create-gojs-kit/dist/samples/floorplannerTS/src/NodeLabelDraggingTool.js

A CLI for downloading GoJS samples, extensions, and docs

/*
 *  Copyright 1998-2025 by Northwoods Software Corporation. All Rights Reserved.
 */
import * as go from 'gojs';
// A custom Tool for moving a label on a Node
export class NodeLabelDraggingTool extends go.Tool {
    constructor(init) {
        super();
        this.name = 'NodeLabelDragging';
        /** @type {GraphObject} */
        this.label = null;
        /** @type {Point} */
        this._offset = new go.Point(); // of the mouse relative to the center of the label object
        /** @type {go.Spot} */
        this._originalAlignment = null;
        /** @type {Point} */
        this._originalCenter = null;
        if (init)
            Object.assign(this, init);
    }
    /**
     * This tool can only start if the mouse has moved enough so that it is not a click,
     * and if the mouse down point is on a GraphObject "label" in a Spot Panel,
     * as determined by findLabel().
     * @this {NodeLabelDraggingTool}
     * @return {boolean}
     */
    canStart() {
        if (!super.canStart())
            return false;
        const diagram = this.diagram;
        if (diagram === null)
            return false;
        // require left button & that it has moved far enough away from the mouse down point, so it isn't a click
        const e = diagram.lastInput;
        if (!e.left)
            return false;
        if (!this.isBeyondDragSize())
            return false;
        return this.findLabel() !== null;
    }
    /**
     * From the GraphObject at the mouse point, search up the visual tree until we get to
     * an object that has the "_isNodeLabel" property set to true, that is in a Spot Panel,
     * and that is not the first element of that Panel (i.e. not the main element of the panel).
     * @this {NodeLabelDraggingTool}
     * @return {GraphObject} This returns null if no such label is at the mouse down point.
     */
    findLabel() {
        const diagram = this.diagram;
        const e = diagram.firstInput;
        let elt = diagram.findObjectAt(e.documentPoint, null, null);
        if (elt === null || !(elt.part instanceof go.Node))
            return null;
        if (elt.part instanceof go.Node) {
            elt.part.isSelected = true;
        }
        while (elt.panel !== null) {
            if (elt._isNodeLabel &&
                elt.panel.type === go.Panel.Spot &&
                elt.panel.findMainElement() !== elt)
                return elt;
            elt = elt.panel;
        }
        return null;
    }
    /**
     * Start a transaction, call findLabel and remember it as the "label" property,
     * and remember the original value for the label's alignment property.
     * @this {NodeLabelDraggingTool}
     */
    doActivate() {
        this.startTransaction('Shifted Label');
        this.label = this.findLabel();
        if (this.label !== null) {
            // compute the offset of the mouse-down point relative to the center of the label
            this._offset = this.diagram.firstInput.documentPoint
                .copy()
                .subtract(this.label.getDocumentPoint(go.Spot.Center));
            this._originalAlignment = this.label.alignment.copy();
            if (this.label !== null && this.label.panel !== null) {
                const main = this.label.panel.findMainElement();
                if (main !== null) {
                    this._originalCenter = main.getDocumentPoint(go.Spot.Center);
                }
            }
        }
        super.doActivate();
    }
    /**
     * Stop any ongoing transaction.
     * @this {NodeLabelDraggingTool}
     */
    doDeactivate() {
        super.doDeactivate();
        this.stopTransaction();
    }
    /**
     * Clear any reference to a label element.
     * @this {NodeLabelDraggingTool}
     */
    doStop() {
        this.label = null;
        super.doStop();
    }
    /**
     * Restore the label's original value for GraphObject.alignment.
     * @this {NodeLabelDraggingTool}
     */
    doCancel() {
        if (this.label !== null && this._originalAlignment !== null) {
            // this.label.alignment = this._originalAlignment;
            const node = this.label.part;
            this.diagram.model.set(node.data, 'labelAlignment', this._originalAlignment);
        }
        super.doCancel();
    }
    /**
     * During the drag, call updateAlignment in order to set the GraphObject.alignment of the label.
     * @this {NodeLabelDraggingTool}
     */
    doMouseMove() {
        if (!this.isActive)
            return;
        this.updateAlignment();
    }
    /**
     * At the end of the drag, update the alignment of the label and finish the tool,
     * completing a transaction.
     * @this {NodeLabelDraggingTool}
     */
    doMouseUp() {
        if (!this.isActive)
            return;
        this.updateAlignment();
        this.transactionResult = 'Shifted Label';
        this.stopTool();
    }
    /**
     * Save the label's GraphObject.alignment as an absolute offset from the center of the Spot Panel
     * that the label is in.
     * @this {NodeLabelDraggingTool}
     */
    updateAlignment() {
        if (this.label === null)
            return;
        const last = this.diagram.lastInput.documentPoint;
        const cntr = this._originalCenter;
        if (cntr !== null) {
            const align = new go.Spot(0.5, 0.5, last.x - this._offset.x - cntr.x, last.y - this._offset.y - cntr.y);
            // this.label.alignment = new go.Spot(0.5, 0.5, last.x - this._offset.x - cntr.x, last.y - this._offset.y - cntr.y);
            const node = this.label.part;
            this.diagram.model.set(node.data, 'labelAlignment', align);
        }
    }
}
// export = NodeLabelDraggingTool;