BarcodeScanner
Barcodescanner
- Demonstration: Barcodescanner
- Java API: Barcodescanner
- JavaScript API: Barcodescanner
Since 8.6.0
- Available for ZK:
-
Browser Support
- IE browsers are not supported
- For iOS Safari only supports 11+
Note: iOS Chrome and other WebView browsers are not supported due to Apple's restriction.
Note: due to Chrome's security policy, starting from Chrome 47, getUserMedia() requests are only allowed from secure origins: HTTPS or localhost.
Employment/Purpose
A Barcodescanner component is used to scan and decode the barcode on the client side. There are many properties to dealing with the barScan component. First, you could use the type property to specify the type of barcode, for example: qr, code128, ..., after choosing the type you want, you could scan the barcode by the scanner. You can choose the continue scanning by setting continuous="true", and setting the scan rate by setting interval="1000", the unit of interval is millisecond. You can turn on the scanner switch by setting enable="true", or close it by enable="false".
Request Camera API permission
Barcodescanner requires access to the camera API from the client's browser. Please refer to the Camera component, Request Permission First documentation section regarding API permissions requests and secure access.
Example
<barcodescanner type="qr,code128" continuous="true" interval="500" height="100px"
onDetect='Clients.log(event.getType() + " " + event.getResult())'/>
Scan the barcode by the Barcodescanner.
type
This component supports 9 types for 1D and 1 type for 2D barcode by default. After choosing the type of barcode, the component can scan the barcode of the type you choose. You also can scan multiple types at one time separated by a comma, for example
<barcodescanner type="qr,code128"/>
The supported types
- 1D CODE Family
- CODE128
- CODE39
- CODE39VIN,
- in the 1D EAN Family
- EAN (which includes EAN13)
- EAN8,
- in the 1D Others Families
- CODABAR
- UPC
- UPC_E
- I2OF5
- 2D Family
- QR
Note:
(1) The type that Barcodescanner supported can be referenced as Supported Barcode Type (Default: CODE128).
(2) Warn: if too many types are set for the widget, it may reduce the detecting accuracy.
(3) The barcode will restart every time you change the type.
continuous
Continuous is a boolean attribute to let the Barcodescanner can interval scan or not.
<barcodescanner type="qr" continuous="true"/>
interval
The interval is a subsidiary, integer attribute for continuous scan. The interval="500" means the scanner will scan once every 500 millisecond.
<barcodescanner type="code128" continuous="true" interval="500"/>
enable
The enable is boolean attribute to switch the BarcodeScanner. You can use the zk mvvm mechanism to to switch the BarcodeScanner.
<window viewModel="@id('vm')@init('xxxVM')">
<barcodescanner type="code128" enable= "@bind('vm.enable')"/>
</window>
registerLibrary
registerLibrary(constructor, library_name, [array of types] ) is a class-level javascript function to register a custom library into barcode widget. The mechanism is like the registerLibrary() in Barcode. The constructor is a json-format parameter to define the required setting for the library.
constructor =
{
create: the function to create a reader prototype,
name: the name of the reader, and we will mount the reader on the widget by wgt._'name'+'Reader',
init: a function to initialize the reader properties,
open: a function to enable the detecting function,
decodeOnce: a reader decode method, and zk will implement the contScan attribute for you,
setType: a function to connect the reader and widget types function,
other: a json properties to let you to attend the reader method.(future feature)
}
Like barcode, if you register your own custom library into Barcodescanner, every single widget should use the custom library object. The way to register is zkmax.barscanner.Barcodescanner.registerLibrary(...). Here is an example that how we inject the quagga library object into the widget:
<?script src="myBarcodescannerLibrary.js"?>
<script>
...
zk.afterLoad('zkmax.barscanner', function () {
zkmax.barscanner.Barcodescanner.registerLibrary({
create: jq.extend(true, {}, Quagga), //the reader
name: "QUAGGA",
init: zkmax.barscanner.Barcodescanner._quaggaInit, //@param(wgt, video, canvas)
open: zkmax.barscanner.Barcodescanner._quaggaOpen, //@param(wgt, video, canvas)
decode: zkmax.barscanner.Barcodescanner._quaggaDecode,//@param(wgt, reader)
setTypes: zkmax.barscanner.Barcodescanner._quaggaSetType, //@param()
other: null
}, 'library-name', ['type1', 'type2', ...]);
});
...
</script>
And, you need to implement some methods to build the reader.
<?script src="implementation.js"?>
<script>
...
zkmax.barscanner.Barcodescanner._quaggaInit: function (wgt, video, canvas) {
/***the reader init method***/
reader.onDetected() {
reader.processing = false;
.......
}
}
zkmax.barscanner.Barcodescanner. _quaggaOpen: function (wgt, video, canvas) {
/***the open method for quagga reader init method***/
}
zkmax.barscanner.Barcodescanner._quaggaDecode: function (wgt, reader) {
reader.processing = true;
/***the decode method for quagga reader***/
}
zkmax.barscanner.Barcodescanner._quaggaSetType: function (wgt, video, canvas) {
/***the set type method for quagga reader***/
}
...
</script>
For most barcode readers, they would have some common points: init, open, decode, on detect... When injecting a reader into the widget, we use those common points to connect the reader and the widget. Here you have to implement some functions for this. As above, you need to implement the init, open, decode, and some other required methods. Here is a little reminder that, because different libraries have different designs for the decode and onDetect in their library, you may need to add a reader.processing = true at the beginning of decoding function, and reader.processing = false at the detected callback function by yourself. After you inject the library object into the widget, we will generate the JavaScript object mount on the widget. We generate zinit, zexecute, zopen, method onto the reader and we will use it internally. You can get the reader by wgt._'your_libarary_name'Reader.
Note:
As a barcode, If you want to register the custom library for all the web applications, you can add <javascript src="myBarcodescannerLibrary.js"/> at WEB-INF/lang-addon.xml.
myRegister.js
zk.afterLoad('zkmax.barcode', function () {
zkmax.barscanner.Barcodescanner.registerLibrary(function mybarcode(wgt) {
...
};
}, 'library-name', ['type1', 'type2', ...]);
});
Consistency Buffer (1D barcode only)
The accuracy of 1D barcode scan is not as good as 2D QR code. The scanned result might be wrong if the image quality is not good (such as blurred or dark). To prevent false positive results, we can set consistencyBufferSize and consistencyThreshold.
- Consistency buffer size: the number of past events to buffer (first in, first out)
- Consistency buffer threshold : the number of buffered events with the same value necessary to fire an event to the server and clear the buffer.
Defaults values
- Consistency buffer size: 5
- Consistency buffer threshold: 3
It means it requires at least 3 out of 5 scan events to be consistent before firing.
If you want to turn off this feature, simply set consistencyBufferSize and consistencyThreshold both 1.
Supported Barcode Type (Default)
| 1D CODE Family |
CODE128, CODE39, CODE39VIN, |
| 1D EAN Family |
EAN, EAN8, |
| 1D Others |
CODABAR, UPC, UPC_E, I2OF5 |
| 2D |
QR |
Supported Events
onDetect |
Event: DetectEvent
Notifies if the barcode scanner detect a barcode message. |
- Inherited Supported Events: XulElement
Supported Children
*NONE
Use Cases
| Version | Description | Example Location |
|---|---|---|
Version History
| Version | Date | Content |
|---|---|---|
| 8.6.0 | May, 2018 | ZK-3923: Provide a Barcode Scanner |
| 8.6.0 | Oct 2018 | ZK-4095: Add a false positive check threshold on the barcode scanner |