gradient.hpp

#pragma once
#include <ossia/dataflow/graph_node.hpp>
#include <ossia/dataflow/node_process.hpp>
#include <ossia/dataflow/port.hpp>
#include <ossia/detail/flat_map.hpp>
#include <ossia/detail/math.hpp>
#include <ossia/editor/curve/curve_segment/easing.hpp>
#include <ossia/network/base/parameter.hpp>
#include <ossia/network/dataspace/color.hpp>
#include <ossia/network/dataspace/dataspace_visitors.hpp>
 
namespace ossia::nodes
{
class gradient final : public ossia::graph_node
{
public:
  using grad_type = ossia::flat_map<double, ossia::hunter_lab>;
 
  static auto clamp_color(ossia::argb col)
  {
    using namespace std;
    for(size_t i = 0; i < col.dataspace_value.size(); i++)
      col.dataspace_value[i] = ossia::clamp<float>(col.dataspace_value[i], 0.f, 1.f);
 
    return col;
  }
 
  gradient()
  {
    ossia::outlet_ptr vp = new ossia::value_outlet;
    vp->target<ossia::value_port>()->type = ossia::argb_u{};
    m_outlets.push_back(std::move(vp));
  }
 
  void set_gradient(grad_type t) { m_data = std::move(t); }
 
  const ossia::unit_t& get_unit() const noexcept
  {
    auto outlet = m_outlets.back();
    if(auto unit = outlet->target<ossia::value_port>()->type.target<ossia::unit_t>())
    {
      return *unit;
    }
    else
    {
      static const ossia::unit_t default_unit = ossia::rgb_u{};
      return default_unit;
    }
  }
 
  ossia::value get_color(ossia::argb c)
  {
    ossia::value res = clamp_color(c).dataspace_value;
    return ossia::convert(res, ossia::argb_u{}, get_unit());
  }
 
  void handle_before_first(const ossia::token_request& tk, int64_t tick_start, double position)
  {
    auto& out = *m_outlets[0]->target<ossia::value_port>();
    auto beg = m_data.begin();
 
    if(beg->first >= position)
    {
      out.write_value(get_color(ossia::argb{beg->second}), tick_start);
    }
    else if(!mustTween)
    {
      out.write_value(get_color(ossia::argb{beg->second}), tick_start);
    }
    else
    {
      if(!tween)
      {
        auto addr = m_outlets[0]->address.target<ossia::net::parameter_base*>();
        if(addr && *addr)
        {
          // TODO if the curve is in another unit, we have to convert it to the
          // correct unit.
          tween = ossia::argb{ossia::convert<ossia::vec4f>((*addr)->value())};
        }
        else
        {
          tween = ossia::argb{beg->second};
        }
      }
      out.write_value(
          ease_color(0., *tween, beg->first, beg->second, position), tick_start);
    }
  }
 
  ossia::time_value process_dur;
  void run(const ossia::token_request& t, ossia::exec_state_facade e) noexcept override
  {
    if(this->process_dur.impl <= 0)
      return;
 
    auto& out = *m_outlets[0]->target<ossia::value_port>();
 
    const auto [tick_start, d] = e.timings(t);
    const double pos = t.position() * double(t.parent_duration.impl) / double(this->process_dur.impl);
 
    switch(m_data.size())
    {
      case 0:
        out.write_value(get_color(ossia::argb{0., 0., 0., 0.}), tick_start);
        return;
      case 1:
        handle_before_first(t, tick_start, pos);
        return;
      default: {
        auto it_next = m_data.lower_bound(pos);
        // Before start
        if(it_next == m_data.begin())
        {
          handle_before_first(t, tick_start, pos);
        }
        // past end
        else if(it_next == m_data.end())
        {
          out.write_value(get_color(ossia::argb{m_data.rbegin()->second}), tick_start);
        }
        else
        {
          auto it_prev = it_next;
          --it_prev;
 
          out.write_value(
              ease_color(
                  it_prev->first, it_prev->second, it_next->first, it_next->second,
                  pos),
              tick_start);
        }
      }
    }
  }
 
  ossia::value ease_color(
      double prev_pos, ossia::hunter_lab prev, double next_pos, ossia::hunter_lab next,
      double pos)
  {
    // Interpolate in La*b* domain
    const auto coeff = (pos - prev_pos) / (next_pos - prev_pos);
 
    ossia::hunter_lab res;
    ossia::easing::ease e{};
    res.dataspace_value = ossia::make_vec(
        e(prev.dataspace_value[0], next.dataspace_value[0], coeff),
        e(prev.dataspace_value[1], next.dataspace_value[1], coeff),
        e(prev.dataspace_value[2], next.dataspace_value[2], coeff));
 
    return get_color(ossia::argb{res});
  }
 
public:
  std::optional<ossia::argb> tween;
 
private:
  grad_type m_data;
 
public:
  bool mustTween{};
};
 
class gradient_process final : public ossia::node_process
{
public:
  using ossia::node_process::node_process;
  void start() override {
    static_cast<gradient*>(node.get())->tween = std::nullopt;
  }
};
}