Class: DisplayObject

• Inheritance
• Description
• Class protocol
  • behavior
  • instance creation
  • queries
• Instance protocol
  • ST-80 drawing
  • accessing
  • component protocol
  • converting
  • drawing
  • dummy event handling
  • initialization
  • queries
  • user actions
  • user actions-move

Inheritance:

   Object
   |
   +--DisplayObject
      |
      +--BarChart3DWidget::Bar
      |
      +--BarChart3DWidget::Label
      |
      +--VisualComponent

Package:

stx:libview2

Category:

Compatibility-ST80-Graphics-Display Objects

Version:

rev: 1.51 date: 2023/09/07 20:42:16

user: stefan

file: DisplayObject.st directory: libview2

module: stx stc-classLibrary: libview2

Description:

generic superclass for Display Objects held in ObjectViews
see DrawObject/LogicObject/DeskTopObject and subclasses for example uses.

copyright
COPYRIGHT (c) 1989 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.

Class protocol:

 dragDashedOutline

if true, outline dragging is done by drawing the line dashed.
if false, the outline is drawn solid.
Can be redefined in subclasses (for solid outline).

 dragOutline

if true, dragging is done by drawing outline only;
if false, dragging is done by full draw (fast servers only).
Can be redefined in subclasses (for full dragging)

 new

(comment from inherited method)
return an instance of myself without indexed variables

 hasOwnScrollbars

a hack for codeView2, which behaves like a TextView, but has its own
scrollbars embedded - sigh (an extra load one).
This allows for the UIBuilder to avoid creating an extra set around such
a view (as is the case with TextSpec with scrollbars when using CodeView2)

 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:

 displayOn: aDisplayMedium at: aPoint

for ST-80 compatibility; not used in ST/X

 displayOn: aDisplayMedium at: aPoint clippingBox: clipRectangle

for ST-80 compatibility; not used in ST/X

 displayOn: aDisplayMedium at: aPoint clippingBox: clip rule: rule mask: aForm

for ST-80 compatibility; not used in ST/X.
in ST-80 programs, this is redefined

 displayOn: aDisplayMedium x: x y: y

(comment from inherited method)
display the receiver in a graphicsContext - this method allows
for any object to be displayed in a ListView (or any view) - for example.

 bottom

 bottomCenter

 bottomLeft

 bottomRight

 bounds

ST80 component compatibility

 corner

return the frame corner

 corner: corner

object must calculate its dimension from outline

** This method must be redefined in concrete classes (subclassResponsibility) **

 extent

return the extent of the frame

 frame

object must return a frame boundary rectangle

 height

return the height of the frame

 heightOn: aGC

return the height of the frame if drawon on aCG

 helpKey

The helpKey (symbol) or nil.
For now, components cannot have their own help

 left

 leftCenter

 origin

return the frame origin

 origin: origin

object must calculate its dimension from outline

** This method must be redefined in concrete classes (subclassResponsibility) **

 origin: origin corner: corner

object must calculate its dimension from outline

 right

 rightCenter

 top

 topCenter

 topLeft

 topRight

 width

return the width of the frame

 widthFrom: startIndex to: endIndex on: aGC

return the width of part of myself if drawn on aCG

** This method must be redefined in concrete classes (subclassResponsibility) **

 widthOn: aGC

return the width of the frame if drawn on aCG

 container: aComponent

ignored here - added to allow images to be used like
VisualComponents (later, Image should inherit from it)

 containerChangedSize

ignored here - added to allow images to be used like
VisualComponents (later, Image should inherit from it)

 destroy

SimpleView>>destroySubviews wants to destroy us (if we are a view's component).
Do nothing here

 middleButtonMenu: ignoredHere

intentionally left blank

 realize

ignored here - added to allow images to be used like
VisualComponents (later, Image should inherit from it)

 asDisplayObject

 drawDashedOutlineIn: aGC offset: anOffset

draw the receiver's outline at its origin offset by anOffset, aPoint

 drawDragIn: aView

draw the receiver for dragging at its origin

 drawDragIn: aView at: drawOrigin

draw the receiver for dragging at some point

 drawDragIn: aView offset: drawOrigin

draw the receiver for dragging offset by some amount

 drawIn: aView

draw the receiver at its origin

 drawIn: aView at: drawOrigin

draw the receiver at drawOrigin, aPoint

 drawIn: aView offset: anOffset

draw the receiver at its origin offset by anOffset, aPoint

** This method must be redefined in concrete classes (subclassResponsibility) **

 drawOutlineIn: aView

draw the receiver's outline at its origin

 drawOutlineIn: aView at: drawOrigin

draw the receiver's outline at drawOrigin, aPoint

 drawOutlineIn: aView offset: anOffset

draw the receiver's outline at its origin offset by anOffset, aPoint

 drawSelectedIn: aView

draw the receiver highlighted at its position

 drawSelectedIn: aView offset: anOffset

draw the receiver highlighted - this is usually redefined

 buttonMotion: buttNr x: x y: y

 buttonPress: buttNr x: x y: y

 buttonRelease: buttNr x: x y: y

 keyPress: key x: x y: y

 keyRelease: key x: x y: y

 computeBoundingBox

compute my boundingBox into the local variable 'frame'.
The box should be computed for Display.

** This method must be redefined in concrete classes (subclassResponsibility) **

 computeBoundingBoxFor: aDevice

compute my boundingBox into the local variable 'frame'.
The box is to be computed for aDevice.

 initialize

 canBeMoved

return true, if the receiver can be moved around (in an ObjectView)

 canBeSelected

return true, if the receiver can be selected (in an ObjectView)

 containsPoint: aPoint

 frameIsHitBy: aPoint withDelta: delta

return true, if my frame is hit by aPoint

 handlesKeyboardInput

return true, if the receiver handles keyboard input

 hasFixedSize

return true, if the receiver has fixed size i.e. cannot be
resized
- by default, we do not allow resizing

 hasOwnScrollbars

a hack for codeView2, which behaves like a TextView, but has its own
scrollbars embedded - sigh (an extra load one).
This allows for the UIBuilder to avoid creating an extra set around such
a view (as is the case with TextSpec with scrollbars when using CodeView2)

 hasRectangularBounds

can be redefined, but then it should also provide handles

 heightOfContentsDependsOnWidth

a very special query which is used by the scrollableView,
to check if it should NOT automatically hide scrollbars, when the
pointer leaves the view.
Currently, there are only a small number of views which return true here,
one being the HTML view, which rearranges its text depending on the width,
and therefore, it is a bad idea to hide/show scrollbars dynamically
(as this might lead to annoying flicker if the hiding of the scrollbar
rearranges the contents)

 intersects: aRectangle

object must decide, if it's intersecting a rectangle

 isContainedIn: aRectangle

object must decide, if it's within a rectangle

 isDisplayObject

 isHitBy: aPoint

object must decide, if hit by a click at aPoint

 isHitBy: aPoint withDelta: delta

object must decide, if hit by a click at aPoint;
usually this method is redefined in subclasses for a more complete
check (i.e. if objects boundary is not rectangular)

 isOpaque

return true, if the object fully covers its frame (i.e. is rectangular
and has no 'holes'. Since we don't know, return false here

 widthOfContentsDependsOnHeight

a very special query which is only used by the scrollableView,
to check if it should NOT automatically hide scrollbars, when the
pointer leaves the view.
Currently, there is no view, which returns true
(maybe if we ever support chinese writing top to bottom...

 keyInput: akey

 moveBy: delta

move the receiver - extent is unchanged

 moveTo: aPoint

object must move to new origin
- default is to stay; ought to be redefined in subclass