wpf – 如何从ViewModel更改视图中的VisualState？

概述我是 WPF和MVVM的新手.我认为这是一个简单的问题.我的ViewModel正在执行一个异步调用,以获取DataGrid的数据,该DataGrid绑定到ViewModel中的一个ObservableCollection.加载数据时,我设置了适当的ViewModel属性,DataGrid显示数据没有问题.但是,我想为用户介绍数据加载的视觉提示.所以,使用Blend,我把它添加到我的标记： <Vis 我是 WPF和MVVM的新手.我认为这是一个简单的问题.我的viewmodel正在执行一个异步调用,以获取DataGrID的数据,该DataGrID绑定到viewmodel中的一个ObservableCollection.加载数据时,我设置了适当的viewmodel属性,DataGrID显示数据没有问题.但是,我想为用户介绍数据加载的视觉提示.所以,使用Blend,我把它添加到我的标记：

<visualstatemanager.VisualStateGroups>        <VisualStateGroup x:@R_502_6889@="LoadingStateGroup">            <VisualState x:@R_502_6889@="HistoryLoading">                <Storyboard>                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.Target@R_502_6889@="HistoryGrID">                        <discreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.HIDden}"/>                    </ObjectAnimationUsingKeyFrames>                </Storyboard>            </VisualState>            <VisualState x:@R_502_6889@="HistoryLoaded">                <Storyboard>                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.Target@R_502_6889@="WorkingStackPanel">                        <discreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.HIDden}"/>                    </ObjectAnimationUsingKeyFrames>                </Storyboard>            </VisualState>        </VisualStateGroup>    </visualstatemanager.VisualStateGroups>

我想我知道如何改变我的代码隐藏状态(类似于此)：

visualstatemanager.GotoElementState(LayoutRoot,"HistoryLoaded",true);

但是,我想要做的这个方面是在我的viewmodel的I / O完成方法中,它没有引用它的相应视图.我将如何使用MVVM模式来实现？

解决方法 你可以这样做：

XAML

<Window x:Class="WpfSOTest.BusyWindow"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:local="clr-@R_502_6889@space:WpfSOTest"    title="BusyWindow"    Height="300"    WIDth="300"><Window.Resources>    <local:VisibilityConverter x:Key="VisibilityConverter" /></Window.Resources><GrID>    <GrID.RowDeFinitions>        <RowDeFinition />        <RowDeFinition Height="auto" />    </GrID.RowDeFinitions>    <border GrID.Row="0">        <GrID>            <border>                <Rectangle WIDth="400"                           Height="400"                           Fill="#EEE" />            </border>            <border Visibility="{Binding IsBusy,Converter={StaticResource VisibilityConverter}}">                <GrID>                    <Rectangle WIDth="400"                               Height="400"                               Fill="#AAA" />                    <TextBlock Text="Busy"                               HorizontalAlignment="Center"                               VerticalAlignment="Center" />                </GrID>            </border>        </GrID>    </border>    <border GrID.Row="1">        <button Click="ChangeVisualState">Change Visual State</button>    </border></GrID>

码：

public partial class BusyWindow : Window{    viewmodel viewmodel = new viewmodel();    public BusyWindow()    {        InitializeComponent();        DataContext = viewmodel;    }    private voID ChangeVisualState(object sender,RoutedEventArgs e)    {        viewmodel.IsBusy = !viewmodel.IsBusy;    }}public class viewmodel : INotifyPropertyChanged{    protected Boolean _isBusy;    public Boolean IsBusy    {        get { return _isBusy; }        set { _isBusy = value; RaisePropertyChanged("IsBusy"); }    }    public viewmodel()    {        IsBusy = false;    }    public event PropertyChangedEventHandler PropertyChanged;    public voID RaisePropertyChanged(String property@R_502_6889@)    {        PropertyChangedEventHandler temp = PropertyChanged;        if (temp != null)        {            temp(this,new PropertyChangedEventArgs(property@R_502_6889@));        }    }}class VisibilityConverter : IValueConverter{    public object Convert(object value,Type targettype,object parameter,System.Globalization.CultureInfo culture)    {        switch (((Boolean)value))        {            case true:                return Visibility.Visible;        }        return Visibility.Collapsed;    }    public object ConvertBack(object value,System.Globalization.CultureInfo culture)    {        throw new NotImplementedException();    }}

———————–更新代码———————–

XAML

<GrID>    <GrID.RowDeFinitions>        <RowDeFinition />        <RowDeFinition Height="auto" />    </GrID.RowDeFinitions>    <border GrID.Row="0">        <GrID>            <local:Myborder IsBusy="{Binding IsBusy}">                <GrID>                    <TextBlock Text="{Binding IsBusy}"                               HorizontalAlignment="Center"                               VerticalAlignment="Center" />                </GrID>            </local:Myborder>        </GrID>    </border>    <border GrID.Row="1">        <button Click="ChangeVisualState">Change Visual State</button>    </border></GrID>

模板

<Style targettype="{x:Type local:Myborder}">    <Setter Property="Template">        <Setter.Value>            <ControlTemplate targettype="{x:Type local:Myborder}">                <border @R_502_6889@="Rootborder">                    <border.Background>                        <SolIDcolorBrush x:@R_502_6889@="normalBrush"                                         color="@R_502_3318@" />                    </border.Background>                    <visualstatemanager.VisualStateGroups>                        <VisualStateGroup @R_502_6889@="CommonGroups">                            <VisualState @R_502_6889@="normal" />                        </VisualStateGroup>                        <VisualStateGroup @R_502_6889@="CustomGroups">                            <VisualState @R_502_6889@="Busy">                                <VisualState.Storyboard>                                    <Storyboard>                                        <colorAnimation Storyboard.Target@R_502_6889@="normalBrush"                                                        Storyboard.TargetProperty="color"                                                        Duration="0:0:0.5"                                                        autoReverse="True"                                                        RepeatBehavior="Forever"                                                        To="#EEE" />                                    </Storyboard>                                </VisualState.Storyboard>                            </VisualState>                        </VisualStateGroup>                    </visualstatemanager.VisualStateGroups>                    <ContentPresenter />                </border>            </ControlTemplate>        </Setter.Value>    </Setter></Style>

自定义元素

[TemplateVisualState(Group@R_502_6889@ = "CustomGroups",@R_502_6889@ = "Busy")]public class Myborder : ContentControl{    static Myborder()    {        DefaultStyleKeyProperty.OverrIDeMetadata(typeof(Myborder),new FrameworkPropertyMetadata(typeof(Myborder)));    }    public Boolean IsBusy    {        get { return (Boolean)GetValue(IsBusyProperty); }        set { SetValue(IsBusyProperty,value); }    }    public static Readonly DependencyProperty IsBusyProperty =        DependencyProperty.Register("IsBusy",typeof(Boolean),typeof(Myborder),new UIPropertyMetadata(IsBusyPropertyChangedCallback));    static voID IsBusyPropertyChangedCallback(DependencyObject d,DependencyPropertyChangedEventArgs e)    {        (d as Myborder).OnIsBusyPropertyChanged(d,e);    }    private voID OnIsBusyPropertyChanged(DependencyObject d,DependencyPropertyChangedEventArgs e)    {        if (Convert.ToBoolean(e.NewValue))        {            visualstatemanager.GoToState(this,"Busy",true);        }        else        {            visualstatemanager.GoToState(this,"normal",true);        }    }}

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