findViewport method

RenderViewport? findViewport(BuildContext? context)

查找视口渲染对象

参数：

• context：上下文
• 返回值：视口渲染对象，如果找不到则返回null

Implementation

RenderViewport? findViewport(BuildContext? context) {
  if (context == null) {
    return null;
  }
  RenderViewport? result;
  context.visitChildElements((Element e) {
    final RenderObject? renderObject = e.findRenderObject();
    if (renderObject is RenderViewport) {
      assert(result == null);
      result = renderObject;
    } else {
      result = findViewport(e);
    }
  });
  return result;
}