UWP BarcodeScanner预览:CaptureElement不显示任何预览 [英] UWP BarcodeScanner Preview: CaptureElement doesn't show any Preview
问题描述
我的CaptureElements显示奇怪的行为.当我将实例化的MediaCapture设置为CaptureElements源，然后调用MediaCapture.StartPreviewAsync()时，CaptureElement不显示任何内容.
My CaptureElements are showing strange behavior. When I set a instantiated MediaCapture as the CaptureElements Source and then call MediaCapture.StartPreviewAsync() the CaptureElement doesn't show anything.
我在LoginPage上有一个功能正常的BarcodeScanner的应用程序(主应用程序). ->有效！
I have one Application (main-app) with a functional BarcodeScanner on the LoginPage. -> Works!
然后我想将相同的代码进行少量修改复制到SettingsPage，以便在连接多个摄像机的情况下可以设置默认摄像机. ->不起作用
Then I wanted to copy the same code to the SettingsPage with small modifications so in case of several attached cameras, the default one can be set. -> Doesn't work
然后，我尝试在远程调试器的帮助下，在与我的计算机具有相同Windows 10版本的其他Windows平板电脑上运行main-app(请记住，登录屏幕上的BarcodeScanner在我的计算机上可以运行). ->不起作用
Then I tried to run the main-app with the help of the remote debugger on other windows tablets with same Windows 10 Version as my machine (keep in mind, that the BarcodeScanner on the Login-Screen works on my machine). -> doesn't work
由于这些失败，我将正在运行的代码从主应用程序LoginPage复制到了一个全新的解决方案(称为test-app)，其设置与原始解决方案相同.我什至尝试引用相同的Dll，实现相同的设计模式等. ->不起作用
Because of these failures I copied the running code from the main-apps LoginPage to a completely new solution (lets call it test-app) with the same settings as the original one. I even experimented with referencing the same Dlls, implementing the same design pattern etc. -> doesn't work
我的机器: 赢10 Pro 1809版 内部版本17763.652
My Machine: Win 10 Pro Version 1809 Build 17763.652
DevEnv: MS Visual Studio 2019专业版 版本16.1.6
DevEnv: MS Visual Studio 2019 Pro Vers. 16.1.6
作为最低要求的Windows版本，我选择了Build 16229和 我的目标版本是Build 17763(我的系统Win版本)
As minimum required Windows Version I selected Build 16229 and my target Version is Build 17763 (my systems Win version)
寡妇设置"中的允许应用程序访问您的相机"选项已打开，因此所有应用程序都可以访问相机.
The "Allow apps to access your camera"-Option in the Widows Settings is switched to ON, so all apps are allowed to access the camera.
Xaml
<Page
x:Class="QrCodeTest.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:QrCodeTest"
xmlns:vm="using:QrCodeTest.ViewModels"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Page.DataContext>
<vm:TestViewModel x:Name="ViewModel" />
</Page.DataContext>
<ScrollViewer>
<StackPanel>
<Button Content="Start Preview" HorizontalAlignment="Center" Click="Button_Click" Margin="5" />
<CaptureElement x:Name="capturePreview" HorizontalAlignment="Center" Stretch="Uniform" Width="0" Height="0" Margin="10" />
<Button Content="Stop Preview" HorizontalAlignment="Center" Click="Button_Click_1" Margin="5" />
<TextBlock Text="{Binding Etikett, Mode=TwoWay}" HorizontalAlignment="Center" Margin="5" />
</StackPanel>
</ScrollViewer>
</Page>
CodeBehind
CodeBehind
private BarcodeScanner scanner { get; set; }
private ClaimedBarcodeScanner claimedScanner { get; set; }
private MediaCapture captureManager { get; set; }
internal async Task StartScannerAsync () {
capturePreview.Visibility = Visibility.Visible;
capturePreview.Width = 400; capturePreview.Height = 300;
scanner = null;
scanner = await DeviceHelpers.GetFirstDeviceAsync(BarcodeScanner.GetDeviceSelector(connectionTypes), async (id) => await BarcodeScanner.FromIdAsync(id));
if (scanner != null) {
captureManager = new MediaCapture();
claimedScanner = await scanner.ClaimScannerAsync();
if (claimedScanner != null) {
claimedScanner.ReleaseDeviceRequested += claimedScanner_ReleaseDeviceRequested;
