add typescript definitions

package.json

@@ -3,6 +3,7 @@
   "version": "1.0.1",
   "description": "A signature pad implementation in React",
   "main": "build/index.js",
+  "types": "src/index.d.ts", 
   "scripts": {
     "test": "webpack && npm pack",
     "start": "webpack-dev-server -d --inline --hot",

src/index.d.ts

@@ -0,0 +1,22 @@
+// signature_pad's props 
+// (taken from https://github.com/szimek/signature_pad/blob/e2af461bca7ceb7cc5afb8349930908ca19f2f56/src/signature_pad.ts#L23)
+export interface IOptions {
+    dotSize?: number | (() => number);
+    minWidth?: number;
+    maxWidth?: number;
+    minDistance?: number;
+    backgroundColor?: string;
+    penColor?: string;
+    throttle?: number;
+    velocityFilterWeight?: number;
+    onBegin?: (event: MouseEvent | Touch) => void;
+    onEnd?: (event: MouseEvent | Touch) => void;
+}
+
+// props specific to the React wrapper
+export interface SignatureCanvasProps extends IOptions {
+    canvasProps: any;
+    clearOnResize: boolean;
+}
+
+export default class SignatureCanvas extends React.Component<SignatureCanvasProps> {}