.NET Core 3 WPF MVVM框架 Prism系列之區域管理器

時間  2020-05-11
標籤 core wpf mvvm 框架 prism 系列 區域 管理器 简体版
原文   原文鏈接

本文將介紹如何在.NET Core3環境下使用MVVM框架Prism的使用區域管理器對於View的管理git

一.區域管理器

咱們在以前的Prism系列構建了一個標準式Prism項目，這篇文章將會講解以前項目中用到的利用區域管理器更好的對咱們的View進行管理，一樣的咱們來看看官方給出的模型圖：github

如今咱們能夠知道的是，大體一個區域管理器RegionMannager對一個控件建立區域的要點：express

  • 建立Region的控件必須包含一個RegionAdapter適配器
  • region是依賴在具備RegionAdapter控件身上的

其實後來我去看了下官方的介紹和源碼，默認RegionAdapter是有三個，且還支持自定義RegionAdapter，所以在官方的模型圖之間我作了點補充：編程

二.區域建立與視圖的注入

咱們先來看看咱們以前項目的區域的劃分，以及如何建立區域而且把View注入到區域中：c#

咱們把整個主窗體劃分了四個區域：app

  • ShowSearchPatientRegion：注入了ShowSearchPatient視圖
  • PatientListRegion：注入了PatientList視圖
  • FlyoutRegion：注入了PatientDetail和SearchMedicine視圖
  • ShowSearchPatientRegion：注入了ShowSearchPatient視圖

在Prism中，咱們有兩種方式去實現區域建立和視圖注入：框架

  1. ViewDiscovery
  2. ViewInjection

1.ViewDiscovery

咱們截取其中PatientListRegion的建立和視圖注入的代碼(更仔細的能夠去觀看demo源碼)：async

MainWindow.xaml：ide

<ContentControl Grid.Row="2" prism:RegionManager.RegionName="PatientListRegion" Margin="10"/>

這裏至關於在後臺MainWindow.cs：模塊化

RegionManager.SetRegionName(ContentControl, "PatientListRegion");

PatientModule.cs：

public class PatientModule : IModule
 {
    public void OnInitialized(IContainerProvider containerProvider)
    {
         var regionManager = containerProvider.Resolve<IRegionManager>();
         //PatientList
         regionManager.RegisterViewWithRegion(RegionNames.PatientListRegion, typeof(PatientList));
         //PatientDetail-Flyout
         regionManager.RegisterViewWithRegion(RegionNames.FlyoutRegion, typeof(PatientDetail));
           
     }

    public void RegisterTypes(IContainerRegistry containerRegistry)
    {
           
    }
 }

2.ViewInjection

咱們在MainWindow窗體的Loaded事件中使用ViewInjection方式注入視圖PatientList

MainWindow.xaml：

<i:Interaction.Triggers>
      <i:EventTrigger EventName="Loaded">
          <i:InvokeCommandAction Command="{Binding LoadingCommand}"/>
       /i:EventTrigger>
  </i:Interaction.Triggers>

MainWindowViewModel.cs:

private IRegionManager _regionManager;
private IRegion _paientListRegion;        
private PatientList _patientListView;

private DelegateCommand _loadingCommand;
public DelegateCommand LoadingCommand =>
     _loadingCommand ?? (_loadingCommand = new DelegateCommand(ExecuteLoadingCommand));

void ExecuteLoadingCommand()
{
     _regionManager = CommonServiceLocator.ServiceLocator.Current.GetInstance<IRegionManager>();
     _paientListRegion = _regionManager.Regions[RegionNames.PatientListRegion];
     _patientListView = CommonServiceLocator.ServiceLocator.Current.GetInstance<PatientList>();
     _paientListRegion.Add(_patientListView);

 }

咱們能夠明顯的感受到兩種方式的不一樣，ViewDiscovery方式是自動地實例化視圖而且加載出來，而ViewInjection方式則是能夠手動控制注入視圖和加載視圖的時機(上述例子是經過Loaded事件)，官方對於二者的推薦使用場景以下：

ViewDiscovery：

  • 須要或要求自動加載視圖
  • 視圖的單個實例將加載到該區域中

ViewInjection：

  • 須要顯式或編程控制什麼時候建立和顯示視圖，或者您須要從區域中刪除視圖
  • 須要在區域中顯示相同視圖的多個實例，其中每一個視圖實例都綁定到不一樣的數據
  • 須要控制添加視圖的區域的哪一個實例
  • 應用程序使用導航API(後面會講到)

