目前我正在开发包含与GridView绑定的ObservableCollection的metro应用。我的问题是，当我选择单个项目并拖放它时，它工作正常，但当我选择多个项目并拖放它会抛出异常。例外如下所示。
#if DEBUG && !DISABLE_XAML_GENERATED_BREAK_ON_UNHANDLED_EXCEPTION
UnhandledException += (sender, e) =>
{
if (global::System.Diagnostics.Debugger.IsAttached) global::System.Diagnostics.Debugger.Break();
};
#endif
我的xaml代码如下所示。
<GridView Name="searchPanelGrid"
SelectionMode="Multiple"
CanReorderItems="True"
AllowDrop="True"
CanDragItems="True"
HorizontalAlignment="Left"
ItemsSource="{Binding Source={StaticResource CollectionItems}}"
Grid.Row="2"
ItemContainerStyle="{StaticResource CustomGridViewItemStyle}"
ScrollViewer.VerticalScrollMode="Auto"
ScrollViewer.VerticalScrollBarVisibility="Auto"
SelectionChanged="searchPanelGrid_SelectionChanged"
Width="920"
Height="Auto" Grid.ColumnSpan="3">
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<WrapGrid Orientation="Horizontal">
</WrapGrid>
</ItemsPanelTemplate>
</GridView.ItemsPanel>
<GridView.ItemTemplate>
<DataTemplate>
............
</DataTemplate>
<GridView.ItemTemplate>
我的容器样式如下所示。
<Style x:Key="CustomGridViewItemStyle" TargetType="GridViewItem">
<Setter Property="FontFamily" Value="{StaticResource ContentControlThemeFontFamily}"/>
<Setter Property="FontSize" Value="{StaticResource ControlContentThemeFontSize}"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="TabNavigation" Value="Local"/>
<Setter Property="IsHoldingEnabled" Value="True"/>
<Setter Property="Margin" Value="0,0,2,2"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="GridViewItem">
<Border x:Name="OuterContainer">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="PointerOver">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="PointerOverBorder"/>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Fill" Storyboard.TargetName="SelectionBackground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedPointerOverBackgroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Stroke" Storyboard.TargetName="SelectedBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="#CCC"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Fill" Storyboard.TargetName="SelectedEarmark">
<DiscreteObjectKeyFrame KeyTime="0" Value="#FF0C6EA6"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<PointerDownThemeAnimation TargetName="ContentContainer"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="PointerOverBorder"/>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Fill" Storyboard.TargetName="SelectionBackground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedPointerOverBackgroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Stroke" Storyboard.TargetName="SelectedBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedPointerOverBorderThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Fill" Storyboard.TargetName="SelectedEarmark">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedPointerOverBackgroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="PointerOverPressed">
<Storyboard>
<PointerDownThemeAnimation TargetName="ContentContainer"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="PointerOverBorder"/>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Fill" Storyboard.TargetName="SelectionBackground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedPointerOverBackgroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Stroke" Storyboard.TargetName="SelectedBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedPointerOverBorderThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Fill" Storyboard.TargetName="SelectedEarmark">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedPointerOverBackgroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Duration="0" To="{StaticResource ListViewItemDisabledThemeOpacity}" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="contentPresenter"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="FocusVisual"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
<VisualState x:Name="PointerFocused"/>
</VisualStateGroup>
<VisualStateGroup x:Name="SelectionHintStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0:0:0.65" To="NoSelectionHint"/>
</VisualStateGroup.Transitions>
<VisualState x:Name="VerticalSelectionHint">
<Storyboard>
<SwipeHintThemeAnimation ToHorizontalOffset="0" TargetName="SelectionBackground" ToVerticalOffset="15"/>
<SwipeHintThemeAnimation ToHorizontalOffset="0" TargetName="ContentBorder" ToVerticalOffset="15"/>
<SwipeHintThemeAnimation ToHorizontalOffset="0" TargetName="SelectedBorder" ToVerticalOffset="15"/>
<SwipeHintThemeAnimation ToHorizontalOffset="0" TargetName="SelectedCheckMark" ToVerticalOffset="15"/>
<DoubleAnimationUsingKeyFrames Duration="0:0:0.500" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="HintGlyph">
<DiscreteDoubleKeyFrame KeyTime="0:0:0" Value="0.5"/>
<DiscreteDoubleKeyFrame KeyTime="0:0:0.500" Value="0"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="HorizontalSelectionHint">
