Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!cs.utexas.edu!husc6!linus!mbunix!bwk
From: bwk@mitre-bedford.ARPA (Barry W. Kort)
Newsgroups: comp.lang.smalltalk
Subject: Color Forms in ParcPlace Smalltalk
Summary: There's got to be a better way.
Message-ID: <40679@linus.UUCP>
Date: 5 Oct 88 19:48:25 GMT
Sender: news@linus.UUCP
Reply-To: bwk@mbunix (Kort)
Organization: The MITRE Corporation, Bedford, Mass.
Lines: 37

At OOPSLA '88, Sam Adams, Nanette Harter, and I discussed the
problem of drawing bi-colored forms using the ColorDevice class.
The following hack transforms an ordinary form into one that will
display a foreground color over a background color.  This method
seems horribly inefficient.  Perhaps someone can offer a better way.

------------Rape and Paste---------------------

'From Smalltalk-80, Version 2.3 of 13 June 1988
on 5 October 1988 at 8:14:31 am'!



!Form methodsFor: 'color forms'!

foreColor: fcolor backColor: bcolor

    "Return a new form which can be displayed in color using ColorDevice.
     This version works only for forms of width 8, 16, and multiples of 16."

    | cform cindex sno cbits cno |
    cform _ self class new width: self width * 8 height: self height.
    cbits _ cform bits.  cindex _ 0.
    1 to: bits size do: [ :sindex | sno _ bits at: sindex.
        14 to: width \\ 16 by: -2 do: [ :bindex | 
        cindex _ cindex + 1.
        cno _ sno bitShift: 0 - bindex.
        cno _ cno bitAnd: 3.
        cno = 0 ifTrue: [ cbits at: cindex put: bcolor * 256 + bcolor].
        cno = 1 ifTrue: [ cbits at: cindex put: bcolor * 256 + fcolor].
        cno = 2 ifTrue: [ cbits at: cindex put: fcolor * 256 + bcolor].
        cno = 3 ifTrue: [ cbits at: cindex put: fcolor * 256 + fcolor]]].
    ^ cform! !

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--Barry Kort