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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /gfx/thebes/gfxLineSegment.h
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
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Add m-esr52 at 52.6.0
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diff --git a/gfx/thebes/gfxLineSegment.h b/gfx/thebes/gfxLineSegment.h
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+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_LINESEGMENT_H
+#define GFX_LINESEGMENT_H
+
+#include "gfxTypes.h"
+#include "gfxPoint.h"
+
+struct gfxLineSegment {
+ gfxLineSegment(const gfxPoint &aStart, const gfxPoint &aEnd)
+ : mStart(aStart)
+ , mEnd(aEnd)
+ {}
+
+ bool PointsOnSameSide(const gfxPoint& aOne, const gfxPoint& aTwo)
+ {
+ // Solve the equation y - mStart.y - ((mEnd.y - mStart.y)/(mEnd.x - mStart.x))(x - mStart.x) for both points
+
+ gfxFloat deltaY = (mEnd.y - mStart.y);
+ gfxFloat deltaX = (mEnd.x - mStart.x);
+
+ gfxFloat one = deltaX * (aOne.y - mStart.y) - deltaY * (aOne.x - mStart.x);
+ gfxFloat two = deltaX * (aTwo.y - mStart.y) - deltaY * (aTwo.x - mStart.x);
+
+ // If both results have the same sign, then we're on the correct side of the line.
+ // 0 (on the line) is always considered in.
+
+ if ((one >= 0 && two >= 0) || (one <= 0 && two <= 0))
+ return true;
+ return false;
+ }
+
+ /**
+ * Determines if two line segments intersect, and returns the intersection
+ * point in aIntersection if they do.
+ *
+ * Coincident lines are considered not intersecting as they don't have an
+ * intersection point.
+ */
+ bool Intersects(const gfxLineSegment& aOther, gfxPoint& aIntersection)
+ {
+ gfxFloat denominator = (aOther.mEnd.y - aOther.mStart.y) * (mEnd.x - mStart.x ) -
+ (aOther.mEnd.x - aOther.mStart.x ) * (mEnd.y - mStart.y);
+
+ // Parallel or coincident. We treat coincident as not intersecting since
+ // these lines are guaranteed to have corners that intersect instead.
+ if (!denominator) {
+ return false;
+ }
+
+ gfxFloat anumerator = (aOther.mEnd.x - aOther.mStart.x) * (mStart.y - aOther.mStart.y) -
+ (aOther.mEnd.y - aOther.mStart.y) * (mStart.x - aOther.mStart.x);
+
+ gfxFloat bnumerator = (mEnd.x - mStart.x) * (mStart.y - aOther.mStart.y) -
+ (mEnd.y - mStart.y) * (mStart.x - aOther.mStart.x);
+
+ gfxFloat ua = anumerator / denominator;
+ gfxFloat ub = bnumerator / denominator;
+
+ if (ua <= 0.0 || ua >= 1.0 ||
+ ub <= 0.0 || ub >= 1.0) {
+ //Intersection is outside of the segment
+ return false;
+ }
+
+ aIntersection = mStart + (mEnd - mStart) * ua;
+ return true;
+ }
+
+ gfxPoint mStart;
+ gfxPoint mEnd;
+};
+
+#endif /* GFX_LINESEGMENT_H */