Back to index...

	/*
	* Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* 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,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	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 + 1);
	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(dxdx + dydy);

	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 - 2x);
	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;
	} else {
	Helpers.subdivide(recCurveStack[recLevel], 0,
	recCurveStack[recLevel+1], 0,
	recCurveStack[recLevel], 0, curveType);
	sides[recLevel] = Side.LEFT;
	recLevel++;
	goLeft();
	}
	}

	// this is a bit of a hack. It returns -1 if we're not on a leaf, and
	// the length of the leaf if we are on a leaf.
	private float onLeaf() {
	float[] curve = recCurveStack[recLevel];
	float polyLen = 0;

	float x0 = curve[0], y0 = curve[1];
	for (int i = 2; i < curveType; i += 2) {
	final float x1 = curve[i], y1 = curve[i+1];
	final float len = Helpers.linelen(x0, y0, x1, y1);
	polyLen += len;
	curLeafCtrlPolyLengths[i/2 - 1] = len;
	x0 = x1;
	y0 = y1;
	}

	final float lineLen = Helpers.linelen(curve[0], curve[1], curve[curveType-2], curve[curveType-1]);
	if (polyLen - lineLen < ERR \|\| recLevel == limit) {
	return (polyLen + lineLen)/2;
	}
	return -1;
	}
	}

	@Override
	public void curveTo(float x1, float y1,
	float x2, float y2,
	float x3, float y3)
	{
	curCurvepts[0] = x0; curCurvepts[1] = y0;
	curCurvepts[2] = x1; curCurvepts[3] = y1;
	curCurvepts[4] = x2; curCurvepts[5] = y2;
	curCurvepts[6] = x3; curCurvepts[7] = y3;
	somethingTo(8);
	}

	@Override
	public void quadTo(float x1, float y1, float x2, float y2) {
	curCurvepts[0] = x0; curCurvepts[1] = y0;
	curCurvepts[2] = x1; curCurvepts[3] = y1;
	curCurvepts[4] = x2; curCurvepts[5] = y2;
	somethingTo(6);
	}

	public void closePath() {
	lineTo(sx, sy);
	if (firstSegidx > 0) {
	if (!dashOn \|\| needsMoveTo) {
	out.moveTo(sx, sy);
	}
	emitFirstSegments();
	}
	moveTo(sx, sy);
	}

	public void pathDone() {
	if (firstSegidx > 0) {
	out.moveTo(sx, sy);
	emitFirstSegments();
	}
	out.pathDone();
	}

	@Override
	public long getNativeConsumer() {
	throw new InternalError("Dasher does not use a native consumer");
	}
	}

Back to index...