text: /*
      Copyright (C) 2007 Krzysztof Kowalczyk <kkowalczyk@gmail.com>
      Copyright (C) 2004, 2005, 2006 Nikolas Zimmermann <wildfox@kde.org>
                    2004, 2005, 2006 Rob Buis <buis@kde.org>
                    2005, 2007 Apple Inc. All Rights reserved.
                    2007 Alp Toker <alp@atoker.com>
                    2008 Dirk Schulze <krit@webkit.org>
                    2011 Igalia S.L.
  
      This library is free software; you can redistribute it and/or
      modify it under the terms of the GNU Library General Public
      License as published by the Free Software Foundation; either
      version 2 of the License, or (at your option) any later version.
  
      This library is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      Library General Public License for more details.
  
      You should have received a copy of the GNU Library General Public License
      aint with this library; see the file COPYING.LIB.  If not, write to
      the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      Boston, MA 02110-1301, USA.
  */
  
  #include "config.h"
  #include "Path.h"
  
  #if USE(CAIRO)
  
  #include "CairoUtilities.h"
  #include "FloatRect.h"
  #include "GraphicsContext.h"
  #include "PlatformPathCairo.h"
  #include "StrokeStyleApplier.h"
  #include <math.h>
  #include <wtf/MathExtras.h>
  #include <wtf/text/WTFString.h>
  
  namespace WebCore {
  
  Path::Path()
      : m_path(0)
  {
  }
  
  Path::~Path()
  {
      if (m_path)
          delete m_path;
  }
  
  Path::Path(const Path& other)
      : m_path(0)
  {
      if (other.isNull())
          return;
  
      cairo_t* cr = ensurePlatformPath()->context();
      auto pathCopy = cairo_copy_path(other.platformPath()->context());
      cairo_append_path(cr, pathCopy);
      cairo_path_destroy(pathCopy);
  }
  
  PlatformPathPtr Path::ensurePlatformPath()
  {
      if (!m_path)
          m_path = new CairoPath();
      return m_path;
  }
  
  Path& Path::operator=(const Path& other)
  {
      if (&other == this)
          return *this;
  
      if (other.isNull()) {
          if (m_path) {
              delete m_path;
              m_path = 0;
          }
      } else {
          clear();
          cairo_t* cr = ensurePlatformPath()->context();
          auto pathCopy = cairo_copy_path(other.platformPath()->context());
          cairo_append_path(cr, pathCopy);
          cairo_path_destroy(pathCopy);
      }
  
      return *this;
  }
  
  void Path::clear()
  {
      if (isNull())
          return;
  
      cairo_t* cr = platformPath()->context();
      cairo_new_path(cr);
  }
  
  bool Path::isEmpty() const
  {
      return isNull() || !cairo_has_current_point(platformPath()->context());
  }
  
  bool Path::hasCurrentPoint() const
  {
      return !isEmpty();
  }
  
  FloatPoint Path::currentPoint() const 
  {
      if (isNull())
          return FloatPoint();
  
      // FIXME: Is this the correct way?
      double x;
      double y;
      cairo_get_current_point(platformPath()->context(), &x, &y);
      return FloatPoint(x, y);
  }
  
  void Path::translate(const FloatSize& p)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_translate(cr, -p.width(), -p.height());
  }
  
  void Path::moveTo(const FloatPoint& p)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_move_to(cr, p.x(), p.y());
  }
  
  void Path::addLineTo(const FloatPoint& p)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_line_to(cr, p.x(), p.y());
  }
  
  void Path::addRect(const FloatRect& rect)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_rectangle(cr, rect.x(), rect.y(), rect.width(), rect.height());
  }
  
  /*
   * inspired by libsvg-cairo
   */
  void Path::addQuadCurveTo(const FloatPoint& controlPoint, const FloatPoint& point)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      double x, y;
      double x1 = controlPoint.x();
      double y1 = controlPoint.y();
      double x2 = point.x();
      double y2 = point.y();
      cairo_get_current_point(cr, &x, &y);
      cairo_curve_to(cr,
                     x  + 2.0 / 3.0 * (x1 - x),  y  + 2.0 / 3.0 * (y1 - y),
                     x2 + 2.0 / 3.0 * (x1 - x2), y2 + 2.0 / 3.0 * (y1 - y2),
                     x2, y2);
  }
  
  void Path::addBezierCurveTo(const FloatPoint& controlPoint1, const FloatPoint& controlPoint2, const FloatPoint& controlPoint3)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_curve_to(cr, controlPoint1.x(), controlPoint1.y(),
                     controlPoint2.x(), controlPoint2.y(),
                     controlPoint3.x(), controlPoint3.y());
  }
  
  void Path::addArc(const FloatPoint& p, float r, float startAngle, float endAngle, bool anticlockwise)
  {
      // http://bugs.webkit.org/show_bug.cgi?id=16449
      // cairo_arc() functions hang or crash when passed inf as radius or start/end angle
      if (!std::isfinite(r) || !std::isfinite(startAngle) || !std::isfinite(endAngle))
          return;
  
      cairo_t* cr = ensurePlatformPath()->context();
      float sweep = endAngle - startAngle;
      const float twoPI = 2 * piFloat;
      if ((sweep <= -twoPI || sweep >= twoPI)
          && ((anticlockwise && (endAngle < startAngle)) || (!anticlockwise && (startAngle < endAngle)))) {
          if (anticlockwise)
              cairo_arc_negative(cr, p.x(), p.y(), r, startAngle, startAngle - twoPI);
          else
              cairo_arc(cr, p.x(), p.y(), r, startAngle, startAngle + twoPI);
          cairo_new_sub_path(cr);
          cairo_arc(cr, p.x(), p.y(), r, endAngle, endAngle);
      } else {
          if (anticlockwise)
              cairo_arc_negative(cr, p.x(), p.y(), r, startAngle, endAngle);
          else
              cairo_arc(cr, p.x(), p.y(), r, startAngle, endAngle);
      }
  }
  
  static inline float areaOfTriangleFormedByPoints(const FloatPoint& p1, const FloatPoint& p2, const FloatPoint& p3)
  {
      return p1.x() * (p2.y() - p3.y()) + p2.x() * (p3.y() - p1.y()) + p3.x() * (p1.y() - p2.y());
  }
  
  void Path::addArcTo(const FloatPoint& p1, const FloatPoint& p2, float radius)
  {
      // FIXME: Why do we return if the path is empty? Can't a path start with an arc?
      if (isEmpty())
          return;
  
      cairo_t* cr = platformPath()->context();
  
      double x0, y0;
      cairo_get_current_point(cr, &x0, &y0);
      FloatPoint p0(x0, y0);
  
      // Draw only a straight line to p1 if any of the points are equal or the radius is zero
      // or the points are collinear (triangle that the points form has area of zero value).
      if ((p1.x() == p0.x() && p1.y() == p0.y()) || (p1.x() == p2.x() && p1.y() == p2.y()) || !radius
          || !areaOfTriangleFormedByPoints(p0, p1, p2)) {
          cairo_line_to(cr, p1.x(), p1.y());
          return;
      }
  
      FloatPoint p1p0((p0.x() - p1.x()),(p0.y() - p1.y()));
      FloatPoint p1p2((p2.x() - p1.x()),(p2.y() - p1.y()));
      float p1p0_length = sqrtf(p1p0.x() * p1p0.x() + p1p0.y() * p1p0.y());
      float p1p2_length = sqrtf(p1p2.x() * p1p2.x() + p1p2.y() * p1p2.y());
  
      double cos_phi = (p1p0.x() * p1p2.x() + p1p0.y() * p1p2.y()) / (p1p0_length * p1p2_length);
      // all points on a line logic
      if (cos_phi == -1) {
          cairo_line_to(cr, p1.x(), p1.y());
          return;
      }
      if (cos_phi == 1) {
          // add infinite far away point
          unsigned int max_length = 65535;
          double factor_max = max_length / p1p0_length;
          FloatPoint ep((p0.x() + factor_max * p1p0.x()), (p0.y() + factor_max * p1p0.y()));
          cairo_line_to(cr, ep.x(), ep.y());
          return;
      }
  
      float tangent = radius / tan(acos(cos_phi) / 2);
      float factor_p1p0 = tangent / p1p0_length;
      FloatPoint t_p1p0((p1.x() + factor_p1p0 * p1p0.x()), (p1.y() + factor_p1p0 * p1p0.y()));
  
