Source/core/platform/graphics/Gradient.h

/*
 * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
 * Copyright (C) 2007 Alp Toker <alp@atoker.com>
 * Copyright (C) 2008 Torch Mobile, Inc.
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * 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.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef Gradient_h
#define Gradient_h

#include "core/platform/graphics/GraphicsTypes.h"
#include "platform/geometry/FloatPoint.h"
#include "platform/transforms/AffineTransform.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefCounted.h"
#include "wtf/RefPtr.h"
#include "wtf/Vector.h"

class SkShader;

namespace WebCore {

class Color;
class FloatRect;
class IntSize;

class Gradient : public RefCounted<Gradient> {
public:
    static PassRefPtr<Gradient> create(const FloatPoint& p0, const FloatPoint& p1)
    {
        return adoptRef(new Gradient(p0, p1));
    }
    static PassRefPtr<Gradient> create(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1, float aspectRatio = 1)
    {
        return adoptRef(new Gradient(p0, r0, p1, r1, aspectRatio));
    }
    ~Gradient();

    struct ColorStop {
        float stop;
        float red;
        float green;
        float blue;
        float alpha;

        ColorStop() : stop(0), red(0), green(0), blue(0), alpha(0) { }
        ColorStop(float s, float r, float g, float b, float a) : stop(s), red(r), green(g), blue(b), alpha(a) { }
    };
    void addColorStop(const ColorStop&);
    void addColorStop(float, const Color&);

    bool hasAlpha() const;

    bool isRadial() const { return m_radial; }
    bool isZeroSize() const { return m_p0.x() == m_p1.x() && m_p0.y() == m_p1.y() && (!m_radial || m_r0 == m_r1); }

    const FloatPoint& p0() const { return m_p0; }
    const FloatPoint& p1() const { return m_p1; }

    void setP0(const FloatPoint& p)
    {
        if (m_p0 == p)
            return;

        m_p0 = p;
        invalidateHash();
    }

    void setP1(const FloatPoint& p)
    {
        if (m_p1 == p)
            return;

        m_p1 = p;
        invalidateHash();
    }

    float startRadius() const { return m_r0; }
    float endRadius() const { return m_r1; }

    void setStartRadius(float r)
    {
        if (m_r0 == r)
            return;

        m_r0 = r;
        invalidateHash();
    }

    void setEndRadius(float r)
    {
        if (m_r1 == r)
            return;

        m_r1 = r;
        invalidateHash();
    }

    float aspectRatio() const { return m_aspectRatio; }

    SkShader* shader();

    void setStopsSorted(bool s) { m_stopsSorted = s; }

    void setDrawsInPMColorSpace(bool drawInPMColorSpace);

    void setSpreadMethod(GradientSpreadMethod);
    GradientSpreadMethod spreadMethod() { return m_spreadMethod; }
    void setGradientSpaceTransform(const AffineTransform& gradientSpaceTransformation);
    AffineTransform gradientSpaceTransform() { return m_gradientSpaceTransformation; }

    void adjustParametersForTiledDrawing(IntSize&, FloatRect&);

    unsigned hash() const;
    void invalidateHash() { m_cachedHash = 0; }

private:
    Gradient(const FloatPoint& p0, const FloatPoint& p1);
    Gradient(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1, float aspectRatio);

    void destroyShader();

    void sortStopsIfNecessary();

    // Keep any parameters relevant to rendering in sync with the structure in Gradient::hash().
    bool m_radial;
    FloatPoint m_p0;
    FloatPoint m_p1;
    float m_r0;
    float m_r1;
    float m_aspectRatio; // For elliptical gradient, width / height.
    mutable Vector<ColorStop, 2> m_stops;
    mutable bool m_stopsSorted;
    GradientSpreadMethod m_spreadMethod;
    AffineTransform m_gradientSpaceTransformation;

    bool m_drawInPMColorSpace;

    mutable unsigned m_cachedHash;

    RefPtr<SkShader> m_gradient;
};

} // namespace WebCore

#endif