function minMaxDecimation()

in Hands-on lab/lab-files/starter-project/NorthwindMVC/wwwroot/lib/Chart.js/chart.js [9501:9553]

• 53 lines of code
• 13 McCabe index (conditional complexity)

function minMaxDecimation(data, start, count, availableWidth) {
  let avgX = 0;
  let countX = 0;
  let i, point, x, y, prevX, minIndex, maxIndex, startIndex, minY, maxY;
  const decimated = [];
  const endIndex = start + count - 1;
  const xMin = data[start].x;
  const xMax = data[endIndex].x;
  const dx = xMax - xMin;
  for (i = start; i < start + count; ++i) {
    point = data[i];
    x = (point.x - xMin) / dx * availableWidth;
    y = point.y;
    const truncX = x | 0;
    if (truncX === prevX) {
      if (y < minY) {
        minY = y;
        minIndex = i;
      } else if (y > maxY) {
        maxY = y;
        maxIndex = i;
      }
      avgX = (countX * avgX + point.x) / ++countX;
    } else {
      const lastIndex = i - 1;
      if (!isNullOrUndef(minIndex) && !isNullOrUndef(maxIndex)) {
        const intermediateIndex1 = Math.min(minIndex, maxIndex);
        const intermediateIndex2 = Math.max(minIndex, maxIndex);
        if (intermediateIndex1 !== startIndex && intermediateIndex1 !== lastIndex) {
          decimated.push({
            ...data[intermediateIndex1],
            x: avgX,
          });
        }
        if (intermediateIndex2 !== startIndex && intermediateIndex2 !== lastIndex) {
          decimated.push({
            ...data[intermediateIndex2],
            x: avgX
          });
        }
      }
      if (i > 0 && lastIndex !== startIndex) {
        decimated.push(data[lastIndex]);
      }
      decimated.push(point);
      prevX = truncX;
      countX = 0;
      minY = maxY = y;
      minIndex = maxIndex = startIndex = i;
    }
  }
  return decimated;
}