Extract grid and line-number color from theme

This changes the output color of the grid and the line numbers to use
the "gutter" foreground color defined in the Sublime `.tmTheme` files.

Sublime Text does the same.

Note: we could go one step further and also extract the "GitGutter"
colors from the themes. These could be used instead of red/green/yellow
to signify Git modifications. The problem is that they are quite a bit
harder to extract from the syntect `Theme` object.

closes #178

Author: sharkdp

Diff for: src/features.rs

@@ -61,7 +61,7 @@ pub fn print_files(assets: &HighlightingAssets, config: &Config) -> Result<bool>
 
     let mut output_type = OutputType::from_mode(config.paging_mode);
     let handle = output_type.handle()?;
-    let mut printer = Printer::new(handle, &config);
+    let mut printer = Printer::new(handle, &config, &theme);
     let mut no_errors: bool = true;
 
     for file in &config.files {

Diff for: src/printer.rs

@@ -1,4 +1,4 @@
-use ansi_term::Colour::{Fixed, Green, Red, White, Yellow};
+use ansi_term::Colour::{Fixed, Green, Red, Yellow};
 use ansi_term::Style;
 use app::Config;
 use console::AnsiCodeIterator;
@@ -9,8 +9,8 @@ use std::boxed::Box;
 use std::io::Write;
 use std::vec::Vec;
 use style::OutputWrap;
-use syntect::highlighting;
-use terminal::as_terminal_escaped;
+use syntect::highlighting::{self, Theme};
+use terminal::{as_terminal_escaped, to_ansi_color};
 
 pub struct Printer<'a> {
     handle: &'a mut Write,
@@ -24,9 +24,9 @@ pub struct Printer<'a> {
 }
 
 impl<'a> Printer<'a> {
-    pub fn new(handle: &'a mut Write, config: &'a Config) -> Self {
+    pub fn new(handle: &'a mut Write, config: &'a Config, theme: &Theme) -> Self {
         let colors = if config.colored_output {
-            Colors::colored()
+            Colors::colored(theme, config.true_color)
         } else {
             Colors::plain()
         };
@@ -274,8 +274,7 @@ impl<'a> Printer<'a> {
     }
 }
 
-const GRID_COLOR: u8 = 238;
-const LINE_NUMBER_COLOR: u8 = 244;
+const DEFAULT_GUTTER_COLOR: u8 = 238;
 
 #[derive(Default)]
 pub struct Colors {
@@ -292,14 +291,20 @@ impl Colors {
         Colors::default()
     }
 
-    fn colored() -> Self {
+    fn colored(theme: &Theme, true_color: bool) -> Self {
+        let gutter_color = theme
+            .settings
+            .gutter_foreground
+            .map(|c| to_ansi_color(c, true_color))
+            .unwrap_or(Fixed(DEFAULT_GUTTER_COLOR));
+
         Colors {
-            grid: Fixed(GRID_COLOR).normal(),
-            filename: White.bold(),
+            grid: gutter_color.normal(),
+            filename: Style::new().bold(),
             git_added: Green.normal(),
             git_removed: Red.normal(),
             git_modified: Yellow.normal(),
-            line_number: Fixed(LINE_NUMBER_COLOR).normal(),
+            line_number: gutter_color.normal(),
         }
     }
 }

Diff for: src/terminal.rs

@@ -1,5 +1,5 @@
 use ansi_term::Colour::{Fixed, RGB};
-use ansi_term::Style;
+use ansi_term::{self, Style};
 use syntect::highlighting::{self, FontStyle};
 
 /// Approximate a 24 bit color value by a 8 bit ANSI code
@@ -20,6 +20,15 @@ fn rgb2ansi(r: u8, g: u8, b: u8) -> u8 {
     }
 }
 
+pub fn to_ansi_color(color: highlighting::Color, true_color: bool) -> ansi_term::Colour {
+    if true_color {
+        RGB(color.r, color.g, color.b)
+    } else {
+        let ansi_code = rgb2ansi(color.r, color.g, color.b);
+        Fixed(ansi_code)
+    }
+}
+
 pub fn as_terminal_escaped(
     style: highlighting::Style,
     text: &str,
@@ -29,12 +38,7 @@ pub fn as_terminal_escaped(
     let style = if !colored {
         Style::default()
     } else {
-        let color = if true_color {
-            RGB(style.foreground.r, style.foreground.g, style.foreground.b)
-        } else {
-            let ansi = rgb2ansi(style.foreground.r, style.foreground.g, style.foreground.b);
-            Fixed(ansi)
-        };
+        let color = to_ansi_color(style.foreground, true_color);
 
         if style.font_style.contains(FontStyle::BOLD) {
             color.bold()