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 * published by the Free Software Foundation.  Oracle designates this

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 * 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

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package sun.java2d.pisces;

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 {

    private final PathConsumer2D out;

    private final float[] dash;

    private final float startPhase;

    private final boolean startDashOn;

    private final 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 float[] curCurvepts;

    /**

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

     *

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

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

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

     */

    public Dasher(PathConsumer2D out, float[] dash, float phase) {

        if (phase < 0) {

            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) % dash.length;

            dashOn = !dashOn;

        }

        this.dash = dash;

        this.startPhase = this.phase = phase;

        this.startDashOn = dashOn;

        this.startIdx = idx;

        this.starting = true;

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

        // dashing curves, we need to subdivide it

        curCurvepts = new float[8 * 2];

    }

    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]);

            break;

        case 6:

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

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

            break;

        case 4:

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

        }

    }

    private void emitFirstSegments() {

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

            emitSeg(firstSegmentsBuffer, i+1, (int)firstSegmentsBuffer[i]);

            i += (((int)firstSegmentsBuffer[i]) - 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 = new float[7];

    private int firstSegidx = 0;

    // 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) {

                firstSegmentsBuffer = Helpers.widenArray(firstSegmentsBuffer,

                                      firstSegidx, type - 2);

                firstSegmentsBuffer[firstSegidx++] = type;

                System.arraycopy(pts, off, firstSegmentsBuffer, firstSegidx, type - 2);

                firstSegidx += type - 2;

            } else {

                if (needsMoveTo) {

                    out.moveTo(x0, y0);

                    needsMoveTo = false;

                }

                emitSeg(pts, off, type);

            }

        } else {

            starting = false;

            needsMoveTo = true;

        }

        this.x0 = x;

        this.y0 = y;

    }

    public void lineTo(float x1, float y1) {

        float dx = x1 - x0;

        float dy = y1 - y0;

        float len = (float) Math.sqrt(dx*dx + dy*dy);

        if (len == 0) {

            return;

        }

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

        // transformed dash segments.

        float cx = dx / len;

        float cy = dy / len;

        while (true) {

            float 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;

                if (len == leftInThisDashSegment) {

                    phase = 0f;

                    idx = (idx + 1) % dash.length;

                    dashOn = !dashOn;

                }

                return;

            }

            float dashdx = dash[idx] * cx;

            float dashdy = dash[idx] * cy;

            if (phase == 0) {

                curCurvepts[0] = x0 + dashdx;

                curCurvepts[1] = y0 + dashdy;

            } else {

                float 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) % dash.length;

            dashOn = !dashOn;

            phase = 0;

        }

    }

    private LengthIterator li = null;

    // 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;

        }

        if (li == null) {

            li = new LengthIterator(4, 0.01f);

        }

        li.initializeIterationOnCurve(curCurvepts, type);

        int curCurveoff = 0; // initially the current curve is at curCurvepts[0...type]

        float lastSplitT = 0;

        float t = 0;

        float leftInThisDashSegment = dash[idx] - phase;

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

            if (t != 0) {

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

                                    curCurvepts, curCurveoff,

                                    curCurvepts, 0,

                                    curCurvepts, type, type);

                lastSplitT = t;

                goTo(curCurvepts, 2, type);

                curCurveoff = type;

            }

            // Advance to next dash segment

            idx = (idx + 1) % dash.length;

            dashOn = !dashOn;

            phase = 0;

            leftInThisDashSegment = dash[idx];

        }

        goTo(curCurvepts, curCurveoff+2, type);

        phase += li.lastSegLen();

        if (phase >= dash[idx]) {

            phase = 0f;

            idx = (idx + 1) % dash.length;

            dashOn = !dashOn;

        }

    }

    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

    private static 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 float[][] recCurveStack;

        // 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 Side[] sides;

        private int curveType;

        private final int limit;

        private final float ERR;

        private final float minTincrement;

