Browse Prior Art Database

CRC Signature Usage for Screen Validation

IP.com Disclosure Number: IPCOM000102631D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 30K

Publishing Venue

IBM

Related People

Baird, JM: AUTHOR [+3]

Abstract

This article describes a method for calculating a CRC signature against a Presentation Manager* (PM) bitmap so that this value can be used at a later time to verify whether or not the contents of the screen have changed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

CRC Signature Usage for Screen Validation

       This article describes a method for calculating a CRC
signature against a Presentation Manager* (PM) bitmap so that this
value can be used at a later time to verify whether or not the
contents of the screen have changed.

      The following figure will help to illustrate the parts of the
screen that are being captured for a later comparison:

      A portion of the screen is clipped into a rectangle. This area
of the screen is then converted to a bitmap using the Presentation
Manager.

      After the bitmap is captured, it can be passed into a CRC
algorithm so that a unique signature can be calculated to represent
the area of the screen that was clipped.  This signature along with
the coordinates of the corners of the clipped area can be saved in a
file.

      In order to perform validation at a later time, the file is
read and the corner coordinates are used to clip the new area on the
screen.  This area is then processed through the CRC algorithm to get
its unique signature. If this signature compares with the original
one, then the areas of the screen match.  Otherwise, there is a
difference in them.
*  Trademark of IBM Corp.