generate method

SvgWidget generate(double xStart, double yStart, double xEnd, double yEnd, List<PlotBase> lines, { bool fillColor = false, })

Implementation

SvgWidget generate(double xStart, double yStart, double xEnd, double yEnd,
    List<PlotBase> lines,
    {bool fillColor = false}) {
  const marginTop = 15.0;
  const marginLeft = 5.0;
  const marginRight = 5.0;
  const lineLength = 10.0;

  // calculate the width based with the maximum string length
  const textLetterLength = 5.6;
  var maxLengthString = 0;
  for (var item in items) {
    maxLengthString = max(maxLengthString, item.name.length);
  }
  final textLength = textLetterLength * maxLengthString;

  const marginLeftText = 5.0;
  final legendWidth =
      marginLeftText + lineLength + marginLeftText + textLength + marginRight;
  final legendHeight = marginTop + marginTop * lines.length;

  // calculate x and y positions
  double x, y;
  switch (position) {
    case LegendPosition.topLeft:
      x = xStart;
      y = yStart;
      break;
    case LegendPosition.topRight:
      x = xEnd - legendWidth;
      y = yStart;
      break;
    case LegendPosition.bottomLeft:
      x = xStart;
      y = yEnd - legendHeight;
      break;
    case LegendPosition.bottomRight:
      x = xEnd - legendWidth;
      y = yEnd - legendHeight;
      break;
    case LegendPosition.center:
      x = xStart + ((xEnd - xStart) / 2) - (legendWidth / 2);
      y = yStart + ((yEnd - yStart) / 2) - (legendHeight / 2);
      break;
  }

  if (lines.length != items.length) {
    throw FormatException(
        'expected legendItems and lines to have the same length');
  }

  var g = Group(id: 'legend', children: []);

  // create legend square
  g.children.add(Rect(
      x: x,
      y: y,
      width: legendWidth,
      height: legendHeight,
      fill: backgroundColor ?? Color.white));

  // create legend items
  for (var i = 0; i < lines.length; i++) {
    var color;
    if (fillColor) {
      color = lines[i].fill;
    } else {
      color = lines[i].stroke ?? lines[i].fill;
    }

    g.children.add(items[i].generate(
        x + marginLeft,
        y + marginTop + (i * marginTop),
        color,
        textColor ?? Color.black,
        lineLength,
        marginLeftText));
  }

  return g;
}