XAML 在.NET MAUI中使用CurrentItem时，CarouselView会导致Android应用程序崩溃

xriantvc  于 2023-09-28  发布在  .NET
关注(0)|答案(1)|浏览(136)

为什么我一刷我的CarouselView就得到一个目标调用异常？
自从我开始学习.NET MAUI以来，CarouselView一直工作，但由于某种原因，现在它不再工作了。就我而言，我没有做任何奇怪的事情，只是一个<CarouselView/>，一个ItemsSource和（显然是这里的罪魁祸首）一个CurrentItem，现在当它以任何方式改变时，它会突然抛出一个异常。无论是将Command与当前项一起用作CommandParameter，还是直接绑定CurrentItem属性，都将引发相同的异常。
System.Reflection.TargetInvocationException: 'Exception has been thrown by the target of an invocation.'

一切都正常工作，直到我将CurrentItem添加到CarouselView。它将呈现页面，但只要我滑动查看其中的其他项目，应用程序就会崩溃。直接绑定CurrentItem或使用命令更改它：

CurrentItemChangedCommand="{Binding CarouselItemChangedCommand}"
CurrentItemChangedCommandParameter="{Binding Source={RelativeSource Self}, Path=CurrentItem}"

都抛出这个异常。

简单的CarouselView：

<VerticalStackLayout>
    <CarouselView ItemsSource="{Binding Supports}"
                  CurrentItem="{Binding Support}"
                  IndicatorView="indicatorView"
                  IsSwipeEnabled="True"
                  Loop="False">
        <CarouselView.ItemTemplate>
            <DataTemplate x:DataType="m:Support">
                <VerticalStackLayout HorizontalOptions="Center">
                    <Frame Style="{StaticResource ItemFrameVisible}"
                            StyleClass="ItemFrame"
                            Padding="0,16,0,8"
                            Margin="0,16">
                        <VerticalStackLayout>
                            <Image Source="{Binding ImageFileSuffix, StringFormat='sp_{0}.svg'}"
                                    WidthRequest="280"/>
                            <Label Text="{Binding Title}"
                                    Style="{StaticResource TitleTiny}"
                                    StyleClass="Title"
                                    HorizontalOptions="Center"
                                    Margin="0,-56,0,0"/>
                        </VerticalStackLayout>
                    </Frame>
                </VerticalStackLayout>
            </DataTemplate>
        </CarouselView.ItemTemplate>
    </CarouselView>
    <IndicatorView SelectedIndicatorColor="{StaticResource GreenMain}"
                   IndicatorColor="{StaticResource Gray200}"
                   HorizontalOptions="Center"
                   x:Name="indicatorView"
                   MaximumVisible="14"
                   IndicatorSize="10"
                   Margin="0,12,0,0"/>
</VerticalStackLayout>

将Loop设置为true或false也没有区别。从CarouselView中删除CurrentItem属性解决了这个问题，但我不再能够使用ViewModel中的当前项来执行任务。

视图模型

private Support support;
public Support Support
{
    get => support;
    set => SetProperty(ref support, value);
}

public ObservableRangeCollection<Support> Supports { get; set; } = new();

BaseViewModel

public event PropertyChangedEventHandler PropertyChanged;

protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

protected bool SetProperty<TValue>(ref TValue backingField, TValue value, [CallerMemberName] string propertyName = null)
{
    if (Comparer<TValue>.Default.Compare(backingField, value) == 0)
    {
        return false;
    }

    backingField = value;

    OnPropertyChanged(propertyName);

    return true;
}

支持模式

标题、描述和ImageFileSuffix等数据在显示数据时正在工作，即使在滑动时，我也可以在应用程序崩溃之前清楚地看到下一个或上一个项目数据。

[Table("Support")]
public class Support
{
    [PrimaryKey]
    public int SupportId { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public string ImageFileSuffix { get; set; }
}

