gojs/extensionsJSM/BalloonLink.js

/*
*  Copyright (C) 1998-2021 by Northwoods Software Corporation. All Rights Reserved.
*/
/*
* This is an extension and not part of the main GoJS library.
* 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 extensionsTS folders.
* See the Extensions intro page (https://gojs.net/latest/intro/extensions.html) for more information.
*/
import * as go from '../release/go-module.js';
/**
 * This custom {@link Link} class customizes its {@link Shape} to surround the comment node (the from node).
 * If the Shape is filled, it will obscure the comment itself unless the Link is behind the comment node.
 * Thus the default layer for BalloonLinks is "Background".
 *
 * If you want to experiment with this extension, try the <a href="../../extensionsJSM/BalloonLink.html">Balloon Links</a> sample.
 * @category Part Extension
 */
export class BalloonLink extends go.Link {
    /**
     * Constructs a BalloonLink and sets the {@link Part#layerName} property to "Background".
     */
    constructor() {
        super();
        this._base = 10;
        this.layerName = 'Background';
    }
    /**
     * Copies properties to a cloned BalloonLink.
     */
    cloneProtected(copy) {
        super.cloneProtected(copy);
        copy._base = this._base;
    }
    /**
     * Gets or sets width of the base of the triangle at the center point of the {@link Link#fromNode}.
     *
     * The default value is 10.
     */
    get base() { return this._base; }
    set base(value) { this._base = value; }
    /**
     * Produce a Geometry from the Link's route that draws a "balloon" shape around the {@link Link#fromNode}
     * and has a triangular shape with the base at the fromNode and the top at the toNode.
     */
    makeGeometry() {
        const fromnode = this.fromNode;
        const tonode = this.toNode;
        if (fromnode === null || tonode === null)
            return super.makeGeometry();
        // assume the fromNode is the comment and the toNode is the commented-upon node
        const bb = fromnode.actualBounds;
        const nb = tonode.actualBounds;
        const p0 = bb.center;
        let pn = this.getPoint(this.pointsCount - 1);
        if (bb.intersectsRect(nb)) {
            pn = nb.center;
        }
        const pos = this.routeBounds;
        // compute the intersection points for the triangular arrow
        const ang = pn.directionPoint(p0);
        const L = new go.Point(this.base, 0).rotate(ang - 90).add(p0);
        const R = new go.Point(this.base, 0).rotate(ang + 90).add(p0);
        this.getLinkPointFromPoint(fromnode, fromnode, L, pn, true, L);
        this.getLinkPointFromPoint(fromnode, fromnode, R, pn, true, R);
        // form a triangular arrow from the comment to the commented node
        const fig = new go.PathFigure(pn.x - pos.x, pn.y - pos.y, true); // filled; start at arrow point at commented node
        fig.add(new go.PathSegment(go.PathSegment.Line, R.x - pos.x, R.y - pos.y)); // a triangle base point on comment's edge
        let side = 0;
        if (L.y >= bb.bottom || R.y >= bb.bottom)
            side = 2;
        else if (L.x <= bb.x && R.x <= bb.x)
            side = 1;
        else if (L.x >= bb.right && R.x >= bb.right)
            side = 3;
        this.pathToCorner(side, bb, fig, pos, L, R);
        this.pathToCorner(side + 1, bb, fig, pos, L, R);
        this.pathToCorner(side + 2, bb, fig, pos, L, R);
        this.pathToCorner(side + 3, bb, fig, pos, L, R);
        fig.add(new go.PathSegment(go.PathSegment.Line, L.x - pos.x, L.y - pos.y).close()); // the other triangle base point on comment's edge
        // return a Geometry
        return new go.Geometry().add(fig);
    }
    /**
     * Draw a line to a corner, but not if the comment arrow encompasses that corner.
     */
    pathToCorner(side, bb, fig, pos, L, R) {
        switch (side % 4) {
            case 0:
                if (!(L.y <= bb.y && R.x <= bb.x))
                    fig.add(new go.PathSegment(go.PathSegment.Line, bb.x - pos.x, bb.y - pos.y));
                break;
            case 1:
                if (!(L.x <= bb.x && R.y >= bb.bottom))
                    fig.add(new go.PathSegment(go.PathSegment.Line, bb.x - pos.x, bb.bottom - pos.y));
                break;
            case 2:
                if (!(L.y >= bb.bottom && R.x >= bb.right))
                    fig.add(new go.PathSegment(go.PathSegment.Line, bb.right - pos.x, bb.bottom - pos.y));
                break;
            case 3:
                if (!(L.x >= bb.right && R.y <= bb.y))
                    fig.add(new go.PathSegment(go.PathSegment.Line, bb.right - pos.x, bb.y - pos.y));
                break;
        }
    }
}