fix missing paging support in branch list (#539)

closes #519

Author: Stephan Dilly

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ![push](assets/char_count.gif)
 
 ### Fixed
+- support missing pageUp/down support in branchlist ([#519](https://github.com/extrawurst/gitui/issues/519))
 - don't hide branch name while in commit dialog ([#529](https://github.com/extrawurst/gitui/issues/529))
 - don't discard commit message without confirmation ([#530](https://github.com/extrawurst/gitui/issues/530))
 - compilation broken on freebsd ([#461](https://github.com/extrawurst/gitui/issues/461))

src/components/select_branch.rs

@@ -16,7 +16,10 @@ use asyncgit::{
     CWD,
 };
 use crossterm::event::Event;
-use std::{cell::Cell, convert::TryInto};
+use std::{
+    cell::Cell,
+    convert::{TryFrom, TryInto},
+};
 use tui::{
     backend::Backend,
     layout::{Alignment, Rect},
@@ -35,6 +38,7 @@ pub struct SelectBranchComponent {
     visible: bool,
     selection: u16,
     scroll_top: Cell<usize>,
+    current_height: Cell<u16>,
     queue: Queue,
     theme: SharedTheme,
     key_config: SharedKeyConfig,
@@ -92,6 +96,8 @@ impl DrawableComponent for SelectBranchComponent {
                 self.branch_names.len(),
                 self.scroll_top.get(),
             );
+
+            self.current_height.set(u16::try_from(height_in_lines)?);
         }
 
         Ok(())
@@ -155,6 +161,10 @@ impl Component for SelectBranchComponent {
                     return self.move_selection(ScrollType::Up);
                 } else if e == self.key_config.move_up {
                     return self.move_selection(ScrollType::Down);
+                } else if e == self.key_config.page_down {
+                    return self.move_selection(ScrollType::PageDown);
+                } else if e == self.key_config.page_up {
+                    return self.move_selection(ScrollType::PageUp);
                 } else if e == self.key_config.enter {
                     if let Err(e) = self.switch_to_selected_branch() {
                         log::error!("switch branch error: {}", e);
@@ -232,6 +242,7 @@ impl SelectBranchComponent {
             queue,
             theme,
             key_config,
+            current_height: Cell::new(0),
         }
     }
     /// Get all the names of the branches in the repo
@@ -273,6 +284,12 @@ impl SelectBranchComponent {
         let mut new_selection = match scroll {
             ScrollType::Up => self.selection.saturating_add(1),
             ScrollType::Down => self.selection.saturating_sub(1),
+            ScrollType::PageDown => self
+                .selection
+                .saturating_add(self.current_height.get()),
+            ScrollType::PageUp => self
+                .selection
+                .saturating_sub(self.current_height.get()),
             _ => self.selection,
         };