Messages not reaching WndProc - C# Discussion Boards

Re: What does the GCHandle object?

31-Jul-02 6:54

Can you tell me where the code comes from, and what it's trying to do?

Anonymous31-Jul-02 9:50

Anonymous

31-Jul-02 9:50

The code comes from the "SampleGrabberNET" sample on http://www.codeproject.com/useritems/directshownet.asp.
The code should save a memory-image with the Bitmap object.

Re: What does the GCHandle object?

Eric Gunnerson (msft)31-Jul-02 10:35

Messages not reaching WndProc

31-Jul-02 10:35

I think you should be able to rewrite this as:

Bitmap b;
fixed (byte* pByte = savedArray)
{
IntPtr bits = new IntPtr(pByte + (h - 1) * stride);
b = new Bitmap( w, h, -stride, PixelFormat.Format24bppRgb, bits );
}

If you knew the size of the bitmap, you could also create a new one that size, use LockBitmap to get to the bits, and just copy the memory across.

Kastro30-Jul-02 19:11

Kastro

30-Jul-02 19:11

I am writing a class that overrides Control and utilizes the non-client area. I need to be able to have hotspots within the non-client area. However, because of what seems to me to be unusual behavior, I am not able to get it working.

I override WndProc to intercept WM_NCMOUSEMOVE and WM_NCPAINT (as well as WM_NCCALCSIZE, WM_NCHITTEST, and WM_LBUTTONDOWN/UP) as follows:

(Please don't flame me for posting VB.NET code. I use both interchangably as they are pretty much the same thing anyways. It just so happens that I wrote this in VB.NET. I posted here because I would guess that C# programmers know more about the Win32 API than VB.NET programmers, and my questions have nothing to do with VB.NET)

Protected Overrides Sub WndProc(ByRef msg As Message)
    Select Case msg.Msg
        Case 131 'WM_NCCALCSIZE
            ...
        Case 132 'WM_NCHITTEST
            ...
        Case 133 'WM_NCPAINT
            Dim dc As Integer
            dc = GetDCEx(msg.HWnd.ToInt32(), msg.WParam.ToInt32(), 65536 + 128 + 1)
            Dim hdc As IntPtr = New IntPtr(dc)
            Dim g As Graphics = Graphics.FromHdc(hdc)
            OnPaintNonClient(New PaintEventArgs(g, Rectangle.Round(g.ClipBounds)))
            ReleaseDC(msg.HWnd.ToInt32(), hdc.ToInt32())
        Case 160 'WM_NCMOUSEMOVE
            Dim pt As PointL
            pt.x = msg.LParam.ToInt32() Mod 65536
            pt.y = msg.LParam.ToInt32() / 65536
            Dim ppt As IntPtr = Marshal.AllocHGlobal(8)
            Marshal.StructureToPtr(pt, ppt, False)
            ScreenToClient(msg.HWnd.ToInt32(), ppt.ToInt32())
            pt = Marshal.PtrToStructure(ppt, GetType(PointL))
            Dim args As MouseEventArgs = New MouseEventArgs(MouseButtons.None, 0, pt.x, pt.y, 0)
            OnNonClientMouseMove(args)
            Marshal.FreeHGlobal(ppt)
        Case 161 'WM_NCLBUTTONDOWN
            ...
        Case 162 'WM_NCLBUTTONUP
            ...
        Case Else
            MyBase.WndProc(msg)
    End Select
End Sub

Protected Overridable Sub OnNonClientMouseMove(ByVal args As MouseEventArgs)
    If ... Then 'Test hotspots
        ...
        PostMessage(Me.Handle, 133, 0, 0) 'WM_NCPAINT
    End If
End Sub

Protected Overridable Sub OnPaintNonClient(ByVal args As PaintEventArgs)
    ...
End Sub

There are no problems painting the non-client area for resizes, max/min, etc. Intercepting WM_NCMOUSEMOVE and testing for mouse-overs on my hotspots works fine. However, the weird thing is that when my code does the PostMessage call, the WM_NCPAINT message never reaches WndProc.

Does anyone know what is going on?
Does Windows.Forms not send every message on to WndProc?
Do I have to do something with PreProcessMessage?

Can what I am trying to do actually be done in Windows.Forms?

Thanks.

Re: Messages not reaching WndProc

Kastro30-Jul-02 19:51

Kastro

30-Jul-02 19:51

I tried something else out that gave me strange results as well...

Instead of using PostMessage, I switched to using SendMessage. The WM_NCPAINT message is now reaching WndProc, however, the strange thing is that the drawing that I do there does not show up.

The drawing code works fine in response to WM_NCPAINT messages caused by resizes, min/maxes, etc...

Any ideas?

How do I hide a property from the property window?

Ray Cassick30-Jul-02 18:42

Ray Cassick

30-Jul-02 18:42

????

Re: How do I hide a property from the property window?

Andy Smith30-Jul-02 19:42

Andy Smith

30-Jul-02 19:42

give it a Browsable(false) attribute.

Re: How do I hide a property from the property window?

Ray Cassick31-Jul-02 2:41

Ray Cassick

31-Jul-02 2:41

I tried this and I thought it did not work. I'l try again.

Re: How do I hide a property from the property window?

Ray Cassick31-Jul-02 18:49

Ray Cassick

31-Jul-02 18:49

I tired this and it did not work. I think I need to add that the property I am trying to hide is not one that I added, but rather one that is available via the control that I inherit. I don't want the user to be able to change the property so I need it hidden.

Re: How do I hide a property from the property window?

Nathan Blomquist1-Aug-02 1:27

Nathan Blomquist

1-Aug-02 1:27

You could override the property in your control and then just call the base.property.

