Interop question

[michelqa]

When executing some win32 messages in c# I get unexpected results.
The following example is suppose to return the handle of an image in a
button control of another application but it return a negative
handle...is anybody know why it return an invalid handle like
"-989523277" ??

IntPtr ImageHandle =
Win32.SendMessa ge(Handle,BM_GE TIMAGE,IntPtr.Z ero,IntPtr.Zero );
MessageBox.Show (ImageHandle.To String());

Note : the third param is set to IMAGE_BITMAP (0); it return 0 if
the button contain no image.

Thanks...

[michelqa]

It's _possible_ that if you describe what you're really trying to do here, *

*from the high-level goal perspective, ignoring completely any particular *
implementation details, someone could offer better advice.

Pete

I'm doing a tool like spy++. Win32 controls are interpreted (runtime
converted) as .net object
for example Win32 control properties are displayed in a managed
propertyGrid of my spy++ application just like any other .Net
control.

My question was about filling Button.Image in my property grid
(selectedObject is a button) when converting a Win32 control to a .net
control.

I was just wondering why WM_GETIMAGE return unusable image handle...
(never seen a negative handle since now) With your help I understand
that it return a negative unasable handle because it's in another
process.

I already use a dll and a windows hook to get things like
Button.ImageLis t with WM_GETIMAGELIST and will probably use the same
kind of code to get the image handle of WM_GETIMAGE from the other
process.

Pete : What you mean By malware-like techniques?? Is there any other
way to do this without hooking windows to inject a dll into the other
process???

Since you always trying to help me in different threads here , you now
know why i'm asking win32 to .net questions. :)

[Peter Duniho]

On Fri, 22 Aug 2008 14:41:00 -0700, michelqa <mi******@yahoo .cawrote:

[...]
I was just wondering why WM_GETIMAGE return unusable image handle...
(never seen a negative handle since now) With your help I understand
that it return a negative unasable handle because it's in another
process.

Just to clarify: the fact that the IntPtr appears as a negative number is
irrelevant. It would look that way (and does) in the process where it's
valid. The reason it's not usable is that it's relative to the process,
and your process isn't the one where the handle is defined.

I already use a dll and a windows hook to get things like
Button.ImageLis t with WM_GETIMAGELIST and will probably use the same
kind of code to get the image handle of WM_GETIMAGE from the other
process.

Pete : What you mean By malware-like techniques?? Is there any other
way to do this without hooking windows to inject a dll into the other
process???

A common malware technique is to take advantage of some vulnerability in a
process that fools it into loading the malware code into that process's
own address space and executing the code. Unless a process is
specifically designed to intentionally execute third-party code (e.g. has
some sort of plug-in interface), fooling it into running code is the only
alternative, and these techniques are all mainly used by malware, not by
legitimate applications.

Pete