claimedScanner.DataReceived += claimedScanner_DataReceived;
claimedScanner.IsDecodeDataEnabled = true;
IReadOnlyList<uint> supportedSymbologies = await scanner.GetSupportedSymbologiesAsync();
foreach (uint symbology in supportedSymbologies) {
listOfSymbologies.Add(new SymbologyListEntry(symbology));
}
await claimedScanner.EnableAsync();
MediaCaptureInitializationSettings _captureInitSettings = new MediaCaptureInitializationSettings {
VideoDeviceId = scanner.VideoDeviceId,
StreamingCaptureMode = StreamingCaptureMode.AudioAndVideo,
PhotoCaptureSource = PhotoCaptureSource.VideoPreview
};
await captureManager.InitializeAsync(_captureInitSettings);
capturePreview.Source = captureManager;
try {
// Change to false, in case you wanna compare different methods of doing the same
bool Like_MP_PAT_UWP = false;
if (Like_MP_PAT_UWP) {
await capturePreview.Source.StartPreviewAsync();
await claimedScanner.StartSoftwareTriggerAsync();
} else {
LocalDataContext.Etikett = "await captureManager.StartPreviewAsync();";
await captureManager.StartPreviewAsync();
await claimedScanner.StartSoftwareTriggerAsync();
Thread.Sleep(2000);
await claimedScanner.StopSoftwareTriggerAsync();
await captureManager.StopPreviewAsync();
LocalDataContext.Etikett = "await capturePreview.Source.StartPreviewAsync();";
await capturePreview.Source.StartPreviewAsync();
await claimedScanner.StartSoftwareTriggerAsync();
Thread.Sleep(2000);
await claimedScanner.StopSoftwareTriggerAsync();
await capturePreview.Source.StopPreviewAsync();
LocalDataContext.Etikett = "await claimedScanner.ShowVideoPreviewAsync();";
await claimedScanner.ShowVideoPreviewAsync();
await claimedScanner.StartSoftwareTriggerAsync();
Thread.Sleep(2000);
await claimedScanner.StopSoftwareTriggerAsync();
claimedScanner.HideVideoPreview();
}
} catch (Exception e) {
Exception x = e; displayRequest.RequestRelease();
} finally {
LocalDataContext.Etikett = string.Empty;
}
}
}
}
ViewModel:
ViewModel:
public class TestViewModel: INotifyPropertyChanged {
public static TestViewModel Instance { get; set; }
private string _Etikett;
public string Etikett { get { return _Etikett; } set { _Etikett = value; NotifyPropertyChanged(); } }
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged ([CallerMemberName] String propertyName = "") {
//PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
if (PropertyChanged != null) {
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
为了比较解决方案，代码等，我已经浪费了4个工作日.以上代码是从test-app复制而来的，但它与主应用程序LoginPage上的代码基本相同("if (Like_MP_PAT_UWP){...}".
I've wasted already 4 working days just to compare the solutions, the codes etc. The above code was copied from the test-app but it's mostly identical to the one on the main-apps LoginPage (except for the "if (Like_MP_PAT_UWP) {...}".
每个提示都是欢迎的.
谢谢.
推荐答案
问题是Kaspersky Endpoint Security的高级威胁防护/主机入侵防御"设置.它阻止了开发硬盘驱动器(即平板电脑或网络驱动器)上的所有外部应用访问相机(Dev-Drive =受信任的区域").
The Problem was Kaspersky Endpoint Security's "advanced Threat Protection/host intrusion prevention"-setting. It prevented ALL apps outside from our dev-harddrive (i. e. on our tablets or from our network-drive) to access the camera (Dev-Drive = "Trusted Zone").
有必要在整个环境中重新配置Kaspersky Endpoint Security中的功能(将必要的位置/客户端声明为受信任的区域).
It was necessary to reconfigure that feature in Kaspersky Endpoint Security for the whole environment (declare necessary locations/clients as a trusted zone).
希望，这可能会帮助遇到类似问题的人，或者至少给某人一些提示.
Hope, this might help someone with a similar problem or at least give a hint to someone.
这篇关于UWP BarcodeScanner预览:CaptureElement不显示任何预览的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
