C# Discussion Boards - CodeProject

Re: How do you cast an IntPtr to a struct in .NET?

16-Feb-03 13:13

I am working with some Win32 interop and handling a windows proc. The lParam value, which is typed as long, actually holds a struct. So I define the struct as below, but I am unclear on how to convert the lParam value into a valid variable of type CWPSTRUCT.

I tried using (CWPSTRUCT)lParam.ToPointer() but that didn't compile. I know I'm close I'm just not sure how to cast it properly.

[StructLayout(LayoutKind.Sequential)]
public struct CWPSTRUCT
{
public IntPtr lParam;
public IntPtr wParam;
public uint message;
public IntPtr hWnd;
}

Mattingly16-Feb-03 13:24

Re: How do you cast an IntPtr to a struct in .NET?

16-Feb-03 13:24

Ok I think I am halfway there. I have used Marshal.PtrToStructure, but its giving me a runtime error that the structure must not be a "value class". The docs mention that Marshal.PtrToStructure don't support value types, but I'm not sure what that means.

How else can I define my struct to get around this?

Richard Deeming17-Feb-03 3:17

Richard Deeming

17-Feb-03 3:17

Use Marshal.PtrToStructure(IntPtr, Type):

CWPSTRUCT cwp = (CWPSTRUCT)Marshal.PtrToStructure(pCWP, typeof(CWPSTRUCT));

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

Space Formatting

Sovman16-Feb-03 13:03

Sovman

16-Feb-03 13:03

I would like to display a set of dates in long format but want to keep all days months and years underneath each other with in a set of text boxes eg

01 January 2003
12 May 2005
14 December 2002

This is similar to how the datepicker works. If I use a space character the years do not line up as all space becomes compressed.

Any Ideas on the character I need to pad out the text with??

Thanks

Steve Graham

Re: Space Formatting

Chris Meech17-Feb-03 4:58

Chris Meech

17-Feb-03 4:58

Not sure if this is possible, but try replacing the space character with a tab character, and then set the tab stops for the text boxes. This is the way I would do it with edit boxes or list boxes in MFC or Win32.

Chris Meech

"what makes CP different is the people and sense of community, things people will only discover if they join up and join in." Christian Graus Nov 14, 2002.

"AAAAAAAAAHHHHHH!!!!! Those leaks are driving me crazy! How does one finds a memory leak in a garbage collected environment ??! Daniel Turini Nov. 2, 2002.

ActiveDesktop

centsi16-Feb-03 11:18

centsi

16-Feb-03 11:18

Is there any way to use the IActiveDesktop interface in c#? The only reason I want to do this, is to change the desktop wallpaper, but SystemParametersInfo only works with .bmp files. Is there some other way to do this?

Adding a browser window

draco_iii16-Feb-03 11:16

draco_iii

16-Feb-03 11:16

How can I add an internet explorer type window to an application to display HTML.

Re: Adding a browser window

Furty16-Feb-03 12:11

Furty

16-Feb-03 12:11

http://www.codeproject.com/buglist/iefix.asp[^]

Re: Adding a browser window

gadgetfbi17-Feb-03 12:25

gadgetfbi

17-Feb-03 12:25

emm..I hope this is what you are looking for.

If you are using VS .NET you can add a toolBox refferance to "Microsoft Web Browser" (swdocvw.dll)
The object can now be dragged and dropped onto a form.
And to navigate, assuming object is named axWebBrowser:
We have access to
axWebBrowser.Navigate("s_URL", ref, ref, ref, ref)
axWebBrowser.GoHome();
axWebBrowser.Refresh();
axWebBrowser.GoBack();
axWebBrowser.GoForward();
axWebBrowser.Stop();
etc

gadget

Why is my call to SetWindowLong failing?

Mattingly16-Feb-03 11:15

16-Feb-03 11:15

I am calling SetWindowLong inside my C# Windows Forms app and passing a valid hWnd and the other needed params.

