(refactor): Wrap upstream signature_pad

- Apparently react-signature-pad (what this repo forked from) just
  copy+pasted most of an older version of signature_pad when it was
  first created
- In order to get all the latest features, fix bugs, and reduce the
  maintenance burden an general surface of this library and its API,
  react-signature-canvas is now a React wrapper around signature_pad
  - It retains the features it added on top of signature_pad, such as
    automatic resizing, a trim feature, and idiomatic React updates
    via props
  - And now has new features like fromDataURL options, toDataURL,
    fromData, and toData! And new props like minDistance and throttle

- Return SignaturePad instance via getSignaturePad
- Use componentDidMount to trigger prop updates via Object.assign on
  the SignaturePad instance

- Move all wrapper methods to below render for better organization

- Update README with new props and API methods
- Add links to signature_pad in the props and API sections
- Change intro to reflect the new changes in this library / repo

- Remove bezier.js and point.js as they are wrapped
- Remove all mouse / click / touch handling and other core calculations
  that are now wrapped
- Remove defaultProps that were for the signature_pad implementation
  - This also once again changes up how the dotSize function works
    - It is now back to how it worked pre-v0.2.0
    - Still debatable if this is a bugfix or a breaking change
      (see v0.2.2)
- Left in propTypes for signature_pad, but maybe those should be
  removed too?

Author: agilgur5

README.md

@@ -11,14 +11,14 @@
 
 [![NPM](https://nodei.co/npm/react-signature-canvas.png?downloads=true&downloadRank=true&stars=true)](https://npmjs.org/package/react-signature-canvas)
 
-A [signature pad](https://github.com/szimek/signature_pad) implementation in
-React.
+A React wrapper component around [signature_pad](https://github.com/szimek/signature_pad).
 
-This is an _unopinionated_ fork of
+Originally, this was just an _unopinionated_ fork of
 [react-signature-pad](https://github.com/blackjk3/react-signature-pad)
-that does not impose any styling or wrap any other unwanted elements around
+that did not impose any styling or wrap any other unwanted elements around
 your canvas -- it's just a wrapper around a single canvas element! Hence the
 naming difference.
+Nowadays, this repo / library has significantly evolved, introducing new features, fixing various bugs, and now wrapping the upstream `signature_pad` to have its updates and bugfixes baked in.
 
 This fork also allows you to directly pass [props](#props) to the underlying
 canvas element, has new, documented [API methods](#api) you can use, and has
@@ -50,9 +50,11 @@ used in drawing. All props are **optional**.
 - `velocityFilterWeight` : `number`, default: `0.7`
 - `minWidth` : `number`, default: `0.5`
 - `maxWidth` : `number`, default: `2.5`
+- `minDistance`: `number`, default: `5`
 - `dotSize` : `number` or `function`,
-  default: `(minWidth, maxWidth) => (minWidth + maxWidth) / 2`
+  default: `() => (this.minWidth + this.maxWidth) / 2`
 - `penColor` : `string`, default: `'black'`
+- `throttle`: `number`, default: `16`
 
 There are also two callbacks that will be called when a stroke ends and one
 begins, respectively.
@@ -70,6 +72,9 @@ Additional props are used to control the canvas element.
 - `clearOnResize`: `bool`, default: `true`
   - whether or not the canvas should be cleared when the window resizes
 
+Of these props, all, except for `canvasProps` and `clearOnResize`, are passed through to `signature_pad` as its [options](https://github.com/szimek/signature_pad#options).
+`signature_pad`'s internal state is automatically kept in sync with prop updates for you (via a `componentDidUpdate` hook).
+
 ### API
 
 All API methods require a ref to the SignatureCanvas in order to use and are
@@ -81,13 +86,21 @@ instance methods of the ref.
 
 - `isEmpty()` : `boolean`, self-explanatory
 - `clear()` : `void`, clears the canvas using the `backgroundColor` prop
-- `fromDataURL(base64String)` : `void`, writes a base64 image to canvas
+- `fromDataURL(base64String, options)` : `void`, writes a base64 image to canvas
+- `toDataURL(mimetype, encoderOptions)`: `base64string`, returns the signature image as a data URL
+- `fromData(pointGroupArray)`: `void`, draws signature image from an array of point groups
+- `toData()`: `pointGroupArray`, returns signature image as an array of point groups
 - `off()`: `void`, unbinds all event handlers
 - `on()`: `void`, rebinds all event handlers
 - `getCanvas()`: `canvas`, returns the underlying canvas ref. Allows you to
   modify the canvas however you want or call methods such as `toDataURL()`
 - `getTrimmedCanvas()`: `canvas`, creates a copy of the canvas and returns a
   trimmed version of it, with all whitespace removed.
+- `getSignaturePad()`: `SignaturePad`, returns the underlying SignaturePad reference.
+
+The API methods are _mostly_ just wrappers around [`signature_pad`'s API](https://github.com/szimek/signature_pad#api).
+`on()` and `off()` will, in addition, bind/unbind the window resize event handler.
+`getCanvas()`, `getTrimmedCanvas()`, and `getSignaturePad()` are new.
 
 ## Example
 

package-lock.json

@@ -47,6 +47,7 @@
     "react-dom": "0.14 - 16"
   },
   "dependencies": {
+    "signature_pad": "^2.3.2",
     "trim-canvas": "^0.1.0"
   }
 }