Windows平台错误上的MAUI媒体选择器

Question

我创建了一个非常基本的Mauiapp，因为我想在Windows平台上尝试MediaPicker。

因此，我从官方文档并尝试运行我的应用程序

，但是，如果我添加＆lt; uap：功能名称=“ webCam”/＆gt;到package> package.appxmanifest file file如文档中所建议的，并运行应用程序给我以下错误：

Error       DEP0700: Registration of the app failed. [0x80080204] error 0xC00CE169: App 
manifest validation error: The app manifest must be valid as per schema: Line 39, Column 
21, Reason: 'webcam' violates enumeration constraint of 'documentsLibrary 
picturesLibrary videosLibrary musicLibrary enterpriseAuthentication 
sharedUserCertificates userAccountInformation removableStorage appointments contacts 
phoneCall blockedChatMessages objects3D voipCall chat'.
The attribute 'Name' with value 'webcam' failed to parse.   MauiApp3            
        

因此，为了解决此问题，我尝试将功能从＆lt; uap：功能名称=“ webcam”/＆gt; to ＆lt; devicecapibility name =“ WebCam”/＆gt;。

这样，我可以无错误地运行应用程序，但是photo始终为null：

public async void TakePhoto(object sender, EventArgs e)
{
    if (MediaPicker.Default.IsCaptureSupported)
    {
        FileResult photo = await MediaPicker.Default.CapturePhotoAsync();
        
        if (photo != null)
        {
            // save the file into local storage
            string localFilePath = Path.Combine(FileSystem.CacheDirectory, photo.FileName);

            using Stream sourceStream = await photo.OpenReadAsync();
            using FileStream localFileStream = File.OpenWrite(localFilePath);

            await sourceStream.CopyToAsync(localFileStream);
        }
        else
        {
            // *** IT ALWAYS ENTERS IN THE ELSE CLAUSE ***
            // *** BECAUSE photo IS ALWAYS NULL ***
            CounterBtn.Text = $"Capture is supported but {photo} is null";
        }
    }
}

注意：当我单击我在mainpage.xaml <我单击此按钮时，上述函数被调用。 /代码>文件：

        <Button 
            x:Name="ImageBtn"
            Text="Take Photo"
            SemanticProperties.Hint="Take Image"
            Clicked="TakePhoto"
            HorizontalOptions="Center" />

Answer 1

不幸的是，这是Winui3的古老而已知的错误。
microsoft/windowsappsdk＃1034

作为一种可行的方法，您可以从用于Android，iOS和催化剂的毛伊岛。

然后，为Windows实现自定义媒体挑选器，并在所有capture ...方法中使用capture> capturephotoasync使用自定义类用于摄像机捕获：

public async Task<FileResult> CaptureAsync(MediaPickerOptions options, bool photo)
{
    var captureUi = new CameraCaptureUI(options);

    var file = await captureUi.CaptureFileAsync(photo ? CameraCaptureUIMode.Photo : CameraCaptureUIMode.Video);

    if (file != null)
        return new FileResult(file.Path,file.ContentType);

    return null;
}

这是新的camerAcaptureui class：

public async Task<StorageFile> CaptureFileAsync(CameraCaptureUIMode mode)
{
    var extension = mode == CameraCaptureUIMode.Photo ? ".jpg" : ".mp4";

    var currentAppData = ApplicationData.Current;
    var tempLocation = currentAppData.LocalCacheFolder;
    var tempFileName = $"CCapture{extension}";
    var tempFile = await tempLocation.CreateFileAsync(tempFileName, CreationCollisionOption.GenerateUniqueName);
    var token = Windows.ApplicationModel.DataTransfer.SharedStorageAccessManager.AddFile(tempFile);

    var set = new ValueSet();
    if (mode == CameraCaptureUIMode.Photo)
    {
        set.Add("MediaType", "photo");
        set.Add("PhotoFileToken", token);
    }
    else
    {
        set.Add("MediaType", "video");
        set.Add("VideoFileToken", token);
    }

    var uri = new Uri("microsoft.windows.camera.picker:");
    var result = await Windows.System.Launcher.LaunchUriForResultsAsync(uri, _launcherOptions, set);
    if (result.Status == LaunchUriStatus.Success && result.Result != null)
    {
        return tempFile;
    }

    return null;
}

也在package.appxmanifest中添加以下功能：

<DeviceCapability Name="microphone"/>
<DeviceCapability Name="webcam"/>

摄像头类的学分

编辑：
修改的代码允许视频捕获，