Class: DragHandler

• Inheritance
• Description
• Class protocol
  • instance creation
  • queries
• Instance protocol
  • accessing
  • event dropTarget
  • protocol
  • testing
• Private classes

Inheritance:

   Object
   |
   +--DragHandler
      |
      +--DragHandler::Generic
      |
      +--DragHandler::Line
      |
      +--DragHandler::Opaque
      |
      +--DragHandler::Rectangle

Package:

stx:libview2

Category:

Interface-DragAndDrop

Version:

rev: 1.28 date: 2022/07/23 15:16:50

user: cg

file: DragHandler.st directory: libview2

module: stx stc-classLibrary: libview2

Description:

this abstract class describes the protocol common to any DragHandler.
The DragAndDropManger creates one instance responsible to show the
dragging objects on the screen.

copyright
COPYRIGHT (c) 1998 by eXept Software AG / 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:

 startArrowDragAt: aRootViewStartPoint

creates and returns the drag handler which is responsible
for an arrow drag.

 startGenericDrag: aTwoArgDragBlock

creates and returns the drag handler which is responsible
for a generic drag.

 startLineDragAt: aRootViewStartPoint

creates and returns the drag handler which is responsible
for a line drag.

 startOpaqueDrag: aTwoArgDragBlock extent: anExtent offset: anOffset

creates and returns the drag handler which is responsible
for a generic opaque drag.

 startRectangleDragAt: aRootViewStartPoint

creates and returns the drag handler which is responsible
for a rectangle drag.

 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:

 dropContext

 dropContext: something

 rootStartPoint

 rootStartPoint: aPointInRootViewCoordinates

Modified (format): / 23-07-2022 / 16:30:29 / cg

 sourceStartPoint

 sourceStartPoint: aPointInSourceViewCoordinates

Modified (format): / 23-07-2022 / 16:30:46 / cg

 targetView

 dropTargetWillChange

called before the drop target or widget changed,
and also when the view announces that it will change the contents
(eg. due to an autoscroll).
Restore the root view from the save-under

 isInterestedInDropTarget

returns true, if the handler is interested in the underlying
drop target and the target should be tested to be able to drop
the objects.

 dragTo: aRootPoint

drag to a root point

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

 flushSaveArea

 postDragging

after dragging; restore root view ...

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

 preDraggingIn: aSourceWidget

called before starting the drag & drop operation

 rereadSaveArea

 restoreFromSaveArea

D372428 - Drag and drop: falsches Redraw

 isDragHandlerLine

default: answer false

 isDragHandlerRectangle

default: answer false

Private classes:

    Generic
    Line
    Opaque
    Rectangle