NET Core 3 WPF MVVM框架 Prism系列之区域管理器

本文将介绍如何在.NET Core3环境下使用MVVM框架Prism的使用区域管理器对于View的管理

一.区域管理器#

我们在之前的Prism系列构建了一个标准式Prism项目，这篇文章将会讲解之前项目中用到的利用区域管理器更好的对我们的View进行管理，同样的我们来看看官方给出的模型图：

现在我们可以知道的是，大致一个区域管理器RegionMannager对一个控件创建区域的要点：

其实后来我去看了下官方的介绍和源码，默认RegionAdapter是有三个，且还支持自定义RegionAdapter，因此在官方的模型图之间我做了点补充：

二.区域创建与视图的注入#

我们先来看看我们之前项目的区域的划分，以及如何创建区域并且把View注入到区域中：

我们把整个主窗体划分了四个区域：

在Prism中，我们有两种方式去实现区域创建和视图注入：

1.ViewDiscovery#

我们截取其中PatientListRegion的创建和视图注入的代码(更仔细的可以去观看demo源码)：

MainWindow.xaml：

<code>Copy /<code>

这里相当于在后台MainWindow.cs：

<code>CopyRegionManager.SetRegionName(ContentControl, "PatientListRegion"); /<code>

PatientModule.cs：

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

2.ViewInjection#

我们在MainWindow窗体的Loaded事件中使用ViewInjection方式注入视图PatientList

MainWindow.xaml：

<code>Copy /i:EventTrigger> /<code>

MainWindowViewModel.cs:

<code>Copy 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(); _paientListRegion = _regionManager.Regions[RegionNames.PatientListRegion]; _patientListView = CommonServiceLocator.ServiceLocator.Current.GetInstance(); _paientListRegion.Add(_patientListView); } /<code>

我们可以明显的感觉到两种方式的不同，ViewDiscovery方式是自动地实例化视图并且加载出来，而ViewInjection方式则是可以手动控制注入视图和加载视图的时机(上述例子是通过Loaded事件)，官方对于两者的推荐使用场景如下：

ViewDiscovery：

ViewInjection：

三.激活与失效视图#

Activate和Deactivate#

首先我们需要控制PatientList和MedicineMainContent两个视图的激活情况，上代码：

MainWindow.xaml：

<code>Copy /<code>

MainWindowViewModel.cs：

<code>Copy 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)); /// /// 窗体加载事件 /// void ExecuteLoadingCommand() { _regionManager = CommonServiceLocator.ServiceLocator.Current.GetInstance(); _paientListRegion = _regionManager.Regions[RegionNames.PatientListRegion]; _patientListView = CommonServiceLocator.ServiceLocator.Current.GetInstance(); _paientListRegion.Add(_patientListView); _medicineListRegion = _regionManager.Regions[RegionNames.MedicineMainContentRegion]; } /// /// 失效medicineMainContent视图 /// void ExecuteDeactiveMedicineListCommand() { _medicineListRegion.Deactivate(_medicineMainContentView); } /// /// 激活medicineMainContent视图 /// void ExecuteActiveMedicineListCommand() { _medicineListRegion.Activate(_medicineMainContentView); } /// /// 失效patientList视图 /// void ExecuteDeactivePaientListCommand() { _paientListRegion.Deactivate(_patientListView); } /// /// 激活patientList视图 /// void ExecuteActivePaientListCommand() { _paientListRegion.Activate(_patientListView); } /// /// 加载MedicineModule /// void ExecuteLoadMedicineModuleCommand() { _moduleManager.LoadModule("MedicineModule"); _medicineMainContentView = (MedicineMainContent)_medicineListRegion.Views .Where(t => t.GetType() == typeof(MedicineMainContent)).FirstOrDefault(); this.IsCanExcute = true; } /<code>

效果如下：

监控视图激活状态#

Prism其中还支持监控视图的激活状态，是通过在View中继承IActiveAware来实现的，我们以监控其中MedicineMainContent视图的激活状态为例子：

