export class D3Util {
  /**
   * Format text content.
   *
   * @param el
   *        tooltip container element.
   * @param data
   *        data passed to showTooltip.
   *        this implementation expects objects (or arrays of objects):
   *        obj.class {String} class attribute for text|tspan.
   *        obj.text {String} content for text|tspan.
   */
  static formatText(el: SVGElement, data: any): void;

  /**
   * Persistently tries to get the bounding box for the given element.
   *
   * @param element
   *      The element for which to get the bounding box.
   * @return
   *      A bounding box object with x, y, width, height attributes
   */
  static getBBox(element: SVGTextElement): DOMRect;

  /**
   * Pad an extent.
   *
   * @param extent
   *        first entry should be minimum.
   *        last entry should be maximum.
   * @param amount
   *        percentage of range to pad.
   *        For example: 0.05 = +/- 5% of range.
   * @return
   *         padded extent.
   */
  static padExtent(extent: number[], amount: number): number[];

  /**
   * Pad a log based extent.
   *
   * Similar to _padExtent(), but padding occurs in log space.
   *
   * @param extent
   *        first entry should be minimum.
   *        last entry should be maximum.
   * @param amount
   *        percentage of range to pad.
   *        For example: 0.05 = +/- 5% of range.
   * @return
   *         padded extent.
   */
  static padLogExtent(extent: number[], amount: number): number;
}