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Class: AlignmentOrigin

Inheritance:

   Object
   |
   +--Layout
      |
      +--LayoutOrigin
         |
         +--AlignmentOrigin
Package:
stx:libview2
Category:
Graphics-Geometry
Version:
rev: 1.37 date: 2024/03/21 17:09:59
user: cg
file: AlignmentOrigin.st directory: libview2
module: stx stc-classLibrary: libview2

Description:


This class is provided to make porting of existing ST-80 applications
easier. Instances can be used to control the geometry of a subview, within
its superview. Like a LayoutOrigin, it controls the components origin
via a relative part plus offset. However, in contrast to LayoutOrigin
(in which the top-left corner is specified by fraction+offset, here any
reference point within the component is positioned.
The reference point itself is specified as fraction of the components size.

Notice: 
    this class was implemented using protocol information
    from alpha testers, literature and by reading public domain code
    - it may be incomplete or oncompatible to the corresponding ST-80 class. 
    If you encounter any incompatibilities, please forward a note 
    describing the incompatibility verbal (i.e. no code) to the ST/X team.


copyright
COPYRIGHT (c) 1995 by Claus Gittinger
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Instance protocol:

accessing
o  leftAlignmentFraction
return leftAlignmentFraction

o  leftAlignmentFraction: aFraction
set leftAlignmentFraction (0..1)

o  leftAlignmentFraction: lF topAlignmentFraction: tF
set both leftAlignmentFraction (0..1) and topAlignmentFraction (0..1)

o  topAlignmentFraction
return topAlignmentFraction

o  topAlignmentFraction: aFraction
set topAlignmentFraction (0..1)

comparing
o  = anObject

o  hash
Modified (format): / 21-03-2024 / 14:14:44 / cg

computing
o  rectangleRelativeTo: superRectangle preferred: prefRectHolder
compute the rectangle represented by the receiver,
given the superView's rectangle and the view's preferredExtent.

Usage example(s): 

     |superRect aO|

     superRect := 0@0 corner:100@100.
     aO := (AlignmentOrigin new).
     aO leftFraction:0.5;
        topFraction:0.5;
        leftAlignmentFraction:0.5;
        topAlignmentFraction:0.5.
     aO rectangleRelativeTo:superRect preferred:(0@0 corner:30@30)

converting
o  fromLiteralArrayEncoding: encodingArray
read my values from an encoding.
The encoding is supposed to be of the form:
(AlignmentOrigin orgOffsX relOrgX orgOffsY relOrgY leftAlignFract topAlignFract)

Usage example(s): 

      AlignmentOrigin new fromLiteralArrayEncoding:#(#AlignmentOrigin 70 0 2 0 0.5 0.25)

o  literalArrayEncoding
encode myself as an array, from which a copy of the receiver
can be reconstructed with #decodeAsLiteralArray.
The encoding is:
(#AlignmentOrigin orgOffsX relOrgX orgOffsY relOrgY leftAlignFract topAlignFract)

initialization
o  initialize
must be called if redefined

printing & storing
o  displayOn: aGCOrStream
return a printed representation of the receiver for displaying

queries
o  isAlignmentOrigin
return true, if this is an alignmentOrigin

Examples:


Although the examples below use a button as component, they work of course with any type of subview .... using a LayoutOrigin, to control the top-left origins position of a component (i.e. origin at:0.5@0.5): 
    |top button|

    top := StandardSystemView new.
    top extent:300@300.

    button := Button label:'component'.
    top add:button in:(LayoutOrigin new
                            leftFraction:0.5;
                            topFraction:0.5).

    top open
using an AlignmentOrigin, to control the centers position of a component (i.e. center of component at:0.5@0.5): 
    |top button|

    top := StandardSystemView new.
    top extent:300@300.

    button := Button label:'component'.
    top add:button in:(AlignmentOrigin new
                            leftFraction:0.5;
                            topFraction:0.5;
                            leftAlignmentFraction:0.5;
                            topAlignmentFraction:0.5).

    top open
using an AlignmentOrigin, to control the bottom-right position of a component (i.e. bottom-right of component at:0.5@0.5): 
    |top button|

    top := StandardSystemView new.
    top extent:300@300.

    button := Button label:'component'.
    top add:button in:(AlignmentOrigin new
                            leftFraction:0.5;
                            topFraction:0.5;
                            leftAlignmentFraction:1.0;
                            topAlignmentFraction:1.0).

    top open
four buttons around relative 0.75@0.75: 
    |top button|

    top := StandardSystemView new.
    top extent:300@300.

    button := Button label:'button1'.
    top add:button in:(AlignmentOrigin new
                            leftFraction:0.75;
                            topFraction:0.75;
                            leftAlignmentFraction:1.0;
                            topAlignmentFraction:1.0).

    button := Button label:'button2'.
    top add:button in:(AlignmentOrigin new
                            leftFraction:0.75;
                            topFraction:0.75;
                            leftAlignmentFraction:0.0;
                            topAlignmentFraction:1.0).

    button := Button label:'button3'.
    top add:button in:(AlignmentOrigin new
                            leftFraction:0.75;
                            topFraction:0.75;
                            leftAlignmentFraction:1.0;
                            topAlignmentFraction:0.0).

    button := Button label:'button4'.
    top add:button in:(AlignmentOrigin new
                            leftFraction:0.75;
                            topFraction:0.75;
                            leftAlignmentFraction:0.0;
                            topAlignmentFraction:0.0).
    top open

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