| (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 |
| (22) |
Date of filing: 23.05.1989 |
|
|
| (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) |
|
| |
|
| (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.