三.激活與失效視圖

Activate和Deactivate

首先咱們須要控制PatientList和MedicineMainContent兩個視圖的激活狀況，上代碼：

MainWindow.xaml：

<StackPanel Grid.Row="1">
    <Button  Content="Load MedicineModule" FontSize="25"  Margin="5" Command="{Binding LoadMedicineModuleCommand}"/>
     <UniformGrid Margin="5">
         <Button Content="ActivePaientList" Margin="5" Command="{Binding ActivePaientListCommand}"/>
         <Button Content="DeactivePaientList" Margin="5" Command="{Binding DeactivePaientListCommand}"/>
         <Button Content="ActiveMedicineList" Margin="5" Command="{Binding ActiveMedicineListCommand}"/>
         <Button Content="DeactiveMedicineList" Margin="5" Command="{Binding DeactiveMedicineListCommand}"/>
     </UniformGrid>
</StackPanel>

<ContentControl Grid.Row="2" prism:RegionManager.RegionName="PatientListRegion" Margin="10"/>
<ContentControl Grid.Row="3" prism:RegionManager.RegionName="MedicineMainContentRegion"/>

MainWindowViewModel.cs：

private IRegionManager _regionManager;
  private IRegion _paientListRegion;
  private IRegion _medicineListRegion;
  private PatientList _patientListView;
  private MedicineMainContent _medicineMainContentView;

  private bool _isCanExcute = false;
  public bool IsCanExcute
  {
     get { return _isCanExcute; }
     set { SetProperty(ref _isCanExcute, value); }
  }

  private DelegateCommand _loadingCommand;
  public DelegateCommand LoadingCommand =>
      _loadingCommand ?? (_loadingCommand = new DelegateCommand(ExecuteLoadingCommand));

  private DelegateCommand _activePaientListCommand;
  public DelegateCommand ActivePaientListCommand =>
      _activePaientListCommand ?? (_activePaientListCommand = new DelegateCommand(ExecuteActivePaientListCommand));

  private DelegateCommand _deactivePaientListCommand;
  public DelegateCommand DeactivePaientListCommand =>
      _deactivePaientListCommand ?? (_deactivePaientListCommand = new DelegateCommand(ExecuteDeactivePaientListCommand));

   private DelegateCommand _activeMedicineListCommand;
   public DelegateCommand ActiveMedicineListCommand =>
      _activeMedicineListCommand ?? (_activeMedicineListCommand = new DelegateCommand(ExecuteActiveMedicineListCommand)
      .ObservesCanExecute(() => IsCanExcute));

   private DelegateCommand _deactiveMedicineListCommand;
   public DelegateCommand DeactiveMedicineListCommand =>
       _deactiveMedicineListCommand ?? (_deactiveMedicineListCommand = new DelegateCommand(ExecuteDeactiveMedicineListCommand)
      .ObservesCanExecute(() => IsCanExcute));

   private DelegateCommand _loadMedicineModuleCommand;
   public DelegateCommand LoadMedicineModuleCommand =>
       _loadMedicineModuleCommand ?? (_loadMedicineModuleCommand = new DelegateCommand(ExecuteLoadMedicineModuleCommand));

 /// <summary>
 /// 窗體加載事件
 /// </summary>
 void ExecuteLoadingCommand()
 {
      _regionManager = CommonServiceLocator.ServiceLocator.Current.GetInstance<IRegionManager>();
      _paientListRegion = _regionManager.Regions[RegionNames.PatientListRegion];
      _patientListView = CommonServiceLocator.ServiceLocator.Current.GetInstance<PatientList>();
      _paientListRegion.Add(_patientListView);
      _medicineListRegion = _regionManager.Regions[RegionNames.MedicineMainContentRegion];
 }

  /// <summary>
  /// 失效medicineMainContent視圖
  /// </summary>
  void ExecuteDeactiveMedicineListCommand()
  {
      _medicineListRegion.Deactivate(_medicineMainContentView);
  }

  /// <summary>
  /// 激活medicineMainContent視圖
  /// </summary>
  void ExecuteActiveMedicineListCommand()
  {
      _medicineListRegion.Activate(_medicineMainContentView);
  }

  /// <summary>
  /// 失效patientList視圖
  /// </summary>
  void ExecuteDeactivePaientListCommand()
  {
       _paientListRegion.Deactivate(_patientListView);
  }

  /// <summary>
  /// 激活patientList視圖
  /// </summary>
  void ExecuteActivePaientListCommand()
  {
       _paientListRegion.Activate(_patientListView);
  }
  
  /// <summary>
  /// 加載MedicineModule
  /// </summary>
  void ExecuteLoadMedicineModuleCommand()
  {
       _moduleManager.LoadModule("MedicineModule");
       _medicineMainContentView = (MedicineMainContent)_medicineListRegion.Views
            .Where(t => t.GetType() == typeof(MedicineMainContent)).FirstOrDefault();
       this.IsCanExcute = true;
   }

