Are we really going to embrace offset?
John-Reed Maffeo (rlpa80)
rlpa80 at email.sps.mot.com
Tue Jan 5 05:55:34 UTC 1999
Dan Ingalls wrote:
> Here's one approach...
> | f |
> f _ (ColorForm mappingWhiteToTransparentFrom: (Form dotOfSize: 50))
> colors: (Array with: Color transparent with: Color blue).
> f displayOn: Display at: 200 at 200 rule: Form paint
>
> This should display properly in every color depth, but you need the "paint" combination rule which treats transparency correctly.
>
> - Dan
This works with the exception of the offset value which gets set in
dotOfSize: ( a class method of Form).
The class methods for instance creation of Forms seems to be incomplete
or maybe immature. I don't know the history of the methods or how
they evolved, but I found the comment in the instance selector, center
(the subject of this post) intriguing.
My proposal is to embrace offset in Form and its decendants. I think
that there should be a private instance method like setExtent:depth:
which also sets the instance variables offset and bits to appropriate
initial values (offset _ 0 at 0. bits _ ????).
This new method would then cascade down to the various other instance
creation methods. There are currently only four users of setExtent:depth:.
They are all in Form or ColorForm.
I am willing to make the changes if they are the right thing to do.
Otherwise I will go back to contemplating Squeaks navel.
Thanks,
John-Reed Maffeo
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