# Module: Viewport


## Overview
Viewports consume a displaySet and display/allow the user to interact with data. An extension can register a Viewport Module by defining a `getViewportModule`
method that returns a React component. Currently, we use viewport components to
add support for:

- 2D Medical Image Viewing (cornerstone ext.)
- Structured Reports as SR (DICOM SR ext.)
- Structured Reports as HTML (DICOM html ext.)
- Encapsulated PDFs as PDFs (DICOM pdf ext.)
- Whole Slide Microscopy Viewing (whole slide ext.)
- etc.



The general pattern is that a mode can define which `Viewport` to use for which specific
`SOPClassHandlerUID`, so if you want to fork just a single Viewport component for a specialized mode, this is possible.

```JSX
// displaySet, viewportIndex, dataSource
const getViewportModule = () => {
  const wrappedViewport = props => {
    return (
      <ExampleViewport
        {...props}
        onEvent={data => {
          commandsManager.runCommand('commandName', data);
        }}
      />
    );
  };

  return [{ name: 'example', component: wrappedViewport }];
};
```


## Example Viewport Component
A simplified version of the tracked CornerstoneViewport is shown below, which creates
a cornerstone viewport and and action bar on top of it.




```JSX
function TrackedCornerstoneViewport({
  children,
  dataSource,
  displaySet,
  viewportIndex,
  servicesManager,
  extensionManager,
  commandsManager,
}) {
  const renderViewport = () => {
    const { component: Component } = extensionManager.getModuleEntry(
      'org.ohif.cornerstone.viewportModule.cornerstone'
    )
    return (
      <Component
        onElementEnabled={onElementEnabled}
        element={element}
        {...props}
      ></Component>
    )
  }

  return (
    <>
      <ViewportActionBar onDoubleClick onSeriesChange />
      <div className="relative flex flex-row w-full h-full overflow-hidden">
        {renderViewport()}
      </div>
    </>
  )
}

```


![viewportModule](../../assets/img/viewportModule.png)
### `@ohif/viewer`

Viewport components are managed by the `ViewportGrid` Component. Which Viewport
component is used depends on:

- Hanging Protocols
- The Layout Configuration
- Registered SopClassHandlers


![viewportModule-layout](../../assets/img/viewportModule-layout.png)
<center><i>An example of three cornerstone Viewports</i></center>