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Simplify and streamline Path._getMonotoneCurves() code.
This commit is contained in:
Jürg Lehni
parent
f6061905be
commit
6af639946b
1 changed files with 68 additions and 72 deletions
140
src/path/Path.js
140
src/path/Path.js
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@ -1716,98 +1716,94 @@ var Path = PathItem.extend(/** @lends Path# */{
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*/
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_getMonotoneCurves: function() {
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var monoCurves = this._monotoneCurves,
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lastCurve,
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INCREASING = 1,
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DECREASING = -1,
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HORIZONTAL = 0;
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if (!monoCurves) {
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// Insert curve values into a cached array
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// Always avoid horizontal curves
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function insertValues(v, dir) {
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var y0 = v[1], y1 = v[7];
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dir = dir || INCREASING;
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if (y0 === y1) {
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dir = HORIZONTAL;
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} else if (y0 > y1) {
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dir = DECREASING;
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}
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// Add a reference to subsequent curves
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v.push(dir);
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if (lastCurve) {
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v[9] = lastCurve;
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lastCurve[10] = v;
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}
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lastCurve = v;
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monoCurves.push(v);
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prevCurve;
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// Insert curve values into a cached array
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function insertCurve(v) {
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var y0 = v[1],
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y1 = v[7];
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// Add the winding direction to the end of the curve values.
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v[8] = y0 === y1
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? 0 // Horizontal
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: y0 > y1
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? -1 // Decreasing
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: 1; // Increasing
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// Add a reference to neighboring curves
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if (prevCurve) {
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v[9] = prevCurve;
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prevCurve[10] = v;
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}
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// Handle bezier curves. We need to chop them into smaller curves
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// with defined orientation, by solving the derivative curve for
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// Y extrema.
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function insertCurves(v, dir) {
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var y0 = v[1], y1 = v[3],
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y2 = v[5], y3 = v[7],
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roots = [], tolerance = /*#=*/ Numerical.TOLERANCE,
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i, li;
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monoCurves.push(v);
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prevCurve = v;
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}
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// Handle bezier curves. We need to chop them into smaller curves
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// with defined orientation, by solving the derivative curve for
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// Y extrema.
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function handleCurve(v) {
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// Filter out curves of zero length.
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// TODO: Do not filter this here.
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if (Curve.getLength(v) === 0)
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return;
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var y0 = v[1],
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y1 = v[3],
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y2 = v[5],
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y3 = v[7];
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if (Curve.isLinear(v)) {
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// Handling linear curves is easy.
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insertCurve(v);
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} else {
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// Split the curve at y extrema, to get bezier curves with clear
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// orientation: Calculate the derivative and find its roots.
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var a = 3 * (y1 - y2) - y0 + y3,
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b = 2 * (y0 + y2) - 4 * y1,
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c = y1 - y0;
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// Keep then range to 0 .. 1 (excluding) in the search
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// for y extrema
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c = y1 - y0,
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tolerance = /*#=*/ Numerical.TOLERANCE,
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roots = [];
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// Keep then range to 0 .. 1 (excluding) in the search for y
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// extrema.
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var count = Numerical.solveQuadratic(a, b, c, roots, tolerance,
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1 - tolerance);
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if (count === 0) {
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insertValues(v, dir);
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insertCurve(v);
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} else {
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roots.sort();
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var parts, t = roots[0];
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parts = Curve.subdivide(v, t);
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var t = roots[0],
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parts = Curve.subdivide(v, t);
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insertCurve(parts[0]);
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if (count > 1) {
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// Now renormalize t1 to the range of the next part.
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// If there are two extremas, renormalize t to the range
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// of the second range and split again.
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t = (roots[1] - t) / (1 - t);
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var subparts = Curve.subdivide(parts[1], t);
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parts.splice(1, 1, subparts[0], subparts[1]);
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// Since we already processed parts[0], we can override
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// the parts array with the new pair now.
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parts = Curve.subdivide(parts[1], t);
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insertCurve(parts[0]);
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}
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for (i = 0, li = parts.length; i < li; i++)
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insertValues(parts[i]);
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insertCurve(parts[1]);
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}
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}
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// Insert curves that are monotonic in y direction into a cached array
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}
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if (!monoCurves) {
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// Insert curves that are monotonic in y direction into cached array
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monoCurves = this._monotoneCurves = [];
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var curves = this.getCurves(),
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crv, vals, i, li,
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segments = this._segments;
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// If the path is not closed, we should join the end points
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// with a straight line, just like how filling open paths works.
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for (var i = 0, l = curves.length; i < l; i++)
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handleCurve(curves[i].getValues());
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// If the path is not closed, we need to join the end points with a
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// straight line, just like how filling open paths works.
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if (!this._closed && segments.length > 1) {
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curves.push(new Curve(segments[segments.length - 1]._point,
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segments[0]._point));
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var p1 = segments[segments.length - 1]._point,
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p2 = segments[0]._point,
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p1x = p1._x, p1y = p1._y,
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p2x = p2._x, p2y = p2._y;
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handleCurve([p1x, p1y, p1x, p1y, p2x, p2y, p2x, p2y]);
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}
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for (i = 0, li = curves.length; i < li; i++) {
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crv = curves[i];
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// Filter out curves of zero length
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vals = crv.getValues();
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if (Curve.getLength(vals) === 0)
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continue;
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// Handle linear and cubic curves seperately
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if (crv.isLinear()) {
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insertValues(vals);
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} else {
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var y0 = vals[1], y1 = vals[7];
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if (y0 > y1) {
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insertCurves(vals, DECREASING);
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} else if (y0 == y1 && y0 == vals[3] && y0 == vals[5]) {
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insertValues(vals, HORIZONTAL);
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} else {
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insertCurves(vals, INCREASING);
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}
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}
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}
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// Link, first and last curves
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lastCurve = monoCurves[monoCurves.length - 1];
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monoCurves[0][9] = lastCurve;
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lastCurve.push(monoCurves[0]);
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// Link first and last curves
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monoCurves[0][9] = prevCurve = monoCurves[monoCurves.length - 1];
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prevCurve[10] = monoCurves[0];
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}
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return monoCurves;
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},
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