The Tor Browser: gfx/thebes/gfxLineSegment.h@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-

     2  * This Source Code Form is subject to the terms of the Mozilla Public

     3  * License, v. 2.0. If a copy of the MPL was not distributed with this

     4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     6 #ifndef GFX_LINESEGMENT_H

     7 #define GFX_LINESEGMENT_H

     9 #include "gfxTypes.h"

    10 #include "gfxPoint.h"

    12 struct gfxLineSegment {

    13   gfxLineSegment(const gfxPoint &aStart, const gfxPoint &aEnd)

    14     : mStart(aStart)

    15     , mEnd(aEnd)

    16   {}

    18   bool PointsOnSameSide(const gfxPoint& aOne, const gfxPoint& aTwo)

    19   {

    20     // Solve the equation y - mStart.y - ((mEnd.y - mStart.y)/(mEnd.x - mStart.x))(x - mStart.x) for both points

    22     gfxFloat deltaY = (mEnd.y - mStart.y);

    23     gfxFloat deltaX = (mEnd.x - mStart.x);

    25     gfxFloat one = deltaX * (aOne.y - mStart.y) - deltaY * (aOne.x - mStart.x);

    26     gfxFloat two = deltaX * (aTwo.y - mStart.y) - deltaY * (aTwo.x - mStart.x);

    28     // If both results have the same sign, then we're on the correct side of the line.

    29     // 0 (on the line) is always considered in.

    31     if ((one >= 0 && two >= 0) || (one <= 0 && two <= 0))

    32       return true;

    33     return false;

    34   }

    36   /**

    37    * Determines if two line segments intersect, and returns the intersection

    38    * point in aIntersection if they do.

    39    *

    40    * Coincident lines are considered not intersecting as they don't have an

    41    * intersection point.

    42    */

    43   bool Intersects(const gfxLineSegment& aOther, gfxPoint& aIntersection)

    44   {

    45     gfxFloat denominator = (aOther.mEnd.y - aOther.mStart.y) * (mEnd.x - mStart.x ) -

    46                            (aOther.mEnd.x - aOther.mStart.x ) * (mEnd.y - mStart.y);

    48     // Parallel or coincident. We treat coincident as not intersecting since

    49     // these lines are guaranteed to have corners that intersect instead.

    50     if (!denominator) {

    51       return false;

    52     }

    54     gfxFloat anumerator = (aOther.mEnd.x - aOther.mStart.x) * (mStart.y - aOther.mStart.y) -

    55                          (aOther.mEnd.y - aOther.mStart.y) * (mStart.x - aOther.mStart.x);

    57     gfxFloat bnumerator = (mEnd.x - mStart.x) * (mStart.y - aOther.mStart.y) -

    58                          (mEnd.y - mStart.y) * (mStart.x - aOther.mStart.x);

    60     gfxFloat ua = anumerator / denominator;

    61     gfxFloat ub = bnumerator / denominator;

    63     if (ua <= 0.0 || ua >= 1.0 ||

    64         ub <= 0.0 || ub >= 1.0) {

    65       //Intersection is outside of the segment

    66       return false;

    67     }

    69     aIntersection = mStart + (mEnd - mStart) * ua;

    70     return true;

    71   }

    73   gfxPoint mStart;

    74   gfxPoint mEnd;

    75 };

    77 #endif /* GFX_LINESEGMENT_H */

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