A computer method and an aparatus for generating a display picture representing a set of object elements including a brush object element

Claim 1

A computer method for pixel-wise generating a display picture representing an object set of object elements, including a brush object element that is a Bezier shape to be moved with its guiding centre along a guiding trajectory that is a non-rational Bezier path included in said object set, said method comprising the steps of: a. for each trajectory Bezier curve providing a trajectory set of trajectory control points in an associated coordinate-wise oriented trajectory curve bounding box and for each brush Bezier curve providing a brush set of brush control points in an associated brush curve bounding box, and providing a brush bounding box containing all points of the brush shape; b. for each pixel determining application coordinate values regarding any relevant object element for an actual point corresponding to that pixel, and then dilating each respective trajectory curve bounding box with the brush bounding box to a dilated box and c. in a determination procedure determining for said actual point either; c1. actual point outside dilated box then reject trajectory curve in question and go to another trajectory curve, or c2. actual point inside brush bounding box when brush guiding centre positioned in either end point of actual trajectory curve, then execute brush procedure with respect to such end point, but c3. otherwise execute a division procedure on the trajectory Bezier curve in question and take any part as secondary trajectory Bezier curve, for processing in said determination procedure; d. in the brush procedure for any brush Bezier curve determining for said actual point either: d1. actual point outside brush Bezier curve bounding box then go to intersection procedure, or d2. actual point coincides with any brush Bezier curve end point then exit to assignment procedure, or d3. all control points of brush Bezier curve lie in a 2x2 discrete point square then go to intersection procedure, but d4. otherwise execute division procedure on brush Bezier curve in question and take any part as secondary brush Bezier curve for processing in said brush procedure; e. in said intersection procedure determine a number of intersections of a particular semi-infinite line starting in said actual point with an actual brush Bezier curve and accumulating said number, until all brush Bezier curves have been processed in the brush procedure and then in case of an odd accumulation result going to said assignment operation but otherwise return to said determination procedure while resetting the accumulation; f. in said assignment procedure assigning an -inside- indication to the pixel in question and exit; g. but otherwise assigning an -outside- indication to the pixel in question, and exit.

Claim 8

A method as claimed in any of Claims 1 to 6, wherein said guiding trajectory is a closed shape and also defines said -­inside- indication, wherein said brush procedure is also executed on the trajectory in isolation, which then operates as a second, stationary, brush.

Claim 10

A method as claimed in any of Claims 1 through 8, wherein any -inside- indication produced for an actual pixel terminates processing of that pixel.

Claim 11

A method as claimed in any of Claims 1 to 9, wherein said brush shape has a dimension that is variable in application coordinates for keeping its dimension fixed in display device coordinates under any zooming/dezooming operation.

Claim 12

A method as claimed in any of Claims 1 to 10, wherein said guiding trajectory defines an alfanumerical character.

Claim 13

A method as claimed in any of Claims 1 to 11, wherein said guiding trajectory interconnects two closed figures.

Claim 14

A method as claimed in any of Claims 1 to 12, for determining spatial coherence within a display window with respect to a region that is outlined by a second closed Bezier path, to be displayed, wherein said second path operates as said guiding trajectory and said window is spatially inverted with respect to an origin point, said origin thereupon operating as guiding centre, and a result of said inverting operating as brush, after which any -inside- indication for said origin point signals non-coherence.

Claim 15

A method as claimed in any of Claims 1 through 13, for use on a multicolor display apparatus.

Claim 16

A method as claimed in any of Claims 1 through 14, for use on a text processor device.

Claim 17

A method as claimed in any of Claims 1 through 15, for use on a graphics processing system.

Claim 18

A method as claimed in any of Claims 1 through 16, wherein said brush shape contains a rational Bezier curve that by means of conical projection with respect to a second origin is transferred into a non-rational Bezier curve in three dimensions, which by means of cylindrical projection parallel to the junction line between the second origin and the actual point transfers to a further non-rational Bezier shape for which the point containment result of the second origin is identical to the point containment of the original point in question with respect to the original brush shape.

Claim 24

A method as claimed in any of Claims 1 through 16, wherein said brush shape is a rectangle.

Claim 25

An apparatus for practising the method as claimed in any of Claims 1 through 23, said apparatus comprising: - first storage means for selectably storing a sequence of trajectory control point coordinates and edge coordinates of brush bounding box (250); - second storage means for storing coordinates of said actual point (154) - first calculating means fed by said first and second storage means for calculating relative coordinates of said trajectory control points; - first test means fed by said first calculating means for testing on all control points of a Bezier curve to lie in a 2 point x 2 point square (260); - second calculating means fed by said first storage means and second storage means for calculating relative values of edges of the dilated box (266,); - second test means fed by said second calculating means for testing whether the actual point is outside said dilated box (272, 274); - third calculating means fed by said first calculating means for calculating control points of a divided trajectory Bezier curve and feeding these to said first and second test means for conditional retrocoupling to its own input; - said apparatus furthermore having an output means fed by said first calculating means for outputting processed control points to a brush routine processing means.