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