Replace tui_react::Terminal with tui::Terminal

This is an experiment in converting a program that used the Terminal
provided by tui-react into a program that uses the Terminal provided by
ratatui. My hypothesis was that the two were not significantly different
from eachother, and this seems to be true in this case.

I found that `Widget` trait used by ratatui's `Terminal` is sufficiently
powerful to pass arbitrary mutable state to rendering code. A relatively
simple `FunctionWidget` trampoline is used to achieve this.

The tui_react dependency is retained. The code still calls some
tui_react utility functions and uses its List widget instead of the
ratatui List widget. These utilities do not depend on the tui_react
Terminal and could, in theory, be split out of tui-react into a separate
crate.

Cargo.toml

@@ -11,8 +11,7 @@ include = ["src/**/*", "Cargo.*", "LICENSE", "README.md", "CHANGELOG.md", "!**/t
 
 [features]
 default = ["tui-crossplatform", "trash-move"]
-tui-crossplatform = ["crosstermion/tui-react-crossterm", "tui", "tui-react", "open", "unicode-segmentation", "unicode-width"]
-
+tui-crossplatform = ["crosstermion/tui-crossterm", "tui", "tui-react", "open", "unicode-segmentation", "unicode-width"]
 trash-move = ["trash"]
 
 [dependencies]

src/interactive/app/eventloop.rs

@@ -14,8 +14,7 @@ use dua::{
     WalkResult,
 };
 use std::path::PathBuf;
-use tui::backend::Backend;
-use tui_react::Terminal;
+use tui::{backend::Backend, buffer::Buffer, layout::Rect, widgets::Widget, Terminal};
 
 use super::state::{AppState, Cursor};
 use super::tree_view::TreeView;
@@ -569,6 +568,55 @@ enum Refresh {
     Selected,
 }
 
+/// A [`Widget`] that renders by calling a function.
+///
+/// The `FunctionWidget` struct holds a function that renders into a portion of
+/// a [`Buffer`] designated by a [`Rect`].
+///
+/// This widget can be used to create custom UI elements that are defined by a
+/// rendering function. and allows for rendering functions that do not implement
+/// the [`Widget`] trait.
+struct FunctionWidget<F>
+where
+    F: FnOnce(Rect, &mut Buffer),
+{
+    render: F,
+}
+
+impl<F> FunctionWidget<F>
+where
+    F: FnOnce(Rect, &mut Buffer),
+{
+    /// Creates a new [`FunctionWidget`] with the given rendering function.
+    ///
+    /// The rendering function must have the signature `FnOnce(Rect, &mut
+    /// Buffer)`, where:
+    /// - [`Rect`] represents the available space for rendering.
+    /// - [`Buffer`] is the buffer to write the rendered content to.
+    ///
+    /// The `FunctionWidget` can then be used to render the provided function in
+    /// a user interface.
+    fn new(function: F) -> FunctionWidget<F>
+    where
+        F: FnOnce(Rect, &mut Buffer),
+    {
+        FunctionWidget { render: function }
+    }
+}
+
+/// Implements the [`Widget`] trait for [`FunctionWidget`].
+///
+/// The implementation simply calls the provided render function with the given
+/// `Rect` and `Buffer`.
+impl<F> Widget for FunctionWidget<F>
+where
+    F: FnOnce(Rect, &mut Buffer),
+{
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        (self.render)(area, buf);
+    }
+}
+
 pub fn draw_window<B>(
     window: &mut MainWindow,
     props: MainWindowProps<'_>,
@@ -578,10 +626,14 @@ pub fn draw_window<B>(
 where
     B: Backend,
 {
-    let area = terminal.pre_render()?;
-    window.render(props, area, terminal, cursor);
-    terminal.post_render()?;
-
+    terminal.draw(|frame| {
+        frame.render_widget(
+            FunctionWidget::new(|area, buf| {
+                window.render(props, area, buf, cursor);
+            }),
+            frame.size(),
+        );
+    })?;
     Ok(())
 }
 

src/interactive/app/handlers.rs

@@ -6,8 +6,7 @@ use crate::interactive::{
 use crosstermion::input::Key;
 use dua::traverse::TreeIndex;
 use std::{fs, io, path::PathBuf};
-use tui::backend::Backend;
-use tui_react::Terminal;
+use tui::{backend::Backend, Terminal};
 
 use super::state::{AppState, FocussedPane::*};
 

src/interactive/app/terminal.rs

@@ -8,8 +8,7 @@ use dua::{
     traverse::{Traversal, TraversalStats},
     ByteFormat, WalkOptions, WalkResult,
 };
-use tui::prelude::Backend;
-use tui_react::Terminal;
+use tui::{backend::Backend, Terminal};
 
 use crate::interactive::widgets::MainWindow;
 

src/interactive/app/tests/utils.rs

@@ -16,8 +16,7 @@ use std::{
     io::ErrorKind,
     path::{Path, PathBuf},
 };
-use tui::backend::TestBackend;
-use tui_react::Terminal;
+use tui::{backend::TestBackend, Terminal};
 
 use crate::interactive::{app::tests::FIXTURE_PATH, terminal::TerminalApp};
 

