fix(performance): undo degredation introduced in 646 (#651)

* fix(performance): undo degredation introduced in 646

* style(fmt): make rustfmt happy

* style(fmt): make clippy happy

3 files changed, 27 insertions, 57 deletions

diff --git a/zellij-server/src/panes/grid.rs b/zellij-server/src/panes/grid.rs
index 85910f3e..f42c1dbc 100644
--- a/zellij-server/src/panes/grid.rs
+++ b/zellij-server/src/panes/grid.rs
@@ -348,7 +348,7 @@ pub struct Grid {
     colors: Palette,
     output_buffer: OutputBuffer,
     title_stack: Vec<String>,
-    pub changed_colors: [Option<AnsiCode>; 256],
+    pub changed_colors: Option<[Option<AnsiCode>; 256]>,
     pub should_render: bool,
     pub cursor_key_mode: bool, // DECCKM - when set, cursor keys should send ANSI direction codes (eg. "OD") instead of the arrow keys (eg. "")
     pub erasure_mode: bool,    // ERM
@@ -402,7 +402,7 @@ impl Grid {
             selection: Default::default(),
             title_stack: vec![],
             title: None,
-            changed_colors: [None; 256],
+            changed_colors: None,
         }
     }
     pub fn render_full_viewport(&mut self) {
@@ -1227,7 +1227,7 @@ impl Grid {
         self.disable_linewrap = false;
         self.cursor.change_shape(CursorShape::Block);
         self.output_buffer.update_all_lines();
-        self.changed_colors = [None; 256];
+        self.changed_colors = None;
     }
     fn set_preceding_character(&mut self, terminal_character: TerminalCharacter) {
         self.preceding_char = Some(terminal_character);
@@ -1356,22 +1356,12 @@ impl Perform for Grid {
     fn print(&mut self, c: char) {
         let c = self.cursor.charsets[self.active_charset].map(c);
 
-        // we add the changed_colors here instead of changing the actual colors on the
-        // TerminalCharacter in real time because these changed colors also affect the area around
-        // the character (eg. empty space after it)
-        // on the other hand, we must do it here and not at render-time because then it would be
-        // wiped out when one scrolls
-        let styles = self
-            .cursor
-            .pending_styles
-            .changed_colors(self.changed_colors);
-
         // apparently, building TerminalCharacter like this without a "new" method
         // is a little faster
         let terminal_character = TerminalCharacter {
             character: c,
             width: c.width().unwrap_or(0),
-            styles,
+            styles: self.cursor.pending_styles,
         };
         self.set_preceding_character(terminal_character);
         self.add_character(terminal_character);
@@ -1447,7 +1437,10 @@ impl Perform for Grid {
                     let index = parse_number(chunk[0]);
                     let color = xparse_color(chunk[1]);
                     if let (Some(i), Some(c)) = (index, color) {
-                        self.changed_colors[i as usize] = Some(c);
+                        if self.changed_colors.is_none() {
+                            self.changed_colors = Some([None; 256]);
+                        }
+                        self.changed_colors.as_mut().unwrap()[i as usize] = Some(c);
                         return;
                     }
                 }
@@ -1526,16 +1519,16 @@ impl Perform for Grid {
             b"104" => {
                 // Reset all color indexes when no parameters are given.
                 if params.len() == 1 {
-                    for i in 0..256 {
-                        self.changed_colors[i] = None;
-                    }
+                    self.changed_colors = None;
                     return;
                 }
 
                 // Reset color indexes given as parameters.
                 for param in &params[1..] {
                     if let Some(index) = parse_number(param) {
-                        self.changed_colors[index as usize] = None
+                        if self.changed_colors.is_some() {
+                            self.changed_colors.as_mut().unwrap()[index as usize] = None
+                        }
                     }
                 }
 
diff --git a/zellij-server/src/panes/terminal_character.rs b/zellij-server/src/panes/terminal_character.rs
index a17c9d7e..2e1a018d 100644
--- a/zellij-server/src/panes/terminal_character.rs
+++ b/zellij-server/src/panes/terminal_character.rs
@@ -21,7 +21,6 @@ pub const EMPTY_TERMINAL_CHARACTER: TerminalCharacter = TerminalCharacter {
         bold: Some(AnsiCode::Reset),
         dim: Some(AnsiCode::Reset),
         italic: Some(AnsiCode::Reset),
-        changed_colors: None,
     },
 };
 
