滚动LongListSelector的奇怪行为 - WP8 [英] Strange behavior scrolling LongListSelector - WP8

问题描述

我有一个应用程序，我将用户的联系人保存在本地数据库中，然后将这些联系人绑定在LongListSelector中。

I have an app where I save the user's contacts in a local Database, then bind this contacts in a LongListSelector.

该应用程序有一个按钮，当点击时，更新本地数据库（使其
与devide相同 ）。

The app has a button that,, when clicked, update the local database (make it identical to the devide).

当有变化时，LongListSelector在从搜索返回到列表（视图）后有一个奇怪的行为：当我快速滚动或滚动一段时间后，会出现一个空白区域列表的中间。然后我发现，显然，
列表正在削减一些项目...

When there is changes, the LongListSelector has a strange behavior after return from search to the list (view): when I scroll fast or after some time scrolling, a blank space appears in the middle of the list. Then I found out that, apparently, the list is cutting some items...

这种行为只有在我有一个很长的列表，比如50个或更多项..

This behavior happens only when I have a long list, like 50 items or more..

我用这样的方式绑定LongListSelector上的项目：

I bind the items on LongListSelector this way:

XAML：

<Grid x:Name="ContentPanelContatos" Grid.Row="1" Margin="0" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" >
    <Grid x:Name="gridContatos" Grid.Row="1" Margin="12,2,12,0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" >
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <Grid Grid.Row="0" Margin="0,0,0,12" >
            <TextBox x:Name="tbxSearch" VerticalAlignment="Top" HorizontalAlignment="Stretch" Visibility="Collapsed" TextChanged="TbxSearch_TextChanged" LostFocus="TbxSearch_LostFocus" Style="{StaticResource TextBoxStyle}" />
        </Grid>

        <phone:LongListSelector Grid.Row="1" x:Name="llsContacts" ItemsSource="{Binding}"  SelectionChanged="llsContacts_SelectionChanged" >
            <phone:LongListSelector.ItemTemplate>
                <DataTemplate>
                    <ListBoxItem local:TiltEffect.IsTiltEnabled="true">
                        <Grid Margin="0,0,0,10" >
                            <TextBlock Text="{Binding NAME, Mode=TwoWay}" FontFamily="Segoe WP" FontSize="28" Margin="77,0,0,0" />
                            <TextBlock Text="{Binding Path=NUMBER, Mode=TwoWay}" FontFamily="Segoe WP Light" FontSize="17" Margin="77,33,0,0"/>
                        </Grid>
                    </ListBoxItem>
                </DataTemplate>
            </phone:LongListSelector.ItemTemplate>
        </phone:LongListSelector>       
    </Grid>

    <!-- more 2 grids with contents -->
</Grid>

我使用ObservableCollection绑定项目，我遇到了这个问题..然后我试图删除列表并再次绑定它（在搜索之后）这样：

I was binding the items using ObservableCollection and I was having this problem.. Then I tried to erase the list and bind it again (after the search) this way:

if (llsContacts.ItemsSource != null)
    llsContacts.ItemsSource.Clear();

llsContacts.DataContext = daoRd.GetData();

但我仍然遇到这个问题.. 。

But I'm still with this problem...

有人能告诉我发生了什么吗？
b $ b我做错了吗？

Does anybody can tell me what is happening?
Am I doing something wrong?

阅读本文：
Windows Phone中的帧速率计数器，我注意到当出现此问题时，调试时屏幕一侧的数字停止变化...

Reading this article: Frame rate counters in Windows Phone, I noticed that when this problem happens, some of the numbers that are on the side of the screen when debugging, stops changing...

他们这样停止：



用户界面线程FPS：000
$
纹理内存使用量：007181
$
表面计数器：050

中间纹理计数器：002

They stops like this:

User Interface Thread FPS: 000
Texture Memory Usage: 007181
Surface Counter: 050
Intermediate Texture Counter: 002

这个数字是否意味着什么？

Does this numbers means something?

推荐答案

您是否转储了从daoRD.GetData（）返回的内容？  可能是该集合中的一个项目有空字符串吗？  另外我注意到在设置DataContext之前清除了ItemsSource。 如果您在此之后立即设置DataContext，则可能不需要
。

have you dumped the contents of what is returned from daoRD.GetData()?   Could be one of the items in the collection has blank strings?   Also I noticed you clear the ItemsSource before setting the DataContext.  That is probably not necessary if you are setting the DataContext immediately after that.

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