Nuclex.Windows.Forms/Source/WindowManager.cs
Markus Ewald 9aa64c4dac Added a placeholder auto binding system to automate binding of views to view models without writing so much boilerplate code
git-svn-id: file:///srv/devel/repo-conversion/nuwi@44 d2e56fa2-650e-0410-a79f-9358c0239efd
2019-02-06 18:34:47 +00:00

422 lines
17 KiB
C#

#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.Collections.Concurrent;
using System.Collections.Generic;
using System.Windows.Forms;
using Nuclex.Support;
using Nuclex.Windows.Forms.AutoBinding;
using Nuclex.Windows.Forms.Views;
namespace Nuclex.Windows.Forms {
/// <summary>Manages an application's windows and views</summary>
public class WindowManager : Observable, IWindowManager {
#region class CancellableDisposer
/// <summary>Disposes an object that potentially implements IDisposable</summary>
private struct CancellableDisposer : IDisposable {
/// <summary>Initializes a new cancellable disposer</summary>
/// <param name="potentiallyDisposable">
/// Object that potentially implements IDisposable
/// </param>
public CancellableDisposer(object potentiallyDisposable = null) {
this.potentiallyDisposable = potentiallyDisposable;
}
/// <summary>
/// Disposes the assigned object if the disposer has not been cancelled
/// </summary>
public void Dispose() {
var disposable = this.potentiallyDisposable as IDisposable;
if(disposable != null) {
disposable.Dispose();
}
}
/// <summary>Cancels the call to Dispose(), keeping the object alive</summary>
public void Dismiss() {
this.potentiallyDisposable = null;
}
/// <summary>Assigns a new potentially disposable object</summary>
/// <param name="potentiallyDisposable">
/// Potentially disposable object that the disposer will dispose
/// </param>
public void Set(object potentiallyDisposable) {
this.potentiallyDisposable = potentiallyDisposable;
}
/// <summary>Object that will be disposed unless the disposer is cancelled</summary>
private object potentiallyDisposable;
}
#endregion // class CancellableDisposer
/// <summary>Initializes a new window manager</summary>
/// <param name="autoBinder">
/// View model binder that will be used to bind all created views to their models
/// </param>
public WindowManager(IAutoBinder autoBinder = null) {
this.autoBinder = autoBinder;
this.rootWindowActivatedDelegate = rootWindowActivated;
this.rootWindowClosedDelegate = rootWindowClosed;
this.viewTypesForViewModels = new ConcurrentDictionary<Type, Type>();
}
/// <summary>The currently active top-level or modal window</summary>
public Form ActiveWindow {
get { return this.activeWindow; }
private set {
if(value != this.activeWindow) {
this.activeWindow = value;
OnPropertyChanged(nameof(ActiveWindow));
}
}
}
/// <summary>Opens a view as a new root window of the application</summary>
/// <typeparam name="TViewModel">
/// Type of view model a root window will be opened for
/// </typeparam>
/// <param name="viewModel">
/// View model a window will be opened for. If null, the view model will be
/// created as well (unless the dialog already specifies one as a resource)
/// </param>
/// <param name="disposeOnClose">
/// Whether the view model should be disposed when the view is closed
/// </param>
/// <returns>The window that has been opened by the window manager</returns>
public Form OpenRoot<TViewModel>(
TViewModel viewModel = null, bool disposeOnClose = true
) where TViewModel : class {
Form window = (Form)CreateView(viewModel);
window.Activated += this.rootWindowActivatedDelegate;
window.Closed += this.rootWindowClosedDelegate;
// If we either created the view model or the user explicitly asked us to
// dispose his view model, tag the window so that we know to dispose it
// when we're done (but still allow the user to change his mind)
if((viewModel == null) || disposeOnClose) {
window.Tag = "DisposeViewModelOnClose"; // TODO: Wrap SetProp() instead?
//window.SetValue(DisposeViewModelOnCloseProperty, true);
}
window.Show();
return window;
}
/// <summary>Displays a view as a modal window</summary>
/// <typeparam name="TViewModel">
/// Type of the view model for which a view will be displayed
/// </typeparam>
/// <param name="viewModel">
/// View model a modal window will be displayed for. If null, the view model will
/// be created as well (unless the dialog already specifies one as a resource)
/// </param>
/// <param name="disposeOnClose">
/// Whether the view model should be disposed when the view is closed
/// </param>
/// <returns>The return value of the modal window</returns>
public bool? ShowModal<TViewModel>(
TViewModel viewModel = null, bool disposeOnClose = true
) where TViewModel : class {
Form window = (Form)CreateView(viewModel);
window.Owner = this.activeWindow;
window.Activated += this.rootWindowActivatedDelegate;
try {
// If we either created the view model or the user explicitly asked us to
// dispose his view model, tag the window so that we know to dispose it
// when we're done (but still allow the user to change his mind)
if((viewModel == null) || disposeOnClose) {
window.Tag = "DisposeViewModelOnClose"; // TODO: Wrap SetProp() instead?
