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What is CornerstoneTools.js

Cornerstone Tools is a JavaScript library that assists in annotating, segmenting, and measuring medical images. This library also provides a framework for creating new tools, managing all tools in a consistent, cohesive manner, and importing/exporting tool measurement data.

This library is not stand-alone. It builds on top of Cornerstone; a standards compliant, fast, and extensible JavaScript library that displays interactive medical images.

Getting Started

The easiest way to try out Cornerstone Tools is using the JSFiddle Hello World example. Feel free to open it in another tab and follow along as we go through some basic examples. Or, you can create an index.html file and include Cornerstone Tools with:

<!-- Dependencies -->
<script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cornerstoneMath.js"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cornerstone.js"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cornerstoneWebImageLoader.js"></script>

<!-- development version, includes helpful console warnings -->
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cornerstoneTools.js"></script>


<!-- Dependencies -->
<script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>

<!-- production version, optimized for size and speed -->
<script src="https://cdn.jsdelivr.net/npm/cornerstone-tools@next"></script>

The Installation page provides more options for installing Cornerstone Tools.


If you find the dependencies confusing, here is a high level overview of why each is included and necessary for Cornerstone Tools to function:

Dependency Purpose Alternatives
Hammer.js Adds cross-browser support for touch events and gestures N/A
Cornerstone Math Is a dependency some tools use to aid in vector math, or other complex operations N/A
Cornerstone (Core) Renders our image, and provides useful events and methods to make tools that respond to viewport changes possible N/A
Cornerstone Web Image Loader Adds the ability to "fetch" PNG / JPEG images from http or https URLs. Other image loaders exist to load NIFTI or DICOM images into Cornerstone CornerstoneWADOImageLoader (DICOM) / CornerstoneNIFTIImageLoader (NIFTI)
debug A tiny JavaScript debugging utility modelled after Node.js core's debugging technique. Works in Node.js and web browsers. N/A

If you find this overly complicated and have alternative solutions to managing and using dependencies, we are always looking for new ideas on how to simplify the process. Please do not hesitate to create a GitHub issue and discuss (:


Previous versions of Cornerstone Tools required a strong knowledge of its internals to enable/disable different features and functionality. Now, sensible defaults are applied when you initialize Cornerstone Tools.

import cornerstone from 'cornerstone-core';
import cornerstoneMath from 'cornerstone-math';
import cornerstoneTools from 'cornerstone-tools';
import Hammer from 'hammerjs';

cornerstoneTools.external.cornerstone = cornerstone;
cornerstoneTools.external.Hammer = Hammer;
cornerstoneTools.external.cornerstoneMath = cornerstoneMath;


The cornerstoneTools.init(); call accepts a configuration object if you would like to deviate from default behaviors of cornerstoneTool's globalConfiguration:

   * When cornerstone elements are enabled,
   * should `mouse` input events be listened for?
  mouseEnabled: true,
   * When cornerstone elements are enabled,
   * should `touch` input events be listened for?
  touchEnabled: true,
   * A special flag that synchronizes newly enabled cornerstone elements. When
   * enabled, their active tools are set to reflect tools that have been
   * activated with `setToolActive`.
  globalToolSyncEnabled: false,
   * Most tools have an associated canvas or SVG cursor. Enabling this flag
   * causes the cursor to be shown when the tool is active, bound to left
   * click, and the user is hovering the enabledElement.
  showSVGCursors: false,

If you wish to change modules other than the globalConfiguration module, you may pass an array of named module configuration like so:

    moduleName: 'globalConfiguration',
    configuration: {
      showSVGCursors: true,
    moduleName: 'segmentation',
    configuration: {
      outlineWidth: 2,

You can go further and configure textStyle, toolStyle, toolColors, etc:

// Set the tool font and font size
const fontFamily =
  'Work Sans, Roboto, OpenSans, HelveticaNeue-Light, Helvetica Neue Light, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif';

cornerstoneTools.textStyle.setFont(`16px ${fontFamily}`);

// Set the tool width

// Set color for inactive tools
cornerstoneTools.toolColors.setToolColor('rgb(255, 255, 0)');

// Set color for active tools
cornerstoneTools.toolColors.setActiveColor('rgb(0, 255, 0)');

// and so on...

A full list of the settings and their defaults can be found here: globalConfigurationModule.js

Adding and Using Tools

In previous versions of Cornerstone Tools, users would need to implement their own Tool manager. This version includes the concept of "adding" Tools to Enabled elements to make tracking and managing Tool state across your application easier.

Adding a Tool to one or more Enabled elements:

In this example, we're adding a built in Tool to an Enabled element.

const LengthTool = cornerstoneTools.LengthTool;

// Make sure we have at least one element Enabled
const element = document.querySelector('#element-1');

// Adds tool to ALL currently Enabled elements

// OR add the tool to a specific Enabled element
cornerstoneTools.addToolForElement(element, LengthTool);

Activating an added Tool:

When a Tool is added, its default mode is Disabled. When a Tool's mode is Active, it can be used; if it has measurement data, that data can be created or interacted with. You can read more about changing a Tool's mode in the anatomy of a tool section of our docs. In this example, we change an added Tool's mode to Active:

// Activate the tool for ALL currently Enabled elements
cornerstoneTools.setToolActive(LengthTool.name, { mouseButtonMask: 1 });

// OR activate the tool for a specific Enabled element
    mouseButtonMask: 1,

Now that our Tool is Active, we should be able to use our LengthTool to draw length annotations on the Enabled element. Having trouble or just want to see a quick demo? Check out this jsfiddle!

Next Steps

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