[vtkusers] Invalid index for GetWindowLongPtr in vtkWin32RenderWindowInteractor ? (x64)

[Andreas Gerndt]

Hi Thomas,

Get/SetWindowLongPtr can also be used to address extra
memory assigned to a window. Therefore, 4 means that the
funtion gets data starting at an offset of 4 in this
block of extra memory.

VTK uses this data to hold the pointer to the originally
instantiated render window object. The first 4 bytes are
reserved for the application. This is only useful when
handling 32-bit long pointers. For 64-bit applications,
the size should be enhanced to 8 bytes.

The main problem, however, is that only 8 bytes in total
for application and VTK is allocated. Therefore, the first
action should be increasing the extra memory size of the
window:

vtkWin32OpenGLRenderWindow::CreateAWindow(...){
   ...
   wndClass.cbWndExtra = 16;
   ...
}

This should already help!

A more generic approach would be to add an offset variable
into the code block embraced by "#if ( _MSC_VER >= 1300 )"
at the beginning of this source file:

#if ( _MSC_VER >= 1300 ) // Visual studio .NET
#pragma warning ( disable : 4311 )
#pragma warning ( disable : 4312 )
#  define vtkGWLP_HINSTANCE GWLP_HINSTANCE
#  define vtkWndOffset sizeof(LONG_PTR)
#  define vtkGetWindowLong GetWindowLongPtr
#  define vtkSetWindowLong SetWindowLongPtr
#else // regular Visual studio 
#  define vtkGWLP_HINSTANCE GWL_HINSTANCE
#  define vtkWndOffset sizeof(LONG)
#  define vtkGetWindowLong GetWindowLong
#  define vtkSetWindowLong SetWindowLong
#endif // 

The extar window memory allocation could modified as 
follows:

vtkWin32OpenGLRenderWindow::CreateAWindow(...){
   ...
   wndClass.cbWndExtra = 2 * vtkWndOffset;
   ...
}

Than replace all 4s in "vtkGetWindowLong(this->WindowId,4)"
as well as "vtkSetWindowLong(this->WindowId,4,(LONG)...);"
with vtkWndOffset. The affected files are:
 - "vtkWin32OpenGLRenderWindow.cxx",
 - "vtkWin32RenderWindowInteractor.cxx",
 - "vtkTKRenderWidget.cxx", and
 - "vtkTKImageViewerWidget.cxx".

Another recommendation could be replacing all (LONG)-castings
with (LONG_PTR) (which might be problematic for older studio
versions). 

Best regards

Andreas



> -----Original Message-----
> From: vtkusers-bounces+gerndt=rz.rwth-aachen.de at vtk.org 
> [mailto:vtkusers-bounces+gerndt=rz.rwth-aachen.de at vtk.org] On 
> Behalf Of Thomas Lambertz
> Sent: Saturday, May 13, 2006 3:08 PM
> To: vtkusers at vtk.org
> Subject: [vtkusers] Invalid index for GetWindowLongPtr in 
> vtkWin32RenderWindowInteractor ? (x64)
> 
> Hello,
> 
> i tried to find a way to make vtkRenderWindowInteractor work under 
> Windows x64. To be honest - i am not very familiar with the 
> Windows API 
> - so if i am talking rubbish please be patient...
> 
> I tried to isolate why there is no render-output when i used 
> vtkWindowRenderInteractor under x64. A good example are the 
> tutorials in 
> vtk/Example/Tutorial. Step 1-4 are working properly as the render 
> "manually" - step 5-6 have changed to vtkWindowRenderInteractor and 
> doesnt work.
> Adding some debug-output i saw that the Render() method wasnt 
> invoked - 
> so no surprise that there is only a black Windows ;-)
> 
> Searching in vtkWin32RenderWindowInteractor and 
> vtkWin32OpenGLRenderWindow i found Code like this:
> vtkGetWindowLong(hWnd,4);
> The returned Pointer/Handle is NULL and GetLastError() gives an Error 
> 1413 which means invalid index. As i understand "4" ist the wrong 
> parameter. Excerpt from Winuser.h:
> /*
>  * Window field offsets for GetWindowLong()
>  */
> #define GWLP_WNDPROC        (-4)
> #define GWLP_HINSTANCE      (-6)
> #define GWLP_HWNDPARENT     (-8)
> #define GWLP_USERDATA       (-21)
> #define GWLP_ID             (-12)
> 
> I assumed GWLP_WNDPROC was intended and i changed the Code in 
> that way. 
> But that is not the solution - now i get this errormessage:
> 
> ERROR: In 
> ..\..\vtk5.0_64\Rendering\vtkWin32OpenGLRenderWindow.cxx, line 809
> vtkWin32OpenGLRenderWindow (0000000000366F40): Could not 
> create window, 
> error:  0
> 
> And consistently there is no output-window...
> 
> 
> Sorry for making a such great hullabaloo. I hope that someone 
> else can 
> grab this information to become more succesful to solve this problem.
> 
> kind regards,
> Tom
> 
> PS: Under win32 the correspondent GWL_WINPROC is also defined 
> as (-4) - 
> but this does not seemes to make Problems (i havent investigate this 
> further)
> 
> 
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