[vtk-developers] Proposed VTK_USE_VIDEO_FOR_WINDOWS / vfw32 / vtkAVIWriter changes

[David Cole]

Unless I hear objections, I'll commit the proposed changes within the 
next day or so. The cvs diff of VTK/CMakeLists.txt appears at the end of 
the email.

Currently, VTK_USE_VIDEO_FOR_WINDOWS:
- defaults to OFF
- has documentation string : "Use Video for Windows for video input."
- depends on VTK_USE_RENDERING and WIN32
- is an "advanced" option
- if ON, includes Hybrid/vtkWin32VideoSource.cxx and, as of yesterday, 
IO/vtkAVIWriter.cxx as source files
- if ON, includes vfw32 as a link library for vtkHybrid and vtkIO

I propose:
- Changing the *default* value of VTK_USE_VIDEO_FOR_WINDOWS to the 
result of a TRY_COMPILE that tells us whether you can successfully 
compile and link against vfw32. (You would still be able to change it or 
specify it explicitly.)
- Changing the documentation string of VTK_USE_VIDEO_FOR_WINDOWS to read 
"Enable using Video for Windows (vfw32) for video input and output."
- Eliminating the option's dependence on VTK_USE_RENDERING and WIN32 and 
relying exlusively on the results of the TRY_COMPILE.

More info:
The TRY_COMPILE would only be executed once if VTK_USE_VIDEO_FOR_WINDOWS 
is NOT already defined (from a previous run, in the  initial cache or on 
the cmake command line...) The source for the TRY_COMPILE is already 
checked in to VTK/CMake/vtkTestvfw32.cxx.

This way, if you can link against vfw32, you'll get the vfw32 dependent 
stuff included automatically in your VTK build. Our reasoning behind 
this change is this: we have the TRY_COMPILE technology and we want to 
get the vtkAVIWriter included on Windows builds by default...

Thanks,
David Cole
Kitware, Inc.


===== PROPOSED CHANGE =====

C:\CvsServers\public.kitware.com\VTK>cvs diff CMakeLists.txt
Index: CMakeLists.txt
===================================================================
RCS file: /cvsroot/VTK/VTK/CMakeLists.txt,v
retrieving revision 1.334
diff -r1.334 CMakeLists.txt
717a718,743
 > # Check for vfw32 support
 > IF("VTK_USE_VIDEO_FOR_WINDOWS" MATCHES "^VTK_USE_VIDEO_FOR_WINDOWS$")
 >   MESSAGE(STATUS "Checking if vfw32 is available")
 >   TRY_COMPILE(VTK_USE_VIDEO_FOR_WINDOWS_TRY_COMPILE
 >     ${VTK_BINARY_DIR}/CMakeTmp
 >     ${VTK_SOURCE_DIR}/CMake/vtkTestvfw32.cxx
 >     CMAKE_FLAGS "-DLINK_LIBRARIES:STRING=vfw32"
 >     OUTPUT_VARIABLE OUTPUT)
 >   IF(VTK_USE_VIDEO_FOR_WINDOWS_TRY_COMPILE)
 >     MESSAGE(STATUS "Checking if vfw32 is available -- yes")
 >     SET(VTK_USE_VIDEO_FOR_WINDOWS 1 CACHE BOOL "Enable using Video 
for Windows (vfw32) for video input and output.")
 >     WRITE_FILE(${CMAKE_BINARY_DIR}/CMakeFiles/CMakeOutput.log
 >       "Checking if vfw32 is available "
 >       "passed with the following output:\n"
 >       "${OUTPUT}\n" APPEND)
 >   ELSE(VTK_USE_VIDEO_FOR_WINDOWS_TRY_COMPILE)
 >     MESSAGE(STATUS "Checking if vfw32 is available -- no")
 >     SET(VTK_USE_VIDEO_FOR_WINDOWS 0 CACHE BOOL "Enable using Video 
for Windows (vfw32) for video input and output.")
 >     WRITE_FILE(${CMAKE_BINARY_DIR}/CMakeFiles/CMakeOutput.log
 >       "Checking if vfw32 is available "
 >       "failed with the following output:\n"
 >       "${OUTPUT}\n" APPEND)
 >   ENDIF(VTK_USE_VIDEO_FOR_WINDOWS_TRY_COMPILE)
 >   MARK_AS_ADVANCED(VTK_USE_VIDEO_FOR_WINDOWS)
 > ENDIF("VTK_USE_VIDEO_FOR_WINDOWS" MATCHES "^VTK_USE_VIDEO_FOR_WINDOWS$")
 >
851,853d876
< VTK_DEPENDENT_OPTION(VTK_USE_VIDEO_FOR_WINDOWS
<                      "Use Video for Windows for video input." OFF
<                      "VTK_USE_RENDERING;WIN32" OFF)
861,862c884
<                  VTK_USE_MPI
<                  VTK_USE_VIDEO_FOR_WINDOWS)
---
 >                  VTK_USE_MPI)