xamarin UWP平台下 HUD 自定义弹窗

   在我的上一篇博客中我写了一个在xamarin的UWP平台下的自定义弹窗控件。在上篇文章中介绍了一种弹窗的写法，但在实际应用中发现了该方法的不足：

   1、当弹窗出现后，我们拖动整个窗口大小的时候，弹窗的窗口大小没有随着主窗口大小变化。

   2、当弹窗出现时，在我们的主窗口上的后退按钮并没有被弹窗遮罩住，这导致了在弹窗的时候窗口还能返回。

   为解决上述问题，我们需更改原来的方式，方法如下：

   1、定义一个uwp平台的用户控件

    xaml文件代码：

<UserControl
    x:Class="Test.UWP.ExtendControls.UWPHUD"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Test.UWP.ExtendControls"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400">

    <Grid Name="mask_grid" Background="{ThemeResource TKHUDColorBrush}" >
        <Grid Grid.Row="0">
            <Border Background="Black" CornerRadius="10" HorizontalAlignment="Center" VerticalAlignment="Center">
                <TextBlock Margin="10" Name="msg_Txt" Foreground="White" Text="..." MinWidth="30" ></TextBlock>
            </Border>
        </Grid>
        
    </Grid>
</UserControl>

    xaml.cs文件代码：

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Core;
using Windows.UI.ViewManagement;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// The User Control item template is documented at http://go.microsoft.com/fwlink/?LinkId=234236

namespace Test.UWP.ExtendControls
{
    public sealed partial class UWPHUD : UserControl
    {
        
        Popup popup;
        public UWPHUD()
        {
            this.InitializeComponent();
            SystemNavigationManager.GetForCurrentView().BackRequested += UWPHUD_BackRequested;
        }
        public UWPHUD(string message)
        {
            this.InitializeComponent();
            SystemNavigationManager.GetForCurrentView().BackRequested += UWPHUD_BackRequested;
            msg_Txt.Text = message;
        }

        private void UWPHUD_BackRequested(object sender, BackRequestedEventArgs e)
        {
            HUDClose();
        }

        public void Show()
        {
            //var appView = ApplicationView.GetForCurrentView();
            popup = new Popup();
            popup.Child = this;
            var bounds = Window.Current.Bounds;
            this.Width = bounds.Width;
            this.Height = bounds.Height;
            popup.IsOpen = true;
        }
        public void HUDClose()
        {
            if (popup.IsOpen)
            {
                popup.IsOpen = false;
            }
        }
        
    }
}

    同时在原来的基础代码上调用现在定义好的uwp用户控件，代码如下：

using Mixin.Dependencies;
using Mixin.UWP.ExtendControls;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.UI;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Media;
using Xamarin.Forms;

[assembly: Dependency(typeof(Mixin.UWP.Dependencies.HUD))]
namespace Test.UWP.Dependencies
{
    public class HUD : IHUD
    {
        private UWPHUD uwpHUD = null; 
        public HUD() { }

        public void Show(string msg)
        {
            ShowProgress(msg);
        }
        public void ShowSuccess(string msg)
        {
            ShowProgress(msg, 2);
        }
        public void ShowError(string msg)
        {
            ShowProgress(msg, 2);
        }
        public void ShowErrorLong(string msg)
        {
            ShowProgress(msg, 30);
        }

        public void ShowProgress(string msg, int second = 0)
        {
            uwpHUD = new UWPHUD(msg);
            uwpHUD.Show();

            if (second > 0)
            {
                Task.Delay(second)
                .ContinueWith(t =>
                {
                    Device.BeginInvokeOnMainThread(() =>
                    {
                        uwpHUD.HUDClose();
                    });
                }
              );
            }
            else
            {
                Task.Delay(3000)
                .ContinueWith(t =>
                {
                    Device.BeginInvokeOnMainThread(() =>
                    {
                        uwpHUD.HUDClose();
                    });
                }
              );
            }
        }
        public void Dismiss()
        {
            Device.BeginInvokeOnMainThread(() =>
            {
                uwpHUD.HUDClose();
            });
        }
    }
}

     经如上方式可解决弹窗的两个问题。