src/interactive/widgets/glob.rs

@@ -5,16 +5,17 @@ use crosstermion::input::Key;
 use dua::traverse::{Tree, TreeIndex};
 use petgraph::Direction;
 use std::borrow::Borrow;
-use tui::backend::Backend;
-use tui::prelude::Buffer;
 use tui::{
+    buffer::Buffer,
     layout::Rect,
     style::Style,
     text::{Line, Span, Text},
     widgets::{Block, Borders, Paragraph, Widget},
 };
-use tui_react::util::{block_width, rect};
-use tui_react::{draw_text_nowrap_fn, Terminal};
+use tui_react::{
+    draw_text_nowrap_fn,
+    util::{block_width, rect},
+};
 use unicode_segmentation::UnicodeSegmentation;
 use unicode_width::UnicodeWidthStr;
 
@@ -100,15 +101,13 @@ impl GlobPane {
         new_cursor_pos.clamp(0, self.input.graphemes(true).count())
     }
 
-    pub fn render<B>(
+    pub fn render(
         &mut self,
         props: impl Borrow<GlobPaneProps>,
         area: Rect,
-        terminal: &mut Terminal<B>,
+        buffer: &mut Buffer,
         cursor: &mut Cursor,
-    ) where
-        B: Backend,
-    {
+    ) {
         let GlobPaneProps {
             border_style,
             has_focus,
@@ -120,18 +119,15 @@ impl GlobPane {
             .border_style(*border_style)
             .borders(Borders::ALL);
         let inner_block_area = block.inner(area);
-        block.render(area, terminal.current_buffer_mut());
+        block.render(area, buffer);
 
         let spans = vec![Span::from(&self.input)];
         Paragraph::new(Text::from(Line::from(spans)))
             .style(Style::default())
-            .render(
-                margin_left_right(inner_block_area, 1),
-                terminal.current_buffer_mut(),
-            );
+            .render(margin_left_right(inner_block_area, 1), buffer);
 
         if *has_focus {
-            draw_top_right_help(area, title, terminal.current_buffer_mut());
+            draw_top_right_help(area, title, buffer);
 
             cursor.show = true;
             cursor.x = inner_block_area.x

src/interactive/widgets/main.rs

@@ -7,13 +7,12 @@ use crate::interactive::{
     DisplayOptions,
 };
 use std::borrow::Borrow;
-use tui::backend::Backend;
+use tui::buffer::Buffer;
 use tui::{
     layout::{Constraint, Direction, Layout, Rect},
     style::Modifier,
     style::{Color, Style},
 };
-use tui_react::Terminal;
 use Constraint::*;
 use FocussedPane::*;
 
@@ -36,15 +35,13 @@ pub struct MainWindow {
 }
 
 impl MainWindow {
-    pub fn render<'a, B>(
+    pub fn render<'a>(
         &mut self,
         props: impl Borrow<MainWindowProps<'a>>,
         area: Rect,
-        terminal: &mut Terminal<B>,
+        buffer: &mut Buffer,
         cursor: &mut Cursor,
-    ) where
-        B: Backend,
-    {
+    ) {
         let MainWindowProps {
             current_path,
             entries_traversed,
@@ -59,7 +56,7 @@ impl MainWindow {
         let (header_area, content_area, footer_area) = main_window_layout(area);
 
         let header_bg_color = header_background_color(self.is_anything_marked(), state.focussed);
-        Header.render(header_bg_color, header_area, terminal.current_buffer_mut());
+        Header.render(header_bg_color, header_area, buffer);
 
         let (entries_area, help_pane, mark_pane) = {
             let (left_pane, right_pane) = content_layout(content_area);
@@ -90,15 +87,15 @@ impl MainWindow {
                 border_style: mark_style,
                 format: display.byte_format,
             };
-            pane.render(props, mark_area, terminal.current_buffer_mut());
+            pane.render(props, mark_area, buffer);
         }
 
         if let Some((help_area, pane)) = help_pane {
             let props = HelpPaneProps {
                 border_style: help_style,
                 has_focus: matches!(state.focussed, Help),
             };
-            pane.render(props, help_area, terminal.current_buffer_mut());
+            pane.render(props, help_area, buffer);
         }
 
         let marked = self.mark_pane.as_ref().map(|p| p.marked());
@@ -113,15 +110,14 @@ impl MainWindow {
             sort_mode: state.sorting,
             show_columns: &state.show_columns,
         };
-        self.entries_pane
-            .render(props, entries_area, terminal.current_buffer_mut());
+        self.entries_pane.render(props, entries_area, buffer);
 
         if let Some((glob_area, pane)) = glob_pane {
             let props = GlobPaneProps {
                 border_style: glob_style,
                 has_focus: matches!(state.focussed, Glob),
             };
-            pane.render(props, glob_area, terminal, cursor);
+            pane.render(props, glob_area, buffer, cursor);
         }
 
         Footer.render(
@@ -135,7 +131,7 @@ impl MainWindow {
                 sort_mode: state.sorting,
             },
             footer_area,
-            terminal.current_buffer_mut(),
+            buffer,
         );
     }