draw method

void draw(Canvas canvas, Size size, Graph graph)

Draws the graph of the function on the given canvas with the provided size and graph settings.

Implementation

void draw(Canvas canvas, Size size, Graph graph) {
  List<Offset> points = [];
  for (double i = -((size.width / 2) - graph.focusPoint.x) / graph.gridStep;
      i < ((size.width / 2) + graph.focusPoint.x) / graph.gridStep;
      i += 0.005) {
    if (!(-function(i) * graph.gridStep).isNaN) {
      points.add(Offset(i * graph.gridStep, -function(i) * graph.gridStep));
    }
  }

  List<Offset> path = [];
  bool isContinue = false;
  int counter = 1;
  for (var point in points) {
    if (point.dy < ((size.height / 2) + graph.focusPoint.y) &&
        point.dy > -((size.height / 2) - graph.focusPoint.y)) {
      if (!isContinue) {
        if (!(counter - 2).isNegative) {
          path.add(points[counter - 2]);
        }
        isContinue = true;
      }
      path.add(point);
      if (counter == points.length) {
        canvas.drawPoints(PointMode.polygon, path, paint);
      }
    } else {
      if (isContinue) {
        path.add(point);
        isContinue = false;
        canvas.drawPoints(PointMode.polygon, path, paint);
        path = [];
      }
    }
    counter++;
  }
}