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- Using DevIL from Visual Basic 6.0
- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- The idea:
- 1) Start by installing the DLLs.
- 2) In your VB-project, add the .BAS files that you need as modules.
- 3) Just use the subs/functions and constants.
- The buts:
- 1) DevIL's data types have been converted to native VB-types. This should generally
- work alright, except that
- a) VB only knows unsigned bytes and signed integers/longs. So sometimes a value is
- defined as signed in VB where it is actually unsigned, and vice-versa.
- b) DevIL's ILboolean type has been converted to byte. Don't treat these as VB
- booleans; only use them to compare to IL_TRUE and IL_FALSE.
- 2) Subs/functions that take a pointer to an array as parameter have been declared to
- take a ByRef Element As ElementType. You should define an array of ElementType (not
- array of variants!), and pass the first element to the function. The function will
- then access the whole array.
- Example: Dim Names(2) As Long
- ilGenImages 3, Names(0) ' Fills all 3 elements of Names
- (If you only use a single element, you do not really need an array. You can just
- pass a variable of the element type.)
- The following subs/functions uses arrays of byte (binary data):
- ilCopyPixels (Outputs data. Make sure your array is big enough!)
- ilIsValidL
- ilLoadL
- ilRegisterPal
- ilSetPixels
- ilTexImage
- ilTexImage is a special case, because you might want to pass it a null-pointer
- instead of actual data. This cannot be done with the same VB declaration, so I've
- made ilTexImage0 for this purpose. Pass ilTexImage0 a zero as the last parameter.
- Other functions that operate on arrays:
- ilDeleteImages array of long (image "names")
- ilGenImages array of long (image "names")
- 3) Functions that return pointers have been converted to return a long. But they are
- effectively useless in VB. These are:
- ilGetData
- ilGetPalette
- ilGetString
- iluErrorString
- iluGetString
- ilutGetString
- ilutGetPaddedData
- 4) ilutGetBmpInfo and all ilutD3D8-functions are not available.
- 5) You will generally not be able to implement the call-back functions in VB, because
- they must be able to handle pointers. But the call-back functions are only used if
- you want to modify the way DevIL loads and saves images, and usually you won't need
- to do that.
- 6) The old VB-examples supplied by Timo Heister don't seem to work. I've yet to write
- some new ones.
- 7) The VB-headers have only seen minimal testing. Bugs may lure on the unwary.
- (I'm especially nervous about iluGetImageInfo).
- 8) The header-files are created specificly for VB 6.0. I very much doubt that they will
- be of any use in VB.net.
- Feel free to send me any comments.
- Rune Kock (rune@vupti.com)
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