flutter_flutter/sky/engine/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 SKY_ENGINE_PLATFORM_GRAPHICS_GRADIENT_H_
#define SKY_ENGINE_PLATFORM_GRAPHICS_GRADIENT_H_

#include "flutter/sky/engine/platform/PlatformExport.h"
#include "flutter/sky/engine/platform/geometry/FloatPoint.h"
#include "flutter/sky/engine/platform/graphics/Color.h"
#include "flutter/sky/engine/platform/graphics/GraphicsTypes.h"
#include "flutter/sky/engine/platform/transforms/AffineTransform.h"
#include "flutter/sky/engine/wtf/PassRefPtr.h"
#include "flutter/sky/engine/wtf/RefCounted.h"
#include "flutter/sky/engine/wtf/RefPtr.h"
#include "flutter/sky/engine/wtf/Vector.h"

class SkShader;

namespace blink {

class PLATFORM_EXPORT 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;
    Color color;

    ColorStop(float s, const Color& c) : stop(s), color(c) {}
  };
  void addColorStop(const ColorStop&);
  void addColorStop(float value, const Color& color) {
    addColorStop(ColorStop(value, color));
  }

  bool hasAlpha() const;
  bool shaderChanged() const { return !m_gradient; }

  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;
  }

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

    m_p1 = p;
  }

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

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

    m_r0 = r;
  }

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

    m_r1 = r;
  }

  float aspectRatio() const { return m_aspectRatio; }

  sk_sp<SkShader> shader();

  void setDrawsInPMColorSpace(bool drawInPMColorSpace);

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

 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();

  FloatPoint m_p0;
  FloatPoint m_p1;
  float m_r0;
  float m_r1;
  float m_aspectRatio;  // For elliptical gradient, width / height.
  Vector<ColorStop, 2> m_stops;
  bool m_radial;
  bool m_stopsSorted;
  bool m_drawInPMColorSpace;
  GradientSpreadMethod m_spreadMethod;
  AffineTransform m_gradientSpaceTransformation;

  sk_sp<SkShader> m_gradient;
};

}  // namespace blink

#endif  // SKY_ENGINE_PLATFORM_GRAPHICS_GRADIENT_H_