Source/WebCore/platform/graphics/FloatQuad.h

/*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer. 
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 */

#ifndef FloatQuad_h
#define FloatQuad_h

#include "FloatPoint.h"
#include "FloatRect.h"
#include "IntRect.h"

namespace WebCore {

// A FloatQuad is a collection of 4 points, often representing the result of
// mapping a rectangle through transforms. When initialized from a rect, the
// points are in clockwise order from top left.
class FloatQuad {
public:
    FloatQuad()
    {
    }

    FloatQuad(const FloatPoint& p1, const FloatPoint& p2, const FloatPoint& p3, const FloatPoint& p4)
        : m_p1(p1)
        , m_p2(p2)
        , m_p3(p3)
        , m_p4(p4)
    {
    }

    FloatQuad(const FloatRect& inRect)
        : m_p1(inRect.location())
        , m_p2(inRect.maxX(), inRect.y())
        , m_p3(inRect.maxX(), inRect.maxY())
        , m_p4(inRect.x(), inRect.maxY())
    {
    }

    FloatPoint p1() const { return m_p1; }
    FloatPoint p2() const { return m_p2; }
    FloatPoint p3() const { return m_p3; }
    FloatPoint p4() const { return m_p4; }

    void setP1(const FloatPoint& p) { m_p1 = p; }
    void setP2(const FloatPoint& p) { m_p2 = p; }
    void setP3(const FloatPoint& p) { m_p3 = p; }
    void setP4(const FloatPoint& p) { m_p4 = p; }

    // isEmpty tests that the bounding box is empty. This will not identify
    // "slanted" empty quads.
    bool isEmpty() const { return boundingBox().isEmpty(); }

    // Tests whether this quad can be losslessly represented by a FloatRect,
    // that is, if two edges are parallel to the x-axis and the other two
    // are parallel to the y-axis. If this method returns true, the
    // corresponding FloatRect can be retrieved with boundingBox().
    bool isRectilinear() const;

    // Tests whether the given point is inside, or on an edge or corner of this quad.
    bool containsPoint(const FloatPoint&) const;

    // Tests whether the four corners of other are inside, or coincident with the sides of this quad.
    // Note that this only works for convex quads, but that includes all quads that originate
    // from transformed rects.
    bool containsQuad(const FloatQuad&) const;

    // Tests whether any part of the rectangle intersects with this quad.
    // This only works for convex quads.
    bool intersectsRect(const FloatRect&) const;

    // Test whether any part of the circle/ellipse intersects with this quad.
    // Note that these two functions only work for convex quads.
    bool intersectsCircle(const FloatPoint& center, float radius) const;
    bool intersectsEllipse(const FloatPoint& center, const FloatSize& radii) const;

    // The center of the quad. If the quad is the result of a affine-transformed rectangle this is the same as the original center transformed.
    FloatPoint center() const
    {
        return FloatPoint((m_p1.x() + m_p2.x() + m_p3.x() + m_p4.x()) / 4.0,
                          (m_p1.y() + m_p2.y() + m_p3.y() + m_p4.y()) / 4.0);
    }

    FloatRect boundingBox() const;
    IntRect enclosingBoundingBox() const
    {
        return enclosingIntRect(boundingBox());
    }

    void move(const FloatSize& offset)
    {
        m_p1 += offset;
        m_p2 += offset;
        m_p3 += offset;
        m_p4 += offset;
    }

    void move(float dx, float dy)
    {
        m_p1.move(dx, dy);
        m_p2.move(dx, dy);
        m_p3.move(dx, dy);
        m_p4.move(dx, dy);
    }

    void scale(float dx, float dy)
    {
        m_p1.scale(dx, dy);
        m_p2.scale(dx, dy);
        m_p3.scale(dx, dy);
        m_p4.scale(dx, dy);
    }

    // Tests whether points are in clock-wise, or counter clock-wise order.
    // Note that output is undefined when all points are colinear.
    bool isCounterclockwise() const;

private:
    FloatPoint m_p1;
    FloatPoint m_p2;
    FloatPoint m_p3;
    FloatPoint m_p4;
};

inline FloatQuad& operator+=(FloatQuad& a, const FloatSize& b)
{
    a.move(b);
    return a;
}

inline FloatQuad& operator-=(FloatQuad& a, const FloatSize& b)
{
    a.move(-b.width(), -b.height());
    return a;
}

inline bool operator==(const FloatQuad& a, const FloatQuad& b)
{
    return a.p1() == b.p1() &&
           a.p2() == b.p2() && 
           a.p3() == b.p3() &&
           a.p4() == b.p4();
}

inline bool operator!=(const FloatQuad& a, const FloatQuad& b)
{
    return a.p1() != b.p1() ||
           a.p2() != b.p2() || 
           a.p3() != b.p3() ||
           a.p4() != b.p4();
}

}   // namespace WebCore


#endif // FloatQuad_h