2021年的UWP(6)——长生命周期Desktop Extension向UWP的反向通知

最新推荐文章于 2024-06-06 09:48:11 发布

转载最新推荐文章于 2024-06-06 09:48:11 发布 · 387 阅读

CC 4.0 BY-SA版权

原文链接：https://www.cnblogs.com/manupstairs/p/14582794.html

我们先从FrontUWP工程讲起，AppServiceHandler.cs是我创建的帮助Class，用来处理AppServiceConnectoin的Connected和RequestReceived事件。

复制代码
public void OnBackgroundActivated(AppServiceTriggerDetails details)
{
Connected?.Invoke(this, new AppServiceConnectionConnectedEventArgs(details.AppServiceConnection));
Connection = details.AppServiceConnection;
Connection.RequestReceived += Connection_RequestReceived;
}

    private void Connection_RequestReceived(AppServiceConnection sender, AppServiceRequestReceivedEventArgs args)
    {
        RequestReceived?.Invoke(this, args);
    }

复制代码
而OnBackgroundActivated事件则是在App.xaml.cs中，通过override UWP Application对象的OnBackgroundActivated方法来触发。这里是AppServiceConnection连接的起点，即源头。

复制代码
protected override void OnBackgroundActivated(BackgroundActivatedEventArgs args)
{
base.OnBackgroundActivated(args);
if (args.TaskInstance.TriggerDetails is AppServiceTriggerDetails details)
{
if (details.CallerPackageFamilyName == Package.Current.Id.FamilyName)
{
var deferral = args.TaskInstance.GetDeferral();
args.TaskInstance.Canceled += (sender, e) => { deferral?.Complete(); };
AppServiceHandler.Instance.OnBackgroundActivated(details);
}
}
}
复制代码
以上这些在前面几篇中都有提及，这里不再赘述。在UWP工程的MainPage中，我们记录了UWP进程的process id，Desktop Extension段会读取该值，用以检测UWP process的Exit事件，在UWP被关闭时释放资源。同时通过RequestReceived事件来将Desktop Extension反向通知的HotKey的值，通过HotKeyList绑定显示到UWP的界面上。

复制代码
protected async override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
Process process = Process.GetCurrentProcess();
ApplicationData.Current.LocalSettings.Values[“processId”] = process.Id;
if (ApiInformation.IsApiContractPresent(“Windows.ApplicationModel.FullTrustAppContract”, 1, 0))
{
await FullTrustProcessLauncher.LaunchFullTrustProcessForCurrentAppAsync();
}
AppServiceHandler.Instance.RequestReceived += Instance_RequestReceived;
}

    private async void Instance_RequestReceived(object sender, Windows.ApplicationModel.AppService.AppServiceRequestReceivedEventArgs e)
    {
        var message = e.Request.Message;
        if (message.TryGetValue("HotKey", out object keyCode))
        {
            await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.High, () => { HotKeyList.Add(keyCode.ToString()); });
        }
    }

复制代码
最后不要忘记给FrontUWP工程添加对Windows Desktop Extension for the UWP的引用。

我们转到Desktop这一边，ReverseNotificatio.Desktop是一个WinForms的程序，通过RegisterHotKey这个Win32的API来监听热键。如何实现监听热键我不做过多介绍，具体请参考示例代码。

    [DllImport("user32.dll")]
    public static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);

同时为了使用AppServiceConnection，添加了对Win10 API的引用，主要是WindowsRuntime和Windows.winmd这两个文件。前者通过Nuget添加，后者请参考《迁移桌面程序到MS Store（4）——桌面程序调用Win10 API》。

我想强调的是，不要在长生命周期的Desktop Extension进程中，去维护一个全局的AppServiceConnection，某软的文档并没有提到细节，但也明确指出AppServiceConnection在UWP进入suspended状态时，可能被释放。我们要做的事情，是在每一次的热键响应事件中，创建新的AppServiceConnection去发送消息。

复制代码
private async void hotkeys_HotkeyPressed(int ID)
{
var key = Enum.GetName(typeof(VirtualKey), ID);

        var message = new ValueSet
        {
            { "HotKey", key }
        };

        var connection = new AppServiceConnection
        {
            PackageFamilyName = Package.Current.Id.FamilyName,
            AppServiceName = "ReverseNotificationAppService"
        };
        connection.ServiceClosed += Connection_ServiceClosed;

        var status = await connection.OpenAsync();
        if (status == AppServiceConnectionStatus.Success)
        {
            var response = await connection.SendMessageAsync(message);
        }
    }

复制代码
不能保存已创建的AppServiceConnection来重复使用，有时会造成不便。但这也正是我将Desktop Extension分为4个场景的原因，针对不同的用途来创建特定类型的background process。

ReverseNotification.Package作为打包工程，我们需要注意添加对FrontUWP和Desktop的引用。以及编辑Package.appxmanifest文件，提供对AppService和Desktop Extension的支持。

复制代码

<uap:VisualElements
DisplayName=“ReverseNotification.Package”
Description=“ReverseNotification.Package”
BackgroundColor=“transparent”
Square150x150Logo=“Images\Square150x150Logo.png”
Square44x44Logo=“Images\Square44x44Logo.png”>
<uap:DefaultTile Wide310x150Logo=“Images\Wide310x150Logo.png” />
<uap:SplashScreen Image=“Images\SplashScreen.png” />
</uap:VisualElements>

<uap:Extension Category=“windows.appService”>
<uap:AppService Name=“ReverseNotificationAppService” />
</uap:Extension>
<desktop:Extension Category=“windows.fullTrustProcess” Executable=“ReverseNotification.Desktop\ReverseNotification.Desktop.exe”/>

USB Microphone https://www.soft-voice.com/
Wooden Speakers https://www.zeshuiplatform.com/
亚马逊测评 www.yisuping.cn
深圳网站建设www.sz886.com