onKey method

@override bool onKey(KeyEvent event, RenderContext ctx)

Implementation

@override
bool onKey(KeyEvent event, RenderContext ctx) {
  // We don't know viewport size here; use a generous default that gets
  // clamped on render. Storage is intentionally a count, not pixel.
  const page = 10;
  switch (event.key) {
    case NamedKey.arrowDown:
      state.offsetY += 1;
      return true;
    case NamedKey.arrowUp:
      if (state.offsetY > 0) state.offsetY -= 1;
      return true;
    case NamedKey.pageDown:
      state.offsetY += page;
      return true;
    case NamedKey.pageUp:
      state.offsetY = (state.offsetY - page).clamp(0, contentHeight);
      return true;
    case NamedKey.home:
      state.offsetY = 0;
      if (horizontal) state.offsetX = 0;
      return true;
    case NamedKey.end:
      state.offsetY = contentHeight;
      return true;
    case NamedKey.arrowLeft:
      if (horizontal && state.offsetX > 0) state.offsetX -= 1;
      return horizontal;
    case NamedKey.arrowRight:
      if (horizontal) state.offsetX += 1;
      return horizontal;
    default:
      return false;
  }
}