XAML ToggleButton使用isChecked=｛Binding xyz｝更改背景图像

Question

我的app.xaml中现在有以下工作代码。。。

<Style x:Key="likeActionButton" TargetType="ToggleButton">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ToggleButton">
                        <Grid>
                            <VisualStateManager.VisualStateGroups>
                                <VisualStateGroup x:Name="CommonStates">
                                    <VisualState x:Name="Normal">
                                    </VisualState>
                                    <VisualState x:Name="PointerOver">
                                        <Storyboard>
                                            <ObjectAnimationUsingKeyFrames
                                                Storyboard.TargetName="HoverBackground"
                                                Storyboard.TargetProperty = "Visibility">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Visible"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </VisualState>
                                    <VisualState x:Name="Pressed">
                                        <Storyboard>
                                            <ObjectAnimationUsingKeyFrames
                                                Storyboard.TargetName="PressedBackground"
                                                Storyboard.TargetProperty = "Visibility">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Visible"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </VisualState>
                                </VisualStateGroup>
                            </VisualStateManager.VisualStateGroups>
                            <Border>
                                <Grid>
                                    <Image Width="25" Source="ms-appx:///AssetsActionIconslike-action.png"></Image>
                                    <Image x:Name="HoverBackground" Width="25" Source="ms-appx:///AssetsActionIconslike-action-onHover.png" Visibility="Collapsed"></Image>
                                    <Image x:Name="PressedBackground" Width="25" Source="ms-appx:///AssetsActionIconslike-action-on-pressed.png" Visibility="Collapsed"></Image>
                                </Grid>
                            </Border>
                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>

我把这个模板称为：

<ToggleButton Grid.Column="4" HorizontalAlignment="Center" 
                                          Style="{StaticResource likeActionButton}" 
                                          IsChecked="{Binding LikeState}"  
                                          Tapped="Favourite_Tapped"></ToggleButton>

LikeState的绑定并不像我希望的那样完美。

这很难解释，但我会试试。。。

我可以选择和取消选择ToggleButton，背景图像将始终翻转。LikeState后面的绑定似乎对属性有效，但对图像无效。这意味着当数据加载和布尔值LikeState = true时，属性ToggleButton.IsChecked = true但是背景图像是VisualState x:Name="Normal"的图像。

再说一遍，换言之。。。我正在用LikeState = true加载数据。如果我第一次点击ToggleButton，背景图像不会改变，但代码隐藏文件执行isChecked = true的代码第二次点击ToggleButton将背景图像更改为VisualState x:Name="Pressed"

那么，我该怎么做才能根据动态填充属性isChecked={Binding LikeState} 设置正确的背景图像呢

干杯，

Chris

Answer 1

在绑定中尝试Mode=TwoWay。由于您在代码后面更改有界属性值，为了在视图中反映这一点，您必须将Mode指定为TwoWay

更新

我已经检查了你的代码。它在没有双向绑定的情况下运行良好。

使用视觉状态检查

<VisualStateManager.VisualStateGroups>
                                <VisualStateGroup x:Name="CommonStates">
                                    <VisualState x:Name="Normal"/>
                                    <VisualState x:Name="PointerOver"/>
                                    <VisualState x:Name="Pressed"/>
                                    <VisualState x:Name="Disabled">
                                      </VisualState>
                                    <VisualState x:Name="Checked">
                                        <Storyboard>
                                            <ObjectAnimationUsingKeyFrames
                                                Storyboard.TargetName="PressedBackground"
                                                Storyboard.TargetProperty = "Visibility">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Visible"/>
                                            </ObjectAnimationUsingKeyFrames>
                                           </Storyboard>
                                    </VisualState>
                                    <VisualState x:Name="CheckedPointerOver">
                                    </VisualState>
                                    <VisualState x:Name="CheckedPressed"/>
                                    <VisualState x:Name="CheckedDisabled">
                                    </VisualState>
                                    <VisualState x:Name="Indeterminate"/>
                                    <VisualState x:Name="IndeterminatePointerOver"/>
                                    <VisualState x:Name="IndeterminatePressed"/>
                                    <VisualState x:Name="IndeterminateDisabled">
                                    </VisualState>
                                </VisualStateGroup>
                            </VisualStateManager.VisualStateGroups>

希望您为LikeState属性实现INotifyPropertyChanged，以便在最初对其进行检查。如果没有，请执行以下操作。以下是我做的

 public sealed partial class MainPage : Page, INotifyPropertyChanged
    {
        bool likeState=true;
        public bool LikeState 
        {
            get { return likeState; }
            set
            {
                if(value!=likeState)
                {
                    value = likeState;
                    OnPropertyChanged("LikeState");
                }
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        void OnPropertyChanged(string propertyName)
        {
           if(this.PropertyChanged!=null)
                this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
        public MainPage()
        {
            this.InitializeComponent();
            this.NavigationCacheMode = NavigationCacheMode.Required;
            LikeState = true;
            toggle.DataContext = this;
        }
}