Export types and add addBackground function

[Ciaanh]

In order to use the alternating row style with in a Typescript project the declaration for the function addBackground has been added.

Also exported the declared interfaces in order to facilitate the configuration in Typescript projects.

[Matheus-Campos1]

This is what this lib needs

[7doctor7]

I’m really looking forward to this PR merge

[VadimOvchinnikov]

@Ciaanh I left two comment to add missing/fix incorrect properties. Also, I suggest to move property comments to JSDoc comments so we have these 'default's available with IDE information.

Here's pdfkit-table.d.ts file I'm using in my projects

// pdfkit-table.d.ts
declare module 'pdfkit-table' {
  import PDFDocument from 'pdfkit';

  export interface Rect {
    x: number;
    y: number;
    width: number;
    height: number;
  }

  export interface Header {
    label?: string;
    property?: string;
    width?: number;
    /** default 'left' */
    align?: string;
    valign?: string;
    /** default '#BEBEBE' */
    headerColor?: string;
    /** default '0.5' */
    headerOpacity?: number;
    /** default 'left' */
    headerAlign?: string;
    columnColor?: string;
    columnOpacity?: number;
    backgroundColor?: string;
    backgroundOpacity?: number;
    background?: { color: string, opacity?: number };
    renderer?: (
      value: any,
      indexColumn?: number,
      indexRow?: number,
      row?: number,
      rectRow?: Rect,
      rectCell?: Rect
    ) => string;
  }

  export interface DataOptions {
    fontSize: number;
    fontFamily: string;
    separation: boolean;
  }

  export interface Data {
    [key: string]: string | { label: string; options?: DataOptions };
  }

  export interface Table {
    title?: string;
    subtitle?: string;
    headers?: (string | Header)[];
    datas?: Data[];
    rows?: string[][];
  }

  export interface DividerOptions {
    disabled?: boolean;
    width?: number;
    opacity?: number;
  }

  export interface Divider {
    header?: DividerOptions;
    horizontal?: DividerOptions;
  }

  export interface Title {
    label: string;
    fontSize?: number;
    fontFamily?: string;
    color?: string;
  }

  export interface Options {
    title?: string | Title;
    subtitle?: string | Title;
    width?: number;
    /** default doc.x */
    x?: number;
    /** default doc.y */
    y?: number;
    divider?: Divider;
    columnsSize?: number[];
    /** default 5 */
    columnSpacing?: number;
    padding?: number[];
    /** default false */
    addPage?: boolean;
    hideHeader?: boolean;
    minRowHeight?: number;
    prepareHeader?: () => PDFDocumentWithTables;
    prepareRow?: (
      row?: any,
      indexColumn?: number,
      indexRow?: number,
      rectRow?: Rect,
      rectCell?: Rect
    ) => PDFDocumentWithTables;
  }

  class PDFDocumentWithTables extends PDFDocument {
    public table(table: Table, options?: Options): Promise<void>;

    public addBackground(
      rect?: Rect,
      fillColor?: string,
      fillOpacity?: number,
      callback?: Function
    );
  }

  export default PDFDocumentWithTables;
}