C#: Excel 2007 Addin, How to Hook Windows Activate and Deactivate Events - add-in

Question

I am writing an Excel 2007 Addin. using VS2008 and .net 3.5, C#.
I catched Microsoft.Office.Interop.Excel.Application's WindowActivate and WindowDeActivate events.
It was surprised to know that WindowActivate and Deactivate only triggers when i switch between two Excel Windows. if i switch to notepad, i expect Deactivate to be triggered, but its not happening. same way from notepad if i switch to excel window, i expect Activate to be triggered but its not happening. It looks like the behaviour indicates windows are MDI-Child windows.
Now what i want to do is get HWnd of Excel's Mainwindow and hook Window Activate and Deactivates using dllimport features.
Can anyone guide to me on this.
Regards

Answer 1

I solved similar problem when writing Excel addin. No dll import is needed. I solved this issue using System.Windows.Forms.NativeWindow class.
At first, I made my own class inherited from NativeWindow class and declared two events Activated and Deactivate in it and finaly overrided WndProc() method to rise these events when message WM_ACTIVATE is passed to the WndProc method. According to "Message" parameter WParm is Excel window activated or deactivated.
public class ExcelWindow: NativeWindow
{
public const int WM_ACTIVATED = 0x0006;
public ExcelWindow():base(){}
//events
public event EventHandler Activated;
public event EventHandler Deactivate;
//catching windows messages
protected override void WndProc(ref Message m)
{
if (m.Msg== WM_ACTIVATED)
{
if (m.WParam.ToInt32() == 1)
{
//raise activated event
if (Activated!=null)
{
Activated(this, new EventArgs());
}
}
else if (m.WParam.ToInt32() == 0)
{
//raise deactivated event
if (Deactivate!=null)
{
Deactivate(this, new EventArgs());
}
}
}
base.WndProc(ref m);
}
}
Then I made in my addin class field "ExcelWindow myExcelWindow" and added following code to OnConnection method of my addin:
ExcelWindow myExcelWindow;
void Extensibility.IDTExtensibility2.OnConnection(object application, Extensibility.ext_ConnectMode ConnectMode, object AddInInst, ref Array custom)
{
excel = application as Excel.Application;
myExcelWindow = new ExcelWindow();
myExcelWindow.AssignHandle(new IntPtr(excel.Hwnd));
myExcelWindow.Activated += new EventHandler(myExcelWindow_Activated);
myExcelWindow.Deactivate += new EventHandler(myExcelWindow_Deactivate);
//addin code here
}
void myExcelWindow_Activated(object sender, EventArgs e)
{
//do some stuff here
}
void myExcelWindow_Deactivate(object sender, EventArgs e)
{
//do some stuff here
}
I hope this will help you.

Answer 2

Finally I found one solution..that works only Activate/Deactivate.
This is not the perfect way to do it. But I did not find any good alternative.
This method uses polling. I have to call following function in each 10 ms interval to check focus in/out.
public static bool ApplicationIsActivated()
{
var activatedHandle = GetForegroundWindow();
if (activatedHandle == IntPtr.Zero)
{
return false; // No window is currently activated
}
var procId = Process.GetCurrentProcess().Id;
int activeProcId;
GetWindowThreadProcessId(activatedHandle, out activeProcId);
return activeProcId == procId;
}