text: /*
   * Copyright 2018 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #include "SkSGGradient.h"
  
  #include "SkGradientShader.h"
  #include "SkPaint.h"
  
  namespace sksg {
  
  sk_sp<SkShader> Gradient::onRevalidateShader() {
      if (fColorStops.empty()) {
          return nullptr;
      }
  
      std::vector<SkColor>  colors;
      std::vector<SkScalar> positions;
      colors.reserve(fColorStops.size());
      positions.reserve(fColorStops.size());
  
      SkScalar position = 0;
      for (const auto& stop : fColorStops) {
          colors.push_back(stop.fColor);
          position = SkTPin(stop.fPosition, position, 1.0f);
          positions.push_back(position);
      }
  
      // TODO: detect even stop distributions, pass null for positions.
      return this->onMakeShader(colors, positions);
  }
  
  sk_sp<SkShader> LinearGradient::onMakeShader(const std::vector<SkColor>& colors,
                                               const std::vector<SkScalar>& positions) const {
      SkASSERT(colors.size() == positions.size());
  
      const SkPoint pts[] = { fStartPoint, fEndPoint };
      return SkGradientShader::MakeLinear(pts, colors.data(), positions.data(), colors.size(),
                                          this->getTileMode());
  }
  
  sk_sp<SkShader> RadialGradient::onMakeShader(const std::vector<SkColor>& colors,
                                               const std::vector<SkScalar>& positions) const {
      SkASSERT(colors.size() == positions.size());
  
      return (fStartRadius <= 0 && fStartCenter == fEndCenter)
          ? SkGradientShader::MakeRadial(fEndCenter, fEndRadius,
                                         colors.data(), positions.data(), colors.size(),
                                         this->getTileMode())
          : SkGradientShader::MakeTwoPointConical(fStartCenter, fStartRadius,
                                                  fEndCenter, fEndRadius,
                                                  colors.data(), positions.data(), colors.size(),
                                                  this->getTileMode());
  }
  
  } //namespace sksg
  