How to change colors without reimplementing formatting?

[ThiefMaster]

The current choice of colors is not ideal, because the blue color for debug messages is pretty much unreadable when using the default ANSI colors on dark background.

However, I could not find any examples on how to change just the colors, and looking at ConfigurableFormatWriter it feels like a LOT of code would need to be duplicated to change the colors in an application.

A good alternative to making colors customizable could be to simply use a color for debug that looks OK on both dark and light backgrounds...

[epage]

The current choice of colors is not ideal, because the blue color for debug messages is pretty much unreadable when using the default ANSI colors on dark background.

A good alternative to making colors customizable could be to simply use a color for debug that looks OK on both dark and light backgrounds...

Note that there is no "default ANSI colors"; they vary from terminal to terminal. See https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit for an example.

Part of the value of ANSI escape codes is that the user has control over them to theme them and make them integrate together as needed. If a standard color does not work with a standard background (black and white being exceptions), then that seems like a bug within the terminal or the configured theme first and foremost.

However, we also have to deal with the reality of where things are at and likely should change our defaults.

One possible source of inspiration is how rustc determines its color for terminal output: https://github.com/rust-lang/annotate-snippets-rs/blob/22e7a137fc0ed8a9f965550e9ec8e6d418c21592/src/renderer/mod.rs#L41-L78

However, I could not find any examples on how to change just the colors, and looking at ConfigurableFormatWriter it feels like a LOT of code would need to be duplicated to change the colors in an application.

ConfigurableFormatWriter is a lot if you want the full flexibility. It doesn't have to be much if you write to what you want, e.g. the following example

env_logger/examples/custom_format.rs

Lines 32 to 43 in 4ed7fb4

	.format(|buf, record| {
	// We are reusing `anstyle` but there are `anstyle-*` crates to adapt it to your
	// preferred styling crate.
	let warn_style = buf.default_level_style(log::Level::Warn);
	let timestamp = buf.timestamp();
	writeln!(
	buf,
	"My formatted log ({timestamp}): {warn_style}{}{warn_style:#}",
	record.args()
	)
	})

Before making things themeable, I would want to understand what would be too much about taking that example work

[ThiefMaster]

Note that there is no "default ANSI colors"; they vary from terminal to terminal.

Ah, I thought the colors are somewhat standardized. At least in PuTTY the "blue" is rather dark:

ConfigurableFormatWriter is a lot if you want the full flexibility. It doesn't have to be much if you write to what you want, e.g. the following example

Fair point, I simply wanted to stick as close as possible to the original format since - besides the debug color choice - it actually looks quite nice.

[ThiefMaster]

The fact that all the utils like subtle_style aren't public don't make it easier to replicate the nice styling with the least amount of code...

[ThiefMaster]

Worse, write_style() is private, which means I cannot even keep the standard behavior of only emitting colors when the output should be colorized...

[epage]

Just wanted to check if you had seen this part of my comment

However, we also have to deal with the reality of where things are at and likely should change our defaults.

Worse, write_style() is private, which means I cannot even keep the standard behavior of only emitting colors when the output should be colorized...

Likely we can remove a lot of that. We switched to using anstream which will strip ANSI escape codes as needed so you can write them indiscriminately.