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Cleaned and added a base class for view models with background processing tha uses the new ThreadedAction class to do its background processing; added a view binding interface for WinForms that emulates the WPF design

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git-svn-id: file:///srv/devel/repo-conversion/nuwi@41 d2e56fa2-650e-0410-a79f-9358c0239efd
This commit is contained in:
Markus Ewald 2019-02-06 07:00:27 +00:00
parent 435935691a
commit 4ef5dd9430
6 changed files with 674 additions and 0 deletions
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12
Nuclex.Windows.Forms (net-4.0).csproj
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@ -55,6 +55,17 @@
</ItemGroup> </ItemGroup>
<ItemGroup> <ItemGroup>
<Compile Include="Properties\AssemblyInfo.cs" /> <Compile Include="Properties\AssemblyInfo.cs" />
<Compile Include="Source\ViewModels\ThreadedViewModel.cs" />
<Compile Include="Source\ViewModels\ThreadedViewModel.Test.cs">
<DependentUpon>ThreadedViewModel.cs</DependentUpon>
</Compile>
<Compile Include="Source\Views\IView.cs" />
<Compile Include="Source\Views\ViewControl.cs">
<SubType>UserControl</SubType>
</Compile>
<Compile Include="Source\Views\ViewForm.cs">
<SubType>Form</SubType>
</Compile>
<EmbeddedResource Include="Source\ProgressReporter\ProgressReporterForm.resx"> <EmbeddedResource Include="Source\ProgressReporter\ProgressReporterForm.resx">
<DependentUpon>ProgressReporterForm.cs</DependentUpon> <DependentUpon>ProgressReporterForm.cs</DependentUpon>
<SubType>Designer</SubType> <SubType>Designer</SubType>
@ -109,6 +120,7 @@
<Link>Foundation.snk</Link> <Link>Foundation.snk</Link>
</None> </None>
</ItemGroup> </ItemGroup>
<ItemGroup />
<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" /> <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
<!-- To modify your build process, add your task inside one of the targets below and uncomment it. <!-- To modify your build process, add your task inside one of the targets below and uncomment it.
Other similar extension points exist, see Microsoft.Common.targets. Other similar extension points exist, see Microsoft.Common.targets.

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Source/ViewModels/ThreadedViewModel.Test.cs Normal file
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#if UNITTEST
using System;
using System.ComponentModel;
using System.Threading;
using NUnit.Framework;
namespace Nuclex.Windows.Forms.ViewModels {
/// <summary>Unit test for the threaded view model base class</summary>
[TestFixture]
public class ThreadedViewModelTest {
#region class DummyContext
/// <summary>Synchronization context that does absolutely nothing</summary>
private class DummyContext : ISynchronizeInvoke {
#region class SimpleAsyncResult
/// <summary>Barebones implementation of an asynchronous result</summary>
private class SimpleAsyncResult : IAsyncResult {
/// <summary>Ehether the asynchronous operation is complete</summary>
/// <remarks>
/// Always true because it completes synchronously
/// </remarks>
public bool IsCompleted { get { return true; } }
/// <summary>
/// Wait handle that can be used to wait for the asynchronous operation
/// </summary>
public WaitHandle AsyncWaitHandle {
get { throw new NotImplementedException("Not implemented"); }
}
/// <summary>Custom state that can be used to pass information around</summary>
public object AsyncState {
get { throw new NotImplementedException("Not implemented"); }
}
/// <summary>Whether the asynchronous operation completed synchronously</summary>
public bool CompletedSynchronously { get { return true; } }
/// <summary>The value returned from the asynchronous operation</summary>
public object ReturnedValue;
}
#endregion // class SimpleAsyncResult
/// <summary>Whether the calling thread needs to use Invoke()</summary>
public bool InvokeRequired {
get { return true; }
