vis.js is a dynamic, browser-based visualization library
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/**
* Created by Alex on 3/3/2015.
*/
class LayoutEngine {
constructor(body) {
this.body = body;
}
setOptions(options) {
}
positionInitially(nodesArray) {
for (var i = 0; i < nodesArray.length; i++) {
let node = nodesArray[i];
if ((node.xFixed == false || node.yFixed == false) && (node.x === null || node.y === null)) {
var radius = 10 * 0.1*nodesArray.length + 10;
var angle = 2 * Math.PI * Math.random();
if (node.xFixed == false) {node.x = radius * Math.cos(angle);}
if (node.yFixed == false) {node.y = radius * Math.sin(angle);}
}
}
}
_resetLevels() {
for (var nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
var node = this.body.nodes[nodeId];
if (node.preassignedLevel == false) {
node.level = -1;
node.hierarchyEnumerated = false;
}
}
}
}
/**
* This is the main function to layout the nodes in a hierarchical way.
* It checks if the node details are supplied correctly
*
* @private
*/
_setupHierarchicalLayout() {
if (this.constants.hierarchicalLayout.enabled == true && this.nodeIndices.length > 0) {
// get the size of the largest hubs and check if the user has defined a level for a node.
var hubsize = 0;
var node, nodeId;
var definedLevel = false;
var undefinedLevel = false;
for (nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
node = this.body.nodes[nodeId];
if (node.level != -1) {
definedLevel = true;
}
else {
undefinedLevel = true;
}
if (hubsize < node.edges.length) {
hubsize = node.edges.length;
}
}
}
// if the user defined some levels but not all, alert and run without hierarchical layout
if (undefinedLevel == true && definedLevel == true) {
throw new Error("To use the hierarchical layout, nodes require either no predefined levels or levels have to be defined for all nodes.");
this.zoomExtent({duration:0},true,this.constants.clustering.enabled);
if (!this.constants.clustering.enabled) {
this.start();
}
}
else {
// setup the system to use hierarchical method.
this._changeConstants();
// define levels if undefined by the users. Based on hubsize
if (undefinedLevel == true) {
if (this.constants.hierarchicalLayout.layout == "hubsize") {
this._determineLevels(hubsize);
}
else {
this._determineLevelsDirected(false);
}
}
// check the distribution of the nodes per level.
var distribution = this._getDistribution();
// place the nodes on the canvas. This also stablilizes the system. Redraw in started automatically after stabilize.
this._placeNodesByHierarchy(distribution);
}
}
}
/**
* This function places the nodes on the canvas based on the hierarchial distribution.
*
* @param {Object} distribution | obtained by the function this._getDistribution()
* @private
*/
_placeNodesByHierarchy(distribution) {
var nodeId, node;
// start placing all the level 0 nodes first. Then recursively position their branches.
for (var level in distribution) {
if (distribution.hasOwnProperty(level)) {
for (nodeId in distribution[level].nodes) {
if (distribution[level].nodes.hasOwnProperty(nodeId)) {
node = distribution[level].nodes[nodeId];
if (this.constants.hierarchicalLayout.direction == "UD" || this.constants.hierarchicalLayout.direction == "DU") {
if (node.xFixed) {
node.x = distribution[level].minPos;
node.xFixed = false;
distribution[level].minPos += distribution[level].nodeSpacing;
}
}
else {
if (node.yFixed) {
node.y = distribution[level].minPos;
node.yFixed = false;
distribution[level].minPos += distribution[level].nodeSpacing;
}
}
this._placeBranchNodes(node.edges,node.id,distribution,node.level);
}
}
}
}
// stabilize the system after positioning. This function calls zoomExtent.
this._stabilize();
}
/**
* This function get the distribution of levels based on hubsize
*
* @returns {Object}
* @private
*/
_getDistribution() {
var distribution = {};
var nodeId, node, level;
// we fix Y because the hierarchy is vertical, we fix X so we do not give a node an x position for a second time.
// the fix of X is removed after the x value has been set.
for (nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
node = this.body.nodes[nodeId];
node.xFixed = true;
node.yFixed = true;
if (this.constants.hierarchicalLayout.direction == "UD" || this.constants.hierarchicalLayout.direction == "DU") {
node.y = this.constants.hierarchicalLayout.levelSeparation*node.level;
}
else {
node.x = this.constants.hierarchicalLayout.levelSeparation*node.level;
}
if (distribution[node.level] === undefined) {
distribution[node.level] = {amount: 0, nodes: {}, minPos:0, nodeSpacing:0};
}
distribution[node.level].amount += 1;
distribution[node.level].nodes[nodeId] = node;
}
}
// determine the largest amount of nodes of all levels
var maxCount = 0;
for (level in distribution) {
if (distribution.hasOwnProperty(level)) {
if (maxCount < distribution[level].amount) {
maxCount = distribution[level].amount;
}
}
}
// set the initial position and spacing of each nodes accordingly
for (level in distribution) {
if (distribution.hasOwnProperty(level)) {
distribution[level].nodeSpacing = (maxCount + 1) * this.constants.hierarchicalLayout.nodeSpacing;
distribution[level].nodeSpacing /= (distribution[level].amount + 1);
distribution[level].minPos = distribution[level].nodeSpacing - (0.5 * (distribution[level].amount + 1) * distribution[level].nodeSpacing);
}
}
return distribution;
}
/**
* this function allocates nodes in levels based on the recursive branching from the largest hubs.
