FreehandRoi Tool

// Init cornerstone tools
cornerstoneTools.init();

// Enable any elements, and display images
// ...

// Add our tool, and set it's mode
const FreehandRoiTool = cornerstoneTools.FreehandRoiTool;

cornerstoneTools.addTool(FreehandRoiTool)
cornerstoneTools.setToolActive('FreehandRoi', { mouseButtonMask: 1 })