markgojs/extensions/SnapLinkReshapingTool.js

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.
*/

// 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.
*/
function SnapLinkReshapingTool() {
  go.LinkReshapingTool.call(this);
  /** @type {Size} */
  this._gridCellSize = new go.Size(NaN, NaN);
  /** @type {Point} */
  this._gridOrigin = new go.Point(NaN, NaN);
  /** @type {boolean} */
  this._isGridSnapEnabled = true;
}
go.Diagram.inherit(SnapLinkReshapingTool, go.LinkReshapingTool);

/**
* 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}
*/
Object.defineProperty(SnapLinkReshapingTool.prototype, "gridCellSize", {
  get: function() { return this._gridCellSize; },
  set: function(val) {
    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}
*/
Object.defineProperty(SnapLinkReshapingTool.prototype, "gridOrigin", {
  get: function() { return this._gridOrigin; },
  set: function(val) {
    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}.
*/
Object.defineProperty(SnapLinkReshapingTool.prototype, "isGridSnapEnabled", {
  get: function() { return this._isGridSnapEnabled; },
  set: function(val) {
    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}
*/
SnapLinkReshapingTool.prototype.computeReshape = function(p) {
  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 go.LinkReshapingTool.prototype.computeReshape.call(this, pt);
}