Whiteboard sharing

The Video SDK lets an app share a whiteboard within a session, allowing users to start, view, and collaborate on a digital canvas. Manage this feature through the dedicated ZMVideoSDKWhiteboardHelper.

Integrate the module

To add whiteboard support to your app, you will primarily use the ZMVideoSDKWhiteboardHelper interface, which is part of the ZMVideoSDKShareHelper interface. You can also manage events using the ZMVideoSDKDelegate protocol.

Share and manage the whiteboard

These helper classes are available for you to manage the whiteboard.

```swift
// 1. Get the Whiteboard Helper
if let whiteboardHelper = ZMVideoSDK.shared().getShareHelper().getWhiteboardHelper() {
    // 2. Start Sharing
    if whiteboardHelper.canStartShareWhiteboard() {
        let result = whiteboardHelper.startShareWhiteboard()
        // Check 'result' for success (.success)
    }
    // 3. Stop Sharing
    if whiteboardHelper.canStopShareWhiteboard() {
        let result = whiteboardHelper.stopShareWhiteboard()
        // Check 'result' for success
    }
}
```
```cpp
// 1. Get the Whiteboard Helper
ZMVideoSDKWhiteboardHelper *whiteboardHelper = [[[ZMVideoSDK sharedVideoSDK] getShareHelper] getWhiteboardHelper];
// 2. Start Sharing
if ([whiteboardHelper canStartShareWhiteboard]) {
    ZMVideoSDKErrors result = [whiteboardHelper startShareWhiteboard];
    // Check 'result' for success (ZMVideoSDKErrors_Success)
}
// 3. Stop Sharing
if ([whiteboardHelper canStopShareWhiteboard]) {
    ZMVideoSDKErrors result = [whiteboardHelper stopShareWhiteboard];
    // Check 'result' for success
}
```

View or subscribe to the whiteboard

Use the SDK interfaces subscribeWhiteboard, unSubscribeWhiteboard, setWhiteboardViewPos, and setWhiteboardViewSize to control the display of the whiteboard in a dedicated window or view. You manage the position and size using NSPoint and NSSize.

To view the whiteboard

    ```swift
    // Get the helper as shown above
    if let whiteboardHelper = ZMVideoSDK.shared().getShareHelper().getWhiteboardHelper() {
        // 1. Subscribe to the whiteboard on your selected NSWindow
        whiteboardHelper.subscribeWhiteboard(selectedNSWindow)
        // 2. Set the position and size of the whiteboard window/view
        let position = NSPoint(x: 100, y: 100) // e.g. x=100, y=100
        let size = NSSize(width: 800, height: 600) // e.g. width=800, height=600
        whiteboardHelper.setWhiteboardViewPos(position)
        whiteboardHelper.setWhiteboardViewSize(size)
    }
    ```
    ```cpp
    // Get the helper as shown above
    ZMVideoSDKWhiteboardHelper *whiteboardHelper = [[[ZMVideoSDK sharedVideoSDK] getShareHelper] getWhiteboardHelper];
    // 1. Subscribe to the whiteboard on your selected NSWindow
    [whiteboardHelper subscribeWhiteboard:selectedNSWindow];
    // 2. Set the position and size of the whiteboard window/view
    NSPoint position = NSMakePoint(100, 100); // e.g. x=100, y=100
    NSSize size = NSMakeSize(800, 600); // e.g. width=800, height=600
    [whiteboardHelper setWhiteboardViewPos:position];
    [whiteboardHelper setWhiteboardViewSize:size];
    ```

To stop viewing the whiteboard

    ```swift
    // Get the helper as shown above
    if let whiteboardHelper = ZMVideoSDK.shared().getShareHelper().getWhiteboardHelper() {
        whiteboardHelper .unSubscribeWhiteboard()
    }
    ```
    ```cpp
    // Get the helper as shown above
    ZMVideoSDKWhiteboardHelper *whiteboardHelper = [[[ZMVideoSDK sharedVideoSDK] getShareHelper] getWhiteboardHelper];
    [whiteboardHelper unSubscribeWhiteboard];
    ```

Whiteboard events and status changes

You'll handle whiteboard events in your ZMVideoSDKDelegate implementation.