Example hiding Label.Text or something similiar:

[Browseable(false)]
public override string Text
{
    get{ return base.Text; }
    set{ base.Text = value; }
}

This would allow get/setting of the property but it would be not be seen in the property grid.

Later,
Nathan

---------------------------
Hmmm... what's a signature?

Bug in VS.NET?

Johnny Zee30-Jul-02 10:01

Johnny Zee

30-Jul-02 10:01

On my MDI Parent Form or SDI Parent Form if I have any control i.e. push button, label etc. When I call my child form those parent controls still there? Anybody knows why, I will be thankful if somebody helps me in that.

Thanks in advance.

Re: Bug in VS.NET?

Johnny Zee1-Aug-02 2:49

Johnny Zee

1-Aug-02 2:49

Okay its not a bug if you set your WindowState property to Maximize of Child Form it will behave in a way it required. Finally I found this.

The Web Service FREEZE the App

laphijia30-Jul-02 9:05

laphijia

30-Jul-02 9:05

I have a program that connects to a Web Service to authenticate a user.

When the user clicks ok the program access the Web Service through the
internet.

This actually seems to FREEZE the program until it has finished, how can I
solve this problem?
It's really not a good user interface like now!

I mean maybe I could make like when you are loggin in in MSN Messenger, but
how to do it?

Thankx!

"Nelle cose del mondo non e' il sapere ma il volere che puo'."

Re: The Web Service FREEZE the App

James T. Johnson30-Jul-02 16:56

James T. Johnson

30-Jul-02 16:56

What you are seeing is that all the work is being done on one thread, including all the waiting that you have to do while you wait for the webservice to respond.

The solution is to use an Async method or a separate thread. The Async method will use a separate thread but it takes care of all the work for you; while you have to do all the work to use a thread yourself.

If I remember correctly the code that the "Add Web Reference" option generates includes some Async methods. The Async methods begin with Begin and End followed by the name of the method.

Using a method from the CodeProject webservice

ArticleBrief[] GetLatestArticleBrief(int NumArticles);

The Async versions of this method are:
IAsyncResult BeginGetLatestArticleBrief(int NumArticles, AsyncCallback callback, object asyncState); and
ArticleBrief[] EndGetLatestArticleBrief(IAsyncResult asyncResult);

Typical usage is as such

IAsyncResult iar = BeginGetLatestArticleBrief(numArticles, null, null);
 
// Later on
if( iar.IsCompleted )
{
  articleBriefs = EndGetLatestArticleBrief(iar);
}
else
{
 // do something else
}

Since you wouldn't be doing anything else while the user is logging in I would do this:

IAsyncResult iar = BeginLoginUser(username, password, null, null);
 
while( !iar.IsCompleted )
{
  Application.DoEvents(); // Let the message pump do some work
}
 
// Continue as before

This is only a brief intro and a limited way of doing things, MSDN contains an entire section on Asynchronous programming which you should read before going much further.

If you use the MSDN that came with VS.NET I found the topic by going to the following nodes: Visual Studio.NET -> .NET Framework -> Programming with the .NET Framework -> Including Asynchronous Calls

HTH,

James
"Java is free - and worth every penny." - Christian Graus

Late binding to objects...

Ryan Cromwell30-Jul-02 7:47

30-Jul-02 7:47

How is late binding done in C#? I'd like to allow for the registration of 'pluggins' (used loosly) for an automation tool for Source Safe. IE as I come across a file type, the appropriate class/library which implements the correct interface is loaded and used to process the file...

Andy Smith30-Jul-02 8:34

Andy Smith

30-Jul-02 8:34

your plugins should implement an interface, which means you don't have to late bind anything beyond checking and casting to the interface.

VB implements its latebinding using reflection behind the scenes (InvokeMember i suppose), which you can do manually in c# if you want.

Ryan Cromwell30-Jul-02 8:44

30-Jul-02 8:44

But I don't want to have to recompile the code after each time or create a switch/if for each type

ie I don't want to do this

IVSSCheckout itemHandler;
switch (fileExt) {
case "asp":
IVSSCheckout itemHandler = new ASPHandler(); //tight bind is problem
case "cls":
IVSSCheckout itemHandler = new VBFileHandler();
case "cpp":
IVSSCheckout itemHandler = new VCPPPHandler();
}

I would rather do something parallel to:

className = GetFromRegistry( fileExt )
itemHandler = CreateObject( className )

I could very well be missing something quite simple and fundamental as I have just moved into .Net languages from C++ and VB.

Eric Gunnerson (msft)30-Jul-02 8:54

30-Jul-02 8:54

You won't have to if you use an interface.

Here's what you need to do:

1) Write an interface that describes the add-in.
2) Build it to a separate assembly.
3) Reference that assembly both in your main program and in the add-in.

Then it's merely a matter of loading the assembly, finding all the types that implement the interface, creating an instance, and casting it to an interface.

If you look on http://www.gotdotnet.com/team/csharp, you'll find two examples of doing this.

On the information page, there's an "execution time code generation" section that does something nearly identical to what you want to do (from the loading perspective).

On the main page, there's a column on app domains and dynamic loading that does something similar, though it's delegate based instead of interface based.

Hope that helps.

Ryan Cromwell30-Jul-02 9:04

30-Jul-02 9:04

Thanks a ton... I'll take a look at it those.

Ryan Cromwell30-Jul-02 9:33

30-Jul-02 9:33

That's great. I knew there would be a way to do it. The reflection namespace was what I was looking for.

I'm not worried about memory resident assemblies as they will be unloaded rather quickly, so loading the Assembly via the Load call appears it will give me what I need. Thanks a lot for your quick responses. And these Reynolds people say you Microsoft guys aren't nice to work with... <sarcasm>

Eric Gunnerson (msft)30-Jul-02 9:49