include/rive/shapes/metrics_path.hpp

#ifndef _RIVE_METRICS_PATH_HPP_
#define _RIVE_METRICS_PATH_HPP_

#include "rive/command_path.hpp"
#include "rive/math/vec2d.hpp"
#include <cassert>
#include <vector>

namespace rive {

    struct CubicSegment {
        float t;
        float length;
        CubicSegment(float tValue, float lengthValue) : t(tValue), length(lengthValue) {}
    };

    struct PathPart {
        static const unsigned char line = 0;
        /// Type is 0 when this is a line segment, it's 1 or greater when it's a
        /// cubic. When it's a cubic it also represents the index in
        /// CubicSegments-1.
        unsigned char type;

        /// Offset is the offset in original path points (which get transformed
        /// when they're added to another path).
        unsigned char offset;

        // Only used by the cubic to count the number of cubic segments used by
        // this part.
        unsigned char numSegments;

        PathPart(unsigned char t, unsigned char l) : type(t), offset(l), numSegments(0) {}
    };

    class MetricsPath : public CommandPath {
    private:
        std::vector<Vec2D> m_Points;
        std::vector<Vec2D> m_TransformedPoints;
        std::vector<CubicSegment> m_CubicSegments;
        std::vector<PathPart> m_Parts;
        std::vector<float> m_Lengths;
        std::vector<MetricsPath*> m_Paths;
        float m_ComputedLength = 0.0f;
        Mat2D m_ComputedLengthTransform;

    public:
        const std::vector<MetricsPath*>& paths() const { return m_Paths; }
        void addPath(CommandPath* path, const Mat2D& transform) override;
        void reset() override;
        void moveTo(float x, float y) override;
        void lineTo(float x, float y) override;
        void cubicTo(float ox, float oy, float ix, float iy, float x, float y) override;
        void close() override;

        float length() const { return m_ComputedLength; }

        /// Add commands to the result RenderPath that will draw the segment
        /// from startLength to endLength of this MetricsPath. Requires
        /// computeLength be called prior to trimming.
        void trim(float startLength, float endLength, bool moveTo, RenderPath* result);

    private:
        float computeLength(const Mat2D& transform);

        /// Extract a single segment from startT to endT as render commands
        /// added to result.
        void extractSubPart(int index, float startT, float endT, bool moveTo, RenderPath* result);
    };

    class OnlyMetricsPath : public MetricsPath {
    public:
        void fillRule(FillRule value) override {}

        RenderPath* renderPath() override {
            // Should never be used for actual rendering.
            assert(false);
            return nullptr;
        }
    };

    class RenderMetricsPath : public MetricsPath {
    private:
        std::unique_ptr<RenderPath> m_RenderPath;

    public:
        RenderMetricsPath(std::unique_ptr<RenderPath>);
        RenderPath* renderPath() override { return m_RenderPath.get(); }
        void addPath(CommandPath* path, const Mat2D& transform) override;

        void fillRule(FillRule value) override;
        void reset() override;
        void moveTo(float x, float y) override;
        void lineTo(float x, float y) override;
        void cubicTo(float ox, float oy, float ix, float iy, float x, float y) override;
        void close() override;
    };
} // namespace rive
#endif