      FloatPoint orth_p1p0(p1p0.y(), -p1p0.x());
      float orth_p1p0_length = sqrt(orth_p1p0.x() * orth_p1p0.x() + orth_p1p0.y() * orth_p1p0.y());
      float factor_ra = radius / orth_p1p0_length;
  
      // angle between orth_p1p0 and p1p2 to get the right vector orthographic to p1p0
      double cos_alpha = (orth_p1p0.x() * p1p2.x() + orth_p1p0.y() * p1p2.y()) / (orth_p1p0_length * p1p2_length);
      if (cos_alpha < 0.f)
          orth_p1p0 = FloatPoint(-orth_p1p0.x(), -orth_p1p0.y());
  
      FloatPoint p((t_p1p0.x() + factor_ra * orth_p1p0.x()), (t_p1p0.y() + factor_ra * orth_p1p0.y()));
  
      // calculate angles for addArc
      orth_p1p0 = FloatPoint(-orth_p1p0.x(), -orth_p1p0.y());
      float sa = acos(orth_p1p0.x() / orth_p1p0_length);
      if (orth_p1p0.y() < 0.f)
          sa = 2 * piDouble - sa;
  
      // anticlockwise logic
      bool anticlockwise = false;
  
      float factor_p1p2 = tangent / p1p2_length;
      FloatPoint t_p1p2((p1.x() + factor_p1p2 * p1p2.x()), (p1.y() + factor_p1p2 * p1p2.y()));
      FloatPoint orth_p1p2((t_p1p2.x() - p.x()),(t_p1p2.y() - p.y()));
      float orth_p1p2_length = sqrtf(orth_p1p2.x() * orth_p1p2.x() + orth_p1p2.y() * orth_p1p2.y());
      float ea = acos(orth_p1p2.x() / orth_p1p2_length);
      if (orth_p1p2.y() < 0)
          ea = 2 * piDouble - ea;
      if ((sa > ea) && ((sa - ea) < piDouble))
          anticlockwise = true;
      if ((sa < ea) && ((ea - sa) > piDouble))
          anticlockwise = true;
  
      cairo_line_to(cr, t_p1p0.x(), t_p1p0.y());
  
      addArc(p, radius, sa, ea, anticlockwise);
  }
  
  void Path::addEllipse(FloatPoint point, float radiusX, float radiusY, float rotation, float startAngle, float endAngle, bool anticlockwise)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_save(cr);
      cairo_translate(cr, point.x(), point.y());
      cairo_rotate(cr, rotation);
      cairo_scale(cr, radiusX, radiusY);
  
      if (anticlockwise)
          cairo_arc_negative(cr, 0, 0, 1, startAngle, endAngle);
      else
          cairo_arc(cr, 0, 0, 1, startAngle, endAngle);
  
      cairo_restore(cr);
  }
  
  void Path::addEllipse(const FloatRect& rect)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_save(cr);
      float yRadius = .5 * rect.height();
      float xRadius = .5 * rect.width();
      cairo_translate(cr, rect.x() + xRadius, rect.y() + yRadius);
      cairo_scale(cr, xRadius, yRadius);
      cairo_arc(cr, 0., 0., 1., 0., 2 * piDouble);
      cairo_restore(cr);
  }
  
  void Path::addPath(const Path& path, const AffineTransform& transform)
  {
      if (path.isNull())
          return;
  
      cairo_matrix_t matrix = toCairoMatrix(transform);
      if (cairo_matrix_invert(&matrix) != CAIRO_STATUS_SUCCESS)
          return;
  
      cairo_t* cr = path.platformPath()->context();
      cairo_save(cr);
      cairo_transform(cr, &matrix);
      auto pathCopy = cairo_copy_path(cr);
      cairo_restore(cr);
      cairo_append_path(ensurePlatformPath()->context(), pathCopy);
      cairo_path_destroy(pathCopy);
  }
  
  void Path::closeSubpath()
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_close_path(cr);
  }
  
