Question

我有以下代码，如果您只想使用Bing Maps的响应填充一个Image，则该代码可以正常工作。但是如果我尝试做两个，那么变量_currentImage总是最终成为“image1”，因为调用是异步的。如何将图像变量传递给ImageryServiceGetMapUriCompleted方法？

using System;
using System.Windows.Controls;
using System.Windows.Media.Imaging;
using BasicBingMapsImagerySvc.ImageryService;

namespace BasicBingMapsImagerySvc
{
    public partial class MainPage : UserControl
    {
        private const string BingMapsKey = "my key";

        private Image _currentImage;

        public MainPage()
        {
            InitializeComponent();

            GetMap(42.573377, -101.032251, image0, MapStyle.AerialWithLabels);

            GetMap(42.573377, -101.032251, image1, MapStyle.Road_v1);
        }


        private void GetMap(double lat, double lon, Image image, MapStyle mapStyle)
        {
            var mapUriRequest = new MapUriRequest();

            // Set credentials using a valid Bing Maps key
            mapUriRequest.Credentials = new Credentials();
            mapUriRequest.Credentials.ApplicationId = BingMapsKey;

            // Set the location of the requested image
            mapUriRequest.Center = new Location();
            mapUriRequest.Center.Latitude = lat;
            mapUriRequest.Center.Longitude = lon;

            // Set the map style and zoom level
            var mapUriOptions = new MapUriOptions();
            mapUriOptions.Style = mapStyle;
            mapUriOptions.ZoomLevel = 13;

            // Set the size of the requested image to match the size of the image control
            mapUriOptions.ImageSize = new SizeOfint();
            mapUriOptions.ImageSize.Height = 256;
            mapUriOptions.ImageSize.Width = 256;

            mapUriRequest.Options = mapUriOptions;

            var imageryService = new ImageryServiceClient("BasicHttpBinding_IImageryService");
            imageryService.GetMapUriCompleted += ImageryServiceGetMapUriCompleted;

            _currentImage = image;

            imageryService.GetMapUriAsync(mapUriRequest);


        }

        private void ImageryServiceGetMapUriCompleted(object sender, GetMapUriCompletedEventArgs e)
        {
            // The result is an MapUriResponse Object
            MapUriResponse mapUriResponse = e.Result;
            var bmpImg = new BitmapImage(new Uri(mapUriResponse.Uri));

            _currentImage.Source = bmpImg;
        }
    }
}

Answer 1

您可以为事件处理程序使用lambda表达式/委托，它允许您“捕获”对图像的引用：

  var imageryService = new ImageryServiceClient("BasicHttpBinding_IImageryService");
  imageryService.GetMapUriCompleted += (s,e) =>
     {
         // The result is an MapUriResponse Object
         MapUriResponse mapUriResponse = e.Result;
         var bmpImg = new BitmapImage(new Uri(mapUriResponse.Uri));

         // set the image source
         image.Source = bmpImg;
    };

如何从Bing Maps异步调用中填充多个Silverlight图像？

1 个答案: