDown, Right, Char: 'l',]
         - action: [PageScrollUp,]
           key: [Ctrl: 'b', PageUp, Left, Char: 'h',]
+        - action: [HalfPageScrollDown,]
+          key: [Char: 'd',]
+        - action: [HalfPageScrollUp,]
+          key: [Char: 'u',]
         - action: [NewPane: ,]
           key: [ Alt: 'n',]
         - action: [MoveFocus: Left,]

zellij-utils/src/errors.rs

@@ -239,6 +239,8 @@ pub enum ScreenContext {
     ScrollToBottom,
     PageScrollUp,
     PageScrollDown,
+    HalfPageScrollUp,
+    HalfPageScrollDown,
     ClearScroll,
     CloseFocusedPane,
     ToggleActiveSyncTab,

zellij-utils/src/input/actions.rs

@@ -56,6 +56,10 @@ pub enum Action {
     PageScrollUp,
     /// Scroll down one page in focus pane.
     PageScrollDown,
+    /// Scroll up half page in focus pane.
+    HalfPageScrollUp,
+    /// Scroll down half page in focus pane.
+    HalfPageScrollDown,
     /// Toggle between fullscreen focus pane and normal layout.
     ToggleFocusFullscreen,
     /// Toggle frames around panes in the UI

zellij-utils/src/input/mod.rs

@@ -48,6 +48,7 @@ pub fn get_mode_info(
         InputMode::Scroll => vec![
             ("↓↑".to_string(), "Scroll".to_string()),
             ("PgUp/PgDn".to_string(), "Scroll Page".to_string()),
+            ("u/d".to_string(), "Scroll Half Page".to_string()),
         ],
         InputMode::RenameTab => vec![("Enter".to_string(), "when done".to_string())],
         InputMode::Session => vec![("d".to_string(), "Detach".to_string())],