[vtk-developers] New VTK tree : Tcl done (Windows)

[Sebastien BARRE]

Hi folks

After some kind of work and CVS hassles, I guess I succeeded in building 
the new tree, as well as the Tcl and Python bindings. There are still some 
glitches to fix for the Tk Render Widgets, but this is just a patch to add 
to CMake. I've tested several Tcl examples (and the tk render widgets), 
this looks good.

The Tcl wrappers are no more located in a single vtktcl.dll file. They are 
split into several DLLs. Hence, the :
	catch {load vtktcl}
is not working anymore (until we find a trick).

I think it might be a good occasion for us to switch to a more serious 
structure, i.e. the *package*. This is also the perfect way to perform Tcl 
commands upon VTK initialization without hard-coding them in the DLL (for 
example, set the default exit method of the render window interactor to the 
'exit ' command) :
	package require vtktcl

I've committed two files to the CVS :
	Wrapping\Tcl\README : installation instruction, and migration path.
	Wrapping\Tcl\pkgIndex.tcl : the package

The contents of these file is listed below.
Feel free to flame me.

*****************************
README :
*****************************


VTK Tcl wrappers (Windows platforms)
===========================================================================

Using VTK inside Tcl/Tk is a two step process :

=============================
I) Load the 'vtktcl' package by issuing the following command before any 
invocation of a VTK function (typically at the top of your Tcl script) :

         package require vtktcl

NOTE: the previous VTK version was built such that the Tcl wrappers were 
stored in a single DLL file. Windows users were accustomed to issue 'catch 
{ load vtktcl }' in their Tcl scripts to load the VTK commands inside the 
Tcl interpreter. The Tcl wrappers are now split in numerous DLL files (i.e. 
shared libraries). Unless a compatibility path is found, you will have to 
replace any 'catch { load vtktcl }' with the line presented above. A Tcl or 
Perl script might be posted later to automate this task.

=============================
II) Install the package :

A good description of the package and library facilities is given in the 
Chapter 12 "Script, Libraries and Packages" (page 135) of "Practical 
Programming in Tcl & Tk", Brent B. Welch, ISBN 0-13-616830-2.

When a package is "required" by the 'package' command (see part I), the Tcl 
interpreter looks through a set of directories and their subdirectories for 
pkgIndex.tcl files. It sources those to build an internal database of 
packages (and version information).

A pkgIndex.tcl file has been included in this VTK distribution to provide 
the 'vtktcl' package to the interpreter. It will load the DLLs, set some 
default behaviours and exits with an error message if the package could not 
be provided (DLL not found, for example).

The package facility assume that Tcl libraries (and packages) are kept in 
well-known directories (and their subdirectories). The list of well-known 
directories is kept in the auto_path Tcl variable. This is initialized by 
tclsh or wish to include many default directories, including the default 
Tcl script library directory. For example :

% puts $auto_path
C:/devel/langages/tcl/8.3/lib/tcl8.3 C:/devel/langages/tcl/8.3/lib 
C:/devel/langages/tcl/8.3/lib/tk8.3

Now let's see how we can make Tcl aware of the vtktcl package. Two 
different ways :

o) EITHER copy the pkgIndex.tcl file :

- locate your Tcl install directory (see auto_path) and the lib directory 
(typically "C:/Program Files/Tcl/lib" or, in my example, 
"C:/devel/langages/tcl/8.3/lib").
- create whatever directory inside the lib directory (for example 
C":/Program Files/Tcl/lib/vtktcl").
- copy the pkgIndex.tcl file to this directory.

That's it. As the subdirectories inside the lib directory are browsed too, 
the pkgIndex.tcl file will be found and interpreted. The major disadvantage 
of this method is that you will have to keep this file up-to-date with 
modifications made to the pkgIndex.tcl file provided by subsequent VTK 
distribution (but most probably the VTK binary installer will copy the 
pkgIndex.tcl file for you).

o) OR Modify the TCLLIBPATH :

This is the way to go :) Tcl provides a way for you to tell the Tcl 
interpreter to search for pkgIndex.tcl files in any user-specified 
directory. Just set the TCLLIBPATH environment variable to a set of 
space-separated directories to search in. If you store the VTK sources on 
your hard disk or if you use the CVS, add the directory holding the 
pkgIndex.tcl file (Wrapping/Tcl). For example :

TCLLIBPATH=S:/src/vtk/vtknew/Wrapping/Tcl

Now check auto_path :

% puts $auto_path
S:/src/vtk/vtknew/Wrapping/Tcl C:/devel/langages/tcl/8.3/lib/tcl8.3 
C:/devel/langages/tcl/8.3/lib C:/devel/langages/tcl/8.3/lib/tk8.3

This works (and was expected to :)).


Sebastien BARRE (sebastien at barre.nom.fr)


*****************************
Package :
*****************************

Wrapping\Tcl\pkgIndex.tcl :

# Tcl package index file, version 1.0

package ifneeded vtktcl 4.0 {
     set ok 1

     if {$tcl_platform(platform) == "windows"} {
         # Try to load at least the Common part
         if {[catch {
             load vtkCommonTCL
         } errormsg ]} {
             puts $errormsg
             set ok 0
         } else {
             # Try to load the other components
             catch {
                 load vtkFilteringTCL
                 load vtkGraphicsTCL
                 load vtkHybridTCL
                 load vtkImagingTCL
                 load vtkIOTCL
                 load vtkParallelTCL
                 load vtkPatentedTCL
             }
             # Try to set the exit method of the interactor
             if {![catch {load vtkRenderingTCL}] && \
                     [catch {
                 vtkWin32RenderWindowInteractor __temp_vtkwin32iren__
                 __temp_vtkwin32iren__ SetClassExitMethod exit
                 __temp_vtkwin32iren__ Delete
             } errormsg ]} {
                 # warn the user, but do not prevent to provide the package
                 puts $errormsg
             }
         }
     }

     if {$ok} {
         package provide vtktcl 4.0
     }
}