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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * This code is free software; you can redistribute it and/or modify it

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 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

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 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

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package sun.java2d.marlin;

import java.util.Arrays;

import sun.awt.geom.PathConsumer2D;

/**

 * The <code>Dasher</code> class takes a series of linear commands

 * (<code>moveTo</code>, <code>lineTo</code>, <code>close</code> and

 * <code>end</code>) and breaks them into smaller segments according to a

 * dash pattern array and a starting dash phase.

 *

 * <p> Issues: in J2Se, a zero length dash segment as drawn as a very

 * short dash, whereas Pisces does not draw anything.  The PostScript

 * semantics are unclear.

 *

 */

final class Dasher implements sun.awt.geom.PathConsumer2D, MarlinConst {

    static final int recLimit = 4;

    static final float ERR = 0.01f;

    static final float minTincrement = 1f / (1 << recLimit);

    private PathConsumer2D out;

    private float[] dash;

    private int dashLen;

    private float startPhase;

    private boolean startDashOn;

    private int startIdx;

    private boolean starting;

    private boolean needsMoveTo;

    private int idx;

    private boolean dashOn;

    private float phase;

    private float sx, sy;

    private float x0, y0;

    // temporary storage for the current curve

    private final float[] curCurvepts;

    // per-thread renderer context

    final RendererContext rdrCtx;

    // dashes array (dirty)

    final float[] dashes_initial = new float[INITIAL_ARRAY];

    // flag to recycle dash array copy

    boolean recycleDashes;

    // per-thread initial arrays (large enough to satisfy most usages

    // +1 to avoid recycling in Helpers.widenArray()

    private final float[] firstSegmentsBuffer_initial = new float[INITIAL_ARRAY + 1];

    /**

     * Constructs a <code>Dasher</code>.

     * @param rdrCtx per-thread renderer context

     */

    Dasher(final RendererContext rdrCtx) {

        this.rdrCtx = rdrCtx;

        firstSegmentsBuffer = firstSegmentsBuffer_initial;

        // we need curCurvepts to be able to contain 2 curves because when

        // dashing curves, we need to subdivide it

        curCurvepts = new float[8 * 2];

    }

    /**

     * Initialize the <code>Dasher</code>.

     *

     * @param out an output <code>PathConsumer2D</code>.

     * @param dash an array of <code>float</code>s containing the dash pattern

     * @param dashLen length of the given dash array

     * @param phase a <code>float</code> containing the dash phase

     * @param recycleDashes true to indicate to recycle the given dash array

     * @return this instance

     */

    Dasher init(final PathConsumer2D out, float[] dash, int dashLen,

                float phase, boolean recycleDashes)

    {

        if (phase < 0f) {

            throw new IllegalArgumentException("phase < 0 !");

        }

        this.out = out;

        // Normalize so 0 <= phase < dash[0]

        int idx = 0;

        dashOn = true;

        float d;

        while (phase >= (d = dash[idx])) {

            phase -= d;

            idx = (idx + 1) % dashLen;

            dashOn = !dashOn;

        }

        this.dash = dash;

        this.dashLen = dashLen;

        this.startPhase = this.phase = phase;

        this.startDashOn = dashOn;

        this.startIdx = idx;

        this.starting = true;

        needsMoveTo = false;

        firstSegidx = 0;

        this.recycleDashes = recycleDashes;

        return this; // fluent API

    }

    /**

     * Disposes this dasher:

     * clean up before reusing this instance

     */

    void dispose() {

        if (doCleanDirty) {

            // Force zero-fill dirty arrays:

            Arrays.fill(curCurvepts, 0f);

            Arrays.fill(firstSegmentsBuffer, 0f);

        }

        // Return arrays:

        if (recycleDashes && dash != dashes_initial) {

            rdrCtx.putDirtyFloatArray(dash);

            dash = null;

        }

        if (firstSegmentsBuffer != firstSegmentsBuffer_initial) {

            rdrCtx.putDirtyFloatArray(firstSegmentsBuffer);

            firstSegmentsBuffer = firstSegmentsBuffer_initial;

        }

    }

    @Override

    public void moveTo(float x0, float y0) {

        if (firstSegidx > 0) {

            out.moveTo(sx, sy);

            emitFirstSegments();

