# 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.

## Set up annotation

1. Check if the annotation feature is supported.

    ```swift
    // Check if the annotation feature is supported.
    ZMVideoSDK.shared()?.getShareHelper()?.isAnnotationFeatureSupport()

    // If you are the share owner, you can check whether your viewer's annotation rights are disabled.
    ZMVideoSDK.shared()?.getShareHelper()?.isViewerAnnotationDisabled()

    // If you are the share owner, you can enable or disable your viewer's annotation rights.
    ZMVideoSDK.shared()?.getShareHelper()?.disableViewerAnnotation(true)
    ```

    ```objectivec
    ZMVideoSDKShareHelper *shareHelper = [[ZMVideoSDK sharedVideoSDK] getShareHelper];

    // Check if the annotation feature is supported.
    [shareHelper isAnnotationFeatureSupport];

    // If you are the share owner, you can check whether your viewer's annotation rights are disabled.
    [shareHelper isViewerAnnotationDisabled];

    // If you are the share owner, you can enable or disable your viewer's annotation rights.
    [shareHelper disableViewerAnnotation:YES];
    ```

    If it is supported, continue.

2. Set up [screen sharing](/docs/video-sdk/macos/share/).

    Now you can use annotation in your implementation.

## Start and stop annotation

In order to start annotation, the viewer must first have already subscribed to a shared view and input the same view to create a new `ZMVideoSDKAnnotationHelper` from the share helper.

```swift
// Same as before, get the user's share canvas that you want to subscribe to.
let userShareCanvas: ZMVideoSDKVideoCanvas
// Render the user's share stream into your view of choice. (This view is required for annotation.)
userShareCanvas.subscribe(with: view, aspectMode: .panAndScan, resolution: .auto)

// Create the annotation helper using the same view above and check for permission again.
if let annotationHelper = ZMVideoSDK.shared()?.getShareHelper()?.createAnnotationHelper(view), annotationHelper.canDoAnnotation() {
    annotationHelper.startAnnotation()
    // To stop annotation later.
    annotationHelper.stopAnnotation()
}
```

```objectivec
// Same as before, get the user's share canvas that you want to subscribe to.
ZMVideoSDKVideoCanvas *userShareCanvas;
// Render the user's share stream into your view of choice. (This view is required for annotation.)
[userShareCanvas subscribeWithView:view aspectMode:ZMVideoSDKVideoAspect_PanAndScan resolution:ZMVideoSDKResolution_Auto];

// Create the annotation helper using the same view above and check for permission again.
ZMVideoSDKShareHelper *shareHelper = [[ZMVideoSDK sharedVideoSDK] getShareHelper];
ZMVideoSDKAnnotationHelper *annotationHelper = [shareHelper createAnnotationHelper:view];
if (annotationHelper && [annotationHelper canDoAnnotation]) {
    [annotationHelper startAnnotation];
    // To stop annotation later.
    [annotationHelper stopAnnotation];
}
```

## Annotation tools

There are a list of annotation tools available. The full list of tools is located under `ZMVideoSDKAnnotationToolType`.

```objectivec
// Enum of ZMVideoSDKAnnotationToolType
ZMVideoSDKAnnotationToolType_None,
ZMVideoSDKAnnotationToolType_Pen,
ZMVideoSDKAnnotationToolType_HighLighter,
ZMVideoSDKAnnotationToolType_AutoLine,
ZMVideoSDKAnnotationToolType_AutoRectangle,
ZMVideoSDKAnnotationToolType_AutoEllipse,
ZMVideoSDKAnnotationToolType_AutoArrow,
ZMVideoSDKAnnotationToolType_AutoRectangleFill,
ZMVideoSDKAnnotationToolType_AutoEllipseFill,
ZMVideoSDKAnnotationToolType_SpotLight,
ZMVideoSDKAnnotationToolType_Arrow,
ZMVideoSDKAnnotationToolType_ERASER,
ZMVideoSDKAnnotationToolType_Textbox,
ZMVideoSDKAnnotationToolType_Picker,
ZMVideoSDKAnnotationToolType_AutoRectangleSemiFill,
ZMVideoSDKAnnotationToolType_AutoEllipseSemiFill,
ZMVideoSDKAnnotationToolType_AutoDoubleArrow,
ZMVideoSDKAnnotationToolType_AutoDiamond,
ZMVideoSDKAnnotationToolType_AutoStampArrow,
ZMVideoSDKAnnotationToolType_AutoStampCheck,
ZMVideoSDKAnnotationToolType_AutoStampX,
ZMVideoSDKAnnotationToolType_AutoStampStar,
ZMVideoSDKAnnotationToolType_AutoStampHeart,
ZMVideoSDKAnnotationToolType_AutoStampQm
```

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

```swift
// Get/set tool type
annotationHelper.getToolType()
annotationHelper.setToolType(.pen)

// Get/set tool's color - Color
annotationHelper.getToolColor()
annotationHelper.setToolColor(.red)

// Get/set tool's width - long
annotationHelper.getToolWidth()
annotationHelper.setToolWidth(5)
```

```objectivec
// Get/set the tool type.
ZMVideoSDKAnnotationToolType toolType;
[annotationHelper getToolType:&toolType];
[annotationHelper setToolType:ZMVideoSDKAnnotationToolType_Pen];

// Get/set the tool's color.
NSColor *toolColor;
[annotationHelper getToolColor:&toolColor];
[annotationHelper setToolColor:[NSColor redColor]];

// Get/set the tool's width.
long toolWidth;
[annotationHelper getToolWidth:&toolWidth];
[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.

```swift
annotationHelper.undo()
annotationHelper.redo()
annotationHelper.clear(.all) // .all, .my, .others
```

```objectivec
[annotationHelper undo];
[annotationHelper redo];
[annotationHelper clear:ZMVideoSDKAnnotationClearType_All]; // _All, _My, _Others
```

For details, see the [ZMVideoSDKAnnotationHelper](https://marketplacefront.zoom.us/sdk/custom/macos/interface_z_m_video_s_d_k_annotation_helper.html) class reference and the [ZMVideoSDKShareHelper](https://marketplacefront.zoom.us/sdk/custom/macos/interface_z_m_video_s_d_k_share_helper.html) class reference.

## Destroy annotation

Once annotation is no longer valid or required, you can destroy it by calling the `destroyAnnotationHelper` method in the [ZMVideoSDKShareHelper](https://marketplacefront.zoom.us/sdk/custom/macos/interface_z_m_video_s_d_k_share_helper.html) class.

```swift
ZMVideoSDK.shared()?.getShareHelper()?.destroyAnnotationHelper(annotationHelper)
```

```objectivec
[[[ZMVideoSDK sharedVideoSDK] getShareHelper] destroyAnnotationHelper:annotationHelper];
```