//window.SetValue(DisposeViewModelOnCloseProperty, true);
}
DialogResult result = window.ShowDialog(this.activeWindow);
if((result == DialogResult.OK) || (result == DialogResult.Yes)) {
return true;
} else if((result == DialogResult.Cancel) || (result == DialogResult.No)) {
return false;
} else {
return null;
}
}
finally {
window.Activated -= this.rootWindowActivatedDelegate;
ActiveWindow = window.Owner;
if(shouldDisposeViewModelOnClose(window)) {
IView windowAsView = window as IView;
if(windowAsView != null) {
object viewModelAsObject = windowAsView.DataContext;
windowAsView.DataContext = null;
disposeIfDisposable(viewModelAsObject);
}
}
disposeIfDisposable(window);
}
}
/// <summary>Creates the view for the specified view model</summary>
/// <typeparam name="TViewModel">
/// Type of view model for which a view will be created
/// </typeparam>
/// <param name="viewModel">
/// View model a view will be created for. If null, the view model will be
/// created as well (unless the dialog already specifies one as a resource)
/// </param>
/// <returns>The view for the specified view model</returns>
public virtual Control CreateView<TViewModel>(
TViewModel viewModel = null
) where TViewModel : class {
Type viewType = LocateViewForViewModel(typeof(TViewModel));
Control viewControl = (Control)CreateInstance(viewType);
using(var viewDisposer = new CancellableDisposer(viewControl)) {
// Create a view model if none was provided, and in either case assign
// the view model to the view (provided it implements IView).
using(var viewModelDisposer = new CancellableDisposer()) {
IView viewControlAsView = viewControl as IView;
if(viewModel == null) { // No view model provided, create one
if(viewControlAsView == null) { // View doesn't implement IView
viewModel = (TViewModel)CreateInstance(typeof(TViewModel));
viewModelDisposer.Set(viewModel);
} else if(viewControlAsView.DataContext == null) { // View has no view model
viewModel = (TViewModel)CreateInstance(typeof(TViewModel));
viewModelDisposer.Set(viewModel);
viewControlAsView.DataContext = viewModel;
} else { // There's an existing view model
viewModel = viewControlAsView.DataContext as TViewModel;
if(viewModel == null) { // The existing view model is another type
viewModel = (TViewModel)CreateInstance(typeof(TViewModel));
viewModelDisposer.Set(viewModel);
viewControlAsView.DataContext = viewModel;
}
}
} else if(viewControlAsView != null) { // Caller has provided a view model
viewControlAsView.DataContext = viewModel;
}
// If an auto binder was provided, automatically bind the view to the view model
if(this.autoBinder != null) {
this.autoBinder.Bind(viewControl, viewModel);
}
viewModelDisposer.Dismiss(); // Everything went well, we keep the view model
}
viewDisposer.Dismiss(); // Everything went well, we keep the view
}
return viewControl;
}
/// <summary>Locates the view that will be used to a view model</summary>
/// <param name="viewModelType">
/// Type of view model for which the view will be located
/// </param>
/// <returns>The type of view that should be used for the specified view model</returns>
protected virtual Type LocateViewForViewModel(Type viewModelType) {
Type viewType;
if(!this.viewTypesForViewModels.TryGetValue(viewModelType, out viewType)) {
string viewName = viewModelType.Name;
if(viewName.EndsWith("ViewModel")) {
viewName = viewName.Substring(0, viewName.Length - 9);
}
Type[] exportedTypes = viewModelType.Assembly.GetExportedTypes();
Type[] namespaceTypes = filterTypesByNamespace(exportedTypes, viewModelType.Namespace);
// First, search the own namespace (because if two identical view models exist in
// different namespaces, the one in the same namespace is most likely the desired one)
viewType = findBestMatch(
namespaceTypes,
viewName + "View",
viewName + "Form",
viewName + "Window",
viewName + "Dialog",
viewName + "Control"
);
// If the view model doesn't exist in the same namespace, expand the search to
// the entire assembly the view is in.
if(viewType == null) {
viewType = findBestMatch(
exportedTypes,
viewName + "View",
viewName + "Form",
viewName + "Window",
viewName + "Dialog",
viewName + "Control"
);
}
// Still no view found? We give up!
if(viewType == null) {
throw new InvalidOperationException(
string.Format("Could not locate view for view model '{0}'", viewModelType.Name)
);
}
this.viewTypesForViewModels.TryAdd(viewModelType, viewType);
}
return viewType;
}
/// <summary>Creates an instance of the specified type</summary>
/// <param name="type">Type an instance will be created of</param>
/// <returns>The created instance</returns>
/// <remarks>
/// Use this to wire up your dependency injection container. By default,
/// the Activator class will be used to create instances which only works
/// if all of your view models are concrete classes.