  FloatRect Path::boundingRect() const
  {
      // Should this be isEmpty() or can an empty path have a non-zero origin?
      if (isNull())
          return FloatRect();
  
      cairo_t* cr = platformPath()->context();
      double x0, x1, y0, y1;
      cairo_path_extents(cr, &x0, &y0, &x1, &y1);
      return FloatRect(x0, y0, x1 - x0, y1 - y0);
  }
  
  FloatRect Path::strokeBoundingRect(StrokeStyleApplier* applier) const
  {
      // Should this be isEmpty() or can an empty path have a non-zero origin?
      if (isNull())
          return FloatRect();
  
      cairo_t* cr = platformPath()->context();
      if (applier) {
          GraphicsContext gc(cr);
          applier->strokeStyle(&gc);
      }
  
      double x0, x1, y0, y1;
      cairo_stroke_extents(cr, &x0, &y0, &x1, &y1);
      return FloatRect(x0, y0, x1 - x0, y1 - y0);
  }
  
  bool Path::contains(const FloatPoint& point, WindRule rule) const
  {
      if (isNull() || !std::isfinite(point.x()) || !std::isfinite(point.y()))
          return false;
      cairo_t* cr = platformPath()->context();
      cairo_fill_rule_t cur = cairo_get_fill_rule(cr);
      cairo_set_fill_rule(cr, rule == RULE_EVENODD ? CAIRO_FILL_RULE_EVEN_ODD : CAIRO_FILL_RULE_WINDING);
      bool contains = cairo_in_fill(cr, point.x(), point.y());
      cairo_set_fill_rule(cr, cur);
      return contains;
  }
  
  bool Path::strokeContains(StrokeStyleApplier* applier, const FloatPoint& point) const
  {
      if (isNull())
          return false;
  
      ASSERT(applier);
      cairo_t* cr = platformPath()->context();
      GraphicsContext gc(cr);
      applier->strokeStyle(&gc);
  
      return cairo_in_stroke(cr, point.x(), point.y());
  }
  
  void Path::apply(const PathApplierFunction& function) const
  {
      if (isNull())
          return;
  
      cairo_t* cr = platformPath()->context();
      auto pathCopy = cairo_copy_path(cr);
      cairo_path_data_t* data;
      PathElement pelement;
      FloatPoint points[3];
      pelement.points = points;
  
      for (int i = 0; i < pathCopy->num_data; i += pathCopy->data[i].header.length) {
          data = &pathCopy->data[i];
          switch (data->header.type) {
          case CAIRO_PATH_MOVE_TO:
              pelement.type = PathElementMoveToPoint;
              pelement.points[0] = FloatPoint(data[1].point.x,data[1].point.y);
              function(pelement);
              break;
          case CAIRO_PATH_LINE_TO:
              pelement.type = PathElementAddLineToPoint;
              pelement.points[0] = FloatPoint(data[1].point.x,data[1].point.y);
              function(pelement);
              break;
          case CAIRO_PATH_CURVE_TO:
              pelement.type = PathElementAddCurveToPoint;
              pelement.points[0] = FloatPoint(data[1].point.x,data[1].point.y);
              pelement.points[1] = FloatPoint(data[2].point.x,data[2].point.y);
              pelement.points[2] = FloatPoint(data[3].point.x,data[3].point.y);
              function(pelement);
              break;
          case CAIRO_PATH_CLOSE_PATH:
              pelement.type = PathElementCloseSubpath;
              function(pelement);
              break;
          }
      }
      cairo_path_destroy(pathCopy);
  }
  
  void Path::transform(const AffineTransform& transform)
  {
      cairo_t* cr = ensurePlatformPath()->context();
      cairo_matrix_t matrix = toCairoMatrix(transform);
      cairo_matrix_invert(&matrix);
      cairo_transform(cr, &matrix);
  }
  
  } // namespace WebCore
  
  #endif // USE(CAIRO)
  