From e0b2572eba7512d336db9e749d0a29cc00c39ed3 Mon Sep 17 00:00:00 2001
From: alvinhochun <alvin@alvinhc.com>
Date: Sun, 20 Sep 2020 20:54:16 +0800
Subject: [PATCH] refactor(backend/crossterm): support more style modifiers on
 Windows and fix build with Crossterm 0.17.8 (#368)

* Support more style modifiers on Windows
* Change Crossterm backend to write directly to buffer instead of String

Crossterm might actually do WinAPI calls instead of writing ANSI excape
codes so writing to an intermediate String may cause issues on older
versions of Windows. It also fails to compile with Crossterm 0.17.8 due
to Crossterm now expecting the writer to support `flush`, which String
doesn't.

Fixes #373
---
 src/backend/crossterm.rs | 47 ++++++----------------------------------
 1 file changed, 7 insertions(+), 40 deletions(-)

diff --git a/src/backend/crossterm.rs b/src/backend/crossterm.rs
index c0a13be..f6703e1 100644
--- a/src/backend/crossterm.rs
+++ b/src/backend/crossterm.rs
@@ -13,10 +13,7 @@ use crossterm::{
     },
     terminal::{self, Clear, ClearType},
 };
-use std::{
-    fmt,
-    io::{self, Write},
-};
+use std::io::{self, Write};
 
 pub struct CrosstermBackend<W: Write> {
     buffer: W,
@@ -52,9 +49,6 @@ where
     where
         I: Iterator<Item = (u16, u16, &'a Cell)>,
     {
-        use fmt::Write;
-
-        let mut string = String::with_capacity(content.size_hint().0 * 3);
         let mut fg = Color::Reset;
         let mut bg = Color::Reset;
         let mut modifier = Modifier::empty();
@@ -62,7 +56,7 @@ where
         for (x, y, cell) in content {
             // Move the cursor if the previous location was not (x - 1, y)
             if !matches!(last_pos, Some(p) if x == p.0 + 1 && y == p.1) {
-                map_error(queue!(string, MoveTo(x, y)))?;
+                map_error(queue!(self.buffer, MoveTo(x, y)))?;
             }
             last_pos = Some((x, y));
             if cell.modifier != modifier {
@@ -70,26 +64,25 @@ where
                     from: modifier,
                     to: cell.modifier,
                 };
-                diff.queue(&mut string)?;
+                diff.queue(&mut self.buffer)?;
                 modifier = cell.modifier;
             }
             if cell.fg != fg {
                 let color = CColor::from(cell.fg);
-                map_error(queue!(string, SetForegroundColor(color)))?;
+                map_error(queue!(self.buffer, SetForegroundColor(color)))?;
                 fg = cell.fg;
             }
             if cell.bg != bg {
                 let color = CColor::from(cell.bg);
-                map_error(queue!(string, SetBackgroundColor(color)))?;
+                map_error(queue!(self.buffer, SetBackgroundColor(color)))?;
                 bg = cell.bg;
             }
 
-            string.push_str(&cell.symbol);
+            map_error(queue!(self.buffer, Print(&cell.symbol)))?;
         }
 
         map_error(queue!(
             self.buffer,
-            Print(string),
             SetForegroundColor(CColor::Reset),
             SetBackgroundColor(CColor::Reset),
             SetAttribute(CAttribute::Reset)
@@ -165,11 +158,10 @@ struct ModifierDiff {
     pub to: Modifier,
 }
 
-#[cfg(unix)]
 impl ModifierDiff {
     fn queue<W>(&self, mut w: W) -> io::Result<()>
     where
-        W: fmt::Write,
+        W: io::Write,
     {
         //use crossterm::Attribute;
         let removed = self.from - self.to;
@@ -227,28 +219,3 @@ impl ModifierDiff {
         Ok(())
     }
 }
-
-#[cfg(windows)]
-impl ModifierDiff {
-    fn queue<W>(&self, mut w: W) -> io::Result<()>
-    where
-        W: fmt::Write,
-    {
-        let removed = self.from - self.to;
-        if removed.contains(Modifier::BOLD) {
-            map_error(queue!(w, SetAttribute(CAttribute::NormalIntensity)))?;
-        }
-        if removed.contains(Modifier::UNDERLINED) {
-            map_error(queue!(w, SetAttribute(CAttribute::NoUnderline)))?;
-        }
-
-        let added = self.to - self.from;
-        if added.contains(Modifier::BOLD) {
-            map_error(queue!(w, SetAttribute(CAttribute::Bold)))?;
-        }
-        if added.contains(Modifier::UNDERLINED) {
-            map_error(queue!(w, SetAttribute(CAttribute::Underlined)))?;
-        }
-        Ok(())
-    }
-}