draw method

@override void draw(Canvas canvas, ChartPainterData painterData, ChartTouchCallbackData touchedData, double tolerance,)

Draw tooltip bar shape.

Implementation

@override
void draw(Canvas canvas, ChartPainterData painterData,
    ChartTouchCallbackData touchedData, double tolerance) {
  final T item = touchedData.selectedItem as T;
  final Offset currentValuePos = currentPos(item);
  final Size currentValueSize = currentSize(item);
  final Offset itemPos = Offset(
      currentValuePos.dx + currentValueSize.width / 2.0, currentValuePos.dy);
  final TextPainter textPainter = TextPainter(
    text: TextSpan(
      text: onTextValue(item),
      style: textStyle,
    ),
    textDirection: TextDirection.ltr,
  )..layout();
  final Offset pos = Offset(
    itemPos.dx - textPainter.width / 2.0,
    itemPos.dy -
        textPainter.height -
        padding.vertical / 2.0 -
        marginBottom -
        triangleSideLength * 0.5,
  );
  final Offset rectPos = Offset(
    pos.dx - padding.horizontal / 2.0,
    pos.dy - padding.vertical / 2.0,
  );
  final Size rectSize = Size(
    textPainter.width + padding.horizontal,
    textPainter.height + padding.vertical,
  );
  final Offset offsetRectAndText = Offset(
    painterData.position.dx - tolerance > rectPos.dx
        ? -(painterData.position.dx - tolerance - rectPos.dx)
        : painterData.position.dx + tolerance + painterData.size.width <
                rectPos.dx + rectSize.width
            ? -(painterData.position.dx +
                painterData.size.width +
                tolerance -
                rectPos.dx -
                rectSize.width)
            : 0.0,
    rectPos.dy < 0 ? rectPos.dy : 0.0,
  );
  final Path rectanglePath = Path()
    ..addRRect(
      RRect.fromRectAndRadius(
        Offset(rectPos.dx - offsetRectAndText.dx,
                rectPos.dy - offsetRectAndText.dy) &
            rectSize,
        Radius.circular(radius),
      ),
    );
  final Offset triangleCenterPos = Offset(
    rectPos.dx + rectSize.width / 2.0,
    rectPos.dy + rectSize.height - offsetRectAndText.dy,
  );
  final Path trianglePath = Path()
    ..moveTo(
      triangleCenterPos.dx - triangleSideLength / 2.0,
      triangleCenterPos.dy - 1.0,
    )
    ..lineTo(
      triangleCenterPos.dx + triangleSideLength / 2.0,
      triangleCenterPos.dy - 1.0,
    )
    ..lineTo(
      triangleCenterPos.dx,
      triangleCenterPos.dy + triangleSideLength * 0.5 - 1.0,
    )
    ..close();
  canvas
    ..drawPath(
      rectanglePath,
      Paint()..color = backgroundColor,
    )
    ..drawPath(
      trianglePath,
      Paint()..color = backgroundColor,
    );
  textPainter.paint(
    canvas,
    Offset(
      pos.dx - offsetRectAndText.dx,
      pos.dy - offsetRectAndText.dy,
    ),
  );
}