c# translation 4

What is the c# translation of this code?:

HDC WINAPI CPaintHook::MyBeginPaint(HWND hWnd, LPPAINTSTRUCT lpPaint)
{
    const CPaintHook * pThis = (CPaintHook *) GetWindowLong(hWnd, GWL_WNDPROC);
   
    pThis = (const CPaintHook *) ( (unsigned) pThis - (unsigned) & pThis->m_thunk[0] + (unsigned) pThis );
   
    if ( pThis->Within_WM_PRINT() )
    {
        memset(lpPaint, 0, sizeof(PAINTSTRUCT));

        lpPaint->hdc = pThis->m_hDC;
       
        GetClientRect(hWnd, & lpPaint->rcPaint);
       
        return pThis->m_hDC;
    }
    else
    {
        __asm   mov     eax, syscall_BeginPaint
        __asm   push    lpPaint
        __asm   push    hWnd
        __asm   call    pBeginPaint
    }
}