Question

我有一个矩形，我希望根据我的page.cs中的值是否在某些值之间设置4个不同的图标，例如：

If value is 0 show icon 1.
if value is larger than 0 but smaller or equal to 0.25 show icon 2.
If value is >0.25 && value is <=0.5 show icon 3.
If value is >0.5 && value is <=0.75, show icon 4.
and If value is >0.75 && value is <=1 show icon 5.

这是我的变量的样子：

private double _double = 0.25;
    public double Volume
    {
        get
        {
            return _double;
        }
        set
        {
            _double = value;
            OnPropertyChanged("Volume");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

我还在INotifyPropertyChanged

旁边设置了partial class

以下是我使用的转换器：

[ValueConversion(typeof(double), typeof(int))]
public class VolumePicture : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (System.Convert.ToDouble(value) <= 0.25)
        {
            return 1;
        }
        else if (System.Convert.ToDouble(value) > 0.25 && System.Convert.ToDouble(value) <= 0.5)
        {
            return 2;
        }
        else if (System.Convert.ToDouble(value) > 0.5 && System.Convert.ToDouble(value) <= 0.75)
        {
            return 3;
        }
        else if (System.Convert.ToDouble(value) > 0.75 && System.Convert.ToDouble(value) <= 1)
        {
            return 4;
        }
        else
        {
            return 0;
        }
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

它基本上需要输入，并且完全按照我在第一部分中的描述进行操作。

Aaaand这里是我对矩形的XAML，我想更改opacitymask：

<Rectangle Height="20" Margin="0,2,0,0">
                <Rectangle.Style>
                    <Style TargetType="{x:Type Rectangle}">
                        <Setter Property="Fill" Value="#FF929292" />
                        <Style.Triggers>
                            <DataTrigger Binding="{Binding IsMouseOver, ElementName=VolumeButton}" 
                                Value="True">
                                <Setter Property="Fill" Value="White" />
                            </DataTrigger>
                            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=NowPlaying.Volume, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource VolumePictureConverter}}" Value="5">
                                <Setter Property="OpacityMask">
                                    <Setter.Value>
                                        <VisualBrush Visual="{StaticResource appbar_sound_mute}"/>
                                    </Setter.Value>
                                </Setter>
                            </DataTrigger>
                            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=NowPlaying.Volume, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource ResourceKey=VolumePictureConverter}}" Value="1">
                                <Setter Property="OpacityMask">
                                    <Setter.Value>
                                        <VisualBrush Visual="{StaticResource appbar_sound_0}"/>
                                    </Setter.Value>
                                </Setter>
                            </DataTrigger>
                            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=NowPlaying.Volume, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource ResourceKey=VolumePictureConverter}}" Value="2">
                                <Setter Property="OpacityMask">
                                    <Setter.Value>
                                        <VisualBrush Visual="{StaticResource appbar_sound_1}"/>
                                    </Setter.Value>
                                </Setter>
                            </DataTrigger>
                            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=NowPlaying.Volume, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource ResourceKey=VolumePictureConverter}}" Value="3">
                                <Setter Property="OpacityMask">
                                    <Setter.Value>
                                        <VisualBrush Visual="{StaticResource appbar_sound_2}"/>
                                    </Setter.Value>
                                </Setter>
                            </DataTrigger>
                            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=NowPlaying.Volume, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource ResourceKey=VolumePictureConverter}}" Value="4">
                                <Setter Property="OpacityMask">
                                    <Setter.Value>
                                        <VisualBrush Visual="{StaticResource appbar_sound_3}"/>
                                    </Setter.Value>
                                </Setter>
                            </DataTrigger>
                        </Style.Triggers>
                    </Style>
                </Rectangle.Style>
            </Rectangle>

这可能看起来很混乱，为此，我很抱歉。

但是，这就是我的问题：当我在运行时更改Volume变量时，似乎什么也没发生。我认为转换器没有触发，但我不知道为什么会发生这种情况（！）而且由于我在绑定和转换器以及WPF方面确实不太好，所以我已经陷入了困境......

任何人都知道麻烦制造者会是什么？

谢谢

有一点需要注意的是，我并不总是拥有＆＃34; NowPlaying.Volume＆＃34;在那里的路径，我只是尝试了一堆东西。当我进行调试时，我会在输出中将其重命名（将其重命名为＆＃34;路径错误：＆＃39;音量＆＃39;＆＃34;当我删除Nowplaying时。

System.Windows.Data Error: 40 : BindingExpression path error: 'NowPlaying' property not found on 'object' ''Rectangle' (Name='')'. BindingExpression:Path=NowPlaying.Volume; DataItem='Rectangle' (Name=''); target element is 'Rectangle' (Name=''); target property is 'NoTarget' (type 'Object')

Answer 1

似乎您绑定到Rectangle而不是它的DataContext。 Rectangle没有属性Volume，因此您将收到绑定错误。尝试将绑定语句更改为类似的内容（请注意此部分：...Path=DataContext.Volume...）：

<Rectangle.Style>
    <Style TargetType="{x:Type Rectangle}">
        .......
        <Style.Triggers>
            .......
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=DataContext.Volume, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource VolumePictureConverter}}" 
                    Value="5">
                <Setter Property="OpacityMask">
                    <Setter.Value>
                        <VisualBrush Visual="{StaticResource appbar_sound_mute}"/>
                    </Setter.Value>
                </Setter>
            </DataTrigger>
            .......
        </Style.Triggers>
        .......
    </Style>
</Rectangle.Style>

使用转换器时Datatrigger不会触发

1 个答案: