New Tree
MinNodes:
MaxNodes:
MinChildren:
MaxChildren:

This sample demonstrates a custom Layout, TreeMapLayout, which assumes that the diagram consists of nested Groups and simple Nodes. Each node is positioned and sized to fill an area of the viewport proportionate to its "size", as determined by its Node.data.size property. Each Group gets a size that is the sum of all of its member Nodes.

The layout is defined in its own file, as TreeMapLayout.js.

Clicking repeatedly at the same point will initially select the Node at that point, and then its containing Group, and so on up the chain of containers.

### GoJS Features in this sample

#### Collections

GoJS provides its own collection classes: List, Set, and Map. You can iterate over a collection by using an Iterator. More information can be found in the GoJS Intro.

Related samples

#### Custom Layouts

GoJS allows for the creation of custom layouts to meet specific needs.

There are also many layouts that are extensions -- not predefined in the `go.js` or `go-debug.js` library, but available as source code in one of the three extension directories, with some documentation and corresponding samples. More information can be found in the GoJS Intro.

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#### Groups

The Group class is used to treat a collection of Nodes and Links as if they were a single Node. Those nodes and links are members of the group; together they constitute a subgraph.

A subgraph is not another Diagram, so there is no separate HTML Div element for the subgraph of a group. All of the Parts that are members of a Group belong to the same Diagram as the Group. There can be links between member nodes and nodes outside of the group as well as links between the group itself and other nodes. There can even be links between member nodes and the containing group itself.

More information can be found in the GoJS Intro.

Related samples

#### ToolTips

A tooltip is an Adornment that is shown when the mouse hovers over an object that has its GraphObject.toolTip set. The tooltip part is bound to the same data as the part itself.

It is typical to implement a tooltip as a "ToolTip" Panel holding a TextBlock or a Panel of TextBlocks and other objects. Each "ToolTip" is just an "Auto" Panel Adornment that is shadowed, and where the border is a rectangular Shape with a light gray fill. However you can implement the tooltip as any arbitrarily complicated Adornment.

More information can be found in the GoJS Intro.

Related samples

#### GoJS Extensions

GoJS can be extended in a variety of ways. The most common way to change the standard behavior is to set properties on the GraphObject, Diagram, CommandHandler, Tool, or Layout. But when the desired property does not exist, you might need to override methods of CommandHandler, Tool, Layout, Link, or Node. Methods that you can override are documented in the API reference. Various features of GoJS can be overriden, either by replacing a method on an instance (a feature of JavaScript) or by defining a subclass. You should not modify the prototypes of any of the GoJS classes.

In addition to our samples, GoJS provides an extensions gallery, showcasing the creation of custom tools and layouts. Those classes and samples are written in TypeScript, available at `../extensionsJSM/`, as ECMAScript/JavaScript modules -- these use the `../release/go-module.js` library. We recommend that you copy the files that you need into your project, so that you can adjust how they refer to the GoJS library that you choose and so that you can include them into your own building and packaging procedures.

More information can be found in the GoJS Intro.

Related samples

#### HTML Interaction

GoJS Diagrams can be used alongside other HTML elements in a webapp. For custom Text Editors, Context Menus, and ToolTips, which are invoked and hidden via GoJS tool operations, it is best to use the HTMLInfo class.

More information can be found in the GoJS Intro.

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