DateTimePicker - OpenNETCF 1.3

[Guest]

So with OpenNETCF 1.2 we had the DateTimePicker. Its “Checked†property did
not work but we had the following code that we could use to uncheck it:

int DTM_SETSYSTEMTIME = 0x1002;
int GDT_NONE = 1;

foreach( Control c in this.Controls )
{
if( c.GetType() == typeof( DateTimePicker )){
Win32Window.SendMessage(
(IntPtr) ( Win32Window.GetWindow((IntPtr)Win32Window.FromControl(
c ),
Win32Window.GetWindowParam.GW_CHILD )),
DTM_SETSYSTEMTIME, GDT_NONE, 0 );
}
}

With the advent of OpenNETCF 1.3 we must change the
Win32Window.GetWindowParam.GW_CHILD statement to OpenNETCF.Win32.GW.CHILD in
order to get things to compile and run. Unfortunately however, this code no
longer unchecks the checkboxes though. I would also note that if you go to
the property window and set the Checked property from true to false that
OpenNETCF produces the following compile error:
“'OpenNETCF.Windows.Forms.DateTimePicker' does not contain a definition for
'Checked'â€.

So what has been changed with the DateTimePicker in the new version and is
there another way to programmatically control the state of its check boxes
that works with 1.3?

Bill

 

[Alex Feinman [MVP]]

What's been changed is that a DTP control is hosted inside MessageWindow
,which is hosted inside generic control. For this reason you need another
level of GetWindow(GW_CHILD).
Fortunately there is also a new property called ChildHandle, which you can
use to obtain DTP control hWnd without resorting to GetWindow

 

[Guest]

Alex, I apologize for being so dense, but this code seems to exist in the
nether-world between C#, OpenNETCF, and MFC code and I'm confused. I'm not
sure what you mean be another "level" of GetWindow(). Also I poked around a
bit in DateTimePicker.Control and I found GetChildIndex(), and
SetChildIndex() methods, but no ChildHandle property. (I hope we aren't
talking about features to become available in .NET 2005 - we need to go live
with this code in August)

I'd be grateful if you could humor me with another post on this thread.

Bill

 

[Alex Feinman [MVP]]

Ok, Bill, my apologies. ChildHandle is a protected member. So, what you do
is this:

foreach( Control c in this.Controls )
{
if( c.GetType() == typeof( DateTimePicker )){
IntPtr hWnd = (IntPtr) (
Win32Window.GetWindow((IntPtr)Win32Window.FromControl( c ),
Win32Window.GetWindowParam.GW_CHILD ));
hWnd = (IntPtr) ( Win32Window.GetWindow(hWnd,
Win32Window.GetWindowParam.GW_CHILD ));
Win32Window.SendMessage( hWnd, DTM_SETSYSTEMTIME, GDT_NONE, 0 );
}
}

As for the missing Checked property - we'll try to get a fix into 1.4 if
possible.

 

[Peter Foot [MVP]]

The ChildHandle property is protected - therefore only accessible if you
derive your own control from the DateTimePicker class. This stores the
native handle to the date time picker control itself (the child of a
modified messagewindow which itself is child of the Control implementation).
This approach (specific to .NETCF v1.0) is described in my MSDN article
here:-
http://msdn.microsoft.com/library/d...netcomp/html/HostingANativeWindowsControl.asp
The DateTimePicker control was updated for v1.3 to use this approach to
support events. I've modified the code in the vault to implement the Checked
property - so for v1.4 you'll see expected behaviour from setting the
property from the designer.

Peter

--
Peter Foot
Windows Embedded MVP
http://www.inthehand.com | http://www.peterfoot.net |
http://www.opennetcf.org

 

[Guest]

Guys,
Thanks for aditional info, I'm sure others will find it useful as well!

Bill