ClaimedBarcodeScanner.ReleaseDeviceRequested イベント

定義

名前空間:

Windows.Devices.PointOfService

デバイスが排他的要求を解放する要求を取得したときに発生します。

// Register
event_token ReleaseDeviceRequested(EventHandler<ClaimedBarcodeScanner> const& handler) const;

// Revoke with event_token
void ReleaseDeviceRequested(event_token const* cookie) const;

// Revoke with event_revoker
ClaimedBarcodeScanner::ReleaseDeviceRequested_revoker ReleaseDeviceRequested(auto_revoke_t, EventHandler<ClaimedBarcodeScanner> const& handler) const;

public event System.EventHandler<ClaimedBarcodeScanner> ReleaseDeviceRequested;

function onReleaseDeviceRequested(eventArgs) { /* Your code */ }
claimedBarcodeScanner.addEventListener("releasedevicerequested", onReleaseDeviceRequested);
claimedBarcodeScanner.removeEventListener("releasedevicerequested", onReleaseDeviceRequested);
- or -
claimedBarcodeScanner.onreleasedevicerequested = onReleaseDeviceRequested;

Public Custom Event ReleaseDeviceRequested As EventHandler(Of ClaimedBarcodeScanner) 

イベントの種類

EventHandler<ClaimedBarcodeScanner>

EventHandler<ClaimedBarcodeScanner>

例

次の例は、イベント ハンドラーを設定する方法を示しています。

void Scenario1::ScenarioStartScanButton_Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
     // Create the barcode scanner. 
    create_task(CreateDefaultScannerObject()).then([this](void)
    {
        if (scanner != nullptr)
        {
            // Claim the scanner for exclusive use by your application.
            create_task(ClaimScanner()).then([this](void)
            {
                if (claimedScanner)
                {
                        
                    // Add a release device requested event handler. If this event is not handled,  
                    // another app can claim the barcode scanner.
                    releaseDeviceRequestedToken = claimedScanner->ReleaseDeviceRequested::add(ref new EventHandler<ClaimedBarcodeScanner^>(this, &Scenario1::OnReleaseDeviceRequested));

  
                    /// Add a data receive event handler.
                    dataReceivedToken =  claimedScanner->DataReceived::add(ref new TypedEventHandler<ClaimedBarcodeScanner^, BarcodeScannerDataReceivedEventArgs^>(this, &Scenario1::OnDataReceived));
                    UpdateOutput("Attached the DataReceived Event handler.");

                    // Set the app to decode the raw data from the barcode scanner 
                    claimedScanner->IsDecodeDataEnabled = true;

                    // Enable the scanner.
                    create_task(EnableScanner()).then([this](void)
                    {
                        UpdateOutput("Ready to Scan.");

                        // Reset the button state
                        ScenarioEndScanButton->IsEnabled = true;
                        ScenarioStartScanButton->IsEnabled = false;
                    });
                }
            });
        }
    });

}

private async void ScenarioStartScanButton_Click(object sender, RoutedEventArgs e)
{
    // Create the barcode scanner. 
    if (await CreateDefaultScannerObject())
    {
        // Claim the scanner for exclusive use by your application.
        if (await ClaimScanner())
        {
            
            // Add a release device requested event handler. If this event is not handled,  
            // another app can claim the barcode scanner.
            claimedScanner.ReleaseDeviceRequested += claimedScanner_ReleaseDeviceRequested;

            // Add a data receive event handler.
            claimedScanner.DataReceived += claimedScanner_DataReceived;
            UpdateOutput("Attached the DataReceived Event handler.");

            // Set the app to decode the raw data from the barcode scanner 
            claimedScanner.IsDecodeDataEnabled = true;

            // Enable the scanner.
            if (await EnableScanner())
            {
                // Reset the button state
                ScenarioEndScanButton.IsEnabled = true;
                ScenarioStartScanButton.IsEnabled = false;

                UpdateOutput("Ready to Scan.");
            }
        } 
    }
    else
    {
        UpdateOutput("No Barcode Scanner found");
    }
}

void Scenario1::OnReleaseDeviceRequested(Platform::Object ^sender, Windows::Devices::PointOfService::ClaimedBarcodeScanner ^args)
{
    Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler( 
        [this,args]() 
    {
        args->RetainDevice(); 
        UpdateOutput("Received event ReleaseDeviceRequested. Retaining the barcode scanner.");
    }));
}

async void claimedScanner_ReleaseDeviceRequested(object sender, ClaimedBarcodeScanner e)
{
    await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        e.RetainDevice();
    }); 
}

注釈

アプリケーションが別のアプリケーションから ReleaseDeviceRequested イベントを受け取った場合、アプリケーションがデバイスを保持しない限り、その排他的な要求が失われる可能性があります。

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