added Numbering to top-level exports and added docs on usage

docs/numbering.md

@@ -0,0 +1,103 @@
+# Bullets and numbering
+
+DOCX is quite flexible in its bullets and numbering system, allowing
+the user great freedom in how bullets and numbers are to be styled and
+displayed. E.g., numbers can be shown using Arabic numerals, roman
+numerals, or even ordinal words ("one", "two", "three", ...). The
+format also supports re-using bullets/numbering styles throughout the
+document, so that different lists using the same style need not
+redefine them.
+
+Because of this flexibility, bullets and numbering in DOCX involves a
+couple of moving pieces:
+
+1. Document-level bullets/numbering definitions (abstract)
+2. Document-level bullets/numbering definitions (concrete)
+3. Paragraph-level bullets/numbering selection
+
+
+## Document-level bullets/numbering definitions (abstract)
+
+Every document contains a set of abstract bullets/numbering
+definitions which define the formatting and layout of paragraphs using
+those bullets/numbering. An abstract numbering system defines how
+bullets/numbers are to be shown for lists, including any sublists that
+may be used. Thus each abstract definition includes a series of
+*levels* which form a sequence starting at 0 indicating the top-level
+list look and increasing from there to descibe the sublists, then
+sub-sublists, etc. Each level includes the following properties:
+
+- **level**: This its 0-based index in the defintion stack
+- **numberFormat**: This indicates how the bullet or number should be
+  generated. Options include `bullet` (meaning don't count), `decimal`
+  (arabic numerals), `upperRoman`, `lowerRoman`, `hex`, and many
+  more.
+- **levelText**: This is a format string using the output of the
+  `numberFormat` function and generating a string to insert before
+  every item in the list. You may use `%1`, `%2`, ... to reference the
+  numbers from each numbering level before this one. Thus a level
+  text of `%d)` with a number format of `lowerLetter` would result in
+  the sequence "a)",  "b)", ...
+- and a few others, which you can see in the OXML spec section 17.9.6
+
+
+## Document-level bullets/numbering defintions (concrete)
+
+Concrete definitions are sort of like concrete subclasses of the
+abstract defintions. They indicate their parent and are allowed to
+override certain level definitions. Thus two lists that differ only in
+how sub-sub-lists are to be displayed can share the same abstract
+numbering definition and have slightly different concrete definitions.
+
+
+## Paragraph-level bullets/numbering selection
+
+In order to use a bullets/numbering definition (which must be
+concrete), paragraphs need to select it, similar to applying a CSS
+class to an element, using both the concrete numbering definition ID
+and the level number that the paragraph should be at. Additionally, MS
+Word and LibreOffice typically apply a "ListParagraph" style to
+paragraphs that are being numbered.
+
+
+## Using bullets/numbering in `docx`
+
+`docx` includes a pre-defined bullet style which you can add to your
+paragraphs using `para.bullets()`. If you require different bullet
+styles or numbering of any kind, you'll have to use the
+`docx.Numbering` class.
+
+First you need to create a new numbering container class and use it to
+create your abstract numbering style, define your levels, and creat
+your concreate numbering style:
+
+```js
+const numbering = new Numbering();
+
+const abstractNum = numbering.createAbstractNumbering();
+abstractNum.createLevel(0, "upperRoman", "%1", "start")
+    .addParagraphProperty(new Indent(720, 260));
+abstractNum.createLevel(1, "decimal", "%2.", "start")
+    .addParagraphProperty(new Indent(1440, 980));
+abstractNum.createLevel(2, "lowerLetter", "%3)", "start")
+    .addParagraphProperty(new Indent(2160, 1700));
+
+const concrete = numbering.createConcreteNumbering(numberedAbstract);
+```
+
+You can then apply your concrete style to paragraphs using their
+`#setNumbering` method:
+
+```js
+topLevelP.setNumbering(concrete, 0);
+subP.setNumbering(concrete, 1);
+subSubP.setNumbering(concrete, 2);
+```
+
+Finally, you need to let your exporter know about your numbering
+styles when you're ready to render the document:
+
+```js
+const packer = new Packer(doc, undefined, undefined, numbering);
+packer.pack(myOutput);
+```

ts/index.ts

@@ -1,2 +1,3 @@
 export * from "./docx";
 export * from "./export";
+export { Numbering } from './numbering';