Class: Layout

• Inheritance
• Description
• Related information
• Class protocol
  • instance creation
  • queries
• Instance protocol
  • computing
  • converting
  • initialization
  • queries

Inheritance:

   Object
   |
   +--Layout
      |
      +--LayoutOrigin

Package:

stx:libview2

Category:

Graphics-Geometry

Version:

rev: 1.22 date: 2019/07/17 08:15:54

user: cg

file: Layout.st directory: libview2

module: stx stc-classLibrary: libview2

Author:

Claus Gittinger

Description:

This is an abstract superclass for geometry controlling objects.
While old smalltalks used relative origin/extent/corner and absolute
origin/corner/extents, these mechanisms are now being removed from the
view itself into geometry controlling objects, which are given a superview's
size and are to return a component's size upon request.
This allows more flexible geometry management, since any algorithm can
be implemented (if the existing ones are not sufficient, add you own subclass
and install it as layout-object in your view).

Notice: 
    this class was implemented using protocol information
    from alpha testers - it may not be complete or compatible 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.

Related information:

    View
    LayoutOrigin
    LayoutFrame
    AlignmentOrigin

Class protocol:

 new

return a new initialized instance

 isAbstract

Return if this class is an abstract class.
True is returned here for myself only; false for subclasses.
Abstract subclasses must redefine this again.

Instance protocol:

 rectangleRelativeTo: superRectangle preferred: prefRectHolder

compute the rectangle represented by the receiver,
given the superView's rectangle and the view's preferredExtent.
Must be implemented by concrete subclasses.

** This method raises an error - it must be redefined in concrete classes **

 asLayout

return the receiver

 initialize

setup the instance - to be redefined by concrete subclasses

** This method raises an error - it must be redefined in concrete classes **

 isAlignmentOrigin

return true, if this is an alignmentOrigin

 isLayout

return true, if the receiver is a layout object.
Always return true here.

 isLayoutFrame

return true, if this is a layoutFrame

 isLayoutOrigin

return true, if this is a layoutOrigin