DataProviderDeferral 類別

定義

命名空間:

Windows.ApplicationModel.DataTransfer

來源應用程式的延遲委派用來通知 DataPackage 物件，來源應用程式會從另一個非同步函式產生資料。

public ref class DataProviderDeferral sealed

/// [Windows.Foundation.Metadata.ContractVersion(Windows.Foundation.UniversalApiContract, 65536)]
/// [Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
class DataProviderDeferral final

[Windows.Foundation.Metadata.ContractVersion(typeof(Windows.Foundation.UniversalApiContract), 65536)]
[Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
public sealed class DataProviderDeferral

Public NotInheritable Class DataProviderDeferral

繼承

Object Platform::Object IInspectable DataProviderDeferral

屬性

ContractVersionAttribute MarshalingBehaviorAttribute

Windows 需求

裝置系列	Windows 10 (已於 10.0.10240.0 引進)
API contract	Windows.Foundation.UniversalApiContract (已於 v1.0 引進)

範例

下列程式碼示範如何使用 DataProviderDeferral 物件來延遲目標應用程式的要求。

async private void OnDeferredImageRequestedHandler(DataProviderRequest request)
{
    if (this.imageFile != null)
    {
        // A deferral object is required because this method uses "await" before setting the 
        // data in the DataPackage.
        var deferral = request.GetDeferral();

        var imageStream = await this.imageFile.OpenAsync(FileAccessMode.Read);

        // Decode the image.
        var imageDecoder = await BitmapDecoder.CreateAsync(imageStream);

        // Re-encode the image at 50% width and height.
        var inMemoryStream = new InMemoryRandomAccessStream();
        var imageEncoder = await BitmapEncoder.CreateForTranscodingAsync(inMemoryStream, imageDecoder);
        imageEncoder.BitmapTransform.ScaledWidth = (uint)(imageDecoder.OrientedPixelWidth * 0.5);
        imageEncoder.BitmapTransform.ScaledHeight = (uint)(imageDecoder.OrientedPixelHeight * 0.5);
        await imageEncoder.FlushAsync();

        request.SetData(RandomAccessStreamReference.CreateFromStream(inMemoryStream));

        await log(OutputText, "Image has been set via deferral");

        // The data is set. Signal that the operation is complete.
        deferral.Complete();
    }
    else
    {
        await log(OutputText, "Error: imageFile is null");
    }
}

備註

來源應用程式可以選擇將資料格式設為目標應用程式，而不是立即提供格式。 常見的範例是來源應用程式支援影像格式，例如 JPG，但除非目標應用程式要求它，否則不會建立格式。 您可能想要下載我們的 共用內容來源應用程式範例。

方法

Complete()

通知 DataPackage 它已準備好進行處理。