drawFlatCoordinates_(flatCoordinates, offset, end, stride) {
    const myBegin = this.coordinates.length;
    const myEnd = this.appendFlatLineCoordinates(
      flatCoordinates,
      offset,
      end,
      stride,
      false,
      false,
    );
    const moveToLineToInstruction = [
      CanvasInstruction.MOVE_TO_LINE_TO,
      myBegin,
      myEnd,
    ];
    this.instructions.push(moveToLineToInstruction);
    this.hitDetectionInstructions.push(moveToLineToInstruction);
    return end;
  }
@param {Array<number>} flatCoordinates Flat coordinates.
@param {number} offset Offset.
@param {number} end End.
@param {number} stride Stride.
@private
@return {number} end.