WebView.CapturePreviewToStreamAsync(IRandomAccessStream) 方法

定义

命名空间:

Windows.UI.Xaml.Controls

创建当前 WebView 内容的图像，并将其写入指定的流。

public:
 virtual IAsyncAction ^ CapturePreviewToStreamAsync(IRandomAccessStream ^ stream) = CapturePreviewToStreamAsync;

/// [Windows.Foundation.Metadata.RemoteAsync]
IAsyncAction CapturePreviewToStreamAsync(IRandomAccessStream const& stream);

[Windows.Foundation.Metadata.RemoteAsync]
public IAsyncAction CapturePreviewToStreamAsync(IRandomAccessStream stream);

function capturePreviewToStreamAsync(stream)

Public Function CapturePreviewToStreamAsync (stream As IRandomAccessStream) As IAsyncAction

参数

stream

IRandomAccessStream

要向其写入映像的流。

返回

IAsyncAction

等待捕获操作的异步操作。

属性

RemoteAsyncAttribute

示例

此示例演示如何使用此方法创建当前内容的缩略图。 有关完整示例，请参阅 WebView 控件示例。

private async void bookmarkBtn_Click(object sender, RoutedEventArgs e)
{
    InMemoryRandomAccessStream ms = new InMemoryRandomAccessStream();
    await webView8.CapturePreviewToStreamAsync(ms);

    // Create a small thumbnail.
    int longlength = 180, width = 0, height = 0;
    double srcwidth = webView8.ActualWidth, srcheight = webView8.ActualHeight;
    double factor = srcwidth / srcheight;
    if (factor < 1)
    {
        height = longlength;
        width = (int)(longlength * factor);
    }
    else
    {
        width = longlength;
        height = (int)(longlength / factor);
    }
    BitmapSource small = await resize(width, height, ms);

    BookmarkItem item = new BookmarkItem();
    item.Title = webView8.DocumentTitle;
    item.PageUrl = webView8.Source;
    item.Preview = small;

    bookmarks.Add(item);
}

另请参阅

• XAML WebView 控件示例