1

我有一个带有 4x LineSeries 的图表。我定义了两种不同的样式来表示线条，并且我希望能够动态更改应用于特定 LineSeries 的样式（例如，基于用户点击按钮等）。

我似乎无法弄清楚如何从 c# 更新样式。任何帮助表示赞赏！

我试过了：

lineChartMood.PolylineStyle = this.Resources.PolylineStyle2 as Style;

但这会返回 Null 异常。

这是页面的 XAML，包括样式定义：

    <phone:PhoneApplicationPage 
    x:Class="Bhutaan.ChartingTest"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:charting="clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit"
    xmlns:local="clr-namespace:Bhutaan"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"
    shell:SystemTray.IsVisible="True">

    <phone:PhoneApplicationPage.Resources>
        <Style x:Key="PolylineStyle" TargetType="Polyline">
            <Setter Property="StrokeThickness" Value="5"/>
        </Style>
        <Style x:Key="PolylineStyle2" TargetType="Polyline">
            <Setter Property="StrokeThickness" Value="1"/>
        </Style>
    </phone:PhoneApplicationPage.Resources>


    <!--LayoutRoot is the root grid where all page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="TEST" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock x:Name="PageTitle" Text="added" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,-0,12,0">
            <ScrollViewer>
                <StackPanel>
                    <TextBlock Text="Great! That's been saved." FontSize="30" Margin="0,0,0,0"/>
                    <!-- Chart  -->
                    <charting:Chart
                        x:Name="myChart"
                        Margin="0,20,0,0"
                        Height="350"
                        Style="{StaticResource PhoneChartStyle}"
                        Template="{StaticResource PhoneChartPortraitTemplate}">

                        <!-- Series -->
                        <charting:LineSeries
                            x:Name="lineChartMood"
                            Title="Mood"
                            ItemsSource="{Binding}"
                            DependentValuePath="MoodValue"
                            IndependentValuePath="Timestamp"
                            PolylineStyle="{StaticResource PolylineStyle}" >

                            <charting:LineSeries.LegendItemStyle>
                                <Style TargetType="charting:LegendItem">
                                    <Setter Property="Margin" Value="5 0 5 0"/>
                                </Style>
                            </charting:LineSeries.LegendItemStyle>
                        </charting:LineSeries>
                        <!-- Series -->
                        <charting:LineSeries
                            Title="Energy"
                            ItemsSource="{Binding}"
                            DependentValuePath="EnergyValue"
                            IndependentValuePath="Timestamp">
                            <charting:LineSeries.LegendItemStyle>
                                <Style TargetType="charting:LegendItem">
                                    <Setter Property="Margin" Value="5 0 5 0"/>
                                </Style>
                            </charting:LineSeries.LegendItemStyle>
                        </charting:LineSeries>
                        <!-- Series -->
                        <charting:LineSeries
                            Title="Mental"
                            ItemsSource="{Binding}"
                            DependentValuePath="MentalValue"
                            IndependentValuePath="Timestamp">
                            <charting:LineSeries.LegendItemStyle>
                                <Style TargetType="charting:LegendItem">
                                    <Setter Property="Margin" Value="5 0 5 0"/>
                                </Style>
                            </charting:LineSeries.LegendItemStyle>
                        </charting:LineSeries>
                        <!-- Series -->
                        <charting:LineSeries
                            Title="Hunger"
                            ItemsSource="{Binding}"
                            DependentValuePath="HungerValue"
                            IndependentValuePath="Timestamp">
                            <charting:LineSeries.LegendItemStyle>
                                <Style TargetType="charting:LegendItem">
                                    <Setter Property="Margin" Value="5 0 5 0"/>
                                </Style>
                            </charting:LineSeries.LegendItemStyle>
                        </charting:LineSeries>
                    </charting:Chart>

                </StackPanel>
            </ScrollViewer>
        </Grid>
    </Grid>


</phone:PhoneApplicationPage>
4

3 回答 3

5

我测试了您的代码并找到了问题的原因。

您收到 NullReferenceException 是因为this.lineChartMood应用程序出于某种未知原因未设置该字段。

您必须自己获取此线系列对象。有两种可能的获取方式：

var lineSeriesWay1 = this.FindName("lineChartMood");
var lineSeriesWay2 = myChart.Series.OfType<LineSeries>().First(ls => ls.Name == "lineChartMood");

但我建议this.lineSeriesMood在构造函数中显式设置字段，如下所示：

public partial class MainPage : PhoneApplicationPage
{
    // Constructor
    public MainPage()
    {
        InitializeComponent();
        // because the code 'this.FindName("lineChartMood")' doesn't work in the constructor, I'll use the following line:
        this.lineChartMood = this.myChart.Series.OfType<LineSeries>().First(ls => ls.Name == "lineChartMood");

        // other code
    }


    private void Button_Click(object sender, RoutedEventArgs e)
    {
        this.lineChartMood.PolylineStyle = (Style)this.Resources["PolylineStyle2"];
        this.lineChartMood.Refresh(); // you should call this method so that the style is applied
    }
}

然后您将能够毫无例外地参考您的系列。

于 2012-08-27T09:50:08.937 回答
3

为什么不在 App.xaml 中添加资源并使用 App.Current.Resources 引用它们？我这样说是因为我觉得程序可能无法引用特定页面上定义的本地资源。我可能错了。这不是解决方案，只是一种解决方法。

于 2012-08-26T09:07:21.863 回答
2

lineChartMood.PolylineStyle = this.Resources.PolylineStyle2 as Style; 应该是 lineChartMood.PolylineStyle = this.Resources["PolylineStyle2"] as Style;？？

于 2012-08-26T08:07:11.817 回答