        }

        needsMoveTo = true;

        this.idx = startIdx;

        this.dashOn = this.startDashOn;

        this.phase = this.startPhase;

        this.sx = this.x0 = x0;

        this.sy = this.y0 = y0;

        this.starting = true;

    }

    private void emitSeg(float[] buf, int off, int type) {

        switch (type) {

        case 8:

            out.curveTo(buf[off+0], buf[off+1],

                        buf[off+2], buf[off+3],

                        buf[off+4], buf[off+5]);

            return;

        case 6:

            out.quadTo(buf[off+0], buf[off+1],

                       buf[off+2], buf[off+3]);

            return;

        case 4:

            out.lineTo(buf[off], buf[off+1]);

            return;

        default:

        }

    }

    private void emitFirstSegments() {

        final float[] fSegBuf = firstSegmentsBuffer;

        for (int i = 0; i < firstSegidx; ) {

            int type = (int)fSegBuf[i];

            emitSeg(fSegBuf, i + 1, type);

            i += (type - 1);

        }

        firstSegidx = 0;

    }

    // We don't emit the first dash right away. If we did, caps would be

    // drawn on it, but we need joins to be drawn if there's a closePath()

    // So, we store the path elements that make up the first dash in the

    // buffer below.

    private float[] firstSegmentsBuffer; // dynamic array

    private int firstSegidx;

    // precondition: pts must be in relative coordinates (relative to x0,y0)

    // fullCurve is true iff the curve in pts has not been split.

    private void goTo(float[] pts, int off, final int type) {

        float x = pts[off + type - 4];

        float y = pts[off + type - 3];

        if (dashOn) {

            if (starting) {

                int len = type - 2 + 1;

                int segIdx = firstSegidx;

                float[] buf = firstSegmentsBuffer;

                if (segIdx + len  > buf.length) {

                    if (doStats) {

                        RendererContext.stats.stat_array_dasher_firstSegmentsBuffer

                            .add(segIdx + len);

                    }

                    firstSegmentsBuffer = buf

                        = rdrCtx.widenDirtyFloatArray(buf, segIdx, segIdx + len);

                }

                buf[segIdx++] = type;

                len--;

                // small arraycopy (2, 4 or 6) but with offset:

                System.arraycopy(pts, off, buf, segIdx, len);

                segIdx += len;

                firstSegidx = segIdx;

            } else {

                if (needsMoveTo) {

                    out.moveTo(x0, y0);

                    needsMoveTo = false;

                }

                emitSeg(pts, off, type);

            }

        } else {

            starting = false;

            needsMoveTo = true;

        }

        this.x0 = x;

        this.y0 = y;

    }

    @Override

    public void lineTo(float x1, float y1) {

        float dx = x1 - x0;

        float dy = y1 - y0;

        float len = dx*dx + dy*dy;

        if (len == 0f) {

            return;

        }

        len = (float) Math.sqrt(len);

        // The scaling factors needed to get the dx and dy of the

        // transformed dash segments.

        final float cx = dx / len;

        final float cy = dy / len;

        final float[] _curCurvepts = curCurvepts;

        final float[] _dash = dash;

        float leftInThisDashSegment;

        float dashdx, dashdy, p;

        while (true) {

            leftInThisDashSegment = _dash[idx] - phase;

            if (len <= leftInThisDashSegment) {

                _curCurvepts[0] = x1;

                _curCurvepts[1] = y1;

                goTo(_curCurvepts, 0, 4);

                // Advance phase within current dash segment

                phase += len;

                // TODO: compare float values using epsilon:

                if (len == leftInThisDashSegment) {

                    phase = 0f;

                    idx = (idx + 1) % dashLen;

                    dashOn = !dashOn;

                }

                return;

            }

            dashdx = _dash[idx] * cx;

            dashdy = _dash[idx] * cy;

            if (phase == 0f) {

                _curCurvepts[0] = x0 + dashdx;

                _curCurvepts[1] = y0 + dashdy;

            } else {

                p = leftInThisDashSegment / _dash[idx];

                _curCurvepts[0] = x0 + p * dashdx;

                _curCurvepts[1] = y0 + p * dashdy;

            }

            goTo(_curCurvepts, 0, 4);

            len -= leftInThisDashSegment;

