c# – UWP – 以编程方式显示ItemTemplate中的进度条
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内容图文
我正在为Windows Mobile构建一个UWP应用程序,但我对进度条有点麻烦.我在应用程序启动的第一页上有一个工作,这很好,但现在我正在尝试在GridView中显示一个.我一次会在屏幕上有N个GridView控件,并希望在每个控件中显示一个ProgressBar.
这适用于数据绑定和数据将显示,但当我尝试在TextBlock之前添加不确定的ProgressBar它似乎没有显示.我只能假设我要么把它放在错误的地方,要么我做错了,因为我的GridView正在使用GridView.ItemTemplate.
以下是一些截图：
Without data in the collection
用答案更新
在贾斯汀XL的帮助下,我成功地解决了问题的根源.我绑定到普通的clr属性而不是DependencyProperty.我更改了代码以使用MVVM并设置IsLoaded属性来处理通知UI.这是我更新和工作的代码：
ViewModel.cs
public class ViewModel
{
public string Name { get; set; }
}
MainPageViewModel.cs
public class MainPageViewModel : INotifyPropertyChanged
{
public ObservableCollection<ViewModel> MyData { get; set; } = new ObservableCollection<ViewModel>();
private bool _isLoaded;
public bool IsLoaded
{
get { return _isLoaded; }
set
{
_isLoaded = value;
OnPropertyChanged();
}
}
public async Task GetDataAsync()
{
// Add items to MyData
IsLoaded = true;
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
MainPage.xaml.cs中
public sealed partial class MainPage : Page
{
public MainPage()
{
InitializeComponent();
DataContext = new MainPageViewModel();
}
public MainPageViewModel Vm => DataContext as MainPageViewModel;
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
await Vm.GetDataAsync();
}
}
MainPage.xaml中
<Page
x:Class="MultiGridProgressBars.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:MultiGridProgressBars"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:models="using:MultiGridProgressBars.Models"
mc:Ignorable="d">
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<GridView IsHitTestVisible="{x:Bind Vm.IsLoaded, Mode=OneWay}"
Header="A Grid View"
HorizontalAlignment="Left"
x:Name="MyDataListView1"
ItemsSource="{x:Bind Vm.MyData}"
Width="164"
Margin="10,53,0,53">
<GridView.ItemTemplate>
<DataTemplate x:DataType="models:ViewModel">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"></ColumnDefinition>
<ColumnDefinition Width="Auto"></ColumnDefinition>
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0" HorizontalAlignment="Stretch" TextWrapping="WrapWholeWords">
<Run Text="{ x:Bind Name }"></Run>
</TextBlock>
</Grid>
</DataTemplate>
</GridView.ItemTemplate>
<GridView.ItemContainerStyle>
<Style TargetType="GridViewItem">
<Setter Property="Margin" Value="0 0 0 10"></Setter>
<Setter Property="BorderThickness" Value="1"></Setter>
<Setter Property="BorderBrush" Value="Blue"></Setter>
<Setter Property="Padding" Value="5"></Setter>
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="VerticalContentAlignment" Value="Stretch"/>
<Setter Property="VerticalAlignment" Value="Stretch"/>
<Setter Property="Width" Value="150"></Setter>
<Setter Property="Height" Value="80"></Setter>
</Style>
</GridView.ItemContainerStyle>
</GridView>
</Grid>
</Page>
App.xaml中
<Application
x:Class="MultiGridProgressBars.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:MultiGridProgressBars"
xmlns:converters="using:MultiGridProgressBars.Converters"
RequestedTheme="Light">
<Application.Resources>
<converters:InvertIsCheckedVisiblityConverter x:Key="InvertIsCheckedVisiblityConverter" />
<Style TargetType="GridView">
<Setter Property="Padding" Value="0,0,0,10" />
<Setter Property="IsTabStop" Value="False" />
<Setter Property="TabNavigation" Value="Once" />
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.HorizontalScrollMode" Value="Disabled" />
<Setter Property="ScrollViewer.IsHorizontalRailEnabled" Value="False" />
<Setter Property="ScrollViewer.VerticalScrollMode" Value="Enabled" />
<Setter Property="ScrollViewer.IsVerticalRailEnabled" Value="True" />
<Setter Property="ScrollViewer.ZoomMode" Value="Disabled" />
<Setter Property="ScrollViewer.IsDeferredScrollingEnabled" Value="False" />
<Setter Property="ScrollViewer.BringIntoViewOnFocusChange" Value="True" />
<Setter Property="IsSwipeEnabled" Value="True" />
<Setter Property="ItemContainerTransitions">
<Setter.Value>
<TransitionCollection>
<AddDeleteThemeTransition />
<ContentThemeTransition />
<ReorderThemeTransition />
<EntranceThemeTransition IsStaggeringEnabled="False" />
</TransitionCollection>
