drawGroupPrimitives method

@override List<MarkElement<ElementStyle>> drawGroupPrimitives(List<Attributes> group, CoordConv coord, Offset origin)

Renders primitive elements of all tuples of a group.

The tuples are rendered in groups. the Attributes.shape of the first tuple of a group will be taken as a represent, and it's drawGroupPrimitives method decides the basic way to render the whole group. If different tuples have different shapes, define and call special element rendering methods for each item.

Implementation

@override
List<MarkElement> drawGroupPrimitives(
  List<Attributes> group,
  CoordConv coord,
  Offset origin,
) {
  assert(coord is RectCoordConv);
  assert(!coord.transposed);

  final primitives = <MarkElement>[];

  for (var item in group) {
    assert(item.shape is CandlestickShape);

    final style = getPaintStyle(item, (item.shape as CandlestickShape).hollow,
        (item.shape as CandlestickShape).strokeWidth, null, null);

    // Candle stick shape dosen't allow NaN value.
    final points = item.position.map((p) => coord.convert(p)).toList();
    final x = points.first.dx;
    final ys = points.map((p) => p.dy).toList()..sort();
    final bias = (item.size ?? defaultSize) / 2;
    final top = ys[0];
    final topEdge = ys[1];
    final bottomEdge = ys[2];
    final bottom = ys[3];

    if ((item.shape as CandlestickShape).hollow) {
      primitives.add(PathElement(segments: [
        MoveSegment(end: Offset(x, top)),
        LineSegment(end: Offset(x, topEdge)),
        MoveSegment(end: Offset(x - bias, topEdge)),
        LineSegment(end: Offset(x + bias, topEdge)),
        LineSegment(end: Offset(x + bias, bottomEdge)),
        LineSegment(end: Offset(x - bias, bottomEdge)),
        CloseSegment(),
        MoveSegment(end: Offset(x, bottomEdge)),
        LineSegment(end: Offset(x, bottom)),
      ], style: style, tag: item.tag));
    } else {
      // If the stoke style is fill, the lines created by Path.lineTo will not
      // be rendered.
      final strokeBias = (item.shape as CandlestickShape).strokeWidth / 2;
      primitives.add(PathElement(segments: [
        MoveSegment(end: Offset(x + strokeBias, top)),
        LineSegment(end: Offset(x + strokeBias, topEdge)),
        LineSegment(end: Offset(x + bias, topEdge)),
        LineSegment(end: Offset(x + bias, bottomEdge)),
        LineSegment(end: Offset(x + strokeBias, bottomEdge)),
        LineSegment(end: Offset(x + strokeBias, bottom)),
        LineSegment(end: Offset(x - strokeBias, bottom)),
        LineSegment(end: Offset(x - strokeBias, bottomEdge)),
        LineSegment(end: Offset(x - bias, bottomEdge)),
        LineSegment(end: Offset(x - bias, topEdge)),
        LineSegment(end: Offset(x - strokeBias, topEdge)),
        LineSegment(end: Offset(x - strokeBias, top)),
        CloseSegment(),
      ], style: style, tag: item.tag));
    }
    // No labels.
  }

  return primitives;
}