<Storyboard>
<SwipeHintThemeAnimation ToHorizontalOffset="-23" TargetName="SelectionBackground" ToVerticalOffset="0"/>
<SwipeHintThemeAnimation ToHorizontalOffset="-23" TargetName="ContentBorder" ToVerticalOffset="0"/>
<SwipeHintThemeAnimation ToHorizontalOffset="-23" TargetName="SelectedBorder" ToVerticalOffset="0"/>
<SwipeHintThemeAnimation ToHorizontalOffset="-23" TargetName="SelectedCheckMark" ToVerticalOffset="0"/>
<DoubleAnimationUsingKeyFrames Duration="0:0:0.500" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="HintGlyph">
<DiscreteDoubleKeyFrame KeyTime="0:0:0" Value="0.5"/>
<DiscreteDoubleKeyFrame KeyTime="0:0:0.500" Value="0"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="NoSelectionHint"/>
</VisualStateGroup>
<VisualStateGroup x:Name="SelectionStates">
<VisualState x:Name="Unselecting">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="HintGlyphBorder"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unselected">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="HintGlyphBorder"/>
</Storyboard>
</VisualState>
<VisualState x:Name="UnselectedPointerOver">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="HintGlyphBorder"/>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="contentPresenter">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedForegroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="UnselectedSwiping">
<Storyboard>
<DoubleAnimation Duration="0" To="0.5" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectingGlyph"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="HintGlyphBorder"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Selecting">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectionBackground"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectedBorder"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectingGlyph"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="HintGlyphBorder"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Selected">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectionBackground"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectedBorder"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectedCheckMark"/>
</Storyboard>
</VisualState>
<VisualState x:Name="SelectedSwiping">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectionBackground"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectedBorder"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectedCheckMark"/>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="contentPresenter">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ListViewItemSelectedForegroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="SelectedUnfocused">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectedBorder"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectedCheckMark"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="DragStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0:0:0.2" To="NotDragging"/>
</VisualStateGroup.Transitions>
<VisualState x:Name="NotDragging"/>
<VisualState x:Name="Dragging">
<Storyboard>
<DoubleAnimation Duration="0" To="{StaticResource ListViewItemDragThemeOpacity}" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="InnerDragContent"/>
<DragItemThemeAnimation TargetName="InnerDragContent"/>
<FadeOutThemeAnimation TargetName="SelectedCheckMarkOuter"/>
<FadeOutThemeAnimation TargetName="SelectedBorder"/>
</Storyboard>
</VisualState>
<VisualState x:Name="DraggingTarget">
<Storyboard>
<DropTargetItemThemeAnimation TargetName="OuterContainer"/>
</Storyboard>
</VisualState>
<VisualState x:Name="MultipleDraggingPrimary">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="MultiArrangeOverlayBackground"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="MultiArrangeOverlayText"/>
<DoubleAnimation Duration="0" To="{StaticResource ListViewItemDragThemeOpacity}" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="ContentBorder"/>
<FadeInThemeAnimation TargetName="MultiArrangeOverlayBackground"/>
<FadeInThemeAnimation TargetName="MultiArrangeOverlayText"/>
<DragItemThemeAnimation TargetName="ContentBorder"/>
<FadeOutThemeAnimation TargetName="SelectionBackground"/>
<FadeOutThemeAnimation TargetName="SelectedCheckMarkOuter"/>
<FadeOutThemeAnimation TargetName="SelectedBorder"/>
<FadeOutThemeAnimation TargetName="PointerOverBorder"/>
</Storyboard>
</VisualState>
<VisualState x:Name="MultipleDraggingSecondary">
<Storyboard>
<FadeOutThemeAnimation TargetName="ContentContainer"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="ReorderHintStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0:0:0.2" To="NoReorderHint"/>
</VisualStateGroup.Transitions>
<VisualState x:Name="NoReorderHint"/>
<VisualState x:Name="BottomReorderHint">
<Storyboard>
<DragOverThemeAnimation Direction="Bottom" ToOffset="{StaticResource ListViewItemReorderHintThemeOffset}" TargetName="ReorderHintContent"/>