</Setter.Value>
</Setter>
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<ItemsWrapGrid Orientation="Horizontal" />
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="GridView">
<Grid BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}">
<ScrollViewer x:Name="ScrollViewer"
AutomationProperties.AccessibilityView="Raw"
BringIntoViewOnFocusChange="{TemplateBinding ScrollViewer.BringIntoViewOnFocusChange}"
HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}"
HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}"
IsHorizontalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsHorizontalScrollChainingEnabled}"
IsVerticalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsVerticalScrollChainingEnabled}"
IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}"
IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}"
TabNavigation="{TemplateBinding TabNavigation}"
VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"
VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}"
ZoomMode="{TemplateBinding ScrollViewer.ZoomMode}">
<ItemsPresenter FooterTransitions="{TemplateBinding FooterTransitions}"
FooterTemplate="{TemplateBinding FooterTemplate}"
Footer="{TemplateBinding Footer}"
HeaderTemplate="{TemplateBinding HeaderTemplate}"
Header="{TemplateBinding Header}"
HeaderTransitions="{TemplateBinding HeaderTransitions}"
Padding="{TemplateBinding Padding}" />
</ScrollViewer>
<ProgressBar x:Name="StatusBar"
Visibility="{Binding IsHitTestVisible, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource InvertIsCheckedVisiblityConverter}}"
IsIndeterminate="True" />
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Application.Resources>
</Application>
InvertIsCheckedVisiblityConverter.cs
public class InvertIsCheckedVisiblityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
bool isChecked = (bool) value;
return isChecked ? Visibility.Collapsed : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, string language)
{
return null;
}
}
解决方法:
如果您想要一个位于GridView中心的ProgressBar,您需要将GridView包装在Grid中,并将ProgressBar放在GridView的顶部.像这样的东西 –
<Grid>
<GridView />
<ProgressBar x:Name="StatusBar"
IsIndeterminate="True"></ProgressBar>
</Grid>
当然,您只想在加载数据时显示它正在进行中,因此您需要一个实现INotifyPropertyChanged的IsLoading属性,然后将IsIndeterminate绑定到它.
IsIndeterminate="{Binding IsLoading}"
更新
为简化起见,您还可以将ProgressBar包装在GridView样式中.首先只是基于默认样式生成一个新样式,然后转到它的ControlTemplate并将根面板从Border更改为Grid,然后只需将ProgressBar放在那里,就像这样 –
<ControlTemplate TargetType="GridView">
<Grid BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}">
<ScrollViewer x:Name="ScrollViewer"
AutomationProperties.AccessibilityView="Raw"
BringIntoViewOnFocusChange="{TemplateBinding ScrollViewer.BringIntoViewOnFocusChange}"
HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}"
HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}"
IsHorizontalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsHorizontalScrollChainingEnabled}"
IsVerticalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsVerticalScrollChainingEnabled}"
IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}"
IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}"
TabNavigation="{TemplateBinding TabNavigation}"
VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"
VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}"
ZoomMode="{TemplateBinding ScrollViewer.ZoomMode}">
<ItemsPresenter FooterTransitions="{TemplateBinding FooterTransitions}"
FooterTemplate="{TemplateBinding FooterTemplate}"
Footer="{TemplateBinding Footer}"
HeaderTemplate="{TemplateBinding HeaderTemplate}"
Header="{TemplateBinding Header}"
HeaderTransitions="{TemplateBinding HeaderTransitions}"
Padding="{TemplateBinding Padding}" />
</ScrollViewer>
<ProgressBar x:Name="StatusBar"
IsIndeterminate="{Binding IsHitTestVisible, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource InvertBoolConverter}}" />
</Grid>
</ControlTemplate>
您还需要一个bool属性来控制ProgressBar的加载.在这里我们可以使用现有属性IsHitTestVisible.请注意,您还需要使用转换器反转该值.
最后,你可以通过这样做直接操纵加载视觉 –
<GridView IsHitTestVisible="{Binding IsLoaded}" Style="{StaticResource LoadingGridViewStyle}" />
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