}
/// <summary>Schedules the specified method for execution in the target thread</summary>
/// <param name="method">Method the target thread will execute when it is idle</param>
/// <param name="arguments">Arguments that will be passed to the method</param>
/// <returns>
/// An asynchronous result handle that can be used to check on the status of
/// the call and wait for its completion
/// </returns>
public IAsyncResult BeginInvoke(Delegate method, object[] arguments) {
var asyncResult = new SimpleAsyncResult();
asyncResult.ReturnedValue = method.Method.Invoke(method.Target, arguments);
return asyncResult;
}
/// <summary>Waits for the asychronous call to complete</summary>
/// <param name="result">
/// Asynchronous result handle returned by the <see cref="BeginInvoke" /> method
/// </param>
/// <returns>The original result returned by the asychronously called method</returns>
public object EndInvoke(IAsyncResult result) {
return ((SimpleAsyncResult)result).ReturnedValue;
}
/// <summary>
/// Schedules the specified method for execution in the target thread and waits
/// for it to complete
/// </summary>
/// <param name="method">Method that will be executed by the target thread</param>
/// <param name="arguments">Arguments that will be passed to the method</param>
/// <returns>The result returned by the specified method</returns>
public object Invoke(Delegate method, object[] arguments) {
return method.Method.Invoke(method.Target, arguments);
}
}
#endregion // class DummyContext
#region class TestViewModel
/// <summary>View model used to unit test the threaded view model base class</summary>
private class TestViewModel : ThreadedViewModel {
/// <summary>
/// Initializes a new view model, letting the base class figure out the UI thread
/// </summary>
public TestViewModel() : base() {
this.finishedGate = new ManualResetEvent(initialState: false);
}
/// <summary>
/// Initializes a new view model, using the specified context for the UI thread
/// </summary>
/// <param name="uiContext">Synchronization context of the UI thread</param>
public TestViewModel(ISynchronizeInvoke uiContext) : base(uiContext) {
this.finishedGate = new ManualResetEvent(initialState: false);
}
/// <summary>Immediately releases all resources owned by the instance</summary>
public override void Dispose() {
base.Dispose();
if(this.finishedGate != null) {
this.finishedGate.Dispose();
this.finishedGate = null;
}
}
/// <summary>Waits until the first background operation is finished</summary>
/// <returns>
/// True if the background operation is finished, false if it is ongoing
/// </returns>
public bool WaitUntilFinished() {
return this.finishedGate.WaitOne(100);
}
/// <summary>Runs a background process that causes the specified error</summary>
/// <param name="error">Error that will be caused in the background process</param>
public void CauseErrorInBackgroundThread(Exception error) {
RunInBackground(() => throw error);
}
/// <summary>Last error that was reported by the threaded view model</summary>
public Exception ReportedError {
get { return this.reportedError; }
}
/// <summary>Called when an error occurs in the background thread</summary>
/// <param name="exception">Exception that was thrown in the background thread</param>
protected override void ReportError(Exception exception) {
this.reportedError = exception;
this.finishedGate.Set();
}
/// <summary>Last error that was reported by the threaded view model</summary>
private Exception reportedError;
/// <summary>Triggered when the </summary>
private ManualResetEvent finishedGate;
}
#endregion // class TestViewModel
/// <summary>Verifies that the threaded view model has a default constructor</summary>
[Test]
public void HasDefaultConstructor() {
using(var mainForm = new System.Windows.Forms.Form()) {
mainForm.Show();
try {
mainForm.Visible = false;
using(new TestViewModel()) { }
}
finally {
mainForm.Close();
}
}
}
/// <summary>
