[_CDCSL_93-16_]<1>Cedar>release>G2dMisc>G2dContour.mesa

G2dContour.mesa

Bloomenthal, July 1, 1992 7:04 pm PDT

Glassner, March 18, 1990 3:28:34 pm PST

DIRECTORY G2dBasic, G2dVector, Imager, ImagerSample, IO, Rope, ViewerClasses;

G2dContour: CEDAR DEFINITIONS

IMPORTS Imager

~ BEGIN

Error: ERROR [code: ATOM, reason: ROPE];

Note

The contour type supported by this interface is, simply, a sequence of two-dimensional points; there is no higher or analytic representation for the contour. The contour may be closed, in which case the last point of the sequence connects to the first point.

Local Types

Contour: TYPE ~ REF ContourRep;

ContourRep: TYPE ~ RECORD [

t: REAL ¬ 0.0, -- curve parameter, if known

closed: BOOL ¬ FALSE, -- if true, last point connects to 1st

circle: BOOL ¬ TRUE, -- if true, normals = points

pairs: PairSequence ¬ NIL, -- 2d points on contour

normals: PairSequence ¬ NIL, -- 2d normals of contour points

percents: RealSequence ¬ NIL, -- % along contour for each point

clientData: REF ¬ NIL

];

ContourSequence: TYPE ~ REF ContourSequenceRep;

ContourSequenceRep: TYPE ~ RECORD [

length: CARDINAL ¬ 0,

element: SEQUENCE maxLength: CARDINAL OF Contour

];

Span: TYPE ~ RECORD [y, x0, x1: INTEGER];

SpanSequence: TYPE ~ REF SpanSequenceRep;

SpanSequenceRep: TYPE ~ RECORD [

length: CARDINAL ¬ 0,

element: SEQUENCE maxLength: CARDINAL OF Span

];

RealIndex: TYPE ~ RECORD [n: NAT ¬ 0, alpha: REAL ¬ 0.0];

Imported Types

ROPE: TYPE ~ Rope.ROPE;

STREAM: TYPE ~ IO.STREAM;

Viewer: TYPE ~ ViewerClasses.Viewer;

Context: TYPE ~ Imager.Context;

SampleMap: TYPE ~ ImagerSample.SampleMap;

Rectangle: TYPE ~ Imager.Rectangle;

Color: TYPE ~ Imager.Color;

Border: TYPE ~ G2dBasic.Border;

Pair: TYPE ~ G2dBasic.Pair; -- RECORD [x, y: REAL]

PairSequence: TYPE ~ G2dBasic.PairSequence;

PairSequenceRep: TYPE ~ G2dBasic.PairSequenceRep;

IntegerPair: TYPE ~ G2dBasic.IntegerPair; -- RECORD [x, y: INTEGER]

IntegerPairSequence: TYPE ~ G2dBasic.IntegerPairSequence;

IntegerPairSequenceRep: TYPE ~ G2dBasic.IntegerPairSequenceRep;

NatPair: TYPE ~ G2dBasic.NatPair; -- RECORD [x, y: Nat]

NatPairSequence: TYPE ~ G2dBasic.NatPairSequence;

NatPairSequenceRep: TYPE ~ G2dBasic.NatPairSequenceRep;

RealSequence: TYPE ~ G2dBasic.RealSequence;

RealSequenceRep: TYPE ~ G2dBasic.RealSequenceRep;

Contour Creation

FromPairs: PROC [pairs: PairSequence, closed: BOOL ¬ FALSE, t: REAL ¬ 0.0]

RETURNS [Contour];

Return the contour given the input sequence.

FromIntegerPairs: PROC [

integerPairs: IntegerPairSequence, closed: BOOL ¬ FALSE, t: REAL ¬ 0.0]

RETURNS [Contour];

Return the contour given the input sequence.

General Operations

IntegerPairsFromPairs: PROC [pairs: PairSequence] RETURNS [IntegerPairSequence];

Convert the sequence.

PairsFromIntegerPairs: PROC [integerPairs: IntegerPairSequence] RETURNS [PairSequence];

Convert the sequence.

ShiftPairs: PROC [pairs: PairSequence, shift: INTEGER];

Barrel shift of the sequence; positive shift is to the left, negative to the right.

Scale: PROC [contour: Contour, scale: Pair] RETURNS [Contour];

Return the input contour scaled by the given amount.

Offset: PROC [contour: Contour, offset: Pair] RETURNS [Contour];

Return the input contour offset by the given amount.

Center: PROC [contour: Contour] RETURNS [Contour];

Return the input contour centered about [0, 0].

Orient: PROC [contour: Contour] RETURNS [Contour];

Return the input contour after orienting it to start at the lowest point in y.

