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Extending OS/2 Presentation Manager Drag and Drop Capabilities

IP.com Disclosure Number: IPCOM000112486D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 85K

Publishing Venue

IBM

Related People

Johnson, KD: AUTHOR [+2]

Abstract

In some operating system environments, the decision of whether to accept or reject a drop is usually made during the drag operation. The window under the mouse pointer receives drag / drop messages and must determine if the object or objects currently being dragged can be dropped. This is accomplished by returning a value to the operating system indicating acceptance or rejection in response to the drag / drop message. If the value signifies acceptance and the mouse pointer is over a container record, the container draws a black rectangle around the target record. If the value signifies acceptance and the mouse pointer is over white space, the container draws a black border around the edge of the client area. If the value signifies rejection, a symbol signifying that no drop is allowed is drawn over the icon.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Extending OS/2 Presentation Manager Drag and Drop Capabilities

      In some operating system environments, the decision of whether
to accept or reject a drop is usually made during the drag operation.
The window under the mouse pointer receives drag / drop messages and
must determine if the object or objects currently being dragged can
be dropped.  This is accomplished by returning a value to the
operating system indicating acceptance or rejection in response to
the drag / drop message.  If the value signifies acceptance and the
mouse pointer is over a container record, the container draws a black
rectangle around the target record.  If the value signifies
acceptance and the mouse pointer is over white space, the container
draws a black border around the edge of the client area.  If the
value signifies rejection, a symbol signifying that no drop is
allowed is drawn over the icon.  If the objects are accepted and the
user completes the drag / drop operation, the new objects are
generally moved or copied (depending on the operation) to their new
location.

      Although this is an acceptable algorithm for many applications,
there are instances where an application would like to defer the
actual moving or copying of records until some specific processing
occurs.  For example, an application might consist of several
containers where one container contains icons representing programs
to be installed and another container contains icons representing
programs that have been installed successfully.  The user installs
the programs by dragging an icon from the "to be installed" container
to the "installed successfully" container.  The application would not
want to put up the "no drop is allowed" symbol when dropping from the
first container to the second container.  However, the application
also might not want to actually move or copy the records from the
first container to the second container until some processing
occurred (i.e. copying files) and no errors occurred during that
processing.  If any errors did occur, it might be appropriate not to
do the move or copy and to put up a message box informing the user of
the error.

      The drag / drop problem can be solved by sending a special
message to the application.  This ...