| 1 | // Mouse support. |
| 2 | // |
| 3 | // Ink has none — it reads keys and nothing else — so this turns tracking on at |
| 4 | // the terminal and parses the reports itself. |
| 5 | // |
| 6 | // Two escape sequences do the enabling. `?1000h` asks for button press/release |
| 7 | // reports; `?1006h` asks for them in SGR form. The second one matters: the |
| 8 | // original X10 encoding packs coordinates into single bytes offset by 32, which |
| 9 | // silently breaks past column 223 — a width any real terminal exceeds. SGR mode |
| 10 | // reports decimal coordinates instead and has no such ceiling. |
| 11 | // |
| 12 | // Both must be turned back off on exit. A terminal left in tracking mode after |
| 13 | // the program dies emits escape sequences into the user's shell every time they |
| 14 | // move the mouse, which looks like the shell is broken. |
| 15 | import { useEffect, useRef } from 'react'; |
| 16 | import { useStdin, useStdout } from 'ink'; |
| 17 | |
| 18 | const ENABLE = '\x1b[?1000h\x1b[?1006h'; |
| 19 | const DISABLE = '\x1b[?1006l\x1b[?1000l'; |
| 20 | |
| 21 | export type MouseButton = 'left' | 'middle' | 'right' | 'wheel-up' | 'wheel-down'; |
| 22 | |
| 23 | export interface MouseEvent { |
| 24 | button: MouseButton; |
| 25 | /** Zero-based, converted from the terminal's one-based coordinates. */ |
| 26 | column: number; |
| 27 | row: number; |
| 28 | pressed: boolean; |
| 29 | } |
| 30 | |
| 31 | // SGR reports look like `ESC [ < button ; column ; row (M|m)`, where M is a |
| 32 | // press and m a release. |
| 33 | // |
| 34 | // The leading ESC is optional here, and that is not defensiveness — Ink's key |
| 35 | // parser consumes the ESC before handing the rest to useInput, so the very same |
| 36 | // report reaches this module as `\x1b[<0;9;6M` on raw stdin and as `[<0;9;6M` |
| 37 | // through the keymap. Both have to be recognised: the first to be acted on, the |
| 38 | // second to be discarded before it gets typed into the buffer. |
| 39 | const SGR = /(?:\x1b)?\[<(\d+);(\d+);(\d+)([Mm])/g; |
| 40 | |
| 41 | /** True if a chunk contains a mouse report — used to keep them out of the keymap. */ |
| 42 | export function isMouseSequence(input: string): boolean { |
| 43 | return /(?:\x1b)?\[<\d+;\d+;\d+[Mm]/.test(input); |
| 44 | } |
| 45 | |
| 46 | function decodeButton(code: number): MouseButton | null { |
| 47 | // Bit 6 marks wheel events; the low bits then say which direction. |
| 48 | if (code & 64) return (code & 1) === 0 ? 'wheel-up' : 'wheel-down'; |
| 49 | // Bits 2-5 are modifier keys (shift/meta/ctrl) and drag state, not the button. |
| 50 | switch (code & 3) { |
| 51 | case 0: return 'left'; |
| 52 | case 1: return 'middle'; |
| 53 | case 2: return 'right'; |
| 54 | default: return null; // 3 is "released, button unknown" |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | /** Parse every mouse report in a chunk. Non-mouse bytes are ignored. */ |
| 59 | export function parseMouse(chunk: string): MouseEvent[] { |
| 60 | const events: MouseEvent[] = []; |
| 61 | SGR.lastIndex = 0; |
| 62 | let match: RegExpExecArray | null; |
| 63 | while ((match = SGR.exec(chunk)) !== null) { |
| 64 | const button = decodeButton(Number(match[1])); |
| 65 | if (!button) continue; |
| 66 | events.push({ |
| 67 | button, |
| 68 | column: Number(match[2]) - 1, |
| 69 | row: Number(match[3]) - 1, |
| 70 | pressed: match[4] === 'M', |
| 71 | }); |
| 72 | } |
| 73 | return events; |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * Enable mouse reporting for as long as the component is mounted, and call |
| 78 | * `onEvent` for each report. |
| 79 | * |
| 80 | * Only presses are delivered — releases would double every click, and nothing |
| 81 | * here needs drag. |
| 82 | */ |
| 83 | export function useMouse(onEvent: (event: MouseEvent) => void): void { |
| 84 | const { stdin, isRawModeSupported } = useStdin(); |
| 85 | const { stdout } = useStdout(); |
| 86 | |
| 87 | // The handler goes through a ref so the effect's dependencies stay stable. |
| 88 | // Its natural dependencies — the layout, the song list — are rebuilt on every |
| 89 | // render, and this component re-renders 25 times a second to animate. With |
| 90 | // `onEvent` in the dependency array the effect would tear down and re-arm at |
| 91 | // that rate: writing the enable/disable sequences continuously, and piling up |
| 92 | // process 'exit' listeners until Node started warning about a leak. Reading |
| 93 | // the latest handler from a ref means the terminal is configured exactly once. |
| 94 | const handler = useRef(onEvent); |
| 95 | handler.current = onEvent; |
| 96 | |
| 97 | useEffect(() => { |
| 98 | if (!isRawModeSupported) return; |
| 99 | |
| 100 | stdout.write(ENABLE); |
| 101 | const listener = (data: Buffer | string): void => { |
| 102 | for (const event of parseMouse(data.toString('utf8'))) { |
| 103 | if (event.pressed) handler.current(event); |
| 104 | } |
| 105 | }; |
| 106 | stdin.on('data', listener); |
| 107 | |
| 108 | // Also disarm if the process is killed outright — an unmount handler alone |
| 109 | // doesn't run on SIGINT/SIGTERM, and that's exactly when a terminal gets |
| 110 | // left in tracking mode. |
| 111 | const restore = (): void => void stdout.write(DISABLE); |
| 112 | process.on('exit', restore); |
| 113 | |
| 114 | return () => { |
| 115 | stdin.off('data', listener); |
| 116 | process.off('exit', restore); |
| 117 | stdout.write(DISABLE); |
| 118 | }; |
| 119 | }, [stdin, stdout, isRawModeSupported]); |
| 120 | } |