</Storyboard>
</VisualState>
<VisualState x:Name="TopReorderHint">
<Storyboard>
<DragOverThemeAnimation Direction="Top" ToOffset="{StaticResource ListViewItemReorderHintThemeOffset}" TargetName="ReorderHintContent"/>
</Storyboard>
</VisualState>
<VisualState x:Name="RightReorderHint">
<Storyboard>
<DragOverThemeAnimation Direction="Right" ToOffset="{StaticResource ListViewItemReorderHintThemeOffset}" TargetName="ReorderHintContent"/>
</Storyboard>
</VisualState>
<VisualState x:Name="LeftReorderHint">
<Storyboard>
<DragOverThemeAnimation Direction="Left" ToOffset="{StaticResource ListViewItemReorderHintThemeOffset}" TargetName="ReorderHintContent"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="DataVirtualizationStates">
<VisualState x:Name="DataAvailable"/>
<VisualState x:Name="DataPlaceholder">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetProperty="Visibility" Storyboard.TargetName="PlaceholderTextBlock">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Duration="0" Storyboard.TargetProperty="Visibility" Storyboard.TargetName="PlaceholderRect">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid x:Name="ReorderHintContent" Background="Transparent">
<Path x:Name="SelectingGlyph" Data="F1 M133.1,17.9 L137.2,13.2 L144.6,19.6 L156.4,5.8 L161.2,9.9 L145.6,28.4 z" Fill="{StaticResource ListViewItemCheckSelectingThemeBrush}" FlowDirection="LeftToRight" HorizontalAlignment="Right" Height="13" Margin="0,9.5,9.5,0" Opacity="0" Stretch="Fill" VerticalAlignment="Top" Width="15"/>
<Border x:Name="HintGlyphBorder" HorizontalAlignment="Right" Height="40" Margin="4" Opacity="0" VerticalAlignment="Top" Width="40">
<Path x:Name="HintGlyph" Data="F1 M133.1,17.9 L137.2,13.2 L144.6,19.6 L156.4,5.8 L161.2,9.9 L145.6,28.4 z" Fill="{StaticResource ListViewItemCheckHintThemeBrush}" FlowDirection="LeftToRight" HorizontalAlignment="Right" Height="13" Margin="0,5.5,5.5,0" Opacity="0" Stretch="Fill" VerticalAlignment="Top" Width="15"/>
</Border>
<Border x:Name="ContentContainer" BorderThickness="0">
<Grid x:Name="InnerDragContent">
<Rectangle x:Name="PointerOverBorder" Fill="#CCC" IsHitTestVisible="False" Opacity="0" Margin="4"/>
<Rectangle x:Name="FocusVisual" IsHitTestVisible="False" Opacity="0" Stroke="{StaticResource ListViewItemFocusBorderThemeBrush}" StrokeThickness="2"/>
<Rectangle x:Name="SelectionBackground" Fill="{StaticResource ListViewItemSelectedBackgroundThemeBrush}" Opacity="0"/>
<ContentPresenter x:Name="contentPresenter" ContentTransitions="{TemplateBinding ContentTransitions}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
<TextBlock x:Name="PlaceholderTextBlock" Foreground="{x:Null}" IsHitTestVisible="False" Margin="{TemplateBinding Padding}" Text="Xg" Visibility="Collapsed"/>
<Rectangle x:Name="PlaceholderRect" Fill="{StaticResource ListViewItemPlaceholderBackgroundThemeBrush}" IsHitTestVisible="False" Visibility="Collapsed"/>
<Rectangle x:Name="MultiArrangeOverlayBackground" Fill="{StaticResource ListViewItemDragBackgroundThemeBrush}" IsHitTestVisible="False" Opacity="0"/>
<Rectangle x:Name="SelectedBorder" Margin="5" IsHitTestVisible="False" Opacity="0" Stroke="#CCC" StrokeThickness="1"/>
<Border x:Name="SelectedCheckMarkOuter" HorizontalAlignment="Right" IsHitTestVisible="False" Margin="0" VerticalAlignment="Top">
<Grid x:Name="SelectedCheckMark" Height="40" Opacity="0" Width="40" Margin="5">
<Path x:Name="SelectedEarmark" Data="M0,0 L40,0 L40,40 z" Fill="#FF0C6EA6" Stretch="Fill"/>
<Path Data="F1 M133.1,17.9 L137.2,13.2 L144.6,19.6 L156.4,5.8 L161.2,9.9 L145.6,28.4 z" Fill="{StaticResource ListViewItemCheckThemeBrush}" FlowDirection="LeftToRight" HorizontalAlignment="Right" Height="13" Margin="0,5.5,5.5,0" Stretch="Fill" VerticalAlignment="Top" Width="15"/>
</Grid>
</Border>
<TextBlock x:Name="MultiArrangeOverlayText" Foreground="{StaticResource ListViewItemDragForegroundThemeBrush}" FontSize="26.667" FontFamily="{StaticResource ContentControlThemeFontFamily}" IsHitTestVisible="False" Margin="18,9,0,0" Opacity="0" TextWrapping="Wrap" Text="{Binding TemplateSettings.DragItemsCount, RelativeSource={RelativeSource Mode=TemplatedParent}}" TextTrimming="WordEllipsis"/>
</Grid>
</Border>
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
为什么多次拖动会发生此异常？
答案 0 :(得分：1)
为什么你的失败，我不知道。但是，让我至少向您证明，可以在GridView中拖放/重新排序多个项目。这应该会给你一些希望。
使用此：
public class ViewModel
{
public ViewModel()
{
foreach (var item in Enumerable.Range(1, 50))
this.Items.Add(item);
}
ObservableCollection<int> _Items = new ObservableCollection<int>();
public ObservableCollection<int> Items { get { return _Items; } }
}
试试这个：
<Grid Background="Black">
<Grid.DataContext>
<local:ViewModel/>
</Grid.DataContext>
<GridView ItemsSource="{Binding Items}"
SelectionMode="Multiple"
AllowDrop="True"
CanDragItems="True"
CanReorderItems="True" />
</Grid>
祝你好运！