            // Advance to next dash segment

            idx = (idx + 1) % dashLen;

            dashOn = !dashOn;

            phase = 0f;

        }

    }

    // shared instance in Dasher

    private final LengthIterator li = new LengthIterator();

    // preconditions: curCurvepts must be an array of length at least 2 * type,

    // that contains the curve we want to dash in the first type elements

    private void somethingTo(int type) {

        if (pointCurve(curCurvepts, type)) {

            return;

        }

        li.initializeIterationOnCurve(curCurvepts, type);

        // initially the current curve is at curCurvepts[0...type]

        int curCurveoff = 0;

        float lastSplitT = 0f;

        float t;

        float leftInThisDashSegment = dash[idx] - phase;

        while ((t = li.next(leftInThisDashSegment)) < 1f) {

            if (t != 0f) {

                Helpers.subdivideAt((t - lastSplitT) / (1f - lastSplitT),

                                    curCurvepts, curCurveoff,

                                    curCurvepts, 0,

                                    curCurvepts, type, type);

                lastSplitT = t;

                goTo(curCurvepts, 2, type);

                curCurveoff = type;

            }

            // Advance to next dash segment

            idx = (idx + 1) % dashLen;

            dashOn = !dashOn;

            phase = 0f;

            leftInThisDashSegment = dash[idx];

        }

        goTo(curCurvepts, curCurveoff+2, type);

        phase += li.lastSegLen();

        if (phase >= dash[idx]) {

            phase = 0f;

            idx = (idx + 1) % dashLen;

            dashOn = !dashOn;

        }

        // reset LengthIterator:

        li.reset();

    }

    private static boolean pointCurve(float[] curve, int type) {

        for (int i = 2; i < type; i++) {

            if (curve[i] != curve[i-2]) {

                return false;

            }

        }

        return true;

    }

    // Objects of this class are used to iterate through curves. They return

    // t values where the left side of the curve has a specified length.

    // It does this by subdividing the input curve until a certain error

    // condition has been met. A recursive subdivision procedure would

    // return as many as 1<<limit curves, but this is an iterator and we

    // don't need all the curves all at once, so what we carry out a

    // lazy inorder traversal of the recursion tree (meaning we only move

    // through the tree when we need the next subdivided curve). This saves

    // us a lot of memory because at any one time we only need to store

    // limit+1 curves - one for each level of the tree + 1.

    // NOTE: the way we do things here is not enough to traverse a general

    // tree; however, the trees we are interested in have the property that

    // every non leaf node has exactly 2 children

    static final class LengthIterator {

        private enum Side {LEFT, RIGHT};

        // Holds the curves at various levels of the recursion. The root

        // (i.e. the original curve) is at recCurveStack[0] (but then it

        // gets subdivided, the left half is put at 1, so most of the time

        // only the right half of the original curve is at 0)

        private final float[][] recCurveStack; // dirty

        // sides[i] indicates whether the node at level i+1 in the path from

        // the root to the current leaf is a left or right child of its parent.

        private final Side[] sides; // dirty

        private int curveType;

        // lastT and nextT delimit the current leaf.

        private float nextT;

        private float lenAtNextT;

        private float lastT;

        private float lenAtLastT;

        private float lenAtLastSplit;

        private float lastSegLen;

        // the current level in the recursion tree. 0 is the root. limit

        // is the deepest possible leaf.

        private int recLevel;

        private boolean done;

        // the lengths of the lines of the control polygon. Only its first

        // curveType/2 - 1 elements are valid. This is an optimization. See

        // next(float) for more detail.

        private final float[] curLeafCtrlPolyLengths = new float[3];

        LengthIterator() {

            this.recCurveStack = new float[recLimit + 1][8];

            this.sides = new Side[recLimit];

            // if any methods are called without first initializing this object

            // on a curve, we want it to fail ASAP.

            this.nextT = Float.MAX_VALUE;

            this.lenAtNextT = Float.MAX_VALUE;

            this.lenAtLastSplit = Float.MIN_VALUE;

            this.recLevel = Integer.MIN_VALUE;

            this.lastSegLen = Float.MAX_VALUE;

            this.done = true;

        }

        /**

         * Reset this LengthIterator.

