gecko/gfx/2d/PathSkia.cpp

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "PathSkia.h"
#include <math.h>
#include "DrawTargetSkia.h"
#include "Logging.h"
#include "HelpersSkia.h"
#include "PathHelpers.h"

namespace mozilla {
namespace gfx {

PathBuilderSkia::PathBuilderSkia(const Matrix& aTransform, const SkPath& aPath, FillRule aFillRule)
  : mPath(aPath)
{
  SkMatrix matrix;
  GfxMatrixToSkiaMatrix(aTransform, matrix);
  mPath.transform(matrix);
  SetFillRule(aFillRule);
}

PathBuilderSkia::PathBuilderSkia(FillRule aFillRule)
{
  SetFillRule(aFillRule);
}

void
PathBuilderSkia::SetFillRule(FillRule aFillRule)
{
  mFillRule = aFillRule;
  if (mFillRule == FillRule::FILL_WINDING) {
    mPath.setFillType(SkPath::kWinding_FillType);
  } else {
    mPath.setFillType(SkPath::kEvenOdd_FillType);
  }
}

void
PathBuilderSkia::MoveTo(const Point &aPoint)
{
  mPath.moveTo(SkFloatToScalar(aPoint.x), SkFloatToScalar(aPoint.y));
}

void
PathBuilderSkia::LineTo(const Point &aPoint)
{
  if (!mPath.countPoints()) {
    MoveTo(aPoint);
  } else {
    mPath.lineTo(SkFloatToScalar(aPoint.x), SkFloatToScalar(aPoint.y));
  }
}

void
PathBuilderSkia::BezierTo(const Point &aCP1,
                          const Point &aCP2,
                          const Point &aCP3)
{
  if (!mPath.countPoints()) {
    MoveTo(aCP1);
  }
  mPath.cubicTo(SkFloatToScalar(aCP1.x), SkFloatToScalar(aCP1.y),
                SkFloatToScalar(aCP2.x), SkFloatToScalar(aCP2.y),
                SkFloatToScalar(aCP3.x), SkFloatToScalar(aCP3.y));
}

void
PathBuilderSkia::QuadraticBezierTo(const Point &aCP1,
                                   const Point &aCP2)
{
  if (!mPath.countPoints()) {
    MoveTo(aCP1);
  }
  mPath.quadTo(SkFloatToScalar(aCP1.x), SkFloatToScalar(aCP1.y),
               SkFloatToScalar(aCP2.x), SkFloatToScalar(aCP2.y));
}

void
PathBuilderSkia::Close()
{
  mPath.close();
}

void
PathBuilderSkia::Arc(const Point &aOrigin, float aRadius, float aStartAngle,
                     float aEndAngle, bool aAntiClockwise)
{
  ArcToBezier(this, aOrigin, Size(aRadius, aRadius), aStartAngle, aEndAngle, aAntiClockwise);
}

Point
PathBuilderSkia::CurrentPoint() const
{
  int pointCount = mPath.countPoints();
  if (!pointCount) {
    return Point(0, 0);
  }
  SkPoint point = mPath.getPoint(pointCount - 1);
  return Point(SkScalarToFloat(point.fX), SkScalarToFloat(point.fY));
}

already_AddRefed<Path>
PathBuilderSkia::Finish()
{
  return MakeAndAddRef<PathSkia>(mPath, mFillRule);
}

void
PathBuilderSkia::AppendPath(const SkPath &aPath)
{
  mPath.addPath(aPath);
}

already_AddRefed<PathBuilder>
PathSkia::CopyToBuilder(FillRule aFillRule) const
{
  return TransformedCopyToBuilder(Matrix(), aFillRule);
}

already_AddRefed<PathBuilder>
PathSkia::TransformedCopyToBuilder(const Matrix &aTransform, FillRule aFillRule) const
{
  return MakeAndAddRef<PathBuilderSkia>(aTransform, mPath, aFillRule);
}

static bool
SkPathContainsPoint(const SkPath& aPath, const Point& aPoint, const Matrix& aTransform)
{
  // Skia's SkPath::contains method does not support the inclusive boundary conditions
  // required by canvas (bug 831259), so we employ the same workaround as used by Blink.
  // First, we scale the path up to the largest coordinates that won't cause precision
  // issues (2^15) and consequently also scale larger paths than that down.
  // Next, we make a clip region representing the point to be tested and convert the
  // path to a region within this clip region.
  // If the resulting region is non-empty, then the path should contain the point.
  Matrix inverse = aTransform;
  inverse.Invert();
  SkPoint point = PointToSkPoint(inverse * aPoint);

