[VB6] Color Functions - Blending, etc

[lizano diaz]

To help someone else, I put together some color functions and thought I'd share it for anyone else to use/abuse. The class contains functions that can be pulled out (for the most part) individually and added to existing projects or it can be used as is. Use it more as a learning tool. Read the comments throughout the class.

The gist of the attached class is manual color modifications: blending, color & lightness addition/subtraction, conversion between different color formats, premultipllication, gray scaling, and several more routines.

I do not plan on appending new routines/functions to this class. However, there are dozens upon dozens of other color functions/matrices out on the web. Maybe start your own collection.

Edited: Here's another function. I'll leave it to you to build an Array version of it if needed.

Public Function UnPremultiplyColor(ByVal Color As Long) As Long
' remove premultiplication and returns a color in RGBA format
' Note: Premultiplication is not 100% recoverable. The returned
'   color compared to its original color is dependent upon the
'   alpha level. The higher the alpha level the closer the
'   returned color is to the original color.
'   Any alpha value of zero will always return vbBlack as the color
    Dim R As Long, G As Long, B As Long, Alpha As Long
    If (Color And &HFF000000) <> 0& Then
         Alpha = Me.Alpha(Color)
         R = ((Color And &HFF&) * &HFF&) \ Alpha
         G = (((Color And &HFF00&) \ &H100&) * &HFF&) \ Alpha
         B = (((Color And &HFF0000) \ &H10000) * &HFF&) \ Alpha
         UnPremultiplyColor = (Color And &HFF000000) Or R Or G * &H100& Or B * &H10000
    End If
End Function

Thank you very much for sharing your valuable code, excuse my ignorance but I would like to know how to send the parameters from a form.

Thank you, teacher