com.sun.javafx.geom.FlatteningPathIterator Maven / Gradle / Ivy
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package com.sun.javafx.geom;
import java.util.NoSuchElementException;
/**
* The FlatteningPathIterator class returns a flattened view of
* another {@link PathIterator} object. Other {@link java.awt.Shape Shape}
* classes can use this class to provide flattening behavior for their paths
* without having to perform the interpolation calculations themselves.
*
* @version 1.6 06/29/98
*/
public class FlatteningPathIterator implements PathIterator {
static final int GROW_SIZE = 24; // Multiple of cubic & quad curve size
PathIterator src; // The source iterator
float squareflat; // Square of the flatness parameter
// for testing against squared lengths
int limit; // Maximum number of recursion levels
// hold field must be volatile to work around a Mac runtime bug (see RT-12386)
volatile float hold[] = new float[14]; // The cache of interpolated coords
// Note that this must be long enough
// to store a full cubic segment and
// a relative cubic segment to avoid
// aliasing when copying the coords
// of a curve to the end of the array.
// This is also serendipitously equal
// to the size of a full quad segment
// and 2 relative quad segments.
float curx, cury; // The ending x,y of the last segment
float movx, movy; // The x,y of the last move segment
int holdType; // The type of the curve being held
// for interpolation
int holdEnd; // The index of the last curve segment
// being held for interpolation
int holdIndex; // The index of the curve segment
// that was last interpolated. This
// is the curve segment ready to be
// returned in the next call to
// currentSegment().
int levels[]; // The recursion level at which
// each curve being held in storage
// was generated.
int levelIndex; // The index of the entry in the
// levels array of the curve segment
// at the holdIndex
boolean done; // True when iteration is done
/**
* Constructs a new FlatteningPathIterator object that
* flattens a path as it iterates over it. The iterator does not
* subdivide any curve read from the source iterator to more than
* 10 levels of subdivision which yields a maximum of 1024 line
* segments per curve.
* @param src the original unflattened path being iterated over
* @param flatness the maximum allowable distance between the
* control points and the flattened curve
*/
public FlatteningPathIterator(PathIterator src, float flatness) {
this(src, flatness, 10);
}
/**
* Constructs a new FlatteningPathIterator object
* that flattens a path as it iterates over it.
* The limit parameter allows you to control the
* maximum number of recursive subdivisions that the iterator
* can make before it assumes that the curve is flat enough
* without measuring against the flatness parameter.
* The flattened iteration therefore never generates more than
* a maximum of (2^limit) line segments per curve.
* @param src the original unflattened path being iterated over
* @param flatness the maximum allowable distance between the
* control points and the flattened curve
* @param limit the maximum number of recursive subdivisions
* allowed for any curved segment
* @exception IllegalArgumentException if
* flatness or limit
* is less than zero
*/
public FlatteningPathIterator(PathIterator src, float flatness,
int limit) {
if (flatness < 0f) {
throw new IllegalArgumentException("flatness must be >= 0");
}
if (limit < 0) {
throw new IllegalArgumentException("limit must be >= 0");
}
this.src = src;
this.squareflat = flatness * flatness;
this.limit = limit;
this.levels = new int[limit + 1];
// prime the first path segment
next(false);
}
/**
* Returns the flatness of this iterator.
* @return the flatness of this FlatteningPathIterator.
*/
public float getFlatness() {
return (float) Math.sqrt(squareflat);
}
/**
* Returns the recursion limit of this iterator.
* @return the recursion limit of this
* FlatteningPathIterator.
*/
public int getRecursionLimit() {
return limit;
}
/**
* Returns the winding rule for determining the interior of the
* path.
* @return the winding rule of the original unflattened path being
* iterated over.
* @see PathIterator#WIND_EVEN_ODD
* @see PathIterator#WIND_NON_ZERO
*/
public int getWindingRule() {
return src.getWindingRule();
}
/**
* Tests if the iteration is complete.
* @return true if all the segments have
* been read; false otherwise.
*/
public boolean isDone() {
return done;
}
/*
* Ensures that the hold array can hold up to (want) more values.
* It is currently holding (hold.length - holdIndex) values.
*/
void ensureHoldCapacity(int want) {
if (holdIndex - want < 0) {
int have = hold.length - holdIndex;
int newsize = hold.length + GROW_SIZE;
float newhold[] = new float[newsize];
System.arraycopy(hold, holdIndex,
newhold, holdIndex + GROW_SIZE,
have);
hold = newhold;
holdIndex += GROW_SIZE;
holdEnd += GROW_SIZE;
}
}
/**
* Moves the iterator to the next segment of the path forwards
* along the primary direction of traversal as long as there are
* more points in that direction.
