Question

我有一个包含4x LineSeries的图表。我定义了两种不同的样式来表示线条，我希望能够动态地更改应用于特定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。

以下是页面的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>

Answer 1

我测试了您的代码并找到了问题的原因。

您收到NullReferenceException，因为应用程序未设置字段this.lineChartMood，原因不明。

您必须自己获取此系列对象。有两种可能的方法：

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

但我建议在构造函数中明确设置字段this.lineSeriesMood，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
    }
}

然后你就可以毫无例外地参考你的系列了。

Answer 2

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。这不仅仅是解决方案的解决方案。

Answer 3

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

使用C＃动态更改元素的样式

3 个答案: