Added bindinghandlers for KnockoutJS

knockout-sortable.js

@@ -0,0 +1,158 @@
+(function () {
+
+    var init = function (element, valueAccessor, allBindings, viewModel, bindingContext, sortableOptions) {
+        var options = buildOptions(valueAccessor, sortableOptions);
+
+        //It's seems that we cannot update the eventhandlers after we've created the sortable, so define them in init instead of update
+        ['onStart', 'onEnd', 'onRemove', 'onAdd', 'onUpdate', 'onSort', 'onFilter'].forEach(function (e) {
+            if (options[e] || eventHandlers[e])
+                options[e] = function (eventType, parentVM, parentBindings, handler, e) {
+                    var itemVM = ko.dataFor(e.item),
+                        //All of the bindings on the parent element
+                        bindings = ko.utils.peekObservable(parentBindings()),
+                        //The binding options for the draggable/sortable binding of the parent element
+                        bindingHandlerBinding = bindings.sortable || bindings.draggable,
+                        //The collection that we should modify
+                        collection = bindingHandlerBinding.collection || bindingHandlerBinding.foreach;
+                    if (handler)
+                        handler(e, itemVM, parentVM, collection, bindings);
+                    if (eventHandlers[eventType])
+                        eventHandlers[eventType](e, itemVM, parentVM, collection, bindings);
+                }.bind(undefined, e, viewModel, allBindings, options[e]);
+        });
+
+        viewModel._sortable = Sortable.create(element, options);
+
+        //Destroy the sortable if knockout disposes the element it's connected to
+        ko.utils.domNodeDisposal.addDisposeCallback(element, function () {
+            viewModel._sortable.destroy();
+        });
+        return ko.bindingHandlers['template']['init'](element, valueAccessor);
+    },
+    update = function (element, valueAccessor, allBindings, viewModel, bindingContext, sortableOptions) {
+
+        //There seems to be some problems with updating the options of a sortable
+        //Tested to change eventhandlers and the group options without any luck
+
+        return ko.bindingHandlers['template']['update'](element, valueAccessor, allBindings, viewModel, bindingContext);
+    },
+    eventHandlers = (function (handlers) {
+
+        var moveOperations = [],
+            tryMoveOperation = function (e, itemVM, parentVM, collection, parentBindings) {
+                //A move operation is the combination of a add and remove event, this is to make sure that we have both the target and origin collections
+                var currentOperation = { event: e, itemVM: itemVM, parentVM: parentVM, collection: collection, parentBindings: parentBindings },
+                    existingOperation = moveOperations.filter(function (op) {
+                        return op.itemVM === currentOperation.itemVM;
+                    })[0];
+
+                if (!existingOperation) {
+                    moveOperations.push(currentOperation);
+                }
+                else {
+                    //We're finishing the operation and already have a handle on the operation item meaning that it's safe to remove it
+                    moveOperations.splice(moveOperations.indexOf(existingOperation), 1);
+
+                    var removeOperation = currentOperation.event.type === 'remove' ? currentOperation : existingOperation,
+                        addOperation = currentOperation.event.type === 'add' ? currentOperation : existingOperation;
+
+                    moveItem(itemVM, removeOperation.collection, addOperation.collection, addOperation.event.clone, addOperation.event);
+                }
+            },
+            //Moves an item from the to (collection to from (collection), these can be references to the same collection which means it's a sort,
+            //clone indicates if we should move or copy the item into the new collection
+            moveItem = function (itemVM, from, to, clone, e) {
+                //Unwrapping this allows us to manipulate the actual array
+                var fromArray = from(),
+                    //It's not certain that the items actual index is the same as the index reported by sortable due to filtering etc.
+                    originalIndex = fromArray.indexOf(itemVM);
+
+                //Remove sortables "unbound" element
+                e.item.parentNode.removeChild(e.item);
+
+                //This splice is necessary for both clone and move/sort
+                //In sort/move since it shouldn't be at this index/in this array anymore
+                //In clone since we have to work around knockouts valuHasMutated when manipulating arrays and avoid a "unbound" item added by sortable
+                fromArray.splice(originalIndex, 1);
+                //Update the array, this will also remove sortables "unbound" clone
+                from.valueHasMutated();
+                if (clone && from !== to) {
+                    //Readd the item
+                    fromArray.splice(originalIndex, 0, itemVM);
+                    //Force knockout to update
+                    from.valueHasMutated();
+                }
+                //Insert the item on its new position
+                to().splice(e.newIndex, 0, itemVM);
+                //Make sure to tell knockout that we've modified the actual array.
+                to.valueHasMutated();
+            };
+
+        handlers.onRemove = tryMoveOperation;
+        handlers.onAdd = tryMoveOperation;
+        handlers.onUpdate = function (e, itemVM, parentVM, collection, parentBindings) {
+            //This will be performed as a sort since the to/from collections reference the same collection and clone is set to false
+            moveItem(itemVM, collection, collection, false, e);
+        }
+
+        return handlers;
+    })({}),
+    //bindingOptions are the options set in the "data-bind" attribute in the ui.
+    //options are custom options, for instance draggable/sortable specific options
+    buildOptions = function (bindingOptions, options) {
+        //deep clone/copy of properties from the "from" argument onto the "into" argument and returns the modified "into"
+        var merge = function (into, from) {
+            for (var prop in from) {
+                if (Object.prototype.toString.call(from[prop]) === '[object Object]') {
+                    if (Object.prototype.toString.call(into[prop]) !== '[object Object]') {
+                        into[prop] = {};
+                    }
+                    into[prop] = merge(into[prop], from[prop]);
+                }
+                else
+                    into[prop] = from[prop];
+            }
+
+            return into;
+        },
+        //unwrap the supplied options
+        unwrappedOptions = ko.utils.peekObservable(bindingOptions()).options || {},
+        //Make sure that we don't modify the provided settings object
+        options = merge({}, options);
+
+        //group is handled differently since we should both allow to change a draggable to a sortable (and vice versa),
+        //but still be able to set a name on a draggable without it becoming a drop target.
+        if (unwrappedOptions.group && Object.prototype.toString.call(unwrappedOptions.group) !== '[object Object]') {
+            //group property is a name string declaration, convert to object.
+            unwrappedOptions.group = { name: unwrappedOptions.group };
+        }
+
+        return merge(options, unwrappedOptions);
+    };
+
+    ko.bindingHandlers.draggable = {
+        sortableOptions: {
+            group: { pull: 'clone', put: false },
+            sort: false
+        },
+        init: function (element, valueAccessor, allBindings, viewModel, bindingContext) {
+            return init(element, valueAccessor, allBindings, viewModel, bindingContext, ko.bindingHandlers.draggable.sortableOptions);
+        },
+        update: function (element, valueAccessor, allBindings, viewModel, bindingContext) {
+            return update(element, valueAccessor, allBindings, viewModel, bindingContext, ko.bindingHandlers.draggable.sortableOptions);
+        }
+    };
+
+    ko.bindingHandlers.sortable = {
+        sortableOptions: {
+            group: { pull: true, put: true }
+        },
+        init: function (element, valueAccessor, allBindings, viewModel, bindingContext) {
+            return init(element, valueAccessor, allBindings, viewModel, bindingContext, ko.bindingHandlers.sortable.sortableOptions);
+        },
+        update: function (element, valueAccessor, allBindings, viewModel, bindingContext) {
+            return update(element, valueAccessor, allBindings, viewModel, bindingContext, ko.bindingHandlers.sortable.sortableOptions);
+        }
+    }
+
+})();