/// </remarks>
protected virtual object CreateInstance(Type type) {
return Activator.CreateInstance(type);
}
/// <summary>Called when one of the application's root windows is closed</summary>
/// <param name="sender">Window that has been closed</param>
/// <param name="arguments">Not used</param>
private void rootWindowClosed(object sender, EventArgs arguments) {
Form closedWindow = (Form)sender;
closedWindow.Closed -= this.rootWindowClosedDelegate;
closedWindow.Activated -= this.rootWindowActivatedDelegate;
// If the view model was created just for this view or if the user asked us
// to dispose of his view model, do so now.
if(shouldDisposeViewModelOnClose(closedWindow)) {
IView windowAsView = closedWindow as IView;
if(windowAsView != null) {
object viewModelAsObject = windowAsView.DataContext;
windowAsView.DataContext = null;
disposeIfDisposable(viewModelAsObject);
}
}
lock(this) {
ActiveWindow = null;
}
}
/// <summary>Called when one of the application's root windows is activated</summary>
/// <param name="sender">Window that has been put in the foreground</param>
/// <param name="arguments">Not used</param>
private void rootWindowActivated(object sender, EventArgs arguments) {
lock(this) {
ActiveWindow = (Form)sender;
}
}
/// <summary>Tries to find the best match for a named type in a list of types</summary>
/// <param name="types">List of types the search will take place in</param>
/// <param name="typeNames">
/// The candidates the method will look for, starting with the best match
/// </param>
/// <returns>The best match in the list of types, if any match was found</returns>
private static Type findBestMatch(Type[] types, params string[] typeNames) {
int bestMatchFound = typeNames.Length;
Type type = null;
for(int index = 0; index < types.Length; ++index) {
for(int nameIndex = 0; nameIndex < bestMatchFound; ++nameIndex) {
if(types[index].Name == typeNames[nameIndex]) {
bestMatchFound = nameIndex;
type = types[index];
if(bestMatchFound == 0) { // There can be no better match
return type;
}
break;
}
}
}
return type;
}
/// <summary>Disposes the specified object if it implements IDisposable</summary>
/// <typeparam name="T">Type of object that will disposed if possible</typeparam>
/// <param name="instance">Object that the method will attempt to dispose</param>
private static void disposeIfDisposable<T>(T instance) where T : class {
var disposable = instance as IDisposable;
if(disposable != null) {
disposable.Dispose();
}
}
/// <summary>Determines if the view owns the view model</summary>
/// <param name="view">View that will be checked for ownership</param>
/// <returns>True if the view owns the view model</returns>
private static bool shouldDisposeViewModelOnClose(Control view) {
string tagAsString = view.Tag as string;
if(tagAsString != null) {
return tagAsString.Contains("DisposeViewModelOnClose");
} else {
return false;
}
}
/// <summary>Filters a list of types to contain only those in a specific namespace</summary>
/// <param name="exportedTypes">List of exported types that will be filtered</param>
/// <param name="filteredNamespace">
/// Namespace the types in the filtered list will be in
/// </param>
/// <returns>A subset of the specified types that are in the provided namespace</returns>
private static Type[] filterTypesByNamespace(Type[] exportedTypes, string filteredNamespace) {
var filteredTypes = new List<Type>(exportedTypes.Length / 2);
for(int index = 0; index < exportedTypes.Length; ++index) {
Type exportedType = exportedTypes[index];
if(exportedType.Namespace == filteredNamespace) {
filteredTypes.Add(exportedType);
}
}
return filteredTypes.ToArray();
}
/// <summary>The application's currently active root window</summary>
private Form activeWindow;
/// <summary>Invoked when a root window is put in the foreground</summary>
private EventHandler rootWindowActivatedDelegate;
/// <summary>Invoked when a root window has been closed</summary>
private EventHandler rootWindowClosedDelegate;
/// <summary>View model binder that will be used on all created views</summary>
private IAutoBinder autoBinder;
/// <summary>Caches the view types to use for a view model</summary>
private ConcurrentDictionary<Type, Type> viewTypesForViewModels;
}
} // namespace Nuclex.Windows.Forms