调用堆栈

0xFFFFFFFFFFFFFFFF in Android.Runtime.JNIEnv.monodroid_debugger_unhandled_exception C#  Annotated Frame
>   0x1A in Android.Runtime.JNINativeWrapper._unhandled_exception at C:\Users\genericUser13\AppData\Local\SourceServer\bb123c2c4d433ebca46498fd0d4b0728a9cd5eedc6e5d8398523e286da2078c9\JNINativeWrapper.g.cs:12,5  C#  Non-user code
0x22 in Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPLII_V at C:\Users\genericUser13\AppData\Local\SourceServer\bb123c2c4d433ebca46498fd0d4b0728a9cd5eedc6e5d8398523e286da2078c9\JNINativeWrapper.g.cs:287,26 C#  Non-user code
0x32 in System.Reflection.MethodInvoker.InterpretedInvoke   C#  Annotated Frame
0x4 in System.Reflection.MethodInvoker.InlinedInvoke    C#  Annotated Frame
0xCE in System.Reflection.RuntimeMethodInfo.Invoke  C#  Annotated Frame
0x6 in System.Reflection.MethodBase.Invoke  C#  Annotated Frame
0x31C in Microsoft.Maui.Controls.BindingExpression.ApplyCore at C:\Users\genericUser13\AppData\Local\SourceServer\62e8268ae92440603c63914b6d8a3b490f47ceaad21fcc1a5e51804834c6a305\BindingExpression.cs:188,5   C#  Non-user code
0x48 in Microsoft.Maui.Controls.BindingExpression.Apply at C:\Users\genericUser13\AppData\Local\SourceServer\62e8268ae92440603c63914b6d8a3b490f47ceaad21fcc1a5e51804834c6a305\BindingExpression.cs:56,5 C#  Non-user code
0x27 in Microsoft.Maui.Controls.Binding.Apply at C:\Users\genericUser13\AppData\Local\SourceServer\6dd575e617d2dceeb55a7d6f2e56ce8ff72455f7905177f12ed1e461a05ed3b4\Binding.cs:114,4    C#  Non-user code
0x108 in Microsoft.Maui.Controls.BindableObject.SetValueActual at C:\Users\genericUser13\AppData\Local\SourceServer\aefda1b85f6059f8ec86428ab2810170588db594e00bdaaaf0dcb2947296edc9\BindableObject.cs:529,6    C#  Non-user code
0x20C in Microsoft.Maui.Controls.BindableObject.SetValueCore at C:\Users\genericUser13\AppData\Local\SourceServer\aefda1b85f6059f8ec86428ab2810170588db594e00bdaaaf0dcb2947296edc9\BindableObject.cs:469,5  C#  Non-user code
0x5 in Microsoft.Maui.Controls.BindableObject.SetValueCore at C:\Users\genericUser13\AppData\Local\SourceServer\aefda1b85f6059f8ec86428ab2810170588db594e00bdaaaf0dcb2947296edc9\BindableObject.cs:401,7    C#  Non-user code
0x4 in Microsoft.Maui.Controls.Element.SetValueFromRenderer at C:\Users\genericUser13\AppData\Local\SourceServer\256b87211b5393e640c1d246067a29d574a61932c703f979f99c781ccba9b4c2\Element.cs:261,4  C#  Non-user code
0x61 in Microsoft.Maui.Controls.Handlers.Items.MauiCarouselRecyclerView.SetCurrentItem at C:\Users\genericUser13\AppData\Local\SourceServer\097a9d3b14092fcbf9468085ff0c7d892d23df3ce428f46e9656242399956b02\MauiCarouselRecyclerView.cs:456,4  C#  Non-user code
0x119 in Microsoft.Maui.Controls.Handlers.Items.MauiCarouselRecyclerView.Microsoft.Maui.Controls.Handlers.Items.IMauiCarouselRecyclerView.UpdateFromPosition at C:\Users\genericUser13\AppData\Local\SourceServer\097a9d3b14092fcbf9468085ff0c7d892d23df3ce428f46e9656242399956b02\MauiCarouselRecyclerView.cs:508,4    C#  Non-user code
0xB in Microsoft.Maui.Controls.Handlers.Items.CarouselViewHandler.MapPosition at C:\Users\genericUser13\AppData\Local\SourceServer\f03296ca69e671647e1230133f792254ee365c7cbaa947f2f3077fdf8d867aab\CarouselViewHandler.Android.cs:45,4 C#  Non-user code
0x21 in Microsoft.Maui.PropertyMapper<Microsoft.Maui.Controls.CarouselView,Microsoft.Maui.Controls.Handlers.Items.CarouselViewHandler>. at C:\Users\genericUser13\AppData\Local\SourceServer\00bf22cc3914378ecafa781a5dea0f3c344a52a09ca64c376cb2202c4c2e1ca3\PropertyMapper.cs:172,6   C#  Non-user code
0x17 in Microsoft.Maui.PropertyMapper.UpdatePropertyCore at C:\Users\genericUser13\AppData\Local\SourceServer\00bf22cc3914378ecafa781a5dea0f3c344a52a09ca64c376cb2202c4c2e1ca3\PropertyMapper.cs:47,4   C#  Non-user code
0x8 in Microsoft.Maui.PropertyMapper.UpdateProperty at C:\Users\genericUser13\AppData\Local\SourceServer\00bf22cc3914378ecafa781a5dea0f3c344a52a09ca64c376cb2202c4c2e1ca3\PropertyMapper.cs:72,4    C#  Non-user code
0x1C in Microsoft.Maui.Handlers.ElementHandler.UpdateValue at C:\Users\genericUser13\AppData\Local\SourceServer\13aa2389aeaa5f2f85d844344acd9ffd5bb52b2308b48237d1a1f7aba0bc87cd\ElementHandler.cs:87,4 C#  Non-user code
