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Class: AbstractBackground


Inheritance:

   Object
   |
   +--AbstractBackground
      |
      +--DiffTextView::DiffTextScrollerBackground
      |
      +--GradientBackground
      |
      +--ImageBackground
      |
      +--NoBackground
      |
      +--SolidBackground
      |
      +--Tools::CodeView2::AnnotationShowingScrollerBackground

Package:
stx:libview
Category:
Graphics-Support
Version:
rev: 1.9 date: 2017/02/22 20:20:31
user: cg
file: AbstractBackground.st directory: libview
module: stx stc-classLibrary: libview
Author:
Claus Gittinger

Description:


This will replace the viewBackground color.
Instances of me (and subclasses) can be set as a widget's
viewBackground, and will get 
    fillRectangleX:x y:y width:w height:h in:aView
messages whenever the widget wants to redraw (parts of) its background.

See the example in GradientBackground.


Related information:

    GradientBackground

Class protocol:

queries
o  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:

drawing
o  fillRectangleX: x y: y width: w height: h in: aView

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

ignored conversion
o  asFormOn: aDevice

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

o  onDevice: aDevice

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

testing
o  isViewBackground

o  needsFullRedrawOnChangeOfHeight

o  needsFullRedrawOnChangeOfWidth


Examples:


|v| v := View new. v viewBackground:(SolidBackground new color:Color red). v open.

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