# Annotation

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Use annotation to draw over shared content. Both users and hosts can annotate during screen sharing.

## Set up annotation

1. Check if the annotation feature is supported.

    ```cpp
    // Create and initialize your videoSDK object (if not already done)
    IZoomVideoSDK* video_sdk_obj_ = CreateZoomVideoSDKObj();
    ZoomVideoSDKErrors err = video_sdk_obj_->initialize(init_params);

    // To check if annotation feature is supported
    video_sdk_obj_->getShareHelper()->isViewerAnnotationDisabled();

    // If you are the share owner, you can check if your viewer has annotation rights.
    video_sdk_obj_->getShareHelper()->isAnnotationFeatureSupport();

    // If you are the share owner, you can enable or disable your viewer from annotation rights.
    video_sdk_obj_->getShareHelper()->disableViewerAnnotation(true/false);
    ```

    If it is supported, continue.

1. Set up [screen sharing](/docs/video-sdk/linux/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 [`IZoomVideoSDKAnnotationHelper`](https://marketplacefront.zoom.us/sdk/custom/linux/class_i_zoom_video_s_d_k_annotation_helper.html) from the share helper.

```cpp
// Set the resolution.
ZoomVideoSDKResolution resolution = ZoomVideoSDKResolution_Auto;

// Get the share pipe for the user.
IZoomVideoSDKRawDataPipe* pPipe = NULL;
pPipe = pUser->GetSharePipe();
if (!pPipe) return;

// Render the user's share stream into your view of choice. (This view is required for annotation)
pPipe->subscribe(resolution, this);

// Get name for associated share window
const char* hwndChar = ":0-0(0,0,1920,1080)-34563456";
void* hwnd = reinterpret_cast<void*>(hwndChar);
//      hostname:display_number-screen_number(x, y, width, height)-winid  " :0-0(0,0,1920,1080)-34563456 "
// format of device_name:
//      hostname:display_number-screen_number(x, y, width, height)-winid  " :0-0(0,0,1920,1080)-34563456 "
//          display_name    hostname:display_number
//          screen_number   use multi X11 virtural device, default is 0
//          device_frame    (x, y, width, height)
//          window_id       winid

// Create annotation helper using the same view above and check for permission again
IZoomVideoSDKAnnotationHelper* annotationHelper = video_sdk_obj_->getShareHelper()->createAnnotationHelper(hwnd);
if (annotationHelper) {
    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 `ZoomVideoSDKAnnotationToolType`.

```cpp
// 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.

```cpp
// Get/set tool type
annotationHelper.getToolType();
annotationHelper.setToolType(ZoomVideoSDKAnnotationToolType_Pen);

// Get/set tool's color - unsigned long
annotationHelper.getToolColor();
annotationHelper.setToolColor(value);

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

## Other annotation methods

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

```cpp
annotationHelper.undo();
annotationHelper.redo();
annotationHelper.clear(ZoomVideoSDKAnnotationClearType_All); // .all, .my, .others
```

For more information, see the [IZoomVideoSDKAnnotationHelper](https://marketplacefront.zoom.us/sdk/custom/linux/class_i_zoom_video_s_d_k_annotation_helper.html) and [IZoomVideoSDKShareHelper](https://marketplacefront.zoom.us/sdk/custom/linux/class_i_zoom_video_s_d_k_share_helper.html) references.

## Destroy annotation

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

```cpp
video_sdk_obj_->getShareHelper()->destroyAnnotationHelper(annotationHelper);
```