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//----------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//----------------------------------------------------------------
namespace System.Activities.Presentation.Hosting
{
using System;
using System.Windows;
using System.Windows.Interop;
using System.Runtime;
using System.Diagnostics.CodeAnalysis;
using Microsoft.Tools.Common;
public delegate void WindowMessage(int msgId, IntPtr parameter1, IntPtr parameter2 );
[Fx.Tag.XamlVisible(false)]
public class WindowHelperService
{
HwndSource hwndSource;
WindowMessage listeners;
[SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", Justification = "hwnd is a well known name.")]
public WindowHelperService(IntPtr hwnd)
{
this.ParentWindowHwnd = hwnd;
}
[SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", Justification = "hwnd is a well known name.")]
public IntPtr ParentWindowHwnd
{
get;
private set;
}
internal FrameworkElement View
{
get;
set;
}
public bool TrySetWindowOwner(DependencyObject source, Window target)
{
bool result = false;
Fx.Assert(target != null, "Target window cannot be null");
if (null != target)
{
if (source != null)
{
//try the easy way first
Window owner = Window.GetWindow(source);
if (null != owner)
{
target.Owner = owner;
result = true;
}
}
//no - it didn't work
if (!result)
{
IntPtr ownerHwnd = Win32Interop.GetActiveWindow();
if (ownerHwnd == IntPtr.Zero)
{
ownerHwnd = this.ParentWindowHwnd;
}
WindowInteropHelper interopHelper = new WindowInteropHelper(target);
interopHelper.Owner = ownerHwnd;
result = true;
}
}
return result;
}
public bool RegisterWindowMessageHandler(WindowMessage callback)
{
bool result = true;
if (null == callback)
{
throw FxTrace.Exception.AsError(new ArgumentNullException("callback"));
}
//if there are no other callbacks registered - create initial multicast delegate
//and hookup message processing
if (null == this.listeners)
{
this.listeners = (WindowMessage)Delegate.Combine(callback);
this.HookupMessageProcessing();
}
//otherwise, check if callback is not in the list already
else
{
Delegate[] initial = this.listeners.GetInvocationList();
//if it isn't - add it to callback list
if (-1 == Array.IndexOf<Delegate>(initial, callback))
{
Delegate[] combined = new Delegate[initial.Length + 1];
combined[initial.Length] = callback;
Array.Copy(initial, combined, initial.Length);
this.listeners = (WindowMessage)Delegate.Combine(combined);
}
else
{
result = false;
}
}
return result;
}
public bool UnregisterWindowMessageHandler(WindowMessage callback)
{
bool result = false;
if (null == callback)
{
throw FxTrace.Exception.AsError(new ArgumentNullException("callback"));
}
//if there are any callbacks
if (null != this.listeners)
{
Delegate[] list = this.listeners.GetInvocationList();
//check if given delegate belongs to the list
if (-1 != Array.IndexOf<Delegate>(list, callback))
{
//if list contained 1 element - there is nobody listening for events - remove hook
if (list.Length == 1)
{
this.hwndSource.RemoveHook(new HwndSourceHook(OnMessage));
}
//yes - remove it
this.listeners = (WindowMessage)Delegate.Remove(this.listeners, callback);
result = true;
}
}
if (!result)
{
System.Diagnostics.Debug.WriteLine("UnregisterWindowMessageHandler - callback not in list");
}
return result;
}
internal static void TrySetWindowOwner(DependencyObject owner, EditingContext editingContext, Window wnd)
{
if (null != editingContext)
{
WindowHelperService service = editingContext.Services.GetService<WindowHelperService>();
if (null != service)
{
service.TrySetWindowOwner(owner, wnd);
}
}
}
void HookupMessageProcessing()
{
//try to create hwnd source object
if (null == this.hwndSource)
{
//first - try to create it using ParentWindow handle
if (IntPtr.Zero != this.ParentWindowHwnd)
{
this.hwndSource = HwndSource.FromHwnd(this.ParentWindowHwnd);
}
//if didn't succeed - (either handle is null or we are hosted in Microsoft app)
//try to create hwnd source out of designer's view
if (null == this.hwndSource)
{
this.hwndSource = HwndSource.FromVisual(this.View) as HwndSource;
}
}
Fx.Assert(null != this.hwndSource, "HwndSource should not be null!");
if (null != this.hwndSource)
{
//register for event notifications
this.hwndSource.AddHook(new HwndSourceHook(OnMessage));
}
}
IntPtr OnMessage(IntPtr hwnd, int msgId, IntPtr wParam, IntPtr lParam, ref bool handled)
{
//notify all listeners about window message
this.listeners(msgId, wParam, lParam);
return IntPtr.Zero;
}
}
}
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