CurvedLinkReshapingTool.js

/*
 *  Copyright 1998-2025 by Northwoods Software Corporation. All Rights Reserved.
 */
/*
 * This is an extension and not part of the main GoJS library.
 * The source code for this is at extensionsJSM/CurvedLinkReshapingTool.ts.
 * Note that the API for this class may change with any version, even point releases.
 * If you intend to use an extension in production, you should copy the code to your own source directory.
 * Extensions can be found in the GoJS kit under the extensions or extensionsJSM folders.
 * See the Extensions intro page (https://gojs.net/latest/intro/extensions.html) for more information.
 */

/**
 * This CurvedLinkReshapingTool class allows for a {@link go.Link}'s path to be modified by the user
 * via the dragging of a single tool handle at the middle of the link.
 * Dragging the handle changes the value of {@link go.Link.curviness}.
 *
 * If you want to experiment with this extension, try the <a href="../../samples/CurvedLinkReshaping.html">Curved Link Reshaping</a> sample.
 * @category Tool Extension
 */
class CurvedLinkReshapingTool extends go.LinkReshapingTool {
    constructor(init) {
        super();
        this._originalCurviness = NaN;
        if (init)
            Object.assign(this, init);
    }
    /**
     * @hidden @internal
     */
    makeAdornment(pathshape) {
        const link = pathshape.part;
        if (link !== null && link.curve === go.Curve.Bezier && link.pointsCount === 4) {
            const adornment = new go.Adornment();
            adornment.type = go.Panel.Link;
            const h = this.makeHandle(pathshape, 0);
            if (h !== null) {
                this.setReshapingBehavior(h, go.ReshapingBehavior.All);
                h.cursor = 'move';
                adornment.add(h);
            }
            adornment.category = this.name;
            adornment.adornedObject = pathshape;
            return adornment;
        }
        else {
            return super.makeAdornment(pathshape);
        }
    }
    /**
     * Start reshaping, if {@link findToolHandleAt} finds a reshape handle at the mouse down point.
     *
     * If successful this sets {@link handle} to be the reshape handle that it finds
     * and {@link adornedLink} to be the {@link go.Link} being routed.
     * It also remembers the original link route (a list of Points) and curviness in case this tool is cancelled.
     * And it starts a transaction.
     */
    doActivate() {
        super.doActivate();
        if (this.adornedLink !== null)
            this._originalCurviness = this.adornedLink.curviness;
    }
    /**
     * Restore the link route to be the original points and curviness and stop this tool.
     */
    doCancel() {
        if (this.adornedLink !== null)
            this.adornedLink.curviness = this._originalCurviness;
        super.doCancel();
    }
    /**
     * Change the route of the {@link adornedLink} by moving the point corresponding to the current
     * {@link handle} to be at the given {@link go.Point}.
     * This is called by {@link doMouseMove} and {@link doMouseUp} with the result of calling
     * {@link computeReshape} to constrain the input point.
     * @param newpt - the value of the call to {@link computeReshape}.
     */
    reshape(newpt) {
        const link = this.adornedLink;
        if (link !== null && link.curve === go.Curve.Bezier && link.pointsCount === 4) {
            const start = link.getPoint(0);
            const end = link.getPoint(3);
            const ang = start.directionPoint(end);
            const mid = new go.Point((start.x + end.x) / 2, (start.y + end.y) / 2);
            const a = new go.Point(9999, 0).rotate(ang + 90).add(mid);
            const b = new go.Point(9999, 0).rotate(ang - 90).add(mid);
            const q = newpt.copy().projectOntoLineSegmentPoint(a, b);
            let curviness = Math.sqrt(mid.distanceSquaredPoint(q));
            const port = link.fromPort;
            if (port === link.toPort && port !== null) {
                if (newpt.y < port.getDocumentPoint(go.Spot.Center).y)
                    curviness = -curviness;
            }
            else {
                const diff = mid.directionPoint(q) - ang;
                if ((diff > 0 && diff < 180) || diff < -180)
                    curviness = -curviness;
            }
            link.curviness = curviness;
        }
        else {
            super.reshape(newpt);
        }
    }
}