*
* @param hubsize
* @private
*/
_determineLevels(hubsize) {
var nodeId, node;
// determine hubs
for (nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
node = this.body.nodes[nodeId];
if (node.edges.length == hubsize) {
node.level = 0;
}
}
}
// branch from hubs
for (nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
node = this.body.nodes[nodeId];
if (node.level == 0) {
this._setLevel(1,node.edges,node.id);
}
}
}
}
/**
* this function allocates nodes in levels based on the direction of the edges
*
* @param hubsize
* @private
*/
_determineLevelsDirected() {
var nodeId, node, firstNode;
var minLevel = 10000;
// set first node to source
firstNode = this.body.nodes[this.nodeIndices[0]];
firstNode.level = minLevel;
this._setLevelDirected(minLevel,firstNode.edges,firstNode.id);
// get the minimum level
for (nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
node = this.body.nodes[nodeId];
minLevel = node.level < minLevel ? node.level : minLevel;
}
}
// subtract the minimum from the set so we have a range starting from 0
for (nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
node = this.body.nodes[nodeId];
node.level -= minLevel;
}
}
}
/**
* Since hierarchical layout does not support:
* - smooth curves (based on the physics),
* - clustering (based on dynamic node counts)
*
* We disable both features so there will be no problems.
*
* @private
*/
_changeConstants() {
this.constants.clustering.enabled = false;
this.constants.physics.barnesHut.enabled = false;
this.constants.physics.hierarchicalRepulsion.enabled = true;
this._loadSelectedForceSolver();
if (this.constants.smoothCurves.enabled == true) {
this.constants.smoothCurves.dynamic = false;
}
this._configureSmoothCurves();
var config = this.constants.hierarchicalLayout;
config.levelSeparation = Math.abs(config.levelSeparation);
if (config.direction == "RL" || config.direction == "DU") {
config.levelSeparation *= -1;
}
if (config.direction == "RL" || config.direction == "LR") {
if (this.constants.smoothCurves.enabled == true) {
this.constants.smoothCurves.type = "vertical";
}
}
else {
if (this.constants.smoothCurves.enabled == true) {
this.constants.smoothCurves.type = "horizontal";
}
}
}
/**
* This is a recursively called function to enumerate the branches from the largest hubs and place the nodes
* on a X position that ensures there will be no overlap.
*
* @param edges
* @param parentId
* @param distribution
* @param parentLevel
* @private
*/
_placeBranchNodes(edges, parentId, distribution, parentLevel) {
for (var i = 0; i < edges.length; i++) {
var childNode = null;
if (edges[i].toId == parentId) {
childNode = edges[i].from;
}
else {
childNode = edges[i].to;
}
// if a node is conneceted to another node on the same level (or higher (means lower level))!, this is not handled here.
var nodeMoved = false;
if (this.constants.hierarchicalLayout.direction == "UD" || this.constants.hierarchicalLayout.direction == "DU") {
if (childNode.xFixed && childNode.level > parentLevel) {
childNode.xFixed = false;
childNode.x = distribution[childNode.level].minPos;
nodeMoved = true;
}
}
else {
if (childNode.yFixed && childNode.level > parentLevel) {
childNode.yFixed = false;
childNode.y = distribution[childNode.level].minPos;
nodeMoved = true;
}
}
if (nodeMoved == true) {
distribution[childNode.level].minPos += distribution[childNode.level].nodeSpacing;
if (childNode.edges.length > 1) {
this._placeBranchNodes(childNode.edges,childNode.id,distribution,childNode.level);
}
}
}
}
/**
* this function is called recursively to enumerate the barnches of the largest hubs and give each node a level.
*
* @param level
* @param edges
* @param parentId
* @private
*/
_setLevel(level, edges, parentId) {
for (var i = 0; i < edges.length; i++) {
var childNode = null;
if (edges[i].toId == parentId) {
childNode = edges[i].from;
}
else {
childNode = edges[i].to;
}
if (childNode.level == -1 || childNode.level > level) {
childNode.level = level;
if (childNode.edges.length > 1) {
this._setLevel(level+1, childNode.edges, childNode.id);
}
}
}
}
/**
* this function is called recursively to enumerate the branched of the first node and give each node a level based on edge direction
*
* @param level
* @param edges
* @param parentId
* @private
*/
_setLevelDirected(level, edges, parentId) {
this.body.nodes[parentId].hierarchyEnumerated = true;
var childNode, direction;
for (var i = 0; i < edges.length; i++) {
direction = 1;
if (edges[i].toId == parentId) {
childNode = edges[i].from;
direction = -1;
}
else {
childNode = edges[i].to;
}
if (childNode.level == -1) {
childNode.level = level + direction;
}
}
for (var i = 0; i < edges.length; i++) {
if (edges[i].toId == parentId) {childNode = edges[i].from;}
else {childNode = edges[i].to;}
if (childNode.edges.length > 1 && childNode.hierarchyEnumerated === false) {
this._setLevelDirected(childNode.level, childNode.edges, childNode.id);
}
}
}
/**
* Unfix nodes
*
* @private
*/
_restoreNodes() {
for (var nodeId in this.body.nodes) {
if (this.body.nodes.hasOwnProperty(nodeId)) {
this.body.nodes[nodeId].xFixed = false;
this.body.nodes[nodeId].yFixed = false;
}
}
}
}
export default LayoutEngine;