create-gojs-kit
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A CLI for downloading GoJS samples, extensions, and docs
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<meta name="description" content="An example of virtualization where a very simple tree layout sets the bounds for each node data." />
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<meta itemprop="name" content="Virtualized Tree" />
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Virtualized Tree | GoJS Diagramming Library
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<div class="flex flex-col prose">
<div class="w-full max-w-screen-xl mx-auto">
<!-- * * * * * * * * * * * * * -->
<!-- Start of GoJS sample code -->
<script src="https://cdn.jsdelivr.net/npm/gojs@3.1.0"></script>
<div id="allSampleContent" class="p-4 w-full">
<script id="code">
// this controls whether the tree grows deeper towards the right or downwards:
var HORIZONTAL = true;
function init() {
// The Diagram just shows what should be visible in the viewport.
// Its model does NOT include node data for the whole graph, but only that
// which might be visible in the viewport.
myDiagram = new go.Diagram('myDiagramDiv', {
initialDocumentSpot: go.Spot.Center,
initialViewportSpot: go.Spot.Center,
// Do manual layout in the layoutTree function below, rather than automatic layout using a
// TreeLayout which would require the Nodes and Links to exist first for an accurate layout.
//layout: new go.TreeLayout(
// { nodeSpacing: 4, compaction: go.TreeCompaction.None }),
// Assume there's no Layout -- all data.bounds are calculated in layoutTree
layout: new go.Layout({ isInitial: false, isOngoing: false }), // never invalidates
// Define the template for Nodes, used by virtualization.
nodeTemplate:
new go.Node('Auto', {
isLayoutPositioned: false,
width: 70, height: 20, // in cooperation with the load function, below
toolTip:
go.GraphObject.build('ToolTip')
.add(
new go.TextBlock({ margin: 3 })
.bind('text', '', d => 'key: ' + d.key + '\nbounds: ' + d.bounds.toString())
)
}) // optimization
.bindTwoWay('position', 'bounds', b => b.position, (p, d) => new go.Rect(p.x, p.y, d.bounds.width, d.bounds.height))
.add(
new go.Shape('Rectangle')
.bind('fill', 'color'),
new go.TextBlock({ margin: 2 })
.bind('text', 'color')
),
// Define the template for Links
linkTemplate:
new go.Link({
isLayoutPositioned: false, // optimization
fromSpot: HORIZONTAL ? go.Spot.Right : go.Spot.Bottom,
toSpot: HORIZONTAL ? go.Spot.Left : go.Spot.Top
})
.add(
new go.Shape()
),
'animationManager.isEnabled': false
});
// This model includes all of the data
myWholeModel = new go.TreeModel(); // must match the TreeModel used by the Diagram, below
// Do not set myDiagram.model = myWholeModel -- that would create a zillion Nodes and Links!
// In the future Diagram may have built-in support for virtualization.
// For now, we have to implement virtualization ourselves by having the Diagram's model
// be different than the "real" model.
myDiagram.model = // this only holds nodes that should be in the viewport
new go.TreeModel(); // must match the model, above
// for now, we have to implement virtualization ourselves
myDiagram.isVirtualized = true;
myDiagram.addDiagramListener('ViewportBoundsChanged', onViewportChanged);
// This is a status message
const textBlock = new go.TextBlock('loading...', { stroke: 'red', font: '20pt sans-serif' });
myLoading =
new go.Part({ layerName: 'ViewportForeground', alignment: go.Spot.Center })
.add(textBlock);
// // temporarily add the status indicator
// const animate = state => {
// textBlock.text = 'loading' + '.'.repeat(state);
// setTimeout(() => {
// animate(state++);
// }, 50);
// };
// animate(0);
myDiagram.add(myLoading);
// Allow the myLoading indicator to be shown now,
// but allow objects added in load to also be considered part of the initial Diagram.
// If you are not going to add temporary initial Parts, don't call delayInitialization.
