(19)
(11) EP 0 349 455 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
20.03.1991 Bulletin 1991/12

(43) Date of publication A2:
03.01.1990 Bulletin 1990/01

(21) Application number: 89480077.0

(22) Date of filing: 23.05.1989
(51) International Patent Classification (IPC)5G09G 5/14, G09G 1/16
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 30.06.1988 US 213427

(71) Applicant: International Business Machines Corporation
Armonk, N.Y. 10504 (US)

(72) Inventors:
  • Barker, Barbara Ann
    Round Rock Texas 78681 (US)
  • Edel, Thomas R.
    Austin, Texas 78750 (US)
  • Stark, Jeffrey A.
    Grapevine Texas 76051 (US)

(74) Representative: Tubiana, Max 
Compagnie IBM France Département de Propriété Intellectuelle
06610 La Gaude
06610 La Gaude (FR)


(56) References cited: : 
   
       


    (54) Method for controlling the presentation of nested overlays


    (57) A method is disclosed for controlling the presentation of nested overlays on a display medium. An overlay function resource is provided which includes its own environment specification which is independent of the space and data environment specifications. Mixing attributes are associated with each overlay and are utilized to determine which overlay space and data are to take precedence and be visible when the overlayed spaces are combined and imaged on a display medium. In a preferred mode of the present invention, the foreground and background of each overlay are separately controlled by the mixing attributes which define the mixing rules for the layered presentation of multiple overlays. Additionally, the order of precedence for displaying multiple overlays may be selectively altered or varied to provide multiple displays and to permit an individual overlay to be repetitively utilized.





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