Class: DragHandler

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

Inheritance:

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

Package:

stx:libview2

Category:

Interface-DragAndDrop

Version:

rev: 1.19 date: 2017/02/10 10:18:21

user: cg

file: DragHandler.st directory: libview2

module: stx stc-classLibrary: libview2

Author:

Claus Gittinger

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.

Related information:

    DragAndDropManager

Class protocol:

 startArrowDragAt: aStartPoint

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: aStartPoint

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.

 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

 targetView

 dropTargetWillChange

called before the drop target or widget changed.
restore root view ... (optional)

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

 flushSaveArea

 postDragging

after dragging; restore root view ...

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

 preDraggingIn: aSourceWidget

called before starting the drag & drop operation

 rereadSaveArea

Private classes:

    Generic
    Line
    Opaque