[RESOLVED] [2.0] API declaration from VB6 to C#

[Atheist]

I've got an API declared in VB6:

Declare Function GetWindowRect Lib "user32" Alias "GetWindowRect" (ByVal hwnd As Long, lpRect As RECT) As Long

Its passed a RECT structure, that is declared like this:

Private Type RECT
    Left As Long
    Top As Long
    Right As Long
    Bottom As Long
End Type

Am I right thinking that this would be the proper translation?

public struct RECT
        {
            public int left;
            public int top;
            public int right;
            public int bottom;
        }
 
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern int GetWindowRect(IntPtr hwnd, RECT lpRect);

I dont see what I mightve done wrong, because everytime I try to call the function I get this error message:

A call to PInvoke function 'WindowHandles!WindowHandles.Form1::GetWindowRect' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

[RobDog888]

You need to add the InteropServices. This is VB but if you need C# I can convert it.

Imports System.Runtime.InteropServices
 
<DllImport("user32.dll", CharSet:=CharSet.Auto, EntryPoint:="GetWindowRect")> _
Private Shared Function GetWindowRect (ByVal hwnd As Int32, ByRef lpRect As RECT) As Int32
End Function
 
<StructLayout(LayoutKind.Sequential)> _ 
Private Structure RECT
    Public Left As Int32
    Public Top As Int32
    Public Right As Int32
    Public Bottom As Int32
End Structure

[RobDog888]

and the converted C#. Not too much dif from yours.

using System.Runtime.InteropServices;
 
[StructLayout(LayoutKind.Sequential)]
private struct RECT
{
    public Int32 Left;
    public Int32 Top;
    public Int32 Right;
    public Int32 Bottom;
}
 
[DllImport("user32.dll", CharSet=CharSet.Auto, EntryPoint="GetWindowRect")]
private extern static Int32 GetWindowRect(Int32 hwnd, ref RECT lpRect);

[jmcilhinney]

The API Viewer can give you C# declarations.

[DllImport("user32.dll")]
static extern int GetWindowRect ( 
	 int hwnd,
	 ref RECT lpRect);

[StructLayout(LayoutKind.Sequential)]
struct RECT{
	internal int Left;
	internal int Top;
	internal int Right;
	internal int Bottom;
}

[RobDog888]

Other then internal vs public I dont see a difference between your code and mine?

[jmcilhinney]

Other then internal vs public I dont see a difference between your code and mine?

I wasn't trying to say that it was better. That code was straight out of the API Viewer. I just posted it as an example of what the API Viewer can do. I've seen you recommend it many times and the fact that you didn't here made me think that perhaps you weren't aware it handled C# too.

[RobDog888]

Actually since I hardly ever code in C# I forgot

I was looking to see what was the difference in the signature as the error message was stating but dont see anything out of the usual.

[jmcilhinney]

The original problem presumably was caused by the fact that the second argument was not declare by reference, because that's the only difference I can see.

[RobDog888]

Yup looks like the only dif and that dif would create the error.

[Atheist]

Thanks guys I declared the second argument by reference and its working perfectly.

[RobDog888]

You should also e using the dllimport attributes too.

[Atheist]

You should also e using the dllimport attributes too.

Where should I use it you mean? If you look at my row 9 in the code in my original post, Ive got an dllimport statement just above the API declaration

[RobDog888]

But not for the rect structure. See post #3 and #4

[StructLayout(LayoutKind.Sequential)]