*/
public void next() {
next(true);
}
private void next(boolean doNext) {
int level;
if (holdIndex >= holdEnd) {
if (doNext) {
src.next();
}
if (src.isDone()) {
done = true;
return;
}
holdType = src.currentSegment(hold);
levelIndex = 0;
levels[0] = 0;
}
switch (holdType) {
case SEG_MOVETO:
case SEG_LINETO:
curx = hold[0];
cury = hold[1];
if (holdType == SEG_MOVETO) {
movx = curx;
movy = cury;
}
holdIndex = 0;
holdEnd = 0;
break;
case SEG_CLOSE:
curx = movx;
cury = movy;
holdIndex = 0;
holdEnd = 0;
break;
case SEG_QUADTO:
if (holdIndex >= holdEnd) {
// Move the coordinates to the end of the array.
holdIndex = hold.length - 6;
holdEnd = hold.length - 2;
hold[holdIndex + 0] = curx;
hold[holdIndex + 1] = cury;
hold[holdIndex + 2] = hold[0];
hold[holdIndex + 3] = hold[1];
hold[holdIndex + 4] = curx = hold[2];
hold[holdIndex + 5] = cury = hold[3];
}
level = levels[levelIndex];
while (level < limit) {
if (QuadCurve2D.getFlatnessSq(hold, holdIndex) < squareflat) {
break;
}
ensureHoldCapacity(4);
QuadCurve2D.subdivide(hold, holdIndex,
hold, holdIndex - 4,
hold, holdIndex);
holdIndex -= 4;
// Now that we have subdivided, we have constructed
// two curves of one depth lower than the original
// curve. One of those curves is in the place of
// the former curve and one of them is in the next
// set of held coordinate slots. We now set both
// curves level values to the next higher level.
level++;
levels[levelIndex] = level;
levelIndex++;
levels[levelIndex] = level;
}
// This curve segment is flat enough, or it is too deep
// in recursion levels to try to flatten any more. The
// two coordinates at holdIndex+4 and holdIndex+5 now
// contain the endpoint of the curve which can be the
// endpoint of an approximating line segment.
holdIndex += 4;
levelIndex--;
break;
case SEG_CUBICTO:
if (holdIndex >= holdEnd) {
// Move the coordinates to the end of the array.
holdIndex = hold.length - 8;
holdEnd = hold.length - 2;
hold[holdIndex + 0] = curx;
hold[holdIndex + 1] = cury;
hold[holdIndex + 2] = hold[0];
hold[holdIndex + 3] = hold[1];
hold[holdIndex + 4] = hold[2];
hold[holdIndex + 5] = hold[3];
hold[holdIndex + 6] = curx = hold[4];
hold[holdIndex + 7] = cury = hold[5];
}
level = levels[levelIndex];
while (level < limit) {
if (CubicCurve2D.getFlatnessSq(hold, holdIndex) < squareflat) {
break;
}
ensureHoldCapacity(6);
CubicCurve2D.subdivide(hold, holdIndex,
hold, holdIndex - 6,
hold, holdIndex);
holdIndex -= 6;
// Now that we have subdivided, we have constructed
// two curves of one depth lower than the original
// curve. One of those curves is in the place of
// the former curve and one of them is in the next
// set of held coordinate slots. We now set both
// curves level values to the next higher level.
level++;
levels[levelIndex] = level;
levelIndex++;
levels[levelIndex] = level;
}
// This curve segment is flat enough, or it is too deep
// in recursion levels to try to flatten any more. The
// two coordinates at holdIndex+6 and holdIndex+7 now
// contain the endpoint of the curve which can be the
// endpoint of an approximating line segment.
holdIndex += 6;
levelIndex--;
break;
}
}
/**
* Returns the coordinates and type of the current path segment in
* the iteration.
* The return value is the path segment type:
* SEG_MOVETO, SEG_LINETO, or SEG_CLOSE.
* A float array of length 6 must be passed in and can be used to
* store the coordinates of the point(s).
* Each point is stored as a pair of float x,y coordinates.
* SEG_MOVETO and SEG_LINETO types return one point,
* and SEG_CLOSE does not return any points.
* @param coords an array that holds the data returned from
* this method
* @return the path segment type of the current path segment.
* @exception NoSuchElementException if there
* are no more elements in the flattening path to be
* returned.
* @see PathIterator#SEG_MOVETO
* @see PathIterator#SEG_LINETO
* @see PathIterator#SEG_CLOSE
*/
public int currentSegment(float[] coords) {
if (isDone()) {
throw new NoSuchElementException("flattening iterator out of bounds");
}
int type = holdType;
if (type != SEG_CLOSE) {
coords[0] = (float) hold[holdIndex + 0];
coords[1] = (float) hold[holdIndex + 1];
if (type != SEG_MOVETO) {
type = SEG_LINETO;
}
}
return type;
}
}
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