Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!bellcore!texbell!uhnix1!sugar!ficc!cliff
From: cliff@ficc.uu.net (cliff click)
Newsgroups: comp.lang.smalltalk
Subject: Re: Smalltalk/V286: moving cursor in Texteditor
Summary: TextSelections
Message-ID: <4629@ficc.uu.net>
Date: 20 Jun 89 13:07:01 GMT
References: <16@piyopiyo.hatori.t.u-tokyo.JUNET>
Organization: Ferranti International Controls
Lines: 50

> A stripped down version of the method I added to TextPane:
> ...[bad code removed]...
> Has anyone figured out where exactly the cursor gets moved and
> the big idea behind TextSelection?

A TextSelection is a pair of points.  The first point is the selection 
start, the second is the selection end.  If the end is before the start
the selection is viewed as a "Gap" or "I-Beam", otherwise a block of text
is selected (and displayed in reverse).  Here is some code for moving to
the start of a line:

! TextPane methods !
jumpLeft
"Move the GapSelector (I-Beam) to line start"
    | line |
"Get the previous Y value"
    line := selection corner y.
"Gaps slide both origin and corner left, selections just origin"
    ^selection isGap
	ifTrue: [selection origin: (1 @ line) corner: (0 @ line)]
	ifFalse: [selection origin: (0 @ line)]! !

I don't call any of the routines for handling the various selections, 
because their smart enough to do proper reverse videoing.  The routines 
which call this simple undo any selection, call this to torture the 
TextSelection, and re-do any selection based only on the new TextSelection.

Good Luck!

==========
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-- 
Cliff Click, Software Contractor at Large
Business: uunet.uu.net!ficc!cliff, cliff@ficc.uu.net, +1 713 274 5368 (w).
Disclaimer: lost in the vortices of nilspace...       +1 713 568 3460 (h).