TermLogger/ConfigBuilder: Make colors optional

White isn't a good default for those with light terminal screens
(brighter background, darker text). This is already trivial in
termcolor, so just allow level colors to be None.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "simplelog"
-version = "0.9.0"
+version = "0.10.0"
 edition = "2018"
 authors = ["Drakulix <github@drakulix.de>"]
 description = "A simple and easy-to-use logging facility for Rust's log crate"

examples/custom_colors.rs

@@ -4,8 +4,8 @@ use simplelog::*;
 #[cfg(feature = "termcolor")]
 fn main() {
     let config = ConfigBuilder::new()
-        .set_level_color(Level::Error, Color::Magenta)
-        .set_level_color(Level::Trace, Color::Green)
+        .set_level_color(Level::Error, Some(Color::Magenta))
+        .set_level_color(Level::Trace, Some(Color::Green))
         .build();
 
     TermLogger::init(LevelFilter::Trace, config, TerminalMode::Stdout).unwrap();
@@ -19,4 +19,4 @@ fn main() {
 #[cfg(not(feature = "termcolor"))]
 fn main() {
     println!("this example requires the termcolor feature.");
-}
+}

examples/rgb_colors.rs

@@ -4,11 +4,11 @@ use simplelog::*;
 #[cfg(all(not(target_family = "windows"), feature = "termcolor"))]
 fn main() {
     let config = ConfigBuilder::new()
-        .set_level_color(Level::Error, Color::Rgb(191, 0, 0))
-        .set_level_color(Level::Warn,  Color::Rgb(255, 127, 0))
-        .set_level_color(Level::Info,  Color::Rgb(192, 192, 0))
-        .set_level_color(Level::Debug, Color::Rgb(63, 127, 0))
-        .set_level_color(Level::Trace, Color::Rgb(127, 127, 255))
+        .set_level_color(Level::Error, Some(Color::Rgb(191, 0, 0)))
+        .set_level_color(Level::Warn,  Some(Color::Rgb(255, 127, 0)))
+        .set_level_color(Level::Info,  Some(Color::Rgb(192, 192, 0)))
+        .set_level_color(Level::Debug, Some(Color::Rgb(63, 127, 0)))
+        .set_level_color(Level::Trace, Some(Color::Rgb(127, 127, 255)))
         .build();
 
     TermLogger::init(LevelFilter::Trace, config, TerminalMode::Stdout).unwrap();
@@ -22,4 +22,4 @@ fn main() {
 #[cfg(any(target_family = "windows", not(feature = "termcolor")))]
 fn main() {
     println!("this example requires the termcolor feature and a non-Windows OS.");
-}
+}

src/config.rs

@@ -64,7 +64,7 @@ pub struct Config {
     pub(crate) filter_allow: Cow<'static, [Cow<'static, str>]>,
     pub(crate) filter_ignore: Cow<'static, [Cow<'static, str>]>,
     #[cfg(feature = "termcolor")]
-    pub(crate) level_color: [Color; 6],
+    pub(crate) level_color: [Option<Color>; 6],
 }
 
 /// Builder for the Logger Configurations (`Config`)
@@ -138,9 +138,10 @@ impl ConfigBuilder {
         self
     }
 
-    /// Set the color used for printing the level (if the logger supports it)
+    /// Set the color used for printing the level (if the logger supports it),
+    /// or None to use the default foreground color
     #[cfg(feature = "termcolor")]
-    pub fn set_level_color<'a>(&'a mut self, level: Level, color: Color) -> &'a mut ConfigBuilder {
+    pub fn set_level_color<'a>(&'a mut self, level: Level, color: Option<Color>) -> &'a mut ConfigBuilder {
         self.0.level_color[level as usize] = color;
         self
     }
@@ -265,12 +266,12 @@ impl Default for Config {
 
             #[cfg(feature = "termcolor")]
             level_color: [
-                Color::White,  // (dummy)
-                Color::Red,    // Error
-                Color::Yellow, // Warn
-                Color::Blue,   // Info
-                Color::Cyan,   // Debug
-                Color::White,  // Trace
+                None,                // Default foreground
+                Some(Color::Red),    // Error
+                Some(Color::Yellow), // Warn
+                Some(Color::Blue),   // Info
+                Some(Color::Cyan),   // Debug
+                Some(Color::White),  // Trace
             ],
         }
     }

src/loggers/termlog.rs

@@ -139,7 +139,7 @@ impl TermLogger {
         }
 
         if self.config.level <= record.level() && self.config.level != LevelFilter::Off {
-            term_lock.set_color(ColorSpec::new().set_fg(Some(color)))?;
+            term_lock.set_color(ColorSpec::new().set_fg(color))?;
             write_level(record, &mut *term_lock, &self.config)?;
             term_lock.reset()?;
         }