engine/src/flutter/impeller/entity/contents/line_contents.h

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef FLUTTER_IMPELLER_ENTITY_CONTENTS_LINE_CONTENTS_H_
#define FLUTTER_IMPELLER_ENTITY_CONTENTS_LINE_CONTENTS_H_

#include <memory>

#include "flutter/impeller/entity/contents/contents.h"
#include "flutter/impeller/entity/geometry/line_geometry.h"
#include "impeller/entity/line.vert.h"

namespace impeller {
class LineContents : public Contents {
 public:
  static const Scalar kSampleRadius;
  static std::vector<uint8_t> CreateCurveData(Scalar width,
                                              Scalar radius,
                                              Scalar scale);

  struct EffectiveLineParameters {
    Scalar width;
    Scalar radius;
  };

  /// Calculates the values needed for the vertex shader, per vertex.
  /// Returns the effective line parameters that are used. These differ from the
  /// ones provided by `geometry` when the line gets clamped for being too thin.
  static fml::StatusOr<EffectiveLineParameters> CalculatePerVertex(
      LineVertexShader::PerVertexData* per_vertex,
      const LineGeometry* geometry,
      const Matrix& entity_transform);

  static std::unique_ptr<LineContents> Make(
      std::unique_ptr<LineGeometry> geometry,
      Color color);

  bool Render(const ContentContext& renderer,
              const Entity& entity,
              RenderPass& pass) const override;

  std::optional<Rect> GetCoverage(const Entity& entity) const override;

 private:
  explicit LineContents(std::unique_ptr<LineGeometry> geometry, Color color);

  std::unique_ptr<LineGeometry> geometry_;
  Color color_;
};
}  // namespace impeller

#endif  // FLUTTER_IMPELLER_ENTITY_CONTENTS_LINE_CONTENTS_H_