@@ -110,7 +109,6 @@ pub struct CharacterStyles {
     pub bold: Option<AnsiCode>,
     pub dim: Option<AnsiCode>,
     pub italic: Option<AnsiCode>,
-    pub changed_colors: Option<[Option<AnsiCode>; 256]>,
 }
 
 impl Default for CharacterStyles {
@@ -127,7 +125,6 @@ impl Default for CharacterStyles {
             bold: None,
             dim: None,
             italic: None,
-            changed_colors: None,
         }
     }
 }
@@ -180,10 +177,6 @@ impl CharacterStyles {
         self.strike = strike_code;
         self
     }
-    pub fn changed_colors(mut self, changed_colors: [Option<AnsiCode>; 256]) -> Self {
-        self.changed_colors = Some(changed_colors);
-        self
-    }
     pub fn clear(&mut self) {
         self.foreground = None;
         self.background = None;
@@ -200,6 +193,7 @@ impl CharacterStyles {
     pub fn update_and_return_diff(
         &mut self,
         new_styles: &CharacterStyles,
+        changed_colors: Option<[Option<AnsiCode>; 256]>,
     ) -> Option<CharacterStyles> {
         let mut diff: Option<CharacterStyles> = None;
 
@@ -329,13 +323,16 @@ impl CharacterStyles {
             }
         }
 
-        if let Some(changed_colors) = new_styles.changed_colors {
-            if let Some(new_diff) = diff.as_mut() {
-                diff = Some(new_diff.changed_colors(changed_colors));
-                self.changed_colors = new_styles.changed_colors;
-            } else {
-                diff = Some(CharacterStyles::new().changed_colors(changed_colors));
-                self.changed_colors = new_styles.changed_colors;
+        if let Some(changed_colors) = changed_colors {
+            if let Some(AnsiCode::ColorIndex(color_index)) = diff.and_then(|diff| diff.foreground) {
+                if let Some(changed_color) = changed_colors[color_index as usize] {
+                    diff.as_mut().unwrap().foreground = Some(changed_color);
+                }
+            }
+            if let Some(AnsiCode::ColorIndex(color_index)) = diff.and_then(|diff| diff.background) {
+                if let Some(changed_color) = changed_colors[color_index as usize] {
+                    diff.as_mut().unwrap().background = Some(changed_color);
+                }
             }
         }
         diff
@@ -498,17 +495,7 @@ impl Display for CharacterStyles {
                     write!(f, "\u{1b}[38;2;{};{};{}m", r, g, b)?;
                 }
                 AnsiCode::ColorIndex(color_index) => {
-                    match self
-                        .changed_colors
-                        .and_then(|changed_colors| changed_colors[color_index as usize])
-                    {
-                        Some(AnsiCode::RgbCode((r, g, b))) => {
-                            write!(f, "\u{1b}[38;2;{};{};{}m", r, g, b)?;
-                        }
-                        _ => {
-                            write!(f, "\u{1b}[38;5;{}m", color_index)?;
-                        }
-                    }
+                    write!(f, "\u{1b}[38;5;{}m", color_index)?;
                 }
                 AnsiCode::Reset => {
                     write!(f, "\u{1b}[39m")?;
@@ -525,17 +512,7 @@ impl Display for CharacterStyles {
                     write!(f, "\u{1b}[48;2;{};{};{}m", r, g, b)?;
                 }
                 AnsiCode::ColorIndex(color_index) => {
-                    match self
-                        .changed_colors
-                        .and_then(|changed_colors| changed_colors[color_index as usize])
-                    {
-                        Some(AnsiCode::RgbCode((r, g, b))) => {
-                            write!(f, "\u{1b}[48;2;{};{};{}m", r, g, b)?;
-                        }
-                        _ => {
-                            write!(f, "\u{1b}[48;5;{}m", color_index)?;
-                        }
-                    }
+                    write!(f, "\u{1b}[48;5;{}m", color_index)?;
                 }
                 AnsiCode::Reset => {
                     write!(f, "\u{1b}[49m")?;
diff --git a/zellij-server/src/panes/terminal_pane.rs b/zellij-server/src/panes/terminal_pane.rs
index 658ecaf6..e9531819 100644
--- a/zellij-server/src/panes/terminal_pane.rs
+++ b/zellij-server/src/panes/terminal_pane.rs
@@ -236,8 +236,8 @@ impl Pane for TerminalPane {
                         break;
                     }
 
-                    if let Some(new_styles) =
-                        character_styles.update_and_return_diff(&t_character.styles)
+                    if let Some(new_styles) = character_styles
+                        .update_and_return_diff(&t_character.styles, self.grid.changed_colors)
                     {
                         vte_output.push_str(&new_styles.to_string());
                     }