MedicineMainContentViewModel.cs:

<code>Copy public class MedicineMainContentViewModel : BindableBase,IActiveAware { public event EventHandler IsActiveChanged; bool _isActive; public bool IsActive { get { return _isActive; } set { _isActive = value; if (_isActive) { MessageBox.Show("视图被激活了"); } else { MessageBox.Show("视图失效了"); } IsActiveChanged?.Invoke(this, new EventArgs()); } } } /<code>

Add和Remove#

上述例子用的是ContentControl，我们再用一个ItemsControl的例子，代码如下：

MainWindow.xaml:

<code>Copy /<code>

MainWindow.cs:

<code>Copy public MainWindow() { InitializeComponent(); var regionManager= ServiceLocator.Current.GetInstance(); if (regionManager != null) { SetRegionManager(regionManager, this.flyoutsControlRegion, RegionNames.FlyoutRegion); //创建WindowCommands控件区域 SetRegionManager(regionManager, this.rightWindowCommandsRegion, RegionNames.ShowSearchPatientRegion); } } void SetRegionManager(IRegionManager regionManager, DependencyObject regionTarget, string regionName) { RegionManager.SetRegionName(regionTarget, regionName); RegionManager.SetRegionManager(regionTarget, regionManager); } /<code>

ShowSearchPatient.xaml：

<code>Copy /<code>

ShowSearchPatientViewModel.cs:

<code>Copy 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; } /// /// 激活视图 /// private void ActiveShowSearchPatient() { if (!_region.ActiveViews.Contains(_showSearchPatientView)) { _region.Add(_showSearchPatientView); } } /// /// 失效视图 /// private async void DeactiveShowSearchPaitent() { _region.Remove(_showSearchPatientView); await Task.Delay(2000); IsShow = true; } /<code>

效果如下：

这里的WindowCommands 的继承链为：WindowCommands

这里重点归纳一下：

四.自定义区域适配器#

我们在介绍整个区域管理器模型图中说过，Prism有三个默认的区域适配器：ItemsControlRegionAdapter，ContentControlRegionAdapter，SelectorRegionAdapter，且支持自定义区域适配器，现在我们来自定义一下适配器

1.创建自定义适配器#

新建类UniformGridRegionAdapter.cs：

<code>Copypublic class UniformGridRegionAdapter : RegionAdapterBase { 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(); } } /<code>

2.注册映射#

App.cs:

<code>Copyprotected override void ConfigureRegionAdapterMappings(RegionAdapterMappings regionAdapterMappings) { base.ConfigureRegionAdapterMappings(regionAdapterMappings); //为UniformGrid控件注册适配器映射 regionAdapterMappings.RegisterMapping(typeof(UniformGrid),Container.Resolve()); } /<code>

3.为控件创建区域#

MainWindow.xaml:

<code>Copy /<code>

4.为区域注入视图#

这里用的是ViewInjection方式：

MainWindowViewModel.cs

<code>Copy void ExecuteLoadingCommand() { _regionManager = CommonServiceLocator.ServiceLocator.Current.GetInstance(); var uniformContentRegion = _regionManager.Regions["UniformContentRegion"]; var regionAdapterView1 = CommonServiceLocator.ServiceLocator.Current.GetInstance(); uniformContentRegion.Add(regionAdapterView1); var regionAdapterView2 = CommonServiceLocator.ServiceLocator.Current.GetInstance(); uniformContentRegion.Add(regionAdapterView2); } /<code>

效果如图：

我们可以看到我们为UniformGrid创建区域适配器，并且注册后，也能够为UniformGrid控件创建区域，并且注入视图显示，如果没有该区域适配器，则是会报错，下一篇我们将会讲解基于区域Region的prism导航系统。

五.源码#

 最后，附上整个demo的源代码：PrismDemo源码

作者： RyzenAdorer

出处：https://www.cnblogs.com/ryzen/p/12605347.html