diff options
Diffstat (limited to 'util/ansi.js')
| -rw-r--r-- | util/ansi.js | 272 |
1 files changed, 272 insertions, 0 deletions
diff --git a/util/ansi.js b/util/ansi.js new file mode 100644 index 0000000..0e6e3fe --- /dev/null +++ b/util/ansi.js @@ -0,0 +1,272 @@ +const ESC = '\x1b' + +const isDigit = char => '0123456789'.indexOf(char) >= 0 + +const ansi = { + ESC, + + // Attributes + A_RESET: 0, + A_BRIGHT: 1, + A_DIM: 2, + A_INVERT: 7, + C_BLACK: 30, + C_RED: 31, + C_GREEN: 32, + C_YELLOW: 33, + C_BLUE: 34, + C_MAGENTA: 35, + C_CYAN: 36, + C_WHITE: 37, + C_RESET: 39, + + clearScreen() { + // Clears the screen, removing any characters displayed, and resets the + // cursor position. + + return `${ESC}[2J` + }, + + moveCursorRaw(line, col) { + // Moves the cursor to the given line and column on the screen. + // Returns the pure ANSI code, with no modification to line or col. + + return `${ESC}[${line};${col}H` + }, + + moveCursor(line, col) { + // Moves the cursor to the given line and column on the screen. + // Note that since in JavaScript indexes start at 0, but in ANSI codes + // the top left of the screen is (1, 1), this function adjusts the + // arguments to act as if the top left of the screen is (0, 0). + + return `${ESC}[${line + 1};${col + 1}H` + }, + + hideCursor() { + // Makes the cursor invisible. + + return `${ESC}[?25l` + }, + + showCursor() { + // Makes the cursor visible. + + return `${ESC}[?25h` + }, + + resetAttributes() { + // Resets all attributes, including text decorations, foreground and + // background color. + + return `${ESC}[0m` + }, + + setAttributes(attrs) { + // Set some raw attributes. See the attributes section of the ansi.js + // source code for attributes that can be used with this; A_RESET resets + // all attributes. + + return `${ESC}[${attrs.join(';')}m` + }, + + setForeground(color) { + // Sets the foreground color to print text with. See C_(COLOR) for colors + // that can be used with this; C_RESET resets the foreground. + // + // If null or undefined is passed, this function will return a blank + // string (no ANSI escape codes). + + if (typeof color === 'undefined' || color === null) { + return '' + } + + return ansi.setAttributes([color]) + }, + + invert() { + // Inverts the foreground and background colors. + + return `${ESC}[7m` + }, + + requestCursorPosition() { + // Requests the position of the cursor. + // Expect a stdin-result '\ESC[l;cR', where l is the line number (1-based), + // c is the column number (also 1-based), and R is the literal character + // 'R' (decimal code 82). + + return `${ESC}[6n` + }, + + isANSICommand(buffer, code = null) { + return ( + buffer[0] === 0x1b && buffer[1] === 0x5b && + (code ? buffer[buffer.length - 1] === code : true) + ) + }, + + + interpret(text, scrRows, scrCols) { + // Interprets the given ansi code, more or less. + + const blank = { + attributes: [], + char: ' ' + } + + const chars = new Array(scrRows * scrCols).fill(blank) + + let cursorRow = 1 + let cursorCol = 1 + const attributes = [] + const getCursorIndex = () => (cursorRow - 1) * scrCols + (cursorCol - 1) + + for (let charI = 0; charI < text.length; charI++) { + if (text[charI] === ESC) { + charI++ + + if (text[charI] !== '[') { + throw new Error('ESC not followed by [') + } + + charI++ + + const args = [] + let val = '' + while (isDigit(text[charI])) { + val += text[charI] + charI++ + + if (text[charI] === ';') { + charI++ + args.push(val) + val = '' + continue + } + } + args.push(val) + + // CUP - Cursor Position (moveCursor) + if (text[charI] === 'H') { + cursorRow = args[0] + cursorCol = args[1] + } + + // ED - Erase Display (clearScreen) + if (text[charI] === 'J') { + // ESC[2J - erase whole display + if (args[0] === '2') { + chars.fill(blank) + charI += 3 + cursorCol = 1 + cursorRow = 1 + } + + // ESC[1J - erase to beginning + else if (args[0] === '1') { + for (let i = 0; i < getCursorIndex(); i++) { + chars[i] = blank + } + } + + // ESC[0J - erase to end + else if (args.length === 0 || args[0] === '0') { + for (let i = getCursorIndex(); i < chars.length; i++) { + chars[i] = blank + } + } + } + + // SGR - Select Graphic Rendition + if (text[charI] === 'm') { + for (let arg of args) { + if (arg === '0') { + attributes.splice(0, attributes.length) + } else { + attributes.push(arg) + } + } + } + + continue + } + + // debug + /* + if (text[charI] === '.') { + console.log( + `#1-char "${text[charI]}" at ` + + `(${cursorRow},${cursorCol}):${getCursorIndex()} ` + + ` attr:[${attributes.join(';')}]` + ) + } + */ + + chars[getCursorIndex()] = { + char: text[charI], + attributes: attributes.slice() + } + + cursorCol++ + + if (cursorCol > scrCols) { + cursorCol = 1 + cursorRow++ + } + } + + // Character concatenation ----------- + + // Move to the top left of the screen initially. + const result = [ ansi.moveCursorRaw(1, 1) ] + + let lastChar = { + char: '', + attributes: [] + } + + //let n = 1 // debug + + for (let char of chars) { + const newAttributes = ( + char.attributes.filter(attr => !(lastChar.attributes.includes(attr))) + ) + + const removedAttributes = ( + lastChar.attributes.filter(attr => !(char.attributes.includes(attr))) + ) + + // The only way to practically remove any character attribute is to + // reset all of its attributes and then re-add its existing attributes. + // If we do that, there's no need to add new attributes. + if (removedAttributes.length) { + // console.log( + // `removed some attributes "${char.char}"`, removedAttributes + // ) + result.push(ansi.resetAttributes()) + result.push(`${ESC}[${char.attributes.join(';')}m`) + } else if (newAttributes.length) { + result.push(`${ESC}[${newAttributes.join(';')}m`) + } + + // debug + /* + if (char.char !== ' ') { + console.log( + `#2-char ${char.char}; ${chars.indexOf(char) - n} inbetween` + ) + n = chars.indexOf(char) + } + */ + + result.push(char.char) + + lastChar = char + } + + return result.join('') + } +} + +module.exports = ansi |