Attributes

ContourOK: PUBLIC PROC [contour: Contour] RETURNS [BOOL];

Return true if contour and contour.pairs are non-nil.

MinMax: PROC [contour: Contour] RETURNS [min, max: Pair];

Return the minimum and maximum of the contour.

Centroid: PROC [contour: Contour] RETURNS [Pair];

Return the center of the contour.

Area: PROC [contour: Contour] RETURNS [REAL];

Return contour area: + if clockwise, - if counterclockwise, 0 if not closed.

Smoothing and Thinning

SmoothPairs: PROC [src: PairSequence, dst: PairSequence ¬ NIL] RETURNS [PairSequence];

Compute weighted local average of src; use dst if # NIL and long enough.

Smooth: PROC [contour: Contour] RETURNS [Contour];

Replace contour points with weighted local average.

Thin: PROC [contour: Contour, epsilon: REAL ¬ 3.0] RETURNS [Contour];

Remove redundant points (epsilon is the permissible angular degree deviation from straight).

Interpolation/Resampling/Comparing

ResampleNats: PROC [src: NatPairSequence, dstnum: NAT, dst: PairSequence ¬ NIL]

RETURNS [PairSequence];

Resample src curve to have dstnum (approx) equally spaced points; nats in, reals out.

Avoids new allocation if dst # NIL and is long enough.

ResamplePairs: PROC [src: PairSequence, dstnum: NAT, dst: PairSequence ¬ NIL]

RETURNS [PairSequence];

Resample src curve to have dstnum (approx) equally spaced points; reals in, reals out.

Avoids new allocation if dst # NIL and is long enough.

Interpolate: PROC [contour0, contour1: Contour, alpha: REAL] RETURNS [Contour];

Return the contour that is alpha*contour0+(1.0-alpha)*contour1.

Sample: PROC [contour: Contour, nPairs: INTEGER] RETURNS [Contour];

Return a sampled copy of contour.

Similar: PROC [contour0, contour1: Contour] RETURNS [REAL];

Return a measure of the similarity between the two g2dContour: 0 => dissimilar, 1 => similar.

Inside/Outside Test

InsideContour: PROC [p: Pair, pairs: PairSequence] RETURNS [Border];

Determine whether p is within the closed boundary defined by pairs.

Circles

CirclePairs: PROC [nPairs: INTEGER] RETURNS [PairSequence];

Return the points of a circle.

Circle: PROC [nPairs: INTEGER] RETURNS [Contour];

Return a circular contour of nPairs number of points.

Normals

Normals: PROC [contour: Contour] RETURNS [PairSequence];

Return the set of two-dimensional normals for the contour.

Percents

Percents: PROC [contour: Contour] RETURNS [RealSequence];

Set the percentages of each point according to its distance along the contour.

AtPercent: PROC [contour: Contour, percent: REAL] RETURNS [RealIndex];

Return the index into contour.pairs which is percent percentage around the contour.

PercentPair: PROC [contour: Contour, percent: REAL] RETURNS [Pair];

Return the contour point at percent percentage around the contour.

PercentNormal: PROC [contour: Contour, percent: REAL] RETURNS [Pair];

Return the (unitized) contour normal at percent percentage around the contour.

Spans

Spans: PROC [contour: Contour, rectangle: Rectangle] RETURNS [SpanSequence];

Create a sequence of scanline segments which constitue the pixelated contour region.

FillSpans: PROC [map: SampleMap, spans: SpanSequence, color: CARDINAL];

Color the spans.

Filling/Outlining

Fill: PROC [context: Context, contour: Contour, color: Color ¬ Imager.black];

Fill the contour with the current Imager color.

Outline: PROC [context: Context, contour: Contour, color: Color ¬ Imager.black];

Outline the contour with the current Imager color.

OutlineMap: PROC [map: SampleMap, contour: Contour, color: CARDINAL ¬ 0];

Outline the contour with the given color.

FillMap: PROC [map: SampleMap, contour: Contour, color: CARDINAL];

Fill the contour with the given color.

Copying

Copy: PROC [contour: Contour] RETURNS [Contour];

Return a copy of the input contour; the contour points and normals are copied.

CopySequence: PROC [contour: ContourSequence] RETURNS [ContourSequence];

Return a copy of the input sequence.

Painting

Paint: PUBLIC PROC [contour: Contour, context: Context, paintNormals: BOOL ¬ FALSE];

Paint the given contour.

Write: PROC [stream: STREAM, contour: Contour];

Write the given contour to the given stream.

Read: PROC [stream: STREAM] RETURNS [Contour];

Read the given contour from the given stream.

END.