    ```swift
    // Implement this method in your class that conforms to ZMVideoSDKDelegate
    func onUserWhiteboardShareStatusChanged(_ user: ZMVideoSDKUser, whiteboardHelper: ZMVideoSDKWhiteboardHelper) {
        if user.getWhiteboardStatus() == ZMVideoSDKWhiteboardStatus_Started {
            // A user has started sharing a whiteboard. Subscribe to the whiteboard on your selected NSWindow
            whiteboardHelper.subscribeWhiteboard(selectedNSWindow)
            // 2. Set the position and size of the whiteboard window/view
            let position = NSPoint(x: 100, y: 100)
            let size = NSSize(width: 800, height: 600)
            whiteboardHelper.setWhiteboardViewPos(position)
            whiteboardHelper.setWhiteboardViewSize(size)
        } else {
            // The whiteboard sharing has ended. Unsubscribe to close the view.
            whiteboardHelper.unSubscribeWhiteboard()
        }
    }
    ```
    ```cpp
    // Implement this method in your class that conforms to ZMVideoSDKDelegate
    - (void)onUserWhiteboardShareStatusChanged:(ZMVideoSDKUser *)user whiteboardHelper:(ZMVideoSDKWhiteboardHelper *)whiteboardHelper {
        if ([user getWhiteboardStatus] == ZMVideoSDKWhiteboardStatus_Started) {
            // A user has started sharing a whiteboard. Subscribe to the whiteboard on your selected NSWindow
            [whiteboardHelper subscribeWhiteboard:selectedNSWindow];
            // Example: Set initial position and size
            NSPoint position = NSMakePoint(100, 100);
            NSSize size = NSMakeSize(800, 600);
            [whiteboardHelper setWhiteboardViewPos:position];
            [whiteboardHelper setWhiteboardViewSize:size];
        } else {
            // The whiteboard sharing has ended. Unsubscribe to close the view.
            [whiteboardHelper unSubscribeWhiteboard];
        }
    }
    ```

Export whiteboard content

Export the whiteboard as a PDF document.

To export and retrieve the data

    ```swift
    // 1. Trigger the export
    if let whiteboardHelper = ZMVideoSDK.shared().getShareHelper().getWhiteboardHelper() {
        whiteboardHelper.exportWhiteboard(ZMVideoSDKExportFormat_PDF)
    }
    // 2. Receive the data in your delegate
    func onWhiteboardExported(_ format: ZMVideoSDKExportFormat, data: UnsafeMutablePointer<UInt8>, dataLength length: Int) {
        if format == ZMVideoSDKExportFormat_PDF {
            // 'data' is the Swift UnsafeMutablePointer<UInt8> object of the PDF file.
            // You can now write these data to a file on the device.
            savePdfFile(data)
        }
    }
    ```
    ```cpp
    // 1. Trigger the export
    ZMVideoSDKWhiteboardHelper *whiteboardHelper = [[[ZMVideoSDK sharedVideoSDK] getShareHelper] getWhiteboardHelper];
    [whiteboardHelper exportWhiteboard:ZMVideoSDKExportFormat_PDF];
    // 2. Receive the data in your delegate
    - (void)onWhiteboardExported:(ZMVideoSDKExportFormat)format data:(unsigned char *)data dataLength:(long)length {
        if (format == ZMVideoSDKExportFormat_PDF) {
            // 'data' is the (unsigned char *) object of the PDF file.
            // You can now write these data to a file on the device.
            [self savePdfFile:data];
        }
    }
    ```

Manage the data

Because the whiteboard data isn't stored in the cloud, you'll need to handle the data storage. Data can be lost when someone stops sharing the whiteboard, a user leaves a session, or when a user joins a sub-session, or when the app crashes or has network connectivity issues.