# Annotation

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Use annotation to draw over shared content. Both the user who is sharing and viewers can annotate during screen sharing.

You must set up [screen sharing](/docs/video-sdk/flutter/share/) before you can use annotation.

## Check whether the SDK supports annotation

Before you use annotation, confirm that the SDK supports the annotation feature.

```dart
// To check if annotation feature is supported
bool isSupported = await zoom.shareHelper.isAnnotationFeatureSupport();

// If you are the share owner, you can check if your viewer has annotation rights.
bool isDisabled = await zoom.annotationHelper.canDoAnnotation();

// If you are the share owner, you can enable or disable your viewer from annotation rights.
await zoom.shareHelper.disableViewerAnnotation(true); //disable
await zoom.shareHelper.disableViewerAnnotation(false); // enable

  // Callback to listen to the annotation privilege change
  var eventListener = ZoomVideoSdkEventListener();
  eventListener.addListener(EventType.onAnnotationPrivilegeChange, (data) async {
      data = data as Map;
      ZoomVideoSdkShareAction shareAction =
          ZoomVideoSdkShareAction.fromJson(jsonDecode(data['shareAction']));
      ZoomVideoSdkUser shareOwner =
          ZoomVideoSdkUser.fromJson(jsonDecode(data['shareOwner'].toString()));
      bool isEnabled = shareAction.isAnnotationPrivilegeEnabled;
  });
```

If the SDK supports it, continue. Be sure to set up [screen sharing](/docs/video-sdk/flutter/share/) first.

## Start and stop annotation

Annotation draws over the shared content, so your app must already render the shared stream before starting annotation. Use the plugin's `View` widget (or your own subclass of `ZoomView`) and pass `sharing: true` in its creation params so it renders the share stream instead of the video stream. For details, see [Video](/docs/video-sdk/flutter/video/) and [Screen sharing](/docs/video-sdk/flutter/share/). The example app includes a complete `VideoView` wrapper at `example/lib/components/video_view.dart`.

After you render the shared view, get the annotation helper from the SDK instance with `zoom.annotationHelper`. Confirm that you have annotation privileges before you start.

```dart
// Get the annotation helper from the SDK instance.
var annotationHelper = zoom.annotationHelper;

// Check for permission before starting.
bool canAnnotate = await annotationHelper.canDoAnnotation();

// You can also check whether the person sharing has disabled annotation.
bool isSenderDisabled = await annotationHelper.isSenderDisableAnnotation();

if (canAnnotate && !isSenderDisabled) {
  // Start annotation.
  await annotationHelper.startAnnotation();

  // Stop annotation later.
  await annotationHelper.stopAnnotation();
}
```

## Annotation tools

The SDK provides a list of annotation tools. [`AnnotationToolType`](https://marketplacefront.zoom.us/sdk/custom/flutter/native_zoom_videosdk/AnnotationToolType-class.html) lists the full set of tools.

```dart
// Constants of AnnotationToolType
AnnotationToolType.None
AnnotationToolType.Pen
AnnotationToolType.HighLighter
AnnotationToolType.Eraser
AnnotationToolType.Picker // not supported for viewers
AnnotationToolType.SpotLight // not supported for viewers
AnnotationToolType.Arrow
AnnotationToolType.AutoLine
AnnotationToolType.AutoRectangle
AnnotationToolType.AutoRectangleFill
AnnotationToolType.AutoRectangleSemiFill
AnnotationToolType.AutoEllipse
AnnotationToolType.AutoEllipseFill
AnnotationToolType.AutoEllipseSemiFill
AnnotationToolType.AutoArrow
AnnotationToolType.AutoDoubleArrow
AnnotationToolType.AutoDiamond
AnnotationToolType.AutoStampArrow
AnnotationToolType.AutoStampCheck
AnnotationToolType.AutoStampX
AnnotationToolType.AutoStampStar
AnnotationToolType.AutoStampHeart
AnnotationToolType.AutoStampQm
AnnotationToolType.VanishingPen
AnnotationToolType.VanishingArrow
AnnotationToolType.VanishingDoubleArrow
AnnotationToolType.VanishingRectangle
AnnotationToolType.VanishingEllipse
AnnotationToolType.VanishingDiamond
```

Upon selecting the tool, the user can also get or set the current tool's color or width.

```dart
// Get/set tool type
String toolType = await annotationHelper.getToolType();
await annotationHelper.setToolType(AnnotationToolType.Pen);

// Get/set tool's color - hex string
String toolColor = await annotationHelper.getToolColor();
await annotationHelper.setToolColor("#FF0000");

// Get/set tool's width - num
num toolWidth = await annotationHelper.getToolWidth();
await annotationHelper.setToolWidth(5);
```

## Other annotation methods

You can also undo or redo annotations. And you can clear all annotations, just your own, or just others' annotations.

```dart
await annotationHelper.undo();
await annotationHelper.redo();
await annotationHelper.clear(AnnotationClearType.All); // All, My, Others
```

For details, see the [`ZoomVideoSdkAnnotationHelper`](https://marketplacefront.zoom.us/sdk/custom/flutter/native_zoom_videosdk_annotation_helper/ZoomVideoSdkAnnotationHelper-class.html) class reference.