公开(公告)号：GB2191917A

公开(公告)日：1987-12-23

申请号：GB8614617

申请日：1986-06-16

Applicant: IBM

Inventor： ANTHIAS TEFCROS ,  HERROD JOHN ANDREW ,  TREES GEORGE MICHAEL

IPC: G06T11/00 ,  G06F3/048 ,  G06F3/14 ,  G09G5/14 ,  G06F15/62

Abstract: A multiple window display system includes a display device and a screen ownership area pointing to the identity of the window which is to contribute the data for each display area of the display device, characterised in that an ordered list is maintained of the active windows in the priority order thereof, means being provided to regenerate the screen ownership area from the list, on each change made to the list, in terms of list position per device display area, by overwriting, progressing through the list in order of increasingly significant priority order, the list indicating, in each position thereof, the identity of the window having the respective priority. The list contains the addresses of the windows in storage and the type thereof. The screen ownership area is reset to the lowest potential priority list position value and is overwritten.

公开(公告)号：DE69132068D1

公开(公告)日：2000-04-27

申请号：DE69132068

申请日：1991-07-05

Applicant: IBM

Inventor： HERROD JOHN ANDREW

IPC: G06F3/153 ,  G06F3/048 ,  G06T11/00 ,  G06T15/30 ,  G06T15/10

公开(公告)号：HUT67428A

公开(公告)日：1995-04-28

申请号：HU9400035

申请日：1992-05-20

Applicant: IBM

Inventor： HERROD JOHN ANDREW

IPC: G06F3/153 ,  G06T11/00 ,  G06T15/30 ,  G06F15/72

Abstract: When clipping a graphics element (2) defined by its element border (6) to a viewing window (4) having a window border (8) within which the graphics element is to be displayed, it is necessary to plot closure lines (10) along the window border between the points (EX, EN) where the element border exits and enters the viewing window. This closure line may be plotted along one of two paths between the points and along the window border. The system detects which of these paths the closure line should take. An effectively infinitely extending line from a point (P) on the window border is tested to see whether it crosses that portion of the element border outside the viewing window between the exit point and the entry point an odd or an even number of times. If it crosses an odd number of times then the closure line is plotted to pass through the predetermined point, and if it crosses an even number of times then the closure line is plotted to not pass through the predetermined point.

公开(公告)号：DE3787125D1

公开(公告)日：1993-09-30

申请号：DE3787125

申请日：1987-04-03

Applicant: IBM

Inventor： ANTHIAS TEFCROS ,  HERROD JOHN ANDREW ,  TREES GEORGE MICHAEL

IPC: G06T11/00 ,  G06F3/048 ,  G06F3/14 ,  G09G5/14 ,  G09G1/00

Abstract: A multiple window display system includes a display device and a screen ownership area pointing to the identity of the window which is to contribute the data for each display area of the display device, characterised in that an ordered list is maintained of the active windows in the priority order thereof, means being provided to regenerate the screen ownership area from the list, on each change made to the list, in terms of list position per device display area, by overwriting, progressing through the list in order of increasingly significant priority order, the list indicating, in each position thereof, the identity of the window having the respective priority. The list contains the addresses of the windows in storage and the type thereof. The screen ownership area is reset to the lowest potential priority list position value and is overwritten.