The problem is its returning with error code 127, which the docs describe as:

127 The specified procedure could not be found. ERROR_PROC_NOT_FOUND

Why is this happening? As far as I can tell I've properly declared the function in my project as such:

[DllImport("user32", CharSet=CharSet.Auto)]
public static extern int SetWindowLong (IntPtr hWnd, int nIndex, long dwNewLong);

I don't have the same problem when I call GetWindowLong, only SetWindowLong.
This is pretty frustrating, any suggestions are welcome.

Thanks,

M.

centsi16-Feb-03 11:28

centsi

16-Feb-03 11:28

I think it might be that the hWnd has become invalid, as the window handle has been 'recreated', during initialization, or after a change of certain properties. Is your code currently inside your main class constructor?, if so, try putting it in the form1_Load event.

Mattingly16-Feb-03 11:58

16-Feb-03 11:58

That might be it.. I am actually doing this inside a WindowHook, after handling a hooktype of CBT_CREATEWND. I think that may mean that its before a WM_CREATE message has been posted for that window and thus the hWnd is not valid yet. Could that be it?

And that implies I am doing this too soon, and should be handing a different type of windows hook, that of WH_CALLWNDPROC.

Does that sound right?

leppie17-Feb-03 6:04

17-Feb-03 6:04

DllImport("user32", CharSet=CharSet.Auto)]
public static extern int SetWindowLong (IntPtr hWnd, int nIndex, int dwNewLong);

MyDUMeter: a .NET DUMeter clone
"Thats like saying "hahahaha he doesnt know the difference between a cyberneticradioactivenuclothermolopticdimswitch and a biocontainingspherogramotron", but with words you have really never heard of."

Mattingly17-Feb-03 20:37

17-Feb-03 20:37

I don't understand. The docs define it as taking a long as the 3rd parameter and returning a long, not ints in those cases. I must be missing something here?

leppie18-Feb-03 3:19

XP App Crash SendReport Sample

18-Feb-03 3:19

MFC LONG is defined as a 32-bit integer, not a 64-bit integer as in the case of .NET long

MyDUMeter: a .NET DUMeter clone
"Thats like saying "hahahaha he doesnt know the difference between a cyberneticradioactivenuclothermolopticdimswitch and a biocontainingspherogramotron", but with words you have really never heard of."

Amber Star16-Feb-03 7:37

Amber Star

16-Feb-03 7:37

Hi,

I thought I saw an article on an implementation of an XP sytle App Crash Report util. That allows your app users to send in a report of a crash.
Anyone know if an article exsist like this.. I can't find it.

Thanks@ Rose | [Rose]

Amber Star

leppie16-Feb-03 9:28

16-Feb-03 9:28

amberstar wrote:
Anyone know if an article exsist like this.. I can't find it.

SOrry I dont know of one, but have a look at Application.ThreadException. You can dig around in Reflector.NET as well, he uses such a system. Unfortunately no source. But that is what he uses. Smile | :)

Nick Parker17-Feb-03 1:45

Nick Parker

17-Feb-03 1:45

leppie wrote:
he uses such a system. Unfortunately no source. But that is what he uses.

Who is "he"?

Nick Parker

The only man who never makes a mistake is the man who never does anything. - Theodore Roosevelt

Richard Deeming17-Feb-03 3:21

Richard Deeming

17-Feb-03 3:21

Nick Parker wrote:
Who is "he"?

Lutz Roeder: http://www.aisto.com/roeder/dotnet/[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

leppie17-Feb-03 4:21

17-Feb-03 4:21

David Stone17-Feb-03 10:40

David Stone

17-Feb-03 10:40

That man is a genius. I update whenever he comes out with a new version.

Hey, what can I say? I'm a chick magnet...a babe conductor...a logarithm for the ladies.
-Strong Bad from HomeStarRunner.com

Essential Tips for Web Developers

leppie18-Feb-03 6:30