Browse Prior Art Database

Providing Visual and Audible Extensions to Enhanced Drag/Drop Paradigm

IP.com Disclosure Number: IPCOM000114810D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 4 page(s) / 138K

Publishing Venue

IBM

Related People

Johnson, KD: AUTHOR [+3]

Abstract

The OS/2* 2.X Presentation Manager* (PM) container control drag and drop paradigm requires that the PM application make the decision of whether to accept or reject a drop during the drag operation. In response to drag and drop PM messages, the application must determine if the object or objects currently being dragged can be dropped and then must communicate this decision to PM by returning an accept or reject response. If a reject response is returned, PM changes the cursor icon to a symbol (NOT sign) which signifies that no drop is allowed at this location.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 40% of the total text.

Providing Visual and Audible Extensions to Enhanced Drag/Drop Paradigm

      The OS/2* 2.X Presentation Manager* (PM) container control drag
and drop paradigm requires that the PM application make the decision
of whether to accept or reject a drop during the drag operation.  In
response to drag and drop PM messages, the application must determine
if the object or objects currently being dragged can be dropped and
then must communicate this decision to PM by returning an accept or
reject response.  If a reject response is returned, PM changes the
cursor icon to a symbol (NOT sign) which signifies that no drop is
allowed at this location.

      The Window Management System (WMS), a PM based extension tool,
expands the PM drag and drop paradigm by allowing a WMS application
to defer, until after the mouse button has been released, the
decision on whether or not a drop is acceptable.  WMS implements this
feature by sending the application a message after the mouse button
is released but before any copying or moving of the dropped record
occurs.  In response to the WMS message, the application returns a
boolean value indicating if the move or copy operation should be
performed.

      This extension to the drag/drop paradigm has proven to be very
useful for those applications that need to perform some action in
response to the drop where such action may or may not be successful
and when not successful, requires that the move or copy operation
resulting from the drop not take place.  However, there has been a
serious usability omission because no direct visual feedback has been
presented to the user when the WMS application requests that the copy
or move operation not take place.  The PM drag/drop algorithm does
not provide the ability to display the "drop not allowed" icon after
the user has already released the mouse.

      This disclosure presents a method used by WMS to extend the WMS
PM drag/drop algorithm by providing immediate visual feedback to the
user in the case where the application decides to reject the move or
copy operation which would normally occur as a result of a drop.

      The PM drag/drop message-driven algorithm consists of three
messages sent to the application program for reaction.  These three
messages correspond to different points within the drag/drop
operation and are all notification codes within the WM_CONTROL
message.  Descriptions of the messages follow:
  1.  CN_INITDRAG - The container control sends a WM_CONTROL message
       with the CN_INITDRAG notification code to its owner when the
drag
       button is pressed and the pointer is moved while the pointer
is
       over the container control.
  2.  CN_DRAGOVER, CN_DRAGAFTER - The container control sends a
       WM_CONTROL message with the CN_DRAGOVER or CN_DRAGAFTER
       notification codes when a container record is being dragged
over
       the container.
  3.  CN_DROP - The container...