com.sun.openpisces.Dasher Maven / Gradle / Ivy
/*
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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*/
package com.sun.openpisces;
import com.sun.javafx.geom.PathConsumer2D;
/**
* The Dasher class takes a series of linear commands
* (moveTo, lineTo, close and
* end) and breaks them into smaller segments according to a
* dash pattern array and a starting dash phase.
*
* 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.
*
*/
public final class Dasher implements PathConsumer2D {
private final PathConsumer2D out;
private float[] dash;
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 float[] curCurvepts;
/**
* Constructs a Dasher.
*
* @param out an output PathConsumer2D.
* @param dash an array of floats containing the dash pattern
* @param phase a float containing the dash phase
*/
public Dasher(PathConsumer2D out, float[] dash, float phase) {
this(out);
reset(dash, phase);
}
public Dasher(PathConsumer2D out) {
this.out = out;
// we need curCurvepts to be able to contain 2 curves because when
// dashing curves, we need to subdivide it
curCurvepts = new float[8 * 2];
}
// More than 24 bits of mantissa means we can no longer accurately
// measure the number of times cycled through the dash array so we
// punt and override the phase to just be 0 past that point.
static float MAX_CYCLES = 16000000f;
public void reset(float[] dash, float phase) {
// Normalize so 0 <= phase < dash[0]
int sidx = 0;
dashOn = true;
float sum = 0f;
for (float d : dash) {
sum += d;
}
float cycles = phase / sum;
if (phase < 0) {
if (-cycles >= MAX_CYCLES) {
phase = 0;
} else {
int fullcycles = (int) Math.floor(-cycles);
if ((fullcycles & dash.length & 1) != 0) {
dashOn = !dashOn;
}
phase += fullcycles * sum;
while (phase < 0) {
if (--sidx < 0) sidx = dash.length-1;
phase += dash[sidx];
dashOn = !dashOn;
}
}
} else if (phase > 0) {
if (cycles >= MAX_CYCLES) {
phase = 0;
} else {
int fullcycles = (int) Math.floor(cycles);
if ((fullcycles & dash.length & 1) != 0) {
dashOn = !dashOn;
}
phase -= fullcycles * sum;
float d;
while (phase >= (d = dash[sidx])) {
phase -= d;
sidx = (sidx + 1) % dash.length;
dashOn = !dashOn;
}
}
}
this.dash = dash;
this.startPhase = this.phase = phase;
this.startDashOn = dashOn;
this.startIdx = sidx;
this.starting = true;
}
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 - 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(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< 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;
} 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");
// }
}