0x14 in Microsoft.Maui.Controls.Element.OnPropertyChanged at C:\Users\genericUser13\AppData\Local\SourceServer\256b87211b5393e640c1d246067a29d574a61932c703f979f99c781ccba9b4c2\Element.cs:383,4    C#  Non-user code
0x11B in Microsoft.Maui.Controls.BindableObject.SetValueActual at C:\Users\genericUser13\AppData\Local\SourceServer\aefda1b85f6059f8ec86428ab2810170588db594e00bdaaaf0dcb2947296edc9\BindableObject.cs:533,5    C#  Non-user code
0x20C in Microsoft.Maui.Controls.BindableObject.SetValueCore at C:\Users\genericUser13\AppData\Local\SourceServer\aefda1b85f6059f8ec86428ab2810170588db594e00bdaaaf0dcb2947296edc9\BindableObject.cs:469,5  C#  Non-user code
0x5 in Microsoft.Maui.Controls.BindableObject.SetValueCore at C:\Users\genericUser13\AppData\Local\SourceServer\aefda1b85f6059f8ec86428ab2810170588db594e00bdaaaf0dcb2947296edc9\BindableObject.cs:401,7    C#  Non-user code
0x4 in Microsoft.Maui.Controls.Element.SetValueFromRenderer at C:\Users\genericUser13\AppData\Local\SourceServer\256b87211b5393e640c1d246067a29d574a61932c703f979f99c781ccba9b4c2\Element.cs:261,4  C#  Non-user code
0x3A in Microsoft.Maui.Controls.Handlers.Items.MauiCarouselRecyclerView.UpdatePosition at C:\Users\genericUser13\AppData\Local\SourceServer\097a9d3b14092fcbf9468085ff0c7d892d23df3ce428f46e9656242399956b02\MauiCarouselRecyclerView.cs:447,5  C#  Non-user code
0x42 in Microsoft.Maui.Controls.Handlers.Items.MauiCarouselRecyclerView.CarouselViewScrolled at C:\Users\genericUser13\AppData\Local\SourceServer\097a9d3b14092fcbf9468085ff0c7d892d23df3ce428f46e9656242399956b02\MauiCarouselRecyclerView.cs:417,4    C#  Non-user code
0xE in Microsoft.Maui.Controls.ItemsView.SendScrolled at C:\Users\genericUser13\AppData\Local\SourceServer\4fe8e933f734ce9480a3c27fc094f2c3ee717b35003a01f015cbf8402e421275\ItemsView.cs:225,4  C#  Non-user code
0xA9 in Microsoft.Maui.Controls.Handlers.Items.RecyclerViewScrollListener<Microsoft.Maui.Controls.CarouselView,Microsoft.Maui.Controls.Handlers.Items.IItemsViewSource>.OnScrolled at C:\Users\genericUser13\AppData\Local\SourceServer\b212eda26d70d29f6668cbfaaf86f1a91cb82a7f5cac658b3d34bb2e99f6fb81\RecyclerViewScrollListener.cs:55,4 C#  Non-user code
0x4 in Microsoft.Maui.Controls.Handlers.Items.CarouselViewOnScrollListener.OnScrolled at C:\Users\genericUser13\AppData\Local\SourceServer\e515b26a062e48cba2b6fd7d25c47f0cbd339d0a041b04aabf55197dc71a562f\CarouselViewOnScrollListener.cs:33,4    C#  Non-user code
0x14 in AndroidX.RecyclerView.Widget.RecyclerView.OnScrollListener.n_OnScrolled_Landroidx_recyclerview_widget_RecyclerView_II at C:\a\_work\3\s\generated\androidx.recyclerview.recyclerview\obj\Release\net6.0-android\generated\src\AndroidX.RecyclerView.Widget.RecyclerView.cs:9152,5   C#  Annotated Frame
0xD in Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPLII_V at C:\Users\genericUser13\AppData\Local\SourceServer\bb123c2c4d433ebca46498fd0d4b0728a9cd5eedc6e5d8398523e286da2078c9\JNINativeWrapper.g.cs:286,5   C#  Non-user code
xaml

1条答案

按热度按时间
bfrts1fy

bfrts1fy1#

我可以重现你的问题，问题是在BaseViewModel的函数protected bool SetProperty<TValue>()中。
请尝试将其更改为以下代码：

bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
    {
        if (Object.Equals(storage, value))
            return false;
        storage = value;
        OnPropertyChanged(propertyName);
        return true;
    }
    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
    public event PropertyChangedEventHandler PropertyChanged;

    //protected bool SetProperty<TValue>(ref TValue backingField, TValue value, [CallerMemberName] string propertyName = null)
    //{

    // throw error here

    //    if (Comparer<TValue>.Default.Compare(backingField, value) == 0)    
    //    {
    //        return false;
    //    }

    //    backingField = value;

    //    OnPropertyChanged(propertyName);

    //    return true;
    //}

注：

请不要忘记为您的绑定添加符号}，就像ToolmakerSteve提到的那样。

CurrentItem="{Binding Support}"
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