Silverlight 图表 - 饼图显示图表上的依赖值

Question

我想在饼图本身上显示相关值（不在图例区域中）。 我正在使用 Silverlight 4 + Silverlight 4 Toolkit（2010 年 4 月）。

这应该是一个很常见的请求，但我还没有找到解决方案。 我该怎么做？

  <toolkit:Chart Name="samplePieChart" Title="Sample" Width="600">
                    <toolkit:Chart.Series>
                        <toolkit:PieSeries Name="samplePieSeries" 
                                           ItemsSource="{Binding Questions}" 
                                           IndependentValueBinding="{Binding Name}" 
                                           DependentValueBinding="{Binding Count}"
                                           IsSelectionEnabled="True"
                                           />
                    </toolkit:Chart.Series>
                </toolkit:Chart>

Answer 1

我记得我有一个 链接，包含与图表相关的资源集合。

在该页面上，您可以找到可以帮助您向饼图添加标签的链接：
LabeledPieChart

此解决方案使用工具包 Chart 类。尽管我说过可以在不创建新类的情况下创建类似的行为，但我认为这并不比使用现有控件更容易。

无论如何，我可以发布显示依赖值的饼图系列的自定义样式。
您所需要的只是某种转换器，它将切片的路径几何形状转换为 Canvas 的 Left 或 Top 属性，并且数据点的自定义样式。

转换器：

public class GeometryToNumberConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var g = value as Geometry;
        var type = parameter as string;
        if (type == "Left")
            return (g.Bounds.Left + g.Bounds.Right) / 2.0;
        else if (type == "Top")
            return (g.Bounds.Top + g.Bounds.Bottom) / 2.0;
        else return null;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

以及 PieDataPoint 类模板内的几行 xaml：

<Canvas Background="Transparent">
     <TextBlock Text="{TemplateBinding FormattedDependentValue}" 
         Canvas.Left="{Binding Geometry, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource GeometryToNumberConverter}, ConverterParameter=Left}"
         Canvas.Top="{Binding Geometry, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource GeometryToNumberConverter}, ConverterParameter=Top}"/>
</Canvas>

这是 PieDataPoint 样式的完整代码：

<UserControl.Resources>
    <local:GeometryToNumberConverter x:Name="GeometryToNumberConverter" />

    <Style x:Key="LabelDataPointStyle" TargetType="chart:PieDataPoint">
        <Setter Property="Background" Value="Orange"/>
        <Setter Property="BorderBrush" Value="White"/>
        <Setter Property="BorderThickness" Value="1"/>
        <Setter Property="IsTabStop" Value="False"/>
        <Setter Property="RatioStringFormat" Value="{}{0:p2}"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="chart:PieDataPoint">
                    <Grid
                    x:Name="Root"
                    Opacity="0">
                        <VisualStateManager.VisualStateGroups>
                            <VisualStateGroup x:Name="CommonStates">
                                <VisualStateGroup.Transitions>
                                    <VisualTransition GeneratedDuration="0:0:0.1"/>
                                </VisualStateGroup.Transitions>
                                <VisualState x:Name="Normal"/>
                                <VisualState x:Name="MouseOver">
                                    <Storyboard>
                                        <DoubleAnimation
                                        Storyboard.TargetName="MouseOverHighlight"
                                        Storyboard.TargetProperty="Opacity"
                                        To="0.6"
                                        Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="SelectionStates">
                                <VisualStateGroup.Transitions>
                                    <VisualTransition GeneratedDuration="0:0:0.1"/>
                                </VisualStateGroup.Transitions>
                                <VisualState x:Name="Unselected"/>
                                <VisualState x:Name="Selected">
                                    <Storyboard>
                                        <DoubleAnimation
                                        Storyboard.TargetName="SelectionHighlight"
                                        Storyboard.TargetProperty="Opacity"
                                        To="0.6"
                                        Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="RevealStates">
                                <VisualStateGroup.Transitions>
                                    <VisualTransition GeneratedDuration="0:0:0.5"/>
                                </VisualStateGroup.Transitions>
                                <VisualState x:Name="Shown">
                                    <Storyboard>
                                        <DoubleAnimation
                                        Storyboard.TargetName="Root"
                                        Storyboard.TargetProperty="Opacity"
                                        To="1"
                                        Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="Hidden">
                                    <Storyboard>
                                        <DoubleAnimation
                                        Storyboard.TargetName="Root"
                                        Storyboard.TargetProperty="Opacity"
                                        To="0"
                                        Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                            </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>
                        <Path
                        x:Name="Slice"
                        Data="{TemplateBinding Geometry}"
                        Fill="{TemplateBinding Background}"
                        Stroke="{TemplateBinding BorderBrush}"
                        StrokeMiterLimit="1">
                            <ToolTipService.ToolTip>
                                <StackPanel>
                                    <ContentControl Content="{TemplateBinding FormattedDependentValue}"/>
                                    <ContentControl Content="{TemplateBinding FormattedRatio}"/>
                                </StackPanel>
                            </ToolTipService.ToolTip>
                        </Path>
                        <Path
                        x:Name="SelectionHighlight"
                        Data="{TemplateBinding GeometrySelection}"
                        Fill="Red"
                        StrokeMiterLimit="1"
                        IsHitTestVisible="False"
                        Opacity="0"/>
                        <Path
                        x:Name="MouseOverHighlight"
                        Data="{TemplateBinding GeometryHighlight}"
                        Fill="White"
                        StrokeMiterLimit="1"
                        IsHitTestVisible="False"
                        Opacity="0"/>
                        <Canvas IsHitTestVisible="False">
                            <TextBlock Text="{TemplateBinding FormattedDependentValue}" IsHitTestVisible="False"
                                       Canvas.Left="{Binding Geometry, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource GeometryToNumberConverter}, ConverterParameter=Left}"
                                       Canvas.Top="{Binding Geometry, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource GeometryToNumberConverter}, ConverterParameter=Top}"/>
                        </Canvas>