         */

        void reset() {

            // keep data dirty

            // as it appears not useful to reset data:

            if (doCleanDirty) {

                final int recLimit = recCurveStack.length - 1;

                for (int i = recLimit; i >= 0; i--) {

                    Arrays.fill(recCurveStack[i], 0f);

                }

                Arrays.fill(sides, Side.LEFT);

                Arrays.fill(curLeafCtrlPolyLengths, 0f);

                Arrays.fill(nextRoots, 0f);

                Arrays.fill(flatLeafCoefCache, 0f);

                flatLeafCoefCache[2] = -1f;

            }

        }

        void initializeIterationOnCurve(float[] pts, int type) {

            // optimize arraycopy (8 values faster than 6 = type):

            System.arraycopy(pts, 0, recCurveStack[0], 0, 8);

            this.curveType = type;

            this.recLevel = 0;

            this.lastT = 0f;

            this.lenAtLastT = 0f;

            this.nextT = 0f;

            this.lenAtNextT = 0f;

            goLeft(); // initializes nextT and lenAtNextT properly

            this.lenAtLastSplit = 0f;

            if (recLevel > 0) {

                this.sides[0] = Side.LEFT;

                this.done = false;

            } else {

                // the root of the tree is a leaf so we're done.

                this.sides[0] = Side.RIGHT;

                this.done = true;

            }

            this.lastSegLen = 0f;

        }

        // 0 == false, 1 == true, -1 == invalid cached value.

        private int cachedHaveLowAcceleration = -1;

        private boolean haveLowAcceleration(float err) {

            if (cachedHaveLowAcceleration == -1) {

                final float len1 = curLeafCtrlPolyLengths[0];

                final float len2 = curLeafCtrlPolyLengths[1];

                // the test below is equivalent to !within(len1/len2, 1, err).

                // It is using a multiplication instead of a division, so it

                // should be a bit faster.

                if (!Helpers.within(len1, len2, err*len2)) {

                    cachedHaveLowAcceleration = 0;

                    return false;

                }

                if (curveType == 8) {

                    final float len3 = curLeafCtrlPolyLengths[2];

                    // if len1 is close to 2 and 2 is close to 3, that probably

                    // means 1 is close to 3 so the second part of this test might

                    // not be needed, but it doesn't hurt to include it.

                    final float errLen3 = err * len3;

                    if (!(Helpers.within(len2, len3, errLen3) &&

                          Helpers.within(len1, len3, errLen3))) {

                        cachedHaveLowAcceleration = 0;

                        return false;

                    }

                }

                cachedHaveLowAcceleration = 1;

                return true;

            }

            return (cachedHaveLowAcceleration == 1);

        }

        // we want to avoid allocations/gc so we keep this array so we

        // can put roots in it,

        private final float[] nextRoots = new float[4];

        // caches the coefficients of the current leaf in its flattened

        // form (see inside next() for what that means). The cache is

        // invalid when it's third element is negative, since in any

        // valid flattened curve, this would be >= 0.

        private final float[] flatLeafCoefCache = new float[]{0f, 0f, -1f, 0f};

        // returns the t value where the remaining curve should be split in

        // order for the left subdivided curve to have length len. If len

        // is >= than the length of the uniterated curve, it returns 1.

        float next(final float len) {

            final float targetLength = lenAtLastSplit + len;

            while (lenAtNextT < targetLength) {

                if (done) {

                    lastSegLen = lenAtNextT - lenAtLastSplit;

                    return 1f;

                }

                goToNextLeaf();

            }

            lenAtLastSplit = targetLength;

            final float leaflen = lenAtNextT - lenAtLastT;

            float t = (targetLength - lenAtLastT) / leaflen;

            // cubicRootsInAB is a fairly expensive call, so we just don't do it

            // if the acceleration in this section of the curve is small enough.

            if (!haveLowAcceleration(0.05f)) {

                // We flatten the current leaf along the x axis, so that we're

                // left with a, b, c which define a 1D Bezier curve. We then

                // solve this to get the parameter of the original leaf that

                // gives us the desired length.

                final float[] _flatLeafCoefCache = flatLeafCoefCache;

                if (_flatLeafCoefCache[2] < 0) {

                    float x = 0f + curLeafCtrlPolyLengths[0],