markgojs/extensionsTS/SnapLinkReshapingTool.ts

Interactive diagrams, charts, and graphs, such as trees, flowcharts, orgcharts, UML, BPMN, or business diagrams

"use strict";
/*
*  Copyright (C) 1998-2019 by Northwoods Software Corporation. All Rights Reserved.
*/

import * as go from "../release/go";

// A custom LinkReshapingTool that snaps dragged reshaping handles to grid points.

/**
* @constructor
* @extends LinkReshapingTool
* @class
* This SnapLinkReshapingTool class supports snapping reshaping handles to go to the nearest grid point.
*/
export class SnapLinkReshapingTool extends go.LinkReshapingTool {
	/** @type {Size} */
	private _gridCellSize = new go.Size(NaN, NaN);
	/** @type {Point} */
	private _gridOrigin = new go.Point(NaN, NaN);
	/** @type {boolean} */
	private _isGridSnapEnabled = true;

	/**
	* Gets or sets the {@link Size} of each grid cell to which link points will be snapped.
	* The default value is NaNxNaN, which means use the {@link Diagram#grid}'s {@link Panel#gridCellSize}.
	* @name SnapLinkReshapingTool#gridCellSize
	* @function.
	* @return {Size}
	*/
	get gridCellSize(): go.Size { return this._gridCellSize; }
	set gridCellSize(val: go.Size) {
		if (!(val instanceof go.Size)) throw new Error("new value for SnapLinkReshapingTool.gridCellSize must be a Size, not: " + val);
		this._gridCellSize = val.copy();
	}

	/**
	* Gets or sets the {@link Point} origin for the grid to which link points will be snapped.
	* The default value is NaN,NaN, which means use the {@link Diagram#grid}'s {@link Panel#gridOrigin}.
	* @name SnapLinkReshapingTool#gridOrigin
	* @function.
	* @return {Point}
	*/
	get gridOrigin(): go.Point { return this._gridOrigin; }
	set gridOrigin(val: go.Point) {
		if (!(val instanceof go.Point)) throw new Error("new value for SnapLinkReshapingTool.gridOrigin must be a Point, not: " + val);
		this._gridOrigin = val.copy();
	}

	/**
	* Gets or sets whether a reshape handle's position should be snapped to a grid point.
	* The default value is true.
	* This affects the behavior of {@link #computeReshape}.
	*/
	get isGridSnapEnabled(): boolean { return this._isGridSnapEnabled; }
	set isGridSnapEnabled(val: boolean) {
		if (typeof val !== "boolean") throw new Error("new value for SnapLinkReshapingTool.isGridSnapEnabled must be a boolean, not: " + val);
		this._isGridSnapEnabled = val;
	}

	/**
	* @override
	* Pretend while dragging a reshape handle the mouse point is at the nearest grid point,
	* if {@link #isGridSnapEnabled} is true.
	* This uses {@link #gridCellSize} and {@link #gridOrigin}, unless those are not real values,
	* in which case this uses the {@link Diagram#grid}'s {@link Panel#gridCellSize} and {@link Panel#gridOrigin}.
	* @this {SnapLinkReshapingTool}
	* @param {Point} p
	* @return {Point}
	*/
	public computeReshape(p: go.Point): go.Point {
		var pt = p;
		if (this.isGridSnapEnabled) {
			// first, find the grid to which we should snap
			var cell = this.gridCellSize;
			var orig = this.gridOrigin;
			if (!cell.isReal() || cell.width === 0 || cell.height === 0) cell = this.diagram.grid.gridCellSize;
			if (!orig.isReal()) orig = this.diagram.grid.gridOrigin;
			// second, compute the closest grid point
			pt = p.copy().snapToGrid(orig.x, orig.y, cell.width, cell.height);
		}
		// then do whatever LinkReshapingTool would normally do as if the mouse were at that point
		return super.computeReshape.call(this, pt);
	}

}