(19)
(11) EP 0 172 433 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
05.04.1989 Bulletin 1989/14

(43) Date of publication A2:
26.02.1986 Bulletin 1986/09

(21) Application number: 85109231.2

(22) Date of filing: 23.07.1985
(51) International Patent Classification (IPC)4: G09G 1/00, G09G 1/16
(84) Designated Contracting States:
DE FR GB NL

(30) Priority: 02.08.1984 US 637375

(71) Applicant: TEKTRONIX, INC.
Beaverton Oregon 97077 (US)

(72) Inventors:
  • Schnarel, Charles B., Jr.
    Aloha Oregon 97007 (US)
  • Wirfs-Brock, Allen
    Sherwood Oregon 97140 (US)

(74) Representative: Liesegang, Roland, Dr.-Ing. 
FORRESTER & BOEHMERT Franz-Joseph-Strasse 38
80801 München
80801 München (DE)


(56) References cited: : 
   
       


    (54) Display method and apparatus employing cursor panning


    (57) A graphics display device is provided with a graphical input device which cooperates with means for addressing the display device's bit map memory (58) so that a viewport (56) into the bit map memory (58) can be panned in conjunction with a cursor (70) controlled by the input device. In particular, if the input device is operated for moving the cursor within the viewport (56) displayed on a cathode-ray-tube screen until the edge of the viewport (56) is encountered, the addressing of the bit map memory (58) is changed whereby the whole viewport appears to be moved by the cursor (70). Thus, if a transition is made in cursor movement from a location "inside" the viewport (56) to a location "outside" the viewport, the viewport is redefined such that the cursor (70) falls just within the viewport, as long as the dimensions of the virtual screen in the bit map memory are not exceeded.






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