From 9ad40bc40b57f88d2c81a5dc55373bd6e31a6c21 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bla=C5=BE=20Hrastnik?= <blaz@mxxn.io>
Date: Mon, 7 Sep 2020 18:10:08 +0900
Subject: [PATCH] Experiment with TUI so we can render selections.

---
 Cargo.lock               | 20 +++++++++++++++
 helix-term/Cargo.toml    |  3 +--
 helix-term/src/editor.rs | 54 ++++++++++++++++++++++++++++++++++++----
 3 files changed, 70 insertions(+), 7 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 244fedeb4..da549c989 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -212,6 +212,12 @@ version = "1.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "631ae5198c9be5e753e5cc215e1bd73c2b466a3565173db433f52bb9d3e66dba"
 
+[[package]]
+name = "cassowary"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df8670b8c7b9dae1793364eafadf7239c40d669904660c5960d74cfd80b46a53"
+
 [[package]]
 name = "cc"
 version = "1.0.59"
@@ -420,6 +426,7 @@ dependencies = [
  "helix-core",
  "num_cpus",
  "smol",
+ "tui",
 ]
 
 [[package]]
@@ -738,6 +745,19 @@ dependencies = [
  "utf-8",
 ]
 
+[[package]]
+name = "tui"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a977b0bb2e2033a6fef950f218f13622c3c34e59754b704ce3492dedab1dfe95"
+dependencies = [
+ "bitflags",
+ "cassowary",
+ "crossterm",
+ "unicode-segmentation",
+ "unicode-width",
+]
+
 [[package]]
 name = "unicode-segmentation"
 version = "1.6.0"
diff --git a/helix-term/Cargo.toml b/helix-term/Cargo.toml
index 32e72825d..b5f7484e0 100644
--- a/helix-term/Cargo.toml
+++ b/helix-term/Cargo.toml
@@ -22,6 +22,5 @@ crossterm = { version = "0.17.7", features = ["event-stream"] }
 smol = "0.4"
 futures = { version = "0.3.5", default-features = false, features = ["std", "async-await"] }
 num_cpus = "1.13.0"
+tui = { version = "0.10.0", default-features = false, features = ["crossterm"] }
 # futures-timer = "3.0.2"
-
-# tui = { version = "0.9.5", default-features = false }
diff --git a/helix-term/src/editor.rs b/helix-term/src/editor.rs
index 6c0d5b495..a6de3e0b1 100644
--- a/helix-term/src/editor.rs
+++ b/helix-term/src/editor.rs
@@ -14,9 +14,17 @@
 use std::path::PathBuf;
 use std::time::Duration;
 
+use tui::backend::CrosstermBackend;
+use tui::buffer::Buffer as Surface;
+use tui::layout::Rect;
+use tui::style::Style;
+
+type Terminal = tui::Terminal<CrosstermBackend<std::io::Stdout>>;
+
 static EX: smol::Executor = smol::Executor::new();
 
 pub struct Editor {
+    terminal: Terminal,
     state: Option<State>,
     first_line: u16,
     size: (u16, u16),
@@ -24,7 +32,12 @@ pub struct Editor {
 
 impl Editor {
     pub fn new(mut args: Args) -> Result<Self, Error> {
+        let backend = CrosstermBackend::new(stdout());
+
+        let mut terminal = Terminal::new(backend)?;
+
         let mut editor = Editor {
+            terminal,
             state: None,
             first_line: 0,
             size: terminal::size().unwrap(),
@@ -45,6 +58,9 @@ pub fn open(&mut self, path: PathBuf) -> Result<(), Error> {
     fn render(&mut self) {
         match &self.state {
             Some(state) => {
+                let area = Rect::new(0, 0, self.size.0, self.size.1);
+                let mut surface = Surface::empty(area);
+
                 let lines = state
                     .doc
                     .lines_at(self.first_line as usize)
@@ -60,12 +76,33 @@ fn render(&mut self) {
                         cursor::MoveTo(0, n as u16),
                         Print((n + 1).to_string())
                     );
-                    execute!(
-                        stdout,
-                        SetForegroundColor(Color::Reset),
-                        cursor::MoveTo(2, n as u16),
-                        Print(line)
+
+                    surface.set_string(2, n as u16, line, Style::default());
+                    // execute!(
+                    //     stdout,
+                    //     SetForegroundColor(Color::Reset),
+                    //     cursor::MoveTo(2, n as u16),
+                    //     Print(line)
+                    // );
+                }
+
+                // iterate over selections and render them
+                let select = Style::default().bg(tui::style::Color::LightBlue);
+                let text = state.doc.slice(..);
+                for range in state.selection.ranges() {
+                    // get terminal coords for x,y for each range pos
+                    // TODO: this won't work with multiline
+                    let (y1, x1) = coords_at_pos(&text, range.from());
+                    let (y2, x2) = coords_at_pos(&text, range.to());
+                    let area = Rect::new(
+                        (x1 + 2) as u16,
+                        y1 as u16,
+                        (x2 - x1 + 1) as u16,
+                        (y2 - y1 + 1) as u16,
                     );
+                    surface.set_style(area, select);
+
+                    // TODO: don't highlight next char in append mode
                 }
 
                 let mode = match state.mode {
@@ -80,6 +117,13 @@ fn render(&mut self) {
                     Print(mode)
                 );
 
+                use tui::backend::Backend;
+                // TODO: double buffer and diff here
+                let empty = Surface::empty(area);
+                self.terminal
+                    .backend_mut()
+                    .draw(empty.diff(&surface).into_iter());
+
                 // set cursor shape
                 match state.mode {
                     Mode::Insert => write!(stdout, "\x1B[6 q"),