[ADD] barcodes: BarcodeHandlerMixin that starts/stops the event handling

Only the barcode handlers in the front view should listen to barcode events.

addons/barcodes/static/src/js/barcode_handler_mixin.js

@@ -0,0 +1,47 @@
+odoo.define('barcodes.BarcodeHandlerMixin', function(require) {
+"use strict";
+
+var core = require('web.core');
+var View = require('web.View');
+
+// Mixin implementing the common basis for barcode handlers.
+// The object on which this mixin is applied must also include ParentedMixin. Example :
+// Widget.extend(BarcodeHandlerMixin, { ... });
+// Class.extend(PropertiesMixin, BarcodeHandlerMixin, { ... });
+
+return {
+    init: function() {
+        var self = this;
+        this._super.apply(this, arguments);
+        this.__on_barcode_scanned = function () {
+            self.on_barcode_scanned.apply(self, arguments);
+        };
+        this.start_listening();
+        // Handlers inside a View managed by a ViewManager only listen to barcode events while their view is displayed
+        var view = this.findAncestor(function(ancestor) { return ancestor instanceof View });
+        if (view) {
+            view.on('attached', this, this.start_listening);
+            view.on('detached', this, this.stop_listening);
+        }
+    },
+
+    start_listening: function() {
+        if (! this.is_listening) {
+            core.bus.on('barcode_scanned', this, this.__on_barcode_scanned);
+            this.is_listening = true;
+        }
+    },
+
+    stop_listening: function() {
+        if (this.is_listening) {
+            core.bus.off('barcode_scanned', this, this.__on_barcode_scanned);
+            this.is_listening = false;
+        }
+    },
+
+    on_barcode_scanned: function(barcode) {
+        console.error('A class implementing BarcodeHandlerMixin must redefine method on_barcode_scanned.');
+    },
+};
+
+});

addons/barcodes/static/src/js/form_view_barcode_handler.js

@@ -4,15 +4,14 @@ odoo.define('barcodes.FormViewBarcodeHandler', function(require) {
 var core = require('web.core');
 var utils = require('web.utils');
 var common = require('web.form_common');
+var BarcodeHandlerMixin = require('barcodes.BarcodeHandlerMixin');
 
 var _t = core._t;
 
-var FormViewBarcodeHandler = common.AbstractField.extend({
-
+var FormViewBarcodeHandler = common.AbstractField.extend(BarcodeHandlerMixin, {
     start: function() {
         this._super();
         this.form_view = this.field_manager;
-        core.bus.on('barcode_scanned', this, this.on_barcode_scanned);
         // Hardcoded barcode actions
         this.map_barcode_method = {
             'O-CMD.NEW': _.bind(this.form_view.on_button_new, this.form_view),

addons/barcodes/views/templates.xml

@@ -6,6 +6,7 @@
             <xpath expr="." position="inside">
                 <script type="text/javascript" src="/barcodes/static/src/js/barcode_parser.js"></script>
                 <script type="text/javascript" src="/barcodes/static/src/js/barcode_events.js"></script>
+                <script type="text/javascript" src="/barcodes/static/src/js/barcode_handler_mixin.js"></script>
                 <script type="text/javascript" src="/barcodes/static/src/js/form_view_barcode_handler.js"></script>
             </xpath>
         </template>