chore: Expose getDisplayedArea util (#561)

* Expose get displayed area util

* Update util path

Author: igoroctaviano

src/index.js

@@ -47,6 +47,7 @@ import { default as fitToWindow } from './fitToWindow.js';
 import { default as generateLut } from './internal/generateLut.js';
 import { default as getDefaultViewport } from './internal/getDefaultViewport.js';
 import { default as getDefaultViewportForImage } from './getDefaultViewportForImage.js';
+import { default as getDisplayedArea } from './internal/getDisplayedArea.js';
 import { default as getImage } from './getImage.js';
 import { default as getPixels } from './getPixels.js';
 import { default as getStoredPixels } from './getStoredPixels.js';
@@ -129,6 +130,7 @@ const cornerstone = {
   setLayerImage,
   fitToWindow,
   getDefaultViewportForImage,
+  getDisplayedArea,
   setDefaultViewport,
   getImage,
   getPixels,
@@ -204,6 +206,7 @@ export {
   setLayerImage,
   fitToWindow,
   getDefaultViewportForImage,
+  getDisplayedArea,
   getImage,
   getPixels,
   getStoredPixels,