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Jeurink · #1 (**permalink**) 04-05-2005

Hi, I that a lot users on the forum have this problem.

When you popup a context menu, or some dialog from an event fired from MapPoint, you get a "Server busy" message after 10 seconds. Realy annoying, it allways happens when you demo your code to your boss.

I found my own (imho nicer than sending "esc" char after 9 seconds) solution. You can have your context menu longer open than 10 seconds without problems.

This solution is for C# (so .NET), but it it is just the concept.

Make a timer that sets off after 1 msec. and two variables that hold the mouse position.

Code:

private System.Windows.Forms.Timer showContextMenuTimer;
private int mouseYloc, mouseXloc;

// This timer is used to popup a context menu, when
// an user has right clicked a symbol on the map
showContextMenuTimer = new Timer();
showContextMenuTimer.Tick+=new EventHandler(showContextMenuTimer_Tick);
showContextMenuTimer.Interval=1;

Event handler:

Code:

private void showContextMenuTimer_Tick(object sender, EventArgs e)
{
	showContextMenuTimer.Stop();
         // insert your contextMenu.show routine here...
	subscriberMenu.Show(this,new Point(mouseXloc+180,mouseYloc+10));

}

When you want to popup a context menu, you simple call
showContextMenuTimer.Start();

Code:

private void axMappointControl1_BeforeClick(object sender, AxMapPoint._IMappointCtrlEvents_BeforeClickEvent e)
{
	if(e.button==2) // right click
	{
		e.cancel=true;
		mouseXloc = e.x; // used in the Timer.Tick event
		mouseYloc= e.y;
		showContextMenuTimer.Start();
	}
}

The problem is (I think) that the contextMenu.show call doesn't return before those 10 seconds. By opening it from a serparate thread it returns immediatly.

have fun with it!

**Wilfried** · #2 (**permalink**) 04-05-2005

Hi,

Thanks for feedback

Yes this is a good idea. The problem is not threading, the timer's tickis executed in same thread context, but the difference is that the code is executed outside the event.

This explains more. A menu is nothing else than a modal form, so displaying a modal form in the event will block mappoint. So when you do it outside it then all is ok.

wonderfull idea

A better approach should be to not use a timer but post a message to the form with the x, y parameters. In de WndProc method there you pop the menu . If someone wants example I be glad to post it of course !

Jeurink · #3 (**permalink**) 04-05-2005

Hmm, if it is not too much work, could you post an example?

I'm not really understanding what you mean with "post wndproc message to the form".
(I've learned java and standard c++ so i'm not really into window messages)

**Wilfried** · #4 (**permalink**) 04-05-2005

Hi,

Ok here is example and I try to explain (my english is not so well

The whole windows thing is based on messages. When you move your mouse over a form thousands of them are sent to it with the x,y coordinates, same if you pull down a button on keyboard and if you lose it again. Messages are handled by each window by a so called message pump. Now you can also make custom message handlers. That is message handlers that does what you want. You need many times execute code outside of a loop or ouside an event (what we are gonna do).

Also it is "the" system if you are in a thread and you want code execute in the thread context of a particular window that is created in another therad. A good example is the User interface.

There are 2 importand ones, that is SendMessage and PostMessage. Both are doeing the same with the difference that SendMessage will block the thread until the custom message handler has finished while PostMesage is async and will return immediatly. In both of the code will execute as soon as the destination start pumping messages.

So we define first our message. It has to be > WM_USER witch is 0x400.:

Code:

        const int WM_POPUPMENU = 0x401;

Now we override the WndProc of the form. This is part of the message pump and is called by the message pump itselfL:

Code:

        private void popup(IntPtr x, IntPtr y)
        {
            // here you popup your menu
        }

        protected override void WndProc(ref Message m)
        {
            switch (m.Msg) {
                case WM_POPUPMENU:
                    popup(m.WParam, m.LParam);
                    break;
                default:
                    base.WndProc(ref m);
                    break;
            }
        }

You have to make sure that you trap all exceptions, because if an execption comes here it is dramaticly;because it comes from the middle of nowhere cleaning the call stack means kill your program... Also be aware that this function is called thousands of times a second. So you dont wat to put slow code in it, so always optimize it for speed.

and in the BeforeClick you post the message:

Code:

        private void MP_BeforeClick_1(object sender, AxMapPoint._IMappointCtrlEvents_BeforeClickEvent e)
        {
            Win32.PostMessage(Handle, WM_POPUPMENU, e.x, e.y);

Now we need to define thw win32 API call, and do it as sutch:

Code:

    public class Win32
    {
        [DllImport("User32.dll")]
        public static extern Boolean PostMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

So what happens is following:
- beforclick post the message, since postmessage is async the event handler continue his work until it end
- then the form start pumping messages again (because noting of your code is running)
- the custom mssage handler is called and the window pups up

I hope my explanation make sence

Jeurink · #5 (**permalink**) 04-06-2005

Quote:

I hope my explanation make sence Smile

Yeah it really is

Thanks for your good explanation!
bye

**Winwaed** · #6 (**permalink**) 04-06-2005

The original timer method is useful for VB though, I use this to fake multi-threading for batch processing in an add-in.

Richard

**Wilfried** · #7 (**permalink**) 04-06-2005

Hi Richard,

Quote:

Originally Posted by Winwaed

The original timer method is useful for VB though

Yes but timers are limited recource. Posting a message is unlimited, take no recourse and is normal windows behavioure. And I'm sure in VB it is possible to call Win32 API call also

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