ViewModel issue

Question

我需要弹出一个需要时间的窗口。按钮处于按下状态，直到打开新窗口。因此，我想在单击按钮之后和窗口打开之前，在UI窗口上添加一个等待指示符。ViewModel的代码是正确的，因为我引用了一个示例代码。但是为什么在我点击按钮后没有回应。

项目文件URL

https://supportcenter.devexpress.com/attachment/file/5268961b-ce35-4e40-b7c1-e33bffab902b

主窗口：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using DevExpress.Xpf.Core;
namespace WaitIndicatorDemo
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : DXWindow
{
public MainWindow()
{
InitializeComponent();
vm = new MainVM();
DataContext = vm;
}
MainVM vm;
private void buttonShow_Click(object sender, RoutedEventArgs e)
{
vm.IsBusy = !vm.IsBusy;
}
}
}

查看模式：

using DevExpress.Mvvm;
namespace WaitIndicatorDemo
{
public class MainVM
{
private readonly ISplashScreenService _waitIndicatorService;
public virtual bool IsBusy { get; set; }
public MainVM()
{
_waitIndicatorService = 
ServiceContainer.Default.GetService<ISplashScreenService>("WaitIndicatorService");
}
protected void OnIsBusyChanged()
{
if (IsBusy)
_waitIndicatorService.ShowSplashScreen();
else
_waitIndicatorService.HideSplashScreen();
}
}
}

下面是XAML，注释部分是原始示例代码。复选框绑定到IsBusy。选中复选框时，指示器会弹出。我现在想在按下按钮后弹出。

<dx:DXWindow x:Class="WaitIndicatorDemo.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
xmlns:dxmvvm="http://schemas.devexpress.com/winfx/2008/xaml/mvvm"
xmlns:waitIndicatorDemo="clr-namespace:WaitIndicatorDemo"
xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
WindowStartupLocation="CenterScreen" SnapsToDevicePixels="True"
Title="MainWindow" Height="350" Width="525">
<!--DataContext="{dxmvvm:ViewModelSource Type=waitIndicatorDemo:MainVM}"-->
<!--Title="MainWindow" Height="350" Width="525">-->
<Grid Margin="10">
<!--<dxe:CheckEdit Content="Is Busy" IsChecked="{Binding IsBusy}" 
VerticalAlignment="Top" HorizontalAlignment="Left" />
<Button Content="Button1" IsEnabled ="{Binding IsBusy, Converter={dxmvvm:BooleanNegationConverter}}"
VerticalAlignment="Top" HorizontalAlignment="Center" Click="Button_Click"/>
<Button Content="Button2" IsEnabled="{Binding IsBusy, Converter={dxmvvm:BooleanNegationConverter}}"
VerticalAlignment="Top" HorizontalAlignment="Right"/>-->
<Button x:Name="buttonShow" Content="Show"  HorizontalAlignment="Left" Height="35" Margin="50,70,0,0" VerticalAlignment="Top" Width="75" Click="buttonShow_Click" />
</Grid>
</dx:DXWindow>

Answer 1

您的代码示例中有几个错误：
1-从未调用ViewModel中的方法OnIsBusyChanged
2-XAML在Window行为中没有声明任何ISplashScreenService对象，例如DXSplashScreenService。

以下是如何解决这两个问题。

首先，修复ViewModel。

public class MainVM
{
private readonly ISplashScreenService _waitIndicatorService;
private bool _isBusy;
public virtual bool IsBusy 
{
get
{
return _isBusy;
}
set
{
_isBusy = value;
OnIsBusyChanged();
}
}
public MainVM()
{
_waitIndicatorService = 
ServiceContainer.Default.GetService<ISplashScreenService>("WaitIndicatorService");
}
protected void OnIsBusyChanged()
{
_waitIndicatorService.SetSplashScreenState("Doing some work...");
if (IsBusy)
_waitIndicatorService.ShowSplashScreen();
else
_waitIndicatorService.HideSplashScreen();
}
}

然后，您的XAML。

<dx:DXWindow x:Class="WaitIndicatorDemo.MainWindow"
<!-- ... -->
Title="MainWindow" Height="350" Width="525">
<dxmvvm:Interaction.Behaviors>
<dx:DXSplashScreenService x:Name="WaitIndicatorService">
<dx:DXSplashScreenService.ViewTemplate>
<DataTemplate>
<Grid>
<Border Background="LightGray" CornerRadius="5">
<Border BorderBrush="#FF0072C6" BorderThickness="1" Margin="15" CornerRadius="5">
<Grid>
<ProgressBar BorderThickness="0" Value="{Binding Progress}" Maximum="{Binding MaxProgress}" IsIndeterminate="{Binding IsIndeterminate}" Height="12" />
<TextBlock Text="{Binding State, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Grid>
</Border>
</Border>
</Grid>
</DataTemplate>
</dx:DXSplashScreenService.ViewTemplate>
</dx:DXSplashScreenService>
</dxmvvm:Interaction.Behaviors>
<Grid Margin="10">
<!-- ... -->
</Grid>
</dx:DXWindow>

此代码主要取自"如何：使用DxSplashScreenService"示例。