Add start_logger function and support for color output

Cargo.toml

@@ -60,7 +60,7 @@ amethyst_input = { path = "amethyst_input", version = "0.3" }
 amethyst_ui = { path = "amethyst_ui", version = "0.2" }
 amethyst_utils = { path = "amethyst_utils", version = "0.2" }
 derivative = "1.0"
-fern = "0.5"
+fern = { version = "0.5", features = ["colored"] }
 log = "0.4"
 rayon = "1.0.1"
 rustc_version_runtime = "0.1"

src/app.rs

@@ -1,14 +1,12 @@
 //! The core engine framework.
 
 use std::error::Error as StdError;
-use std::io;
 use std::path::Path;
 use std::sync::Arc;
 use std::time::Duration;
 
 use core::shrev::{EventChannel, ReaderId};
-use fern;
-use log::LevelFilter;
+use log::Level;
 use rayon::ThreadPoolBuilder;
 use shred::Resource;
 #[cfg(feature = "profiler")]
@@ -377,21 +375,11 @@ impl<S> ApplicationBuilder<S> {
     pub fn new<P: AsRef<Path>>(path: P, initial_state: S) -> Result<Self> {
         use rustc_version_runtime;
 
-        fern::Dispatch::new()
-            .format(|out, message, record| {
-                out.finish(format_args!(
-                    "[{}][{}] {}",
-                    record.target(),
-                    record.level(),
-                    message
-                ))
-            })
-            .level(LevelFilter::Debug)
-            .chain(io::stdout())
-            .apply()
-            .unwrap_or_else(|_| {
-                debug!("Global logger already set, default amethyst logger will not be used")
-            });
+        if !log_enabled!(Level::Error) {
+            println!(
+                "WARNING: No logger detected! Did you forget to call `amethyst::start_logger()`?"
+            );
+        }
 
         info!("Initializing Amethyst...");
         info!("Version: {}", env!("CARGO_PKG_VERSION"));

src/lib.rs

@@ -80,6 +80,7 @@ extern crate rustc_version_runtime;
 pub use self::app::{Application, ApplicationBuilder};
 pub use self::error::{Error, Result};
 pub use self::game_data::{DataInit, GameData, GameDataBuilder};
+pub use self::logger::start_logger;
 pub use self::state::{State, StateData, StateMachine, Trans};
 pub use core::shred;
 pub use core::shrev;
@@ -90,5 +91,6 @@ pub mod prelude;
 mod app;
 mod error;
 mod game_data;
+mod logger;
 mod state;
 mod vergen;

src/logger.rs

@@ -0,0 +1,33 @@
+use std::io;
+
+use fern;
+use log::LevelFilter;
+
+/// Starts a basic logger outputting to stdout with color on supported platforms.
+///
+/// If you do not intend on using the logger builtin to Amethyst, it's highly recommended you
+/// initialise your own.
+pub fn start_logger() {
+    let color_config = fern::colors::ColoredLevelConfig::new();
+
+    fern::Dispatch::new()
+        .format(move |out, message, record| {
+            out.finish(format_args!(
+                "{color}[{level}][{target}] {message}{color_reset}",
+                color = format_args!(
+                    "\x1B[{}m",
+                    color_config.get_color(&record.level()).to_fg_str()
+                ),
+                level = record.level(),
+                target = record.target(),
+                message = message,
+                color_reset = "\x1B[0m"
+            ))
+        })
+        .level(LevelFilter::Debug)
+        .chain(io::stdout())
+        .apply()
+        .unwrap_or_else(|_| {
+            debug!("Global logger already set, default Amethyst logger will not be used")
+        });
+}