Update README.md

README.md

@@ -1,6 +1,8 @@
 quaggaJS
 ========
 
+- [Changelog](#changelog) (2015-01-21)
+
 QuaggaJS is a barcode-scanner entirely written in JavaScript supporting real-time localization and decoding of 
 various types of barcodes such as __EAN__ and __CODE128__. The library is also capable of using `getUserMedia` to get direct 
 access to the user's camera stream. Although the code relies on heavy image-processing even recent smartphones are 
@@ -46,24 +48,23 @@ by simply typing:
 You can check out the [examples](http://serratus.github.io/quaggaJS/examples) to get an idea of how to use QuaggaJS.
 Basically the library exposes the following API:
 
-### Quagga.init(config)
+### Quagga.init(config, callback)
 
-This method initializes the library for a given configuration (see below) which also includes a callback function (`readyFunc`) which is called when Quagga is ready to start. The initialization process also requests for camera access if real-time detection is configured.
+This method initializes the library for a given configuration `config` (see below) and invokes the `callback` when Quagga is ready to start. The initialization process also requests for camera access if real-time detection is configured.
 
 ```javascript
 Quagga.init({
-  inputStream : {
+    inputStream : {
-    name : "Live",
+      name : "Live",
-    type : "LiveStream"
+      type : "LiveStream"
-  },
+    },
-  decoder : {
+    decoder : {
-    readers : ["code_128_reader"]
+      readers : ["code_128_reader"]
-  },
+    }
-  readyFunc : function() {
+  }, function() {
-    console.log("Initialization finished. Ready to start");
+      console.log("Initialization finished. Ready to start");
-    Quagga.start();
+      Quagga.start();
-  }
+  });
-});
 ```
 
 ### Quagga.start()
@@ -73,18 +74,91 @@ the images.
 
 ### Quagga.stop()
 
-If the decoder is currently running, after calling `stop()` the decoder does not process any more images.
+If the decoder is currently running, after calling `stop()` the decoder does not process any more images. Additionally, if a camera-stream was requested upon initialization, this operation also disconnects the camera.
+
+### Quagga.onProcessed(callback)
+
+This method registers a `callback(data)` function that is called for each frame after the processing is done. The `data` object contains detailed information about the success/failure of the operation. The output varies, depending whether the detection and/or decoding were successful or not. 
 
 ### Quagga.onDetected(callback)
 
-Registers a callback function which is triggered whenever a barcode-pattern has been located and decoded
+Registers a `callback(data)` function which is triggered whenever a barcode-pattern has been located and decoded
-successfully. The callback function is called with the decoded data as the first parameter.
+successfully. The passed `data` object contains information about the decoding process including the detected code which can be obtained by calling `data.codeResult.code`.
 
 ### Quagga.decodeSingle(config, callback)
 
 In contrast to the calls described above, this method does not rely on `getUserMedia` and operates on a
-single image instead. The provided callback is the same as in `onDetected` and contains the decoded data
+single image instead. The provided callback is the same as in `onDetected` and contains the result `data`
-as first parameter.
+object.
+
+## <a name="resultobject">The result object</a>
+
+The callbacks passed into `onProcessed`, `onDetected` and `decodeSingle` receive a `data` object upon execution. The `data` object contains the following information. Depending on the success, some fields may be `undefined` or just empty.
+
+```javascript
+{
+  "codeResult": {
+    "code": "FANAVF1461710",
+    "start": 355,
+    "end": 26,
+    "codeset": 100,
+    "startInfo": {
+      "error": 1.0000000000000002,
+      "code": 104,
+      "start": 21,
+      "end": 41
+    },
+    "decodedCodes": [{
+      "code": 104,
+      "start": 21,
+      "end": 41
+    },
+    // stripped for brevity
+    {
+      "error": 0.8888888888888893,
+      "code": 106,
+      "start": 328,
+      "end": 350
+    }],
+    "endInfo": {
+      "error": 0.8888888888888893,
+      "code": 106,
+      "start": 328,
+      "end": 350
+    },
+    "direction": -1
+  },
+  "line": [{
+    "x": 25.97278706156836,
+    "y": 360.5616435369468
+  }, {
+    "x": 401.9220519377024,
+    "y": 70.87524989906444
+  }],
+  "angle": -0.6565217179979483,
+  "pattern": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, /* ... */ 1],
+  "box": [
+    [77.4074243622672, 410.9288668804402],
+    [0.050203235235130705, 310.53619724086366],
+    [360.15706727788256, 33.05711026051813],
+    [437.5142884049146, 133.44977990009465]
+  ],
+  "boxes": [
+    [
+      [77.4074243622672, 410.9288668804402],
+      [0.050203235235130705, 310.53619724086366],
+      [360.15706727788256, 33.05711026051813],
+      [437.5142884049146, 133.44977990009465]
+    ],
+    [
+      [248.90769330706507, 415.2041489551161],
+      [198.9532321622869, 352.62160512937635],
+      [339.546160777576, 240.3979259789976],
+      [389.5006219223542, 302.98046980473737]
+    ]
+  ]
+}
+```
 
 ## Config
 
@@ -99,11 +173,13 @@ The default `config` object is set as followed:
   debug: false,
   controls: false,
   locate: true,
+  numOfWorkers: 4,
+  scriptName: 'quagga.js',
   visual: {
     show: true
   },
   decoder:{
-    drawBoundingBox: true,
+    drawBoundingBox: false,
     showFrequency: false,
     drawScanline: true,
     showPattern: false,
@@ -112,6 +188,7 @@ The default `config` object is set as followed:
     ]
   },
   locator: {
+    halfSample: true,
     showCanvas: false,
     showPatches: false,
     showFoundPatches: false,
@@ -151,7 +228,21 @@ Unit Tests can be run with [Karma][karmaUrl] and written using [Mocha][mochaUrl]
 > npm install
 > grunt test
 ```
+## Image Debugging
 
+In case you want to take a deeper dive into the inner workings of Quagga, get to know the _debugging_ capabilities of the current implementation. The various flags exposed through the `config` object give you the abilily to visualize almost every step in the processing. Because of the introduction of the web-workers, and their restriction not to have access to the DOM, the configuration must be explicitly set to `config.numOfWorkers = 0` in order to work.
+
+## <a name="changelog">Changelog</a>
+
+### 2015-01-21
+- Features
+  - Added support for web-worker (using 4 workers as default, can be changed through `config.numOfWorkers`)
+  - Due to the way how web-workers are created, the name of the script file (`config.scriptName`) should be kept in sync with your actual filename
+  - Removed canvas-overlay for decoding (boxes & scanline) which can now be easily implemented using the existing API (see example)
+- API Changes
+In the course of implementing web-workers some breaking changes were introduced to the API.
+  - The `Quagga.init` function no longer receives the callback as part of the config but rather as a second argument: `Quagga.init(config, cb)`
+  - The callback to `Quagga.onDetected` now receives an object containing much more information in addition to the decoded code. (see [data](#resultobject))
 
 [zxing_github]: https://github.com/zxing/zxing
 [teaser_left]: https://github.com/serratus/quaggaJS/blob/master/doc/img/mobile-located.png