// This may look like C code, but it's really -*- C++ -*-

/*

 * Copyright (C) 2013 Emweb bv, Herent, Belgium.

 *

 * See the LICENSE file for terms of use.

 */

#ifndef WGRADIENT_H_

#define WGRADIENT_H_

#include <Wt/WColor.h>

#include <Wt/WLineF.h>

#include <Wt/WPointF.h>

namespace Wt {

/*! \class WGradient Wt/WGradient.h Wt/WGradient.h

 *  \brief A linear or radial gradient.

 *

 * \sa WPen::setGradient(), WBrush::setGradient()

 *

 * \ingroup painting

 */

class WT_API WGradient

{

public:

  /*! \brief A gradient color stop.

   *

   * A color stop is defined by a color and a (relative) position. The

   * interpretation of the position depends on the gradient style.

   *

   * \sa addColorStop()

   */

  class ColorStop {

  public:

    /*! \brief Constructor.

     */

    ColorStop(double position, const WColor& color)

      : position_(position), color_(color)

    { }

    /*! \brief Returns the position.

     */

    double position() const { return position_; }

    /*! \brief Returns the color.

     */

    const WColor& color() const { return color_; }

    /*! \brief Comparison operator.

     */

    bool operator==(const ColorStop& other) const {

      return (position_ == other.position_) && (color_ == other.color_);

    }

    /*! \brief Comparison operator.

     */

    bool operator!=(const ColorStop& other) const {

      return !(*this == other);

    }

  private:

    double position_;

    WColor color_;

  };

  /*! \brief Default constructor.

   *

   * Creates an empty linear gradient from (0,0) to (1,1) (without

   * color stops).

   *

   * \sa isEmpty()

   */

  WGradient();

  /*! \brief Returns the gradient style.

   *

   * \sa setLinearGradient(), setRadialGradient()

   */

  GradientStyle style() const { return style_; }

  /*! \brief Returns whether the gradient is empty.

   *

   * A gradient is empty if no color stops are defined.

   */

  bool isEmpty() const { return colorstops_.empty(); }

  /*! \brief Configures a linear gradient.

   *

   * The coordinates describe a line which provides an origin and

   * orientation of the gradient in user-space coordinates.

   */

  void setLinearGradient(double x0, double y0, double x1, double y1);

  /*! \brief Configures a radial gradient.

   *

   * A radial gradient is described by a center, a radial and a focus

   * point. All coordinates are user-space coordinates.

   */

  void setRadialGradient(double cx, double cy, double r,

                         double fx, double fy);

  /*! \brief Adds a color stop.

   *

   * For a linear gradient, the position is relative to the position on the

   * line (from 0 to 1 corresponding to p0 to p1).

   *

   * For a radial gradient, the position indicates the distance from the

   * center (from 0 to 1 corresponding to center to radius).

   */

  void addColorStop(double position, const WColor& color);

  /*! \brief Adds a color stop.

   *

   * Adds a color stop.

   */

  void addColorStop(const ColorStop& colorstop);

  /*! \brief Removes all color stops.

   *

   * \sa addColorStop()

   */

  void clearColorStops() { colorstops_.clear(); }

  /*! \brief Returns the color stops.

   *

   * \sa addColorStop()

   */

  const std::vector<ColorStop>& colorstops() const { return colorstops_; }

  /*! \brief Returns the line positioning the linear gradient.

   *

   * This returns the line set in setLinearGradient().

   */

  const WLineF& linearGradientVector() const { return gradientVector_; }

  /*! \brief Returns the center of a radial gradient.

   *

   * This returns the center point set in setRadialGradient().

   */

  const WPointF& radialCenterPoint() const { return center_; }

  /*! \brief Returns the focal point of a radial gradient.

   *

   * This returns the focal point set in setRadialGradient().

   */

  const WPointF& radialFocalPoint() const { return focal_; }

  /*! \brief Returns the radius of a radial gradient.

   *

   * This returns the radius set in setRadialGradient().

   */

  double radialRadius() const { return radius_; }

  /*! \brief Comparison operator.

   */

  bool operator==(const WGradient& other) const;

  /*! \brief Comparison operator.

   */

  bool operator!=(const WGradient& other) const;

private:

  GradientStyle style_;

  std::vector<ColorStop> colorstops_;

  // linear gradient parameters

  WLineF gradientVector_;

  // radial gradient parameters

  WPointF center_, focal_;

  double radius_;

};

}

#endif