  SkRect bounds = aPath.getBounds();
  if (point.fX < bounds.fLeft || point.fY < bounds.fTop ||
      point.fX > bounds.fRight || point.fY > bounds.fBottom) {
    return false;
  }

  SkPoint scale = SkPoint::Make(SkMaxScalar(bounds.fRight, -bounds.fLeft),
                                SkMaxScalar(bounds.fBottom, -bounds.fTop));
  if (SkScalarNearlyZero(scale.fX) || SkScalarNearlyZero(scale.fY)) {
    return false;
  }
  scale.set(SkMaxScalar(scale.fX, SkScalarAbs(point.fX) + SK_Scalar1),
            SkMaxScalar(scale.fY, SkScalarAbs(point.fY) + SK_Scalar1));

  const SkScalar maxCoord = SkIntToScalar(1 << 15);
  SkMatrix scaleMatrix;
  scaleMatrix.setScale(maxCoord / scale.fX, maxCoord / scale.fY);

  SkPath scaledPath(aPath);
  scaledPath.transform(scaleMatrix, nullptr);

  scaleMatrix.mapPoints(&point, 1);
  SkRegion pointClip(SkIRect::MakeXYWH(SkScalarRoundToInt(point.fX) - 1,
                                       SkScalarRoundToInt(point.fY) - 1,
                                       2, 2));

  SkRegion pathRegion;
  return pathRegion.setPath(scaledPath, pointClip);
}

bool
PathSkia::ContainsPoint(const Point &aPoint, const Matrix &aTransform) const
{
  if (!mPath.isFinite()) {
    return false;
  }

  return SkPathContainsPoint(mPath, aPoint, aTransform);
}

bool
PathSkia::StrokeContainsPoint(const StrokeOptions &aStrokeOptions,
                              const Point &aPoint,
                              const Matrix &aTransform) const
{
  if (!mPath.isFinite()) {
    return false;
  }

  SkPaint paint;
  StrokeOptionsToPaint(paint, aStrokeOptions);

  SkPath strokePath;
  paint.getFillPath(mPath, &strokePath);

  return SkPathContainsPoint(strokePath, aPoint, aTransform);
}

Rect
PathSkia::GetBounds(const Matrix &aTransform) const
{
  if (!mPath.isFinite()) {
    return Rect();
  }

  Rect bounds = SkRectToRect(mPath.getBounds());
  return aTransform.TransformBounds(bounds);
}

Rect
PathSkia::GetStrokedBounds(const StrokeOptions &aStrokeOptions,
                           const Matrix &aTransform) const
{
  if (!mPath.isFinite()) {
    return Rect();
  }

  SkPaint paint;
  StrokeOptionsToPaint(paint, aStrokeOptions);
  
  SkPath result;
  paint.getFillPath(mPath, &result);

  Rect bounds = SkRectToRect(result.getBounds());
  return aTransform.TransformBounds(bounds);
}

void
PathSkia::StreamToSink(PathSink *aSink) const
{
  SkPath::RawIter iter(mPath);

  SkPoint points[4];
  SkPath::Verb currentVerb;
  while ((currentVerb = iter.next(points)) != SkPath::kDone_Verb) {
    switch (currentVerb) {
    case SkPath::kMove_Verb:
      aSink->MoveTo(SkPointToPoint(points[0]));
      break;
    case SkPath::kLine_Verb:
      aSink->LineTo(SkPointToPoint(points[1]));
      break;
    case SkPath::kCubic_Verb:
      aSink->BezierTo(SkPointToPoint(points[1]),
                      SkPointToPoint(points[2]),
                      SkPointToPoint(points[3]));
      break;
    case SkPath::kQuad_Verb:
      aSink->QuadraticBezierTo(SkPointToPoint(points[1]),
                               SkPointToPoint(points[2]));
      break;
    case SkPath::kClose_Verb:
      aSink->Close();
      break;
    default:
      MOZ_ASSERT(false);
      // Unexpected verb found in path!
    }
  }
}

} // namespace gfx
} // namespace mozilla