drawAssists method Null safety

void drawAssists(
  1. Canvas canvas,
  2. Size size
)

Draws any assist lines that the object has on canvas with size.

Implementation

void drawAssists(Canvas canvas, Size size) {
  // Draw the rotation assist line
  //
  // This assist line passes through the center point of the object
  // and extends according to the object's rotation angle
  if (assists.contains(ObjectDrawableAssist.rotation)) {
    // Calculate the tangent of the angle
    final angleTan = tan(rotationAngle);
    // Calculate the points at which a line passing through the object's center
    // with an angle tangent crosses the borders of the drawing size
    final intersections =
        _calculateBoxIntersections(position, angleTan, size);

    if (intersections.length == 2) {
      // Should be redundant, added for safety
      // Draw the line between the two points on the size border
      canvas.drawLine(
        intersections[0],
        intersections[1],
        assistPaints[ObjectDrawableAssist.rotation] ??
            defaultRotationAssistPaint,
      );
    }
  }

  // Draw the horizontal assist line
  //
  // This assist line passes through the center point of the object
  // and extends horizontally (with a constant dy value)
  if (assists.contains(ObjectDrawableAssist.horizontal)) {
    canvas.drawLine(Offset(0, position.dy), Offset(size.width, position.dy),
        assistPaints[ObjectDrawableAssist.horizontal] ?? defaultAssistPaint);
  }

  // Draw the vertical assist line
  //
  // This assist line passes through the center point of the object
  // and extends vertically (with a constant dx value)
  if (assists.contains(ObjectDrawableAssist.vertical)) {
    canvas.drawLine(Offset(position.dx, 0), Offset(position.dx, size.height),
        assistPaints[ObjectDrawableAssist.horizontal] ?? defaultAssistPaint);
  }
}