Color white - (Color white alpha:0) = Color white
Color white - (Color white alpha:0.5) = Color gray.
Color white - (Color white alpha:1.0) = Color black.
For what do you need the color arithmetic ?
Maybe there are already other operations defined on Color that you can
used instead.

That is too complicated :)
The idea was to have one-line fix that just leaves the behaviour as it was before, simply makes it not produce garbage.

Basically there should be a long discussion after pharo 4 is released.

How it is now:

(Color white alpha: 0) = Color transparent => false

Color white - (Color white alpha: 0) = Color black => true

From logical point of view is should not be black. But from mathematical point of view Color is just a vector and operations with it should be the same or almost the same as with vectors.

For what do you need the color arithmetic ?

I wanted to get linear discrete transformation from one color to another to use it in animation��

Cheers,

Alex

On Sun, Mar 22, 2015 at 1:54 PM, Marcus Denker <marcus.denker@inria.fr> wrote:

On 22 Mar 2015, at 13:35, Nicolai Hess <nicolaihess@web.de> wrote:

2015-03-22 12:43 GMT+01:00 Nicolai Hess <nicolaihess@web.de>:

2015-03-21 15:51 GMT+01:00 Eliot Miranda <eliot.miranda@gmail.com>:

Why not take the average of alpha in all cases?

Eliot (phone)

On Mar 21, 2015, at 6:32 AM, Aliaksei Syrel <alex.syrel@gmail.com> wrote:

Or weight the argument by its alpha and don't change the alpha of the receiver:

Color white - (Color white alpha:0) = Color white

Color white - (Color white alpha:0.5) = Color gray.

Color white - (Color white alpha:1.0) = Color black.

For what do you need the color arithmetic ?

Maybe there are already other operations defined on Color that you can

used instead.

As the arithmetic operations on Color doesn't work (for years?), maybe we should remove

the operation now, and replace them with a more verbose api

addRGB/ addRGBA/ subRGBA ....

nicolai

Ah, this issue is already closed. That was a rather short discussion. And #/ and #* still don't work

for colors.

Yes��� I think we have a problem that there is no ���this is ready for integration��� check.

We need to get more careful���

Marcus