CommunityToolkit.Maui.Core.Views.MauiPopup在Close()上抛出System.ObjectDisposedException
CommunityToolkit.Maui.Core.Views.MauiPopup在Close()上抛出System.ObjectDisposedException
提问于 2022-09-27 21:00:31
当条形码被System.ObjectDisposedException检测到时，下面的代码会在BarcodeScannerPopup.xaml.cs中的行Close(result);上产生一个CameraBarcodeReaderView。
检测到的条形码在BarcodePage中的标签中正确显示。
知道为什么会抛出这个异常吗？
BarcodePage.xaml
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage
x:Class="MyApp.BarcodePage"
x:DataType="vm:BarcodeViewModel"
xmlns:vm="clr-namespace:MyApp.ViewModels"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns="http://schemas.microsoft.com/dotnet/2021/maui">
<VerticalStackLayout
Margin="20">
<Label
Text="{Binding Barcode}"/>
<Button
Command="{Binding ScanBarcodeClickCommand}"
Text="Scan barcode"/>
</VerticalStackLayout>
</ContentPage>BarcodePage.xaml.cs
using MyApp.ViewModels;
namespace MyApp.Views;
public partial class BarcodePage : ContentPage
{
public BarcodePage(BarcodeViewModel viewModel)
{
InitializeComponent();
BindingContext = viewModel;
}
}BarcodeScannerPopup.xaml
<?xml version="1.0" encoding="utf-8" ?>
<toolkit:Popup
x:Class="MyApp.BarcodeScannerPopup"
xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:zxing="clr-namespace:ZXing.Net.Maui.Controls;assembly=ZXing.Net.MAUI"
xmlns="http://schemas.microsoft.com/dotnet/2021/maui">
<VerticalStackLayout
Margin="20">
<Label
Text="Add a barcode by scanning it."
VerticalOptions="Center"
HorizontalOptions="Center"/>
<zxing:CameraBarcodeReaderView
x:Name="barcodeReader"
BarcodesDetected="BarcodesDetected"
HeightRequest="300"
IsDetecting="True"
Margin="5"
WidthRequest="300"/>
</VerticalStackLayout>
</toolkit:Popup>BarcodeScannerPopup.xaml.cs
using CommunityToolkit.Maui.Views;
using ZXing.Net.Maui;
namespace MyApp.Views;
public partial class BarcodeScannerPopup : Popup
{
public BarcodeScannerPopup()
{
InitializeComponent();
barcodeReader.Options = new BarcodeReaderOptions
{
AutoRotate = true,
Multiple = false
};
}
private void BarcodesDetected(object sender, BarcodeDetectionEventArgs e)
{
var result = e.Results[0].Value;
Close(result);
}
}BarcodeViewModel.cs
using CommunityToolkit.Maui.Views;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using MyApp.Views;
namespace MyApp.ViewModels;
public partial class BarcodeViewModel : ObservableObject
{
[ObservableProperty]
private string _barcode;
private BarcodeScannerPopup _popup = new BarcodeScannerPopup();
[RelayCommand]
public async Task ScanBarcodeClick()
{
Barcode = (string)await Application.Current.MainPage.ShowPopupAsync(_popup);
}
}回答 1
Stack Overflow用户
回答已采纳
发布于 2022-09-28 05:01:58
@ToolmakerSteve是对的。CameraBarcodeReaderView继续发送数据，这将导致System.ObjectDisposedException。将IsDetecting属性设置为false可以防止这种情况发生。由于这是一个PoC，我没有在e上添加一个适当的空检查，所以我在这个示例中添加了一个很好的编码实践。
BarcodeScannerPopup.xaml.cs
using CommunityToolkit.Maui.Views;
using ZXing.Net.Maui;
namespace MyApp.Views;
public partial class BarcodeScannerPopup : Popup
{
public BarcodeScannerPopup()
{
InitializeComponent();
barcodeReader.Options = new BarcodeReaderOptions
{
AutoRotate = true,
Multiple = false
};
}
private void BarcodesDetected(object sender, BarcodeDetectionEventArgs e)
{
var result = e?.Results?.Any() == true
? e.Results[0].Value
: string.Empty;
IsDetecting = false;
Close(result);
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/73873760
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