/// Verifies that the threaded view model can be constructed with a custom UI context
/// </summary>
[Test]
public void HasCustomSychronizationContextConstructor() {
using(new TestViewModel(new DummyContext())) { }
}
/// <summary>Checks that a new view model starts out idle and not busy</summary>
[Test]
public void NewInstanceIsNotBusy() {
using(var viewModel = new TestViewModel(new DummyContext())) {
Assert.IsFalse(viewModel.IsBusy);
}
}
/// <summary>
/// Verifies that errors happening in the background processing threads are
/// reported to the main thread
/// </summary>
[Test]
public void ErrorsInBackgroundThreadAreReported() {
using(var viewModel = new TestViewModel(new DummyContext())) {
var testError = new ArgumentException("Mooh");
viewModel.CauseErrorInBackgroundThread(testError);
viewModel.WaitUntilFinished();
Assert.AreSame(testError, viewModel.ReportedError);
}
}
}
} // namespace Nuclex.Windows.Forms.ViewModels
#endif // UNITTEST

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Source/ViewModels/ThreadedViewModel.cs Normal file
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#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2019 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
using System.ComponentModel;
using System.Windows.Forms;
using Nuclex.Support;
using Nuclex.Support.Threading;
namespace Nuclex.Windows.Forms.ViewModels {
/// <summary>View model that can execute tasks in a background thread</summary>
public abstract class ThreadedViewModel : Observable, IDisposable {
#region class ViewModelThreadRunner
/// <summary>Thread runner for the threaded view model</summary>
private class ViewModelThreadRunner : ThreadRunner {
/// <summary>Initializes a new thread runner for the threaded view model</summary>
public ViewModelThreadRunner(ThreadedViewModel viewModel) {
this.viewModel = viewModel;
}
/// <summary>Reports an error</summary>
/// <param name="exception">Error that will be reported</param>
protected override void ReportError(Exception exception) {
this.viewModel.reportErrorFromThread(exception);
}
/// <summary>Called when the status of the busy flag changes</summary>
protected override void BusyChanged() {
this.viewModel.OnIsBusyChanged();
}
/// <summary>View model the thread runner belongs to</summary>
private ThreadedViewModel viewModel;
}
#endregion // class ViewModelThreadRunner
/// <summary>Initializes a new view model for background processing</summary>
/// <param name="uiContext">
/// UI dispatcher that can be used to run callbacks in the UI thread
/// </param>
protected ThreadedViewModel(ISynchronizeInvoke uiContext = null) {
if(uiContext == null) {
this.uiContext = getMainWindow();
} else {
this.uiContext = uiContext;
}
this.reportErrorDelegate = new Action<Exception>(ReportError);
this.threadRunner = new ViewModelThreadRunner(this);
}
/// <summary>Immediately releases all resources owned by the instance</summary>
public virtual void Dispose() {
if(this.threadRunner != null) {
this.threadRunner.Dispose();
this.threadRunner = null;
}
}
/// <summary>Whether the view model is currently busy executing a task</summary>
public bool IsBusy {
get { return this.threadRunner.IsBusy; }
}
/// <summary>Reports an error to the user</summary>
/// <param name="exception">Error that will be reported</param>
/// <remarks>
/// <para>
/// You can use this method as a default handling method for your own error reporting
/// (displaying the error to the user, logging it or whatever else is appropriate).
/// </para>
/// <para>
/// When <see cref="RunInBackground(System.Action)" /> is used, this method will also
/// be called in case an exception within the asynchronously running code goes unhandled.
/// This choice was made because, in the context of UI code, you would wrap any
/// operations that might fail in a try..catch pair anyway in order to inform
/// the user instead of aborting the entire application.
