Add support for ansi colors and add .ansi256ToAnsi(), .rgbToAnsi() and .hexToAnsi() (#71)

Co-authored-by: Qix <Qix-@users.noreply.github.com>

Author: Richienb

index.d.ts

@@ -16,6 +16,8 @@ export interface ColorBase {
 	*/
 	readonly close: string;
 
+	ansi(code: number): string;
+
 	ansi256(code: number): string;
 
 	ansi16m(red: number, green: number, blue: number): string;
@@ -153,6 +155,29 @@ export interface ConvertColor {
 	@param hex - A hexadecimal string containing RGB data.
 	*/
 	hexToAnsi256(hex: string): number;
+
+	/**
+	Convert from the ANSI 256 color space to the ANSI 16 color space.
+
+	@param code - A number representing the ANSI 256 color.
+	*/
+	ansi256ToAnsi(code: number): number;
+
+	/**
+	Convert from the RGB color space to the ANSI 16 color space.
+
+	@param red - (`0...255`)
+	@param green - (`0...255`)
+	@param blue - (`0...255`)
+	*/
+	rgbToAnsi(red: number, green: number, blue: number): number;
+
+	/**
+	Convert from the RGB HEX color space to the ANSI 16 color space.
+
+	@param hex - A hexadecimal string containing RGB data.
+	*/
+	hexToAnsi(hex: string): number;
 }
 
 declare const ansiStyles: {

index.js

@@ -1,5 +1,7 @@
 const ANSI_BACKGROUND_OFFSET = 10;
 
+const wrapAnsi16 = (offset = 0) => code => `\u001B[${code + offset}m`;
+
 const wrapAnsi256 = (offset = 0) => code => `\u001B[${38 + offset};5;${code}m`;
 
 const wrapAnsi16m = (offset = 0) => (red, green, blue) => `\u001B[${38 + offset};2;${red};${green};${blue}m`;
@@ -93,8 +95,10 @@ function assembleStyles() {
 	styles.color.close = '\u001B[39m';
 	styles.bgColor.close = '\u001B[49m';
 
+	styles.color.ansi = wrapAnsi16();
 	styles.color.ansi256 = wrapAnsi256();
 	styles.color.ansi16m = wrapAnsi16m();
+	styles.bgColor.ansi = wrapAnsi16(ANSI_BACKGROUND_OFFSET);
 	styles.bgColor.ansi256 = wrapAnsi256(ANSI_BACKGROUND_OFFSET);
 	styles.bgColor.ansi16m = wrapAnsi16m(ANSI_BACKGROUND_OFFSET);
 
@@ -149,6 +153,58 @@ function assembleStyles() {
 		hexToAnsi256: {
 			value: hex => styles.rgbToAnsi256(...styles.hexToRgb(hex)),
 			enumerable: false
+		},
+		ansi256ToAnsi: {
+			value: code => {
+				if (code < 8) {
+					return 30 + code;
+				}
+
+				if (code < 16) {
+					return 90 + (code - 8);
+				}
+
+				let red;
+				let green;
+				let blue;
+
+				if (code >= 232) {
+					red = (((code - 232) * 10) + 8) / 255;
+					green = red;
+					blue = red;
+				} else {
+					code -= 16;
+
+					const remainder = code % 36;
+
+					red = Math.floor(code / 36) / 5;
+					green = Math.floor(remainder / 6) / 5;
+					blue = (remainder % 6) / 5;
+				}
+
+				const value = Math.max(red, green, blue) * 2;
+
+				if (value === 0) {
+					return 30;
+				}
+
+				let result = 30 + ((Math.round(blue) << 2) | (Math.round(green) << 1) | Math.round(red));
+
+				if (value === 2) {
+					result += 60;
+				}
+
+				return result;
+			},
+			enumerable: false
+		},
+		rgbToAnsi: {
+			value: (red, green, blue) => styles.ansi256ToAnsi(styles.rgbToAnsi256(red, green, blue)),
+			enumerable: false
+		},
+		hexToAnsi: {
+			value: hex => styles.ansi256ToAnsi(styles.hexToAnsi256(hex)),
+			enumerable: false
 		}
 	});
 

readme.md

@@ -25,6 +25,7 @@ console.log(`${styles.green.open}Hello world!${styles.green.close}`);
 //       may be degraded to fit the new color palette. This means terminals
 //       that do not support 16 million colors will best-match the
 //       original color.
+console.log(`${styles.color.ansi(styles.rgbToAnsi(199, 20, 250))}Hello World${styles.color.close}`)
 console.log(`${styles.color.ansi256(styles.rgbToAnsi256(199, 20, 250))}Hello World${styles.color.close}`)
 console.log(`${styles.color.ansi16m(...styles.hexToRgb('#abcdef'))}Hello World${styles.color.close}`)
 ```
@@ -112,21 +113,25 @@ console.log(styles.codes.get(36));
 //=> 39
 ```
 
-## [256 / 16 million (TrueColor) support](https://gist.github.com/XVilka/8346728)
+## 16 / 256 / 16 million (TrueColor) support
 
-`ansi-styles` allows converting between various color formats and ANSI escapes, with support for 256 and 16 million colors.
+`ansi-styles` allows converting between various color formats and ANSI escapes, with support for 16, 256 and [16 million colors](https://gist.github.com/XVilka/8346728).
 
-The following color spaces from `color-convert` are supported:
+The following color spaces are supported:
 
 - `rgb`
 - `hex`
 - `ansi256`
+- `ansi`
 
 To use these, call the associated conversion function with the intended output, for example:
 
 ```js
 import styles from 'ansi-styles';
 
+styles.color.ansi(styles.rgbToAnsi(100, 200, 15)); // RGB to 16 color ansi foreground code
+styles.bgColor.ansi(styles.hexToAnsi('#C0FFEE')); // HEX to 16 color ansi foreground code
+
 styles.color.ansi256(styles.rgbToAnsi256(100, 200, 15)); // RGB to 256 color ansi foreground code
 styles.bgColor.ansi256(styles.hexToAnsi256('#C0FFEE')); // HEX to 256 color ansi foreground code
 

test/test.js

@@ -19,6 +19,16 @@ test('groups should not be enumerable', t => {
 	t.false(Object.keys(ansiStyles).includes('modifier'));
 });
 
+test('support conversion to ansi (16 colors)', t => {
+	t.is(ansiStyles.color.ansi(ansiStyles.rgbToAnsi(255, 255, 255)), '\u001B[97m');
+	t.is(ansiStyles.color.ansi(ansiStyles.hexToAnsi('#990099')), '\u001B[35m');
+	t.is(ansiStyles.color.ansi(ansiStyles.hexToAnsi('#FF00FF')), '\u001B[95m');
+
+	t.is(ansiStyles.bgColor.ansi(ansiStyles.rgbToAnsi(255, 255, 255)), '\u001B[107m');
+	t.is(ansiStyles.bgColor.ansi(ansiStyles.hexToAnsi('#990099')), '\u001B[45m');
+	t.is(ansiStyles.bgColor.ansi(ansiStyles.hexToAnsi('#FF00FF')), '\u001B[105m');
+});
+
 test('support conversion to ansi (256 colors)', t => {
 	t.is(ansiStyles.color.ansi256(ansiStyles.rgbToAnsi256(255, 255, 255)), '\u001B[38;5;231m');
 	t.is(ansiStyles.color.ansi256(ansiStyles.hexToAnsi256('#990099')), '\u001B[38;5;127m');