/// <summary>
/// 弹出
/// </summary>
/// <param name="popupItem">窗体实例</param>
/// <param name="rect">矩形区域</param>
/// <returns>Task</returns>
private async Task ShowPopup(PopupItem popupItem, Rectangle rect)
{
//重绘
_rect = rect;
_canvasView.InvalidateSurface();
// 响应不传递
_absoluteLayout.InputTransparent = false;
// 画布可见
_canvasView.IsVisible = true;
// 获取弹窗的view对象
var popup = ((AbsoluteLayout)Children[1]).Children.First(c => c == popupItem.Content);
// 向内偏移2
var localRect = new Rectangle(rect.X + 2, rect.Y + 2, rect.Width - 4, rect.Height - 4);
// 设置弹窗位置
popup.SetValue(AbsoluteLayout.LayoutBoundsProperty, localRect);
// 弹窗对象可见
//popupItem.IsShown = true;
// 弹窗view可见
popup.IsVisible = true;
// 显示动画
await Task.WhenAll(
popup.FadeTo(1, 200, Easing.CubicInOut),
_canvasView.FadeTo(1, 200, Easing.CubicInOut)
).ConfigureAwait(false);
}