ListView 不会更新 Android 和 iOS 中的单元格高度 [英] ListView doesn't update Cell height in Android and iOS
问题描述
我正在尝试制作一个可扩展的 ListView，但在 Android 和 iOS(在 UWP 中有效)中遇到了问题(不工作).尝试了很多布局，也尝试在列表中创建一个列表并面临相同的结果.Android 和 iOS 拒绝更新 Cell 的高度.
I'm trying to make an expandable ListView, but facing issues (not working) in Android and iOS (Works in UWP). Tried, many layouts and also tried to make a List inside the list and faced the same result. Android and iOS refuse to update the height of the Cell.
我的 Xaml
<ListView ItemsSource="{Binding groups}"
IsGroupingEnabled="true"
HasUnevenRows="False"
SelectionMode="None"
VerticalScrollBarVisibility="Never"
>
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell>
<StackLayout Padding="5" VerticalOptions="FillAndExpand">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding HideShowItems}" CommandParameter="{Binding .}" />
</StackLayout.GestureRecognizers>
<Label Text="{Binding GroupKey}" HorizontalOptions="Center" HorizontalTextAlignment="Center" VerticalTextAlignment="Center" VerticalOptions="FillAndExpand"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<Grid Padding="0" HeightRequest="{Binding rowHeight}" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<BoxView Grid.Row="0" HorizontalOptions="FillAndExpand"
BackgroundColor="{Binding BtnColour}" />
</Grid>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
处理更改的命令
public Command HideShowItems => new Command(async (sender) =>
{
var dropDown = sender as DropDownMenu;
foreach(DropDownButton dr in dropDown)
{
if (dr.rowHeight > 0)
{
while(dr.rowHeight > 0)
{
dr.rowHeight = dr.rowHeight - 5;
await Task.Delay(5);
}
}
else
{
while(dr.rowHeight < 40)
{
dr.rowHeight = dr.rowHeight + 5;
await Task.Delay(5);
}
}
}
});
尝试了很多网上找到的例子，但似乎都没有.
Tried quite a few examples found online and none seem to do it.
仍处于学习阶段，如果您在代码中看到任何可以做得更好的地方时提供反馈会很有帮助.
Still being in the learning stage, it would be helpful if you'd give a feedback when you see anything in the code that could be done better.
非常感谢！
推荐答案
我已经使用其他 Xamarin 表单创建了所需的逻辑.这并不是说我已经回答了有关 ListView 的问题，并且更改可能需要由 Xamarin 团队完成，但这就是我创建可扩展列表的目的.
I have created the needed logic using other Xamarin Forms. This is not to say I have answered the question about ListView and changes will probably need to be done by the Xamarin team, but this is what I came out with to create an expandable List.
XAML
<ScrollView x:Name="ScrollActivity" VerticalScrollBarVisibility="Never" >
<Grid x:Name="GridContent" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="20*"/>
<ColumnDefinition Width="80*"/>
</Grid.ColumnDefinitions>
<StackLayout BackgroundColor="#f0dfe2" x:Name="buttonHolder" BindableLayout.ItemsSource="{Binding sideMenu}" >
<BindableLayout.ItemTemplate>
<DataTemplate>
<StackLayout BackgroundColor="#f0dfe2">
<StackLayout HeightRequest="50" BackgroundColor="#38292c">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding Source={x:Reference buttonHolder}, Path=BindingContext.ShowHideCommand}"
CommandParameter="{Binding .}"/>
</StackLayout.GestureRecognizers>
<Label FontSize="Medium" HorizontalOptions="Center" VerticalOptions="Center" HorizontalTextAlignment="Center" VerticalTextAlignment="Center" TextColor="White" Text="{Binding title}"/>
</StackLayout>
<StackLayout HeightRequest="{Binding rowHeight}"
BindableLayout.ItemsSource="{Binding device}" >
<BindableLayout.ItemTemplate>
<DataTemplate>
<Frame Padding="0" CornerRadius="10">
<Frame.GestureRecognizers>
<PanGestureRecognizer PanUpdated="PanGestureRecognizer_PanUpdated_1">
</PanGestureRecognizer>
</Frame.GestureRecognizers>
<Grid HeightRequest="40" BackgroundColor="{Binding btnBkColour}" IsVisible="{Binding visibility}" >
<Label HorizontalOptions="Center" VerticalOptions="Center" HorizontalTextAlignment="Center" VerticalTextAlignment="Center" TextColor="White" Text="{Binding deviceTitle}" />
</Grid>
</Frame>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout >
</StackLayout>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout >
</Grid>
</ScrollView>
处理扩展的命令
public Command ShowHideCommand => new Command(async (sender) =>
{
var sideMenu = sender as SideMenuObject;
if (changeTriggered == false)
{
changeTriggered = true;
if (sideMenu.rowHeight > 0)
{
foreach (SideMenuDevice dev in sideMenu.device)
{
dev.visibility = false;
while (sideMenu.rowHeight >(sideMenu.device.Count - (sideMenu.device.IndexOf(dev) + 1))*40)
{
sideMenu.rowHeight = sideMenu.rowHeight - 5;
await Task.Delay(5);
}
}
}
else
{
foreach (SideMenuDevice dev in sideMenu.device)
{
while (sideMenu.rowHeight <= (sideMenu.device.IndexOf(dev) +1 ) *40)
{
sideMenu.rowHeight = sideMenu.rowHeight + 5;
await Task.Delay(5);
}
dev.visibility = true;
}
}
}
changeTriggered = false;
});
如果可以，请提供反馈！
Please give feedback, if you can!
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