                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</UserControl.Resources>

您可以这样应用此样式：

<chart:PieSeries DataPointStyle="{StaticResource LabelDataPointStyle}" ...

以及图表将显示为单色橙色图表。

如果您不喜欢它，这里是链接我在其中展示了如何更改图表的 Palette 属性。

这是具有 3 种颜色的调色板的示例，您可以通过类推添加其他颜色：

<datavis:ResourceDictionaryCollection x:Key="DefaultPalette">
        <!-- Blue -->
        <ResourceDictionary>
            <RadialGradientBrush x:Key="Background" GradientOrigin="-0.1,-0.1" Center="0.075,0.015" RadiusX="1.05" RadiusY="0.9">
                <GradientStop Color="#FFB9D6F7" />
                <GradientStop Color="#FF284B70" Offset="1" />
            </RadialGradientBrush>
            <Style x:Key="DataPointStyle" TargetType="chart:PieDataPoint" BasedOn="{StaticResource LabelDataPointStyle}">
                <Setter Property="Background" Value="{StaticResource Background}" />
            </Style>
        </ResourceDictionary>
        <!-- Red -->
        <ResourceDictionary>
            <RadialGradientBrush x:Key="Background" GradientOrigin="-0.1,-0.1" Center="0.075,0.015" RadiusX="1.05" RadiusY="0.9">
                <GradientStop Color="#FFFBB7B5" />
                <GradientStop Color="#FF702828" Offset="1" />
            </RadialGradientBrush>
            <Style x:Key="DataPointStyle" TargetType="chart:PieDataPoint" BasedOn="{StaticResource LabelDataPointStyle}">
                <Setter Property="Background" Value="{StaticResource Background}" />
            </Style>
        </ResourceDictionary>
        <!-- Light Green -->
        <ResourceDictionary>
            <RadialGradientBrush x:Key="Background" GradientOrigin="-0.1,-0.1" Center="0.075,0.015" RadiusX="1.05" RadiusY="0.9">
                <GradientStop Color="#FFB8C0AC" />
                <GradientStop Color="#FF5F7143" Offset="1" />
            </RadialGradientBrush>
            <Style x:Key="DataPointStyle" TargetType="chart:PieDataPoint" BasedOn="{StaticResource LabelDataPointStyle}">
                <Setter Property="Background" Value="{StaticResource Background}" />
            </Style>
        </ResourceDictionary>
    </datavis:ResourceDictionaryCollection>

并且不要忘记从系列定义中删除 DataPointStyle 属性：
=>
<图表：PieSeries ...