Price Channel Overlay

[char101]

Just sharing my parallel channel overlay since the formula is not easy to find. This is different from the stock parallel channel overlay because it does not span the whole chart.

export default {
  totalStep: 4,
  needDefaultPointFigure: true,
  needDefaultXAxisFigure: false,
  needDefaultYAxisFigure: false,
  createPointFigures({ coordinates }) {
    const figures = [];
    if (coordinates.length >= 2) {
      const c1 = coordinates[0];
      const c2 = coordinates[1];
      figures.push({
        type: 'line',
        attrs: { coordinates: [c1, c2] },
      });
      if (coordinates.length === 3) {
        const c3 = coordinates[2];
        const dx = c2.x - c1.x;
        const dy = c2.y - c1.y;
        const ydist = (dy * c3.x - dx * c3.y + c2.x * c1.y - c2.y * c1.x) / dx;
        figures.push({
          type: 'line',
          attrs: {
            coordinates: [
              { x: c1.x, y: c1.y - ydist },
              { x: c2.x, y: c2.y - ydist },
            ],
          },
        });
      }
    }
    return figures;
  },
};