allow scrolling syntax text (see #725)

src/components/revision_files.rs

@@ -31,6 +31,11 @@ const FOLDER_ICON_COLLAPSED: &str = "\u{25b8}"; //▸
 const FOLDER_ICON_EXPANDED: &str = "\u{25be}"; //▾
 const EMPTY_STR: &str = "";
 
+enum Focus {
+    Tree,
+    File,
+}
+
 pub struct RevisionFilesComponent {
     queue: Queue,
     title: String,
@@ -43,6 +48,7 @@ pub struct RevisionFilesComponent {
     scroll_top: Cell<usize>,
     revision: Option<CommitId>,
     visible: bool,
+    focus: Focus,
     key_config: SharedKeyConfig,
 }
 
@@ -67,6 +73,7 @@ impl RevisionFilesComponent {
             files: Vec::new(),
             revision: None,
             visible: false,
+            focus: Focus::Tree,
             key_config,
         }
     }
@@ -276,18 +283,26 @@ impl Component for RevisionFilesComponent {
     ) -> Result<EventState> {
         if self.is_visible() {
             if let Event::Key(key) = event {
+                let is_tree_focused =
+                    matches!(self.focus, Focus::Tree);
                 if key == self.key_config.exit_popup {
                     self.hide();
+                } else if is_tree_focused
+                    && tree_nav(&mut self.tree, &self.key_config, key)
+                {
+                    self.selection_changed();
                 } else if key == self.key_config.blame {
                     if self.blame() {
                         self.hide();
                     }
-                } else if tree_nav(
-                    &mut self.tree,
-                    &self.key_config,
-                    key,
-                ) {
-                    self.selection_changed();
+                } else if key == self.key_config.move_right {
+                    if is_tree_focused {
+                        self.focus = Focus::File;
+                    } else {
+                        self.focus = Focus::Tree;
+                    }
+                } else if !is_tree_focused {
+                    self.current_file.event(event)?;
                 }
             }
 

src/components/syntax_text.rs

@@ -13,8 +13,9 @@ use asyncgit::{
     AsyncNotification, CWD,
 };
 use crossbeam_channel::Sender;
+use crossterm::event::Event;
 use itertools::Either;
-use std::{convert::From, path::Path};
+use std::{cell::Cell, convert::From, path::Path};
 use tui::{
     backend::Backend,
     layout::Rect,
@@ -27,7 +28,8 @@ pub struct SyntaxTextComponent {
     current_file: Option<(String, Either<ui::SyntaxText, String>)>,
     async_highlighting:
         AsyncSingleJob<AsyncSyntaxJob, AsyncNotification>,
-    _key_config: SharedKeyConfig,
+    key_config: SharedKeyConfig,
+    scroll_top: Cell<u16>,
 }
 
 impl SyntaxTextComponent {
@@ -42,7 +44,8 @@ impl SyntaxTextComponent {
                 AsyncNotification::SyntaxHighlighting,
             ),
             current_file: None,
-            _key_config: key_config,
+            scroll_top: Cell::new(0),
+            key_config,
         }
     }
 
@@ -115,14 +118,16 @@ impl DrawableComponent for SyntaxTextComponent {
         f: &mut Frame<B>,
         area: Rect,
     ) -> Result<()> {
-        let content =
-            Paragraph::new(self.current_file.as_ref().map_or_else(
-                || Text::from(""),
-                |(_, content)| match content {
-                    Either::Left(syn) => syn.into(),
-                    Either::Right(s) => Text::from(s.as_str()),
-                },
-            ))
+        let text = self.current_file.as_ref().map_or_else(
+            || Text::from(""),
+            |(_, content)| match content {
+                Either::Left(syn) => syn.into(),
+                Either::Right(s) => Text::from(s.as_str()),
+            },
+        );
+
+        let content = Paragraph::new(text)
+            .scroll((self.scroll_top.get(), 0))
             .wrap(Wrap { trim: false });
         f.render_widget(content, area);
 
@@ -142,9 +147,18 @@ impl Component for SyntaxTextComponent {
 
     fn event(
         &mut self,
-        _event: crossterm::event::Event,
+        event: crossterm::event::Event,
     ) -> Result<EventState> {
-        //TODO: scrolling
+        if let Event::Key(key) = event {
+            if key == self.key_config.move_down {
+                self.scroll_top
+                    .set(self.scroll_top.get().saturating_add(1));
+            } else if key == self.key_config.move_up {
+                self.scroll_top
+                    .set(self.scroll_top.get().saturating_sub(1));
+            }
+        }
+
         Ok(EventState::NotConsumed)
     }
 }