效果以下：

監控視圖激活狀態

Prism其中還支持監控視圖的激活狀態，是經過在View中繼承IActiveAware來實現的，咱們以監控其中MedicineMainContent視圖的激活狀態爲例子：

MedicineMainContentViewModel.cs:

public class MedicineMainContentViewModel : BindableBase,IActiveAware
 {
     public event EventHandler IsActiveChanged;

     bool _isActive;
     public bool IsActive
     {
         get { return _isActive; }
         set
         {
             _isActive = value;
             if (_isActive)
             {
                 MessageBox.Show("視圖被激活了");
             }
             else
             {
                 MessageBox.Show("視圖失效了");
             }
             IsActiveChanged?.Invoke(this, new EventArgs());
          }
      }

  }

Add和Remove

上述例子用的是ContentControl，咱們再用一個ItemsControl的例子，代碼以下：

MainWindow.xaml:

<metro:MetroWindow.RightWindowCommands>
      <metro:WindowCommands x:Name="rightWindowCommandsRegion" />
  </metro:MetroWindow.RightWindowCommands>

MainWindow.cs:

public MainWindow()
 {
    InitializeComponent();
    var regionManager= ServiceLocator.Current.GetInstance<IRegionManager>();
    if (regionManager != null)
    {
       SetRegionManager(regionManager, this.flyoutsControlRegion, RegionNames.FlyoutRegion);
       //建立WindowCommands控件區域
       SetRegionManager(regionManager, this.rightWindowCommandsRegion, RegionNames.ShowSearchPatientRegion);
    }
 }

 void SetRegionManager(IRegionManager regionManager, DependencyObject regionTarget, string regionName)
 {
     RegionManager.SetRegionName(regionTarget, regionName);
     RegionManager.SetRegionManager(regionTarget, regionManager);
 }

ShowSearchPatient.xaml：

<StackPanel x:Class="PrismMetroSample.MedicineModule.Views.ShowSearchPatient"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       xmlns:prism="http://prismlibrary.com/"  
       xmlns:const="clr-namespace:PrismMetroSample.Infrastructure.Constants;assembly=PrismMetroSample.Infrastructure"
       Orientation="Horizontal"    
       xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
       prism:ViewModelLocator.AutoWireViewModel="True">
   <i:Interaction.Triggers>
       <i:EventTrigger EventName="Loaded">
           <i:InvokeCommandAction Command="{Binding ShowSearchLoadingCommand}"/>
       </i:EventTrigger>
   </i:Interaction.Triggers>
   <CheckBox IsChecked="{Binding IsShow}"/>
   <Button Command="{Binding ApplicationCommands.ShowCommand}" CommandParameter="{x:Static const:FlyoutNames.SearchMedicineFlyout}">
       <StackPanel Orientation="Horizontal">
           <Image Height="20" Source="pack://application:,,,/PrismMetroSample.Infrastructure;Component/Assets/Photos/按鈕.png"/>
           <TextBlock Text="Show" FontWeight="Bold" FontSize="15" VerticalAlignment="Center"/>
       </StackPanel>
   </Button>
</StackPanel>

ShowSearchPatientViewModel.cs:

private IApplicationCommands _applicationCommands;
 private readonly IRegionManager _regionManager;
 private ShowSearchPatient _showSearchPatientView;
 private IRegion _region;

 public IApplicationCommands ApplicationCommands
 {
      get { return _applicationCommands; }
      set { SetProperty(ref _applicationCommands, value); }
 }

 private bool _isShow=true;
 public bool IsShow
 {
      get { return _isShow=true; }
      set 
      { 
          SetProperty(ref _isShow, value);
          if (_isShow)
          {
               ActiveShowSearchPatient();
          }
          else
          {
               DeactiveShowSearchPaitent();
          }
      }
 }

 private DelegateCommand _showSearchLoadingCommand;
 public DelegateCommand ShowSearchLoadingCommand =>
         _showSearchLoadingCommand ?? (_showSearchLoadingCommand = new DelegateCommand(ExecuteShowSearchLoadingCommand));

 void ExecuteShowSearchLoadingCommand()
 {
        _region = _regionManager.Regions[RegionNames.ShowSearchPatientRegion];
        _showSearchPatientView = (ShowSearchPatient)_region.Views
            .Where(t => t.GetType() == typeof(ShowSearchPatient)).FirstOrDefault();
 }


  public ShowSearchPatientViewModel(IApplicationCommands applicationCommands,IRegionManager regionManager)
  {
        this.ApplicationCommands = applicationCommands;
        _regionManager = regionManager;
  }

  /// <summary>
  /// 激活視圖
  /// </summary>
  private void ActiveShowSearchPatient()
  {
       if (!_region.ActiveViews.Contains(_showSearchPatientView))
       {
           _region.Add(_showSearchPatientView);
       }         
  }
   