/// </para>
/// </remarks>
protected abstract void ReportError(Exception exception);
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
protected void RunInBackground(Action action) {
this.threadRunner.RunInBackground(action);
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
protected void RunInBackground(CancellableAction action) {
this.threadRunner.RunInBackground(action);
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
protected void RunInBackground<P1>(Action<P1> action, P1 parameter1) {
this.threadRunner.RunInBackground(action, parameter1);
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
protected void RunInBackground<P1>(CancellableAction<P1> action, P1 parameter1) {
this.threadRunner.RunInBackground(action, parameter1);
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
protected void RunInBackground<P1, P2>(Action<P1, P2> action, P1 parameter1, P2 parameter2) {
this.threadRunner.RunInBackground(action, parameter1, parameter2);
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
protected void RunInBackground<P1, P2>(
CancellableAction<P1, P2> action, P1 parameter1, P2 parameter2
) {
this.threadRunner.RunInBackground(action, parameter1, parameter2);
}
/// <summary>Cancels the currently running background operation</summary>
protected void CancelBackgroundOperation() {
this.threadRunner.CancelBackgroundOperation();
}
/// <summary>Cancels all queued and the currently running background operation</summary>
protected void CancelAllBackgroundOperations() {
this.threadRunner.CancelAllBackgroundOperations();
}
/// <summary>Whether the background operation has been cancelled</summary>
//[Obsolete("Please use a method accepting a cancellation token instead of using this")]
protected bool IsBackgroundOperationCancelled {
get { return this.threadRunner.IsBackgroundOperationCancelled; }
}
/// <summary>Throws an exception if the background operation was cancelled</summary>
//[Obsolete("Please use a method accepting a cancellation token instead of using this")]
protected void ThrowIfBackgroundOperationCancelled() {
this.threadRunner.ThrowIfBackgroundOperationCancelled();
}
/// <summary>Executes the specified action in the UI thread</summary>
/// <param name="action">Action that will be executed in the UI thread</param>
protected void RunInUIThread(Action action) {
this.uiContext.Invoke(action, EmptyObjectArray);
}
/// <summary>Executes the specified action in the UI thread</summary>
/// <param name="action">Action that will be executed in the UI thread</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
protected void RunInUIThread<P1>(Action<P1> action, P1 parameter1) {
this.uiContext.Invoke(action, new object[1] { parameter1 });
}
/// <summary>Executes the specified action in the UI thread</summary>
/// <param name="action">Action that will be executed in the UI thread</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
protected void RunInUIThread<P1, P2>(Action<P1, P2> action, P1 parameter1, P2 parameter2) {
this.uiContext.Invoke(action, new object[2] { parameter1, parameter2 });
}
/// <summary>Called when the thread runner's busy flag changes</summary>
protected virtual void OnIsBusyChanged() {
OnPropertyChanged(nameof(IsBusy));
}
/// <summary>Reports an error that occurred in the runner's background thread</summary>
/// <param name="exception">Exception that the thread has encountered</param>
private void reportErrorFromThread(Exception exception) {
this.uiContext.Invoke(this.reportErrorDelegate, new object[1] { exception });
}
/// <summary>Finds the application's main window</summary>
/// <returns>Main window of the application</returns>
private static Form getMainWindow() {
IntPtr mainWindowHandle = System.Diagnostics.Process.GetCurrentProcess().MainWindowHandle;
// We can get two things: a list of all open windows and the handle of
// the window that the process has registered as main window. Use the latter
// to pick the correct window from the former.
FormCollection openForms = Application.OpenForms;
int openFormCount = openForms.Count;
for(int index = 0; index < openFormCount; ++index) {
if(openForms[index].IsHandleCreated) {
if(openForms[index].Handle == mainWindowHandle) {
return openForms[index];
}
}
}
// No matching main window found: use the first one in good faith or fail.
if(openFormCount > 0) {
return openForms[0];
} else {
return null;
}
}
/// <summary>An array of zero objects</summary>
private static readonly object[] EmptyObjectArray = new object[0];
/// <summary>UI dispatcher of the thread in which the view runs</summary>
private ISynchronizeInvoke uiContext;
/// <summary>Delegate for the ReportError() method</summary>
private Action<Exception> reportErrorDelegate;
/// <summary>Thread runner that manages the view model's thread</summary>
private ViewModelThreadRunner threadRunner;
}
} // namespace Nuclex.Windows.Forms.ViewModels

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#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2019 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
namespace Nuclex.Windows.Forms.Views {
/// <summary>View with support for data binding</summary>
public interface IView {
/// <summary>Provides the data binding target for the view</summary>
/// <remarks>
/// This property is identical to the same-named one in WPF, it provides
/// the view model to which the view should bind its controls.
