gojs
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Interactive diagrams, charts, and graphs, such as trees, flowcharts, orgcharts, UML, BPMN, or business diagrams
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text/typescript
/*
* Copyright (C) 1998-2020 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';
/**
* The LinkLabelOnPathDraggingTool class lets the user move a label on a {@link Link} while keeping the label on the link's path.
* This tool only works when the Link has a label marked by the "_isLinkLabel" property.
*
* If you want to experiment with this extension, try the <a href="../../extensionsTS/LinkLabelOnPathDragging.html">Link Label On Path Dragging</a> sample.
* @category Tool Extension
*/
export class LinkLabelOnPathDraggingTool extends go.Tool {
/**
* The label being dragged.
*/
public label: go.GraphObject | null = null;
private _originalFraction: number = 0.0;
/**
* Constructs a LinkLabelOnPathDraggingTool and sets the name for the tool.
*/
constructor() {
super();
this.name = 'LinkLabelOnPathDragging';
}
/**
* From the GraphObject at the mouse point, search up the visual tree until we get to
* an object that has the "_isLinkLabel" property set to true and that is an immediate child of a Link Panel.
* @return {GraphObject} This returns null if no such label is at the mouse down point.
*/
public findLabel(): go.GraphObject | null {
const diagram = this.diagram;
const e = diagram.lastInput;
let elt = diagram.findObjectAt(e.documentPoint, null, null);
if (elt === null || !(elt.part instanceof go.Link)) return null;
while (elt !== null && elt.panel !== elt.part) {
elt = elt.panel;
}
// If it's not marked as "_isLinkLabel", don't consider it a label:
if (!(elt as any)['_isLinkLabel']) return null;
return elt;
}
/**
* 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 Link Panel,
* as determined by {@link #findLabel}.
*/
public canStart(): boolean {
if (!super.canStart()) return false;
const diagram = this.diagram;
// 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;
}
/**
* Start a transaction, call findLabel and remember it as the "label" property,
* and remember the original values for the label's segment properties.
*/
public doActivate(): void {
this.startTransaction('Shifted Label');
this.label = this.findLabel();
if (this.label !== null) {
this._originalFraction = this.label.segmentFraction;
}
super.doActivate();
}
/**
* Stop any ongoing transaction.
*/
public doDeactivate(): void {
super.doDeactivate();
this.stopTransaction();
}
/**
* Clear any reference to a label element.
*/
public doStop(): void {
this.label = null;
super.doStop();
}
/**
* Restore the label's original value for GraphObject.segment... properties.
*/
public doCancel(): void {
if (this.label !== null) {
this.label.segmentFraction = this._originalFraction;
}
super.doCancel();
}
/**
* During the drag, call {@link #updateSegmentOffset} in order to set the segment... properties of the label.
*/
public doMouseMove(): void {
if (!this.isActive) return;
this.updateSegmentOffset();
}
/**
* At the end of the drag, update the segment properties of the label and finish the tool,
* completing a transaction.
*/
public doMouseUp(): void {
if (!this.isActive) return;
this.updateSegmentOffset();
this.transactionResult = 'Shifted Label';
this.stopTool();
}
/**
* Save the label's {@link GraphObject#segmentFraction}
* at the closest point to the mouse.
*/
public updateSegmentOffset(): void {
const lab = this.label;
if (lab === null) return;
const link = lab.part;
if (!(link instanceof go.Link) || link.path === null) return;
const last = this.diagram.lastInput.documentPoint;
// find the fractional distance along the link path closest to this point
const path = link.path;
if (path.geometry === null) return;
const localpt = path.getLocalPoint(last);
lab.segmentFraction = path.geometry.getFractionForPoint(localpt);
}
}