Miguel Palhas
3ce1a6f331
PgUp/PgDn and the `- / | ~` symbols the soft keyboard buries behind a page switch join the bar, in an 8-column grid that keeps the cursor inverted-T. Columns hold a thumb's width, so a narrow phone scrolls the bar sideways instead of shrinking the caps. Closes #7
41 lines
1.7 KiB
TypeScript
41 lines
1.7 KiB
TypeScript
// Terminal key encoding: control characters, meta prefixes, and cursor escape
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// sequences. Table-driven and easy to get subtly wrong, so it lives apart from
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// the DOM and is tested directly.
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export function toCtrl(ch: string): string {
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if (ch.length !== 1) return ch;
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const upper = ch.toUpperCase().codePointAt(0) ?? 0;
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if (upper >= 0x40 && upper <= 0x5f) return String.fromCodePoint(upper & 0x1f);
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if (ch === " ") return "\x00";
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if (ch === "?") return "\x7f";
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return ch;
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}
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/** Apply pending modifiers to a single typed character: Ctrl → control code,
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* Alt → ESC prefix (xterm meta). Both compose (Ctrl+Alt = ESC + control). */
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export function applyModsToChar(ch: string, ctrl: boolean, alt: boolean): string {
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let out = ctrl ? toCtrl(ch) : ch;
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if (alt) out = "\x1b" + out;
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return out;
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}
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/** Cursor/nav-key sequence, promoted to the modified CSI form when Ctrl/Alt are
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* pending — `\x1b[1;<n><final>`, n = 1 + alt(2) + ctrl(4) (xterm convention). */
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export function cursorSeq(final: string, ctrl: boolean, alt: boolean): string {
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if (!ctrl && !alt) return `\x1b[${final}`;
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return `\x1b[1;${modParam(ctrl, alt)}${final}`;
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}
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/** Modifier parameter of the xterm CSI forms: n = 1 + alt(2) + ctrl(4). */
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function modParam(ctrl: boolean, alt: boolean): number {
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return 1 + (alt ? 2 : 0) + (ctrl ? 4 : 0);
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}
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/** Sequence for the `~`-terminated navigation keys (PgUp `5`, PgDn `6`), which
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* carry modifiers as `\x1b[<code>;<n>~` rather than the cursor keys' `1;<n>`
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* form. */
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export function tildeSeq(code: number, ctrl: boolean, alt: boolean): string {
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if (!ctrl && !alt) return `\x1b[${code}~`;
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return `\x1b[${code};${modParam(ctrl, alt)}~`;
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}
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