/// </remarks>
object DataContext { get; set; }
}
} // namespace Nuclex.Windows.Forms.Views

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#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2019 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
using System.ComponentModel;
using System.Windows.Forms;
using Nuclex.Support;
namespace Nuclex.Windows.Forms.Views {
/// <summary>
/// Base class for MVVM user controls that act as views connected to a view model
/// </summary>
public class ViewControl : UserControl, IView {
/// <summary>Initializes a new view control</summary>
public ViewControl() {
this.onViewModelPropertyChangedDelegate = OnViewModelPropertyChanged;
}
/// <summary>Called when the control's data context is changed</summary>
/// <param name="sender">Control whose data context was changed</param>
/// <param name="oldDataContext">Data context that was previously used</param>
/// <param name="newDataContext">Data context that will be used from now on</param>
protected virtual void OnDataContextChanged(
object sender, object oldDataContext, object newDataContext
) {
var oldViewModel = oldDataContext as INotifyPropertyChanged;
if(oldViewModel != null) {
oldViewModel.PropertyChanged -= this.onViewModelPropertyChangedDelegate;
}
var newViewModel = newDataContext as INotifyPropertyChanged;
if(newViewModel != null) {
newViewModel.PropertyChanged += this.onViewModelPropertyChangedDelegate;
InvalidateAllViewModelProperties();
}
}
/// <summary>Refreshes all properties from the view model</summary>
protected void InvalidateAllViewModelProperties() {
OnViewModelPropertyChanged(this.dataContext, PropertyChangedEventArgsHelper.Wildcard);
}
/// <summary>Called when a property of the view model is changed</summary>
/// <param name="sender">View model in which a property was changed</param>
/// <param name="arguments">Contains the name of the property that has changed</param>
protected virtual void OnViewModelPropertyChanged(
object sender, PropertyChangedEventArgs arguments
) { }
/// <summary>Provides the data binding target for the view</summary>
public object DataContext {
get { return this.dataContext; }
set {
if(value != this.dataContext) {
this.dataContext = value;
}
}
}
/// <summary>Active data binding target, can be null</summary>
private object dataContext;
/// <summary>Delegate for the OnViewModelPropertyChanged() method</summary>
private PropertyChangedEventHandler onViewModelPropertyChangedDelegate;
}
} // namespace Nuclex.Windows.Forms.Views

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#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2019 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
using System.ComponentModel;
using System.Windows.Forms;
using Nuclex.Support;
namespace Nuclex.Windows.Forms.Views {
/// <summary>
/// Base class for MVVM windows that act as views connected to a view model
/// </summary>
public class ViewForm : Form, IView {
/// <summary>Initializes a new view control</summary>
public ViewForm() {
this.onViewModelPropertyChangedDelegate = OnViewModelPropertyChanged;
}
/// <summary>Called when the window's data context is changed</summary>
/// <param name="sender">Window whose data context was changed</param>
/// <param name="oldDataContext">Data context that was previously used</param>
/// <param name="newDataContext">Data context that will be used from now on</param>
protected virtual void OnDataContextChanged(
object sender, object oldDataContext, object newDataContext
) {
var oldViewModel = oldDataContext as INotifyPropertyChanged;
if(oldViewModel != null) {
oldViewModel.PropertyChanged -= this.onViewModelPropertyChangedDelegate;
}
var newViewModel = newDataContext as INotifyPropertyChanged;
if(newViewModel != null) {
newViewModel.PropertyChanged += this.onViewModelPropertyChangedDelegate;
InvalidateAllViewModelProperties();
}
}
/// <summary>Refreshes all properties from the view model</summary>
protected void InvalidateAllViewModelProperties() {
OnViewModelPropertyChanged(this.dataContext, PropertyChangedEventArgsHelper.Wildcard);
}
/// <summary>Called when a property of the view model is changed</summary>
/// <param name="sender">View model in which a property was changed</param>
/// <param name="arguments">Contains the name of the property that has changed</param>
protected virtual void OnViewModelPropertyChanged(
object sender, PropertyChangedEventArgs arguments
) { }
/// <summary>Provides the data binding target for the view</summary>
public object DataContext {
get { return this.dataContext; }
set {
if(value != this.dataContext) {
this.dataContext = value;
}
}
}
/// <summary>Active data binding target, can be null</summary>
private object dataContext;
/// <summary>Delegate for the OnViewModelPropertyChanged() method</summary>
private PropertyChangedEventHandler onViewModelPropertyChangedDelegate;
}
} // namespace Nuclex.Windows.Forms.Views