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我正在开发一个天气应用程序，我想根据天气（晴天、阴天等）动态更改背景图像。我为 App.xaml.cs 中的所有页面设置了背景图像，如下所示：

  rootFrame.Background = new ImageBrush
            {
                Stretch = Windows.UI.Xaml.Media.Stretch.UniformToFill,
                ImageSource = new BitmapImage { UriSource = new Uri("ms-appx:///Assets/blueSky.jpg") }
            };

我在 App.xaml.cs 中设置了图像，因此所有页面都获得相同的图像，并且我不需要每次都加载图像。App.xaml.cs 的完整代码：

 sealed partial class App : Application
{

    /// <summary>
    /// Initializes the singleton application object.  This is the first line of authored code
    /// executed, and as such is the logical equivalent of main() or WinMain().
    /// </summary>
    public App()
    {
        this.InitializeComponent();
        this.Suspending += OnSuspending;

    }

    /// <summary>
    /// Invoked when the application is launched normally by the end user.  Other entry points
    /// will be used when the application is launched to open a specific file, to display
    /// search results, and so forth.
    /// </summary>
    /// <param name="args">Details about the launch request and process.</param>
    protected async override void OnLaunched(LaunchActivatedEventArgs args)
    {
        Frame rootFrame = Window.Current.Content as Frame;


        // Do not repeat app initialization when the Window already has content,
        // just ensure that the window is active
        if (rootFrame == null)
        {
            // Create a Frame to act as the navigation context and navigate to the first page
            rootFrame = new Frame();


            // Her we set the application background Image for all pages
            rootFrame.Background = new ImageBrush
            {
                Stretch = Windows.UI.Xaml.Media.Stretch.UniformToFill,
                ImageSource = new BitmapImage { UriSource = new Uri("ms-appx:///Assets/blueSky.jpg") }
            };
            weather.Common.SuspensionManager.RegisterFrame(rootFrame, "appFrame");


            if (args.PreviousExecutionState == ApplicationExecutionState.Terminated)
            {
                //TODO: Load state from previously suspended application
                await weather.Common.SuspensionManager.RestoreAsync();
            }

            // Place the frame in the current Window
            Window.Current.Content = rootFrame;
        }

        if (rootFrame.Content == null)
        {
            // When the navigation stack isn't restored navigate to the first page,
            // configuring the new page by passing required information as a navigation
            // parameter
            if (!rootFrame.Navigate(typeof(MainPage), args.Arguments))
            {
                throw new Exception("Failed to create initial page");
            }
        }
        // Ensure the current window is active
        Window.Current.Activate();
    }

    /// <summary>
    /// Invoked when application execution is being suspended.  Application state is saved
    /// without knowing whether the application will be terminated or resumed with the contents
    /// of memory still intact.
    /// </summary>
    /// <param name="sender">The source of the suspend request.</param>
    /// <param name="e">Details about the suspend request.</param>
    private async void OnSuspending(object sender, SuspendingEventArgs e)
    {
        var deferral = e.SuspendingOperation.GetDeferral();
        //TODO: Save application state and stop any background activity
        await weather.Common.SuspensionManager.SaveAsync();
        deferral.Complete();
    }
}

这适用于 1 张图像，但我无法自动更改图像。有任何想法吗？

4

1 回答 1

1

从 Web 服务获取天气的代码在哪里？在该代码中，获取当前天气，然后根据预报设置背景图片。

于 2013-03-25T13:48:10.260 回答