TTY detection foreground/background color

What is the problem this feature will solve?

For tty’s if you output any text in black, particularly when doing TUI’s one is likely to get a rude awakening when they discover that their users are using dark mode and none of that text is visible because it’s jet black on a charcoal gray background. It would be best in such cases to simply print this text in the default foreground color, but that does not guarantee that other colors will be high contrast. For instance dark blue on charcoal gray, or yellow text on iTerm's default eggshell white background, versus orange which shows well on both light and dark mode terminals.

What is the feature you are proposing to solve the problem?

Add a function to write stream to query the foreground color the way color depth can be queried. And if at all possible, also the background color.

What alternatives have you considered?

Workarounds include:

• setting a background color and printing over it, but that makes the text/graphic look more important than it is
• resetting the tty codes rather than setting “black” - but this fails if you are looking for a more general case of high contrast colors, like dark gray on a bright background and light gray on a dark one.

未指定实现文件或测试。首先定位用于查询终端色深的现有 stream API，然后检查在受支持的平台上如何处理 TTY 行为。当一个已定义的 stream 函数能够查询前景色，并在可能的情况下查询背景色，且相关情况都有覆盖时，即视为完成。