  /// <summary>
  /// 失效視圖
  /// </summary>
   private async void DeactiveShowSearchPaitent()
   {
        _region.Remove(_showSearchPatientView);
        await Task.Delay(2000);
        IsShow = true;
   }

效果以下：

這裏的WindowCommands 的繼承鏈爲：WindowCommands <-- ToolBar <-- HeaderedItemsControl <--ItemsControl，所以因爲Prism默認的適配器有ItemsControlRegionAdapter,所以其子類也繼承了其行爲

這裏重點概括一下：

  • 當進行模塊化時，加載完模塊纔會去注入視圖到區域(可參考MedicineModule視圖加載順序)
  • ContentControl控件因爲Content只能顯示一個，在其區域中能夠經過Activate和Deactivate方法來控制顯示哪一個視圖，其行爲是由ContentControlRegionAdapter適配器控制
  • ItemsControl控件及其子控件因爲顯示一個集合視圖，默認所有集合視圖是激活的，這時候不能經過Activate和Deactivate方式來控制(會報錯),經過Add和Remove來控制要顯示哪些視圖，其行爲是由ItemsControlRegionAdapter適配器控制
  • 這裏沒講到Selector控件，由於也是繼承自ItemsControl，所以其SelectorRegionAdapter適配器和ItemsControlRegionAdapter適配器殊途同歸
  • 能夠經過繼承IActiveAware接口來監控視圖激活狀態

四.自定義區域適配器

咱們在介紹整個區域管理器模型圖中說過，Prism有三個默認的區域適配器：ItemsControlRegionAdapter，ContentControlRegionAdapter，SelectorRegionAdapter，且支持自定義區域適配器，如今咱們來自定義一下適配器

1.建立自定義適配器

新建類UniformGridRegionAdapter.cs：

public class UniformGridRegionAdapter : RegionAdapterBase<UniformGrid>
{
    public UniformGridRegionAdapter(IRegionBehaviorFactory regionBehaviorFactory) : base(regionBehaviorFactory)
    {

    }

    protected override void Adapt(IRegion region, UniformGrid regionTarget)
    {
        region.Views.CollectionChanged += (s, e) =>
        {
          if (e.Action==System.Collections.Specialized.NotifyCollectionChangedAction.Add)
          {
              foreach (FrameworkElement element in e.NewItems)
              {
                   regionTarget.Children.Add(element);
              }
          }
        };
    }

    protected override IRegion CreateRegion()
    {
        return new AllActiveRegion();
    }
 }

2.註冊映射

App.cs:

protected override void ConfigureRegionAdapterMappings(RegionAdapterMappings regionAdapterMappings)
{
    base.ConfigureRegionAdapterMappings(regionAdapterMappings);
    //爲UniformGrid控件註冊適配器映射
    regionAdapterMappings.RegisterMapping(typeof(UniformGrid),Container.Resolve<UniformGridRegionAdapter>());
}

3.爲控件建立區域

MainWindow.xaml:

<UniformGrid Margin="5" prism:RegionManager.RegionName="UniformContentRegion" Columns="2">
        <Button Content="ActivePaientList" Margin="5" Command="{Binding ActivePaientListCommand}"/>
        <Button Content="DeactivePaientList" Margin="5" Command="{Binding DeactivePaientListCommand}"/>
        <Button Content="ActiveMedicineList" Margin="5" Command="{Binding ActiveMedicineListCommand}"/>
        <Button Content="DeactiveMedicineList" Margin="5" Command="{Binding DeactiveMedicineListCommand}"/>
     </UniformGrid>

4.爲區域注入視圖

這裏用的是ViewInjection方式：

MainWindowViewModel.cs

void ExecuteLoadingCommand()
  {
         _regionManager = CommonServiceLocator.ServiceLocator.Current.GetInstance<IRegionManager>();

         var uniformContentRegion = _regionManager.Regions["UniformContentRegion"];
         var regionAdapterView1 = CommonServiceLocator.ServiceLocator.Current.GetInstance<RegionAdapterView1>();
         uniformContentRegion.Add(regionAdapterView1);
         var regionAdapterView2 = CommonServiceLocator.ServiceLocator.Current.GetInstance<RegionAdapterView2>();
         uniformContentRegion.Add(regionAdapterView2); 
  }

效果如圖：

咱們能夠看到咱們爲UniformGrid建立區域適配器，而且註冊後，也可以爲UniformGrid控件建立區域，而且注入視圖顯示，若是沒有該區域適配器，則是會報錯，下一篇咱們將會講解基於區域Region的prism導航系統。

五.源碼

 最後，附上整個demo的源代碼：PrismDemo源碼

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