Drag and drop nodes over other elements

18 Nov 20186 minutes to read

Diagram provides support to drop a node/connector over another node/connector. The drop event is raised to notify that an element is dropped over another one and it is disabled, by default. It can be enabled with the constraints property.

User handles

• User handles are used to add some frequently used commands around the selector. To create user handles, define and add them to the userHandles collection of the selectedItems property.
• The name property of user handle is used to define the name of the user handle and its further used to find the user handle at runtime and do any customization.

Alignment

User handles can be aligned relative to the node boundaries. It has margin, offset, side, horizontalAlignment, and verticalAlignment settings. It is quite tricky when all four alignments are used together but gives more control over alignment.

Offset

The offset property of userHandles is used to align the user handle based on fractions. 0 represents top/left corner, 1 represents bottom/right corner, and 0.5 represents half of width/height.

Side

The side property of userHandles is used to align the user handle by using the Top, Bottom, Left, and Right options.

Horizontal and vertical alignments

The horizontalAlignment property of userHandles is used to set how the user handle is horizontally aligned at the position based on the offset. The verticalAlignment property is used to set how user handle is vertically aligned at the position.

Margin

Margin is an absolute value used to add some blank space in any one of its four sides. The userHandles can be displaced with the margin property.

Notification for the mouse button clicked

The diagram component notifies the mouse button clicked. For example, whenever the right mouse button is clicked, the clicked button is notified as right. The mouse click is notified with,

Notification	Description
Left	When the left mouse button is clicked, left is notified
Middle	When the mouse wheel is clicked, middle is notified
Right	When the right mouse button is clicked, right is notified

function click(arg) {
    //Obtains the clicked mouse button
    var button = arg.button
}

Appearance

The appearance of the user handle can be customized by using the size, borderColor, backgroundColor, visible, pathData, and pathColor properties of the userHandles.

function getTool(action) {
        var tool;
        if (action === 'clone') {
            tool = new CloneTool(diagram.commandHandler);
        }
        return tool;
    }
    var __extends = (this && this.__extends) || (function () {
    var extendStatics = Object.setPrototypeOf ||
        /* jshint proto: true */
        ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
        function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
var CloneTool = (function (_super) {
    __extends(CloneTool, _super);
    function CloneTool() {
        return _super !== null && _super.apply(this, arguments) || this;
    }
    CloneTool.prototype.mouseDown = function (args) {
        var newObject;
        if (diagram.selectedItems.nodes.length > 0) {
            newObject = ej.diagrams.cloneObject(diagram.selectedItems.nodes[0]);
        }
        else {
            newObject = ej.diagrams.cloneObject(diagram.selectedItems.connectors[0]);
        }
        newObject.id += ej.diagrams.randomId();
        diagram.paste([newObject]);
        args.source = diagram.nodes[diagram.nodes.length - 1];
        args.sourceWrapper = args.source.wrapper;
        _super.prototype.mouseDown.call(this, args);
        this.inAction = true;
    };
    return CloneTool;
}(ej.diagrams.MoveTool));