Make mobile terminals load faster (#1147)

* Speed up terminal restores on mobile * Preserve terminal output bytes in the app
2026-05-23 18:41:10 +08:00
parent 84f1dfc8cb
commit 846c9b9da3
32 changed files with 1304 additions and 357 deletions
@@ -0,0 +1,205 @@
+import type { TerminalCell, TerminalState } from "./messages.js";
+
+interface TerminalStyle {
+  fg: number | undefined;
+  bg: number | undefined;
+  fgMode: number | undefined;
+  bgMode: number | undefined;
+  bold: boolean;
+  italic: boolean;
+  underline: boolean;
+  dim: boolean;
+  inverse: boolean;
+  strikethrough: boolean;
+}
+
+const DEFAULT_STYLE: TerminalStyle = {
+  fg: undefined,
+  bg: undefined,
+  fgMode: undefined,
+  bgMode: undefined,
+  bold: false,
+  italic: false,
+  underline: false,
+  dim: false,
+  inverse: false,
+  strikethrough: false,
+};
+
+export function renderTerminalSnapshotToAnsi(state: TerminalState): string {
+  const rows = [...state.scrollback, ...state.grid];
+  const lines: string[] = ["\u001b[?7l"];
+
+  for (let rowIndex = 0; rowIndex < rows.length; rowIndex += 1) {
+    const row = rows[rowIndex] ?? [];
+    lines.push(renderTerminalRow(row));
+    if (rowIndex < rows.length - 1) {
+      lines.push("\r\n");
+    }
+  }
+
+  lines.push("\u001b[0m");
+  const cursorPresentationAnsi = renderCursorPresentationToAnsi(state.cursor);
+  if (cursorPresentationAnsi) {
+    lines.push(cursorPresentationAnsi);
+  }
+  lines.push(`\u001b[${state.cursor.row + 1};${state.cursor.col + 1}H`);
+  lines.push(state.cursor.hidden ? "\u001b[?25l" : "\u001b[?25h");
+  lines.push("\u001b[?7h");
+  return lines.join("");
+}
+
+function renderCursorPresentationToAnsi(cursor: TerminalState["cursor"]): string | null {
+  if (!cursor.style) {
+    return null;
+  }
+
+  const cursorStyleCode = (() => {
+    if (cursor.style === "block") {
+      return cursor.blink === false ? 2 : 1;
+    }
+    if (cursor.style === "underline") {
+      return cursor.blink === false ? 4 : 3;
+    }
+    return cursor.blink === false ? 6 : 5;
+  })();
+
+  return `\u001b[${cursorStyleCode} q`;
+}
+
+function renderTerminalRow(row: TerminalCell[]): string {
+  const output: string[] = [];
+  const length = getTerminalRowLength(row);
+  let previousStyle = DEFAULT_STYLE;
+
+  for (let index = 0; index < length; index += 1) {
+    const cell = row[index] ?? { char: " " };
+    const nextStyle = getTerminalStyle(cell);
+    if (!terminalStylesEqual(previousStyle, nextStyle)) {
+      output.push(styleToAnsi(nextStyle));
+      previousStyle = nextStyle;
+    }
+    output.push(cell.char || " ");
+  }
+
+  if (!terminalStylesEqual(previousStyle, DEFAULT_STYLE)) {
+    output.push("\u001b[0m");
+  }
+
+  return output.join("");
+}
+
+function getTerminalRowLength(row: TerminalCell[]): number {
+  for (let index = row.length - 1; index >= 0; index -= 1) {
+    const cell = row[index];
+    if (!cell) {
+      continue;
+    }
+    if (cell.char !== " ") {
+      return index + 1;
+    }
+    if (
+      cell.fg !== undefined ||
+      cell.bg !== undefined ||
+      cell.fgMode !== undefined ||
+      cell.bgMode !== undefined ||
+      cell.bold ||
+      cell.italic ||
+      cell.underline ||
+      cell.dim ||
+      cell.inverse ||
+      cell.strikethrough
+    ) {
+      return index + 1;
+    }
+  }
+  return 0;
+}
+
+function getTerminalStyle(cell: TerminalCell): TerminalStyle {
+  return {
+    fg: cell.fg,
+    bg: cell.bg,
+    fgMode: cell.fgMode,
+    bgMode: cell.bgMode,
+    bold: Boolean(cell.bold),
+    italic: Boolean(cell.italic),
+    underline: Boolean(cell.underline),
+    dim: Boolean(cell.dim),
+    inverse: Boolean(cell.inverse),
+    strikethrough: Boolean(cell.strikethrough),
+  };
+}
+
+function terminalStylesEqual(left: TerminalStyle, right: TerminalStyle): boolean {
+  return (
+    left.fg === right.fg &&
+    left.bg === right.bg &&
+    left.fgMode === right.fgMode &&
+    left.bgMode === right.bgMode &&
+    left.bold === right.bold &&
+    left.italic === right.italic &&
+    left.underline === right.underline &&
+    left.dim === right.dim &&
+    left.inverse === right.inverse &&
+    left.strikethrough === right.strikethrough
+  );
+}
+
+function styleToAnsi(style: TerminalStyle): string {
+  const codes = ["0"];
+
+  if (style.bold) {
+    codes.push("1");
+  }
+  if (style.dim) {
+    codes.push("2");
+  }
+  if (style.italic) {
+    codes.push("3");
+  }
+  if (style.underline) {
+    codes.push("4");
+  }
+  if (style.inverse) {
+    codes.push("7");
+  }
+  if (style.strikethrough) {
+    codes.push("9");
+  }
+
+  if (style.fg !== undefined && style.fgMode !== undefined) {
+    codes.push(...colorToSgr(style.fgMode, style.fg, false));
+  }
+
+  if (style.bg !== undefined && style.bgMode !== undefined) {
+    codes.push(...colorToSgr(style.bgMode, style.bg, true));
+  }
+
+  return `\u001b[${codes.join(";")}m`;
+}
+
+function colorToSgr(mode: number, value: number, background: boolean): string[] {
+  if (mode === 1) {
+    if (value >= 8) {
+      return [String((background ? 100 : 90) + (value - 8))];
+    }
+    return [String((background ? 40 : 30) + value)];
+  }
+
+  if (mode === 2) {
+    return [background ? "48" : "38", "5", String(value)];
+  }
+
+  if (mode === 3) {
+    return [
+      background ? "48" : "38",
+      "2",
+      String((value >> 16) & 0xff),
+      String((value >> 8) & 0xff),
+      String(value & 0xff),
+    ];
+  }
+
+  return [];
+}