Method render

lib/renderer.ts:267–503

* Render the terminal buffer to canvas

(
    buffer: IRenderable,
    forceAll: boolean = false,
    viewportY: number = 0,
    scrollbackProvider?: IScrollbackProvider,
    scrollbarOpacity: number = 1
  )

   * Render the terminal buffer to canvas
   */
  public render(
    buffer: IRenderable,
    forceAll: boolean = false,
    viewportY: number = 0,
    scrollbackProvider?: IScrollbackProvider,
    scrollbarOpacity: number = 1
  ): void {
    // Store buffer reference for grapheme lookups in renderCell
    this.currentBuffer = buffer;

    // getCursor() calls update() internally to ensure fresh state.
    // Multiple update() calls are safe - dirty state persists until clearDirty().
    const cursor = buffer.getCursor();
    const dims = buffer.getDimensions();
    const scrollbackLength = scrollbackProvider ? scrollbackProvider.getScrollbackLength() : 0;

    // Check if buffer needs full redraw (e.g., screen change between normal/alternate)
    if (buffer.needsFullRedraw?.()) {
      forceAll = true;
    }

    // Resize canvas if dimensions changed
    const needsResize =
      this.canvas.width !== dims.cols * this.metrics.width * this.devicePixelRatio ||
      this.canvas.height !== dims.rows * this.metrics.height * this.devicePixelRatio;

    if (needsResize) {
      this.resize(dims.cols, dims.rows);
      forceAll = true; // Force full render after resize
    }

    // Force re-render when viewport changes (scrolling)
    if (viewportY !== this.lastViewportY) {
      forceAll = true;
      this.lastViewportY = viewportY;
    }

    // Check if cursor position changed or if blinking (need to redraw cursor line)
    const cursorMoved =
      cursor.x !== this.lastCursorPosition.x || cursor.y !== this.lastCursorPosition.y;
    if (cursorMoved || this.cursorBlink) {
      // Mark cursor lines as needing redraw
      if (!forceAll && !buffer.isRowDirty(cursor.y)) {
        // Need to redraw cursor line
        const line = buffer.getLine(cursor.y);
        if (line) {
          this.renderLine(line, cursor.y, dims.cols);
        }
      }
      if (cursorMoved && this.lastCursorPosition.y !== cursor.y) {
        // Also redraw old cursor line if cursor moved to different line
        if (!forceAll && !buffer.isRowDirty(this.lastCursorPosition.y)) {
          const line = buffer.getLine(this.lastCursorPosition.y);
          if (line) {
            this.renderLine(line, this.lastCursorPosition.y, dims.cols);
          }
        }
      }