        // 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 float[] curLeafCtrlPolyLengths = new float[3];

        public LengthIterator(int reclimit, float err) {

            this.limit = reclimit;

            this.minTincrement = 1f / (1 << limit);

            this.ERR = err;

            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;

        }

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

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

            this.curveType = type;

            this.recLevel = 0;

            this.lastT = 0;

            this.lenAtLastT = 0;

            this.nextT = 0;

            this.lenAtNextT = 0;

            goLeft(); // initializes nextT and lenAtNextT properly

            this.lenAtLastSplit = 0;

            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 = 0;

        }

        // 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.

                    if (!(Helpers.within(len2, len3, err*len3) &&

                          Helpers.within(len1, len3, err*len3))) {

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

        // 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.

        public float next(final float len) {

            final float targetLength = lenAtLastSplit + len;

            while(lenAtNextT < targetLength) {

                if (done) {

                    lastSegLen = lenAtNextT - lenAtLastSplit;

                    return 1;

                }

                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.

                if (flatLeafCoefCache[2] < 0) {

                    float x = 0+curLeafCtrlPolyLengths[0],

                          y = x+curLeafCtrlPolyLengths[1];

                    if (curveType == 8) {

                        float z = y + curLeafCtrlPolyLengths[2];

                        flatLeafCoefCache[0] = 3*(x - y) + z;

                        flatLeafCoefCache[1] = 3*(y - 2*x);

                        flatLeafCoefCache[2] = 3*x;

                        flatLeafCoefCache[3] = -z;

                    } else if (curveType == 6) {

                        flatLeafCoefCache[0] = 0f;

                        flatLeafCoefCache[1] = y - 2*x;

                        flatLeafCoefCache[2] = 2*x;

                        flatLeafCoefCache[3] = -y;

                    }

                }

                float a = flatLeafCoefCache[0];

                float b = flatLeafCoefCache[1];

                float c = flatLeafCoefCache[2];

                float d = t*flatLeafCoefCache[3];

                // we use cubicRootsInAB here, because we want only roots in 0, 1,

                // and our quadratic root finder doesn't filter, so it's just a

                // matter of convenience.

                int n = Helpers.cubicRootsInAB(a, b, c, d, nextRoots, 0, 0, 1);

                if (n == 1 && !Float.isNaN(nextRoots[0])) {

                    t = nextRoots[0];

                }

            }

            // t is relative to the current leaf, so we must make it a valid parameter

            // of the original curve.

            t = t * (nextT - lastT) + lastT;

            if (t >= 1) {

                t = 1;

                done = true;

            }

            // even if done = true, if we're here, that means targetLength

            // is equal to, or very, very close to the total length of the

            // curve, so lastSegLen won't be too high. In cases where len

            // overshoots the curve, this method will exit in the while

            // loop, and lastSegLen will still be set to the right value.

            lastSegLen = len;

            return t;

        }

        public float lastSegLen() {

            return lastSegLen;

        }

        // go to the next leaf (in an inorder traversal) in the recursion tree

        // preconditions: must be on a leaf, and that leaf must not be the root.

        private void goToNextLeaf() {

            // We must go to the first ancestor node that has an unvisited

            // right child.

            recLevel--;

            while(sides[recLevel] == Side.RIGHT) {

                if (recLevel == 0) {

                    done = true;

                    return;

                }

                recLevel--;

            }

            sides[recLevel] = Side.RIGHT;

            System.arraycopy(recCurveStack[recLevel], 0, recCurveStack[recLevel+1], 0, curveType);

            recLevel++;

            goLeft();

        }

        // go to the leftmost node from the current node. Return its length.

        private void goLeft() {

            float len = onLeaf();

            if (len >= 0) {

                lastT = nextT;

                lenAtLastT = lenAtNextT;

                nextT += (1 << (limit - recLevel)) * minTincrement;

                lenAtNextT += len;

                // invalidate caches

                flatLeafCoefCache[2] = -1;

                cachedHaveLowAcceleration = -1;