drawDataPoints method

Implementation

@override
void drawDataPoints() {
  var minY = getLabelMinY();
  var maxY = getLabelMaxY();
  var totalBarWidth = getBarWidth();

  var barMinPxX = gridMinPxX;
  var barMaxPxX = gridMaxPxX;
  if (maxLabelWidthX > getBarWidth()) {
    barMinPxX = gridMinPxX + max(0, (maxLabelWidthX - getBarWidth())/2);
    barMaxPxX = gridMaxPxX - max(0, (maxLabelWidthX - getBarWidth())/2);
  }

  var barSetIndex = 0;
  var spaceX = (barMaxPxX - totalBarWidth - barMinPxX) / (_dataPoints.length - 1);
  var alignmentOffsetX = 0.0;
  if (_dataPoints.length == 1) { // Start to draw from the center
    alignmentOffsetX = (barMaxPxX - barMinPxX - totalBarWidth)/2 - barMinPxX - totalBarWidth/2;
    spaceX = 0;
  }

  _hoverPaths.clear();
  for (var x in keys) {
    var mapPoints = _dataPoints[x];
    var barIndex = 0;
    for (var graphName in _graphKeys) {
      var y = mapPoints![graphName];
      if (y == null) {
        barIndex++;
        continue;
      }

      var offset = barIndex * singleBarWidth + barIndex * barMargin + spaceX * barSetIndex + alignmentOffsetX;
      // Clamp the value so it does not get drawn outside the graph.
      var clampedY = min(y, maxY);
      var pxY = lerp(clampedY, minY, maxY, gridMaxPxY, gridMinPxY);
      var bar = Path2D();
      var hoverPath = _BarHoverPath(bar, barMinPxX + offset, pxY, max(gridMaxPxY - pxY, 1));
      bar.rect(hoverPath.pxX, hoverPath.pxY, singleBarWidth, hoverPath.height);
      ctx.fillStyle = (barFillStyle[graphName] ?? barFillStyle[keyAllGraph])!.toJS;
      ctx.fillRect(hoverPath.pxX, hoverPath.pxY, singleBarWidth, hoverPath.height);
      if (_hoverPaths[x] == null) {
        _hoverPaths[x] = {graphName: hoverPath};
      } else {
        _hoverPaths[x]![graphName] = hoverPath;
      }
      barIndex++;
    }
    barSetIndex++;
  }
}