myDiagram.delayInitialization(load);
}
function load(diagram) {
// create a lot of data for the myWholeModel
var total = 123456;
var treedata = [];
for (var i = 0; i < total; i++) {
var d = {
key: i, // this node data's key
color: go.Brush.randomColor(), // the node's color
parent: i > 0 ? Math.floor((Math.random() * i) / 2) : undefined // the random parent's key
};
//!!!???@@@ this needs to be customized to account for your chosen Node template
d.bounds = new go.Rect(0, 0, 70, 20);
treedata.push(d);
}
myWholeModel.nodeDataArray = treedata;
// make it faster to get from a model parent data object to all of the children data
improveNavigation(myWholeModel);
// this sets the data.bounds on each node data
// and Diagram.fixedBounds on the diagram, so the diagram knows how far it can scroll
layoutTree(myWholeModel);
// remove the status indicator
diagram.remove(myLoading);
}
// this adds ._parent and ._children properties on each node data
function improveNavigation(model) {
// this must be a TreeModel
var ndata = model.nodeDataArray;
// create an Array of child data references for each parent data
for (var i = 0; i < ndata.length; i++) {
var child = ndata[i];
var parentkey = model.getParentKeyForNodeData(child);
var parent = model.findNodeDataForKey(parentkey);
if (parent) {
child._parent = parent;
var childarr = parent._children;
if (childarr) {
childarr.push(child);
} else {
parent._children = [child];
}
}
}
}
// The following functions implement virtualization of the Diagram
// Assume data.bounds is a Rect of the area occupied by the Node in document coordinates.
// The normal mechanism for determining the size of the document depends on all of the
// Nodes and Links existing, so we need to use a function that depends only on the model data.
function computeDocumentBounds() {
var b = new go.Rect();
var ndata = myWholeModel.nodeDataArray;
for (var i = 0; i < ndata.length; i++) {
var d = ndata[i];
if (!d.bounds) continue;
if (i === 0) {
b.set(d.bounds);
} else {
b.unionRect(d.bounds);
}
}
return b;
}
// As the user scrolls or zooms, make sure the Parts (Nodes and Links) exist in the viewport.
function onViewportChanged(e) {
var diagram = e.diagram;
// make sure there are Nodes for each node data that is in the viewport
// or that is connected to such a Node
var viewb = diagram.viewportBounds; // the new viewportBounds
var model = diagram.model;
var oldskips = diagram.skipsUndoManager;
diagram.skipsUndoManager = true;
var b = new go.Rect();
var ndata = myWholeModel.nodeDataArray;
for (var i = 0; i < ndata.length; i++) {
var n = ndata[i];
if (model.containsNodeData(n)) continue;
if (!n.bounds) continue;
if (n.bounds.intersectsRect(viewb)) {
model.addNodeData(n);
}
// make sure links to all parent nodes appear
var parentkey = myWholeModel.getParentKeyForNodeData(n);
var parent = myWholeModel.findNodeDataForKey(parentkey);
if (parent !== null) {
if (n.bounds.intersectsRect(viewb)) {
// N is inside viewport
model.addNodeData(parent); // so that link to parent appears
} else {
// N is outside of viewport
// see if there's a parent that is in the viewport,
// or if the link might cross over the viewport
b.set(n.bounds);
b.unionRect(parent.bounds);
if (b.intersectsRect(viewb)) {
model.addNodeData(n); // add N so that link to parent appears
}
}
}
}
diagram.skipsUndoManager = oldskips;
if (myRemoveTimer === null) {
// only remove offscreen nodes after a delay
myRemoveTimer = setTimeout(() => removeOffscreen(diagram), 3000);
}
updateCounts(); // only for this sample
}
// occasionally remove Parts that are offscreen from the Diagram
var myRemoveTimer = null;
function removeOffscreen(diagram) {
myRemoveTimer = null;
var viewb = diagram.viewportBounds;
var model = diagram.model;
var remove = []; // collect for later removal
var it = diagram.nodes;
while (it.next()) {
var n = it.value;
var d = n.data;
if (d === null) continue;
if (!n.actualBounds.intersectsRect(viewb) && !n.isSelected) {
// even if the node is out of the viewport, keep it if it is selected or
// if any link connecting with the node is still in the viewport
if (!n.linksConnected.any(l => l.actualBounds.intersectsRect(viewb))) {
remove.push(d);
}
}
}
if (remove.length > 0) {
var oldskips = diagram.skipsUndoManager;
diagram.skipsUndoManager = true;
model.removeNodeDataCollection(remove);
diagram.skipsUndoManager = oldskips;
}
updateCounts(); // only for this sample
}
// end of virtualized Diagram
// A very simple tree layout.
// Basic tree layout parameters
var nodeSpacing = 4;
var layerSpacing = 50;
// Layout the whole tree just using the model, not any Nodes or Links.
function layoutTree(model) {
var ndata = model.nodeDataArray;
// layout each tree root
if (HORIZONTAL) {
var y = 0;
for (var i = 0; i < ndata.length; i++) {
var d = ndata[i];
// is this a root node?
if (!d._parent) {
y = walkTreeH(d, 0, y) + d.bounds.height + nodeSpacing;
}
}
} else {
// !HORIZONTAL
var x = 0;
for (var i = 0; i < ndata.length; i++) {
var d = ndata[i];
// is this a root node?
if (!d._parent) {
x = walkTreeV(d, x, 0) + d.bounds.width + nodeSpacing;
}
}
}
// can't depend on regular bounds computation that depends on all Nodes existing
myDiagram.fixedBounds = computeDocumentBounds();
}
// Walk subtrees from each root node, positioning as we go.
function walkTreeH(parent, oldx, oldy) {
// HORIZONTAL
var origy = oldy;
var newy = oldy;
var childarr = parent._children;
if (childarr) {
for (var i = 0; i < childarr.length; i++) {
var child = childarr[i];
newy = walkTreeH(child, oldx + child.bounds.width + layerSpacing, oldy);
oldy = newy + child.bounds.height + nodeSpacing;
}
}
parent.bounds.x = oldx;
parent.bounds.y = (origy + newy) / 2;
return newy;
}
function walkTreeV(parent, oldx, oldy) {
// !HORIZONTAL
var origx = oldx;
var newx = oldx;
var childarr = parent._children;
if (childarr) {
for (var i = 0; i < childarr.length; i++) {
var child = childarr[i];
newx = walkTreeV(child, oldx, oldy + child.bounds.height + layerSpacing);
oldx = newx + child.bounds.width + nodeSpacing;
}
}
parent.bounds.x = (origx + newx) / 2;
parent.bounds.y = oldy;
return newx;
}
// end of layoutTree functionality
// This function is only used in this sample to demonstrate the effects of the virtualization.
// In a real application you would delete this function and all calls to it.
function updateCounts() {
document.getElementById('myMessage1').textContent = myWholeModel.nodeDataArray.length;
document.getElementById('myMessage2').textContent = myDiagram.nodes.count;
document.getElementById('myMessage4').textContent = myDiagram.links.count;
}
window.addEventListener('DOMContentLoaded', init);
</script>
<div id="sample">
<div id="myDiagramDiv" style="background-color: white; border: solid 1px black; width: 100%; height: 600px"></div>
<div id="description">
<p>This uses a <a>TreeModel</a> but not <a>TreeLayout</a>.</p>
Node data in Model: <span id="myMessage1"></span>. Actual Nodes in Diagram: <span id="myMessage2"></span>. Actual Links in Diagram:
<span id="myMessage4"></span>.
</div>
<br>
<p>
See also <a href="./virtualized.html">Virtualized</a>.
</p>
</div>
</div>
<!-- * * * * * * * * * * * * * -->
<!-- End of GoJS sample code -->
</div>
<div id="allTagDescriptions" class="p-4 w-full max-w-screen-xl mx-auto">
<hr/>
<h3 class="text-xl">GoJS Features in this sample</h3>
<!-- blacklist tags that do not correspond to a specific GoJS feature -->
<h4>Tree Layout</h4>
<p>
This predefined layout is used for placing Nodes of a tree-structured graph in layers (rows or columns).
For discussion and examples of the most commonly used properties of the <a href="../api/symbols/TreeLayout.html">TreeLayout</a>,
see the <a href="../intro/trees.html">Trees</a> page in the Introduction.
More information can be found in the <a href="../intro/layouts.html#TreeLayout">GoJS Intro</a>.
</p>
<p>
<a href="../samples/index.html#treelayout">Related samples</a>
</p>
<hr>
<!-- blacklist tags that do not correspond to a specific GoJS feature -->
<h4>ToolTips</h4>
<p>
A tooltip is an <a href="../api/symbols/Adornment.html" target="api">Adornment</a> that is shown when the mouse hovers over an object that has its <a href="../api/symbols/GraphObject.html#toolTip" target="api">GraphObject.toolTip</a> set.
The tooltip part is bound to the same data as the part itself.
</p>
<p>
It is typical to implement a tooltip as a "ToolTip" Panel holding a <a href="../api/symbols/TextBlock.html" target="api">TextBlock</a> or a Panel of TextBlocks and other objects.
Each "ToolTip" is just an "Auto" Panel <a href="../api/symbols/Adornment.html" target="api">Adornment</a> that is shadowed, and where the border is a rectangular <a href="../api/symbols/Shape.html" target="api">Shape</a> with a light gray fill.
However you can implement the tooltip as any arbitrarily complicated Adornment.
</p>
<p>
More information can be found in the <a href="../intro/tooltips.html">GoJS Intro</a>.
</p>
<p>
<a href="../samples/index.html#tooltips">Related samples</a>
</p>
<hr>
<!-- blacklist tags that do not correspond to a specific GoJS feature -->
</div>
</div>
</body>
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<script src="../assets/js/goSamples.js"></script>
</html>