From 31d9e1cd6eb847e53c766d82313cfdc7e17d24d2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Lehni?= <juerg@scratchdisk.com>
Date: Sun, 6 Sep 2015 17:56:12 +0200
Subject: [PATCH] Implement Curve#isLinear() to check for parametrical
linearity.
Along with some unit tests for it.
---
src/path/Curve.js | 128 +++++++++++++++++++++++++-------------------
test/tests/Curve.js | 12 +++++
2 files changed, 84 insertions(+), 56 deletions(-)
diff --git a/src/path/Curve.js b/src/path/Curve.js
index e2e36cad..03558218 100644
--- a/src/path/Curve.js
+++ b/src/path/Curve.js
@@ -797,8 +797,8 @@ statics: {
* @type Rectangle
* @ignore
*/
-}), new function() { // Injection scope for tests
- function isStraight(l, h1, h2) {
+}), Base.each({ // Injection scope for tests both as instance and static methods
+ isStraight: function(l, h1, h2) {
if (h1.isZero() && h2.isZero()) {
// No handles.
return true;
@@ -814,63 +814,79 @@ statics: {
return p1 >= 0 && p1 <= 1 && p2 <= 0 && p2 >= -1;
}
return false;
+ },
+
+ isLinear: function(l, h1, h2) {
+ var third = l.divide(3);
+ return h1.equals(third) && h2.negate().equals(third);
}
+}, function(test, name) {
+ this[name] = function() {
+ var seg1 = this._segment1,
+ seg2 = this._segment2;
+ return test(seg2._point.subtract(seg1._point),
+ seg1._handleOut, seg2._handleIn);
+ };
- return /** @lends Curve# */{
- /**
- * {@grouptitle Tests}
- *
- * Checks if this curve has any curve handles set.
- *
- * @return {Boolean} {@true if the curve has handles set}
- * @see Curve#handle1
- * @see Curve#handle2
- * @see Segment#hasHandles()
- * @see Path#hasHandles()
- */
- hasHandles: function() {
- return !this._segment1._handleOut.isZero()
- || !this._segment2._handleIn.isZero();
- },
-
- /**
- * Checks if this curve appears as a straight line. This can mean that
- * it has no handles defined, or that the handles run collinear with the
- * line that connects the curve's start and end point, not falling
- * outside of the line.
- *
- * @return {Boolean} {@true if the curve is straight}
- */
- isStraight: function() {
- var seg1 = this._segment1,
- seg2 = this._segment2;
- return isStraight(seg2._point.subtract(seg1._point),
- seg1._handleOut, seg2._handleIn);
- },
-
- /**
- * Checks if the the two curves describe straight lines that are
- * collinear, meaning they run in parallel.
- *
- * @param {Curve} curve the other curve to check against
- * @return {Boolean} {@true if the two lines are collinear}
- */
- isCollinear: function(curve) {
- return this.isStraight() && curve.isStraight()
- && this.getVector().isCollinear(curve.getVector());
- },
-
- statics: {
- isStraight: function(v) {
- var p1x = v[0], p1y = v[1],
- p2x = v[6], p2y = v[7];
- return isStraight(new Point(p2x - p1x, p2y - p1y),
- new Point(v[2] - p1x, v[3] - p1y),
- new Point(v[4] - p2x, v[5] - p2y));
- }
- }
- }
+ this.statics[name] = function(v) {
+ var p1x = v[0], p1y = v[1],
+ p2x = v[6], p2y = v[7];
+ return test(new Point(p2x - p1x, p2y - p1y),
+ new Point(v[2] - p1x, v[3] - p1y),
+ new Point(v[4] - p2x, v[5] - p2y));
+ };
}, /** @lends Curve# */{
+ statics: {}, // Filled in the loop above
+
+ /**
+ * {@grouptitle Tests}
+ *
+ * Checks if this curve has any curve handles set.
+ *
+ * @return {Boolean} {@true if the curve has handles set}
+ * @see Curve#handle1
+ * @see Curve#handle2
+ * @see Segment#hasHandles()
+ * @see Path#hasHandles()
+ */
+ hasHandles: function() {
+ return !this._segment1._handleOut.isZero()
+ || !this._segment2._handleIn.isZero();
+ },
+
+ /**
+ * Checks if this curve appears as a straight line. This can mean that
+ * it has no handles defined, or that the handles run collinear with the
+ * line that connects the curve's start and end point, not falling
+ * outside of the line.
+ *
+ * @name Curve#isStraight
+ * @function
+ * @return {Boolean} {@true if the curve is straight}
+ */
+
+ /**
+ * Checks if this curve is parametrically linear, meaning that its
+ * handles are positioned at 1/3 and 2/3 of the total length of the
+ * straight curve.
+ *
+ * @name Curve#isLinear
+ * @function
+ * @return {Boolean} {@true if the curve is parametrically linear}
+ */
+
+ /**
+ * Checks if the the two curves describe straight lines that are
+ * collinear, meaning they run in parallel.
+ *
+ * @param {Curve} curve the other curve to check against
+ * @return {Boolean} {@true if the two lines are collinear}
+ */
+ isCollinear: function(curve) {
+ return this.isStraight() && curve.isStraight()
+ && this.getVector().isCollinear(curve.getVector());
+ }
+}), /** @lends Curve# */{
// Explicitly deactivate the creation of beans, as we have functions here
// that look like bean getters but actually read arguments.
// See #getParameterOf(), #getLocationOf(), #getNearestLocation(), ...
diff --git a/test/tests/Curve.js b/test/tests/Curve.js
index a154dc5e..2e79f27e 100644
--- a/test/tests/Curve.js
+++ b/test/tests/Curve.js
@@ -211,3 +211,15 @@ test('Curve#isStraight()', function() {
return new Curve([100, 100], null, [-50, -50], [100, 100]).isStraight();
}, false);
});
+
+test('Curve#isLinear()', function() {
+ equals(function() {
+ return new Curve([100, 100], [100 / 3, 100 / 3], [-100 / 3, -100 / 3], [200, 200]).isLinear();
+ }, true);
+ equals(function() {
+ return new Curve([100, 100], null, null, [100, 100]).isLinear();
+ }, true);
+ equals(function() {
+ return new Curve([100, 100], null, null, [200, 200]).isLinear();
+ }, false);
+});