修复 当没有DataLabel 时会出现的bug

WpfApp1/App.xaml

@@ -2,7 +2,7 @@
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:local="clr-namespace:WpfApp1"
-             StartupUri="ColumnRangeExample.xaml">
+             StartupUri="Column2Example.xaml">
     <Application.Resources>
          
     </Application.Resources>

WpfApp1/Column2Example.xaml

+<Window x:Class="WpfApp1.Column2Example"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:lvc="clr-namespace:LiveCharts.Wpf;assembly=LiveCharts.Wpf"
+        xmlns:local="clr-namespace:WpfApp1"
+        mc:Ignorable="d"
+        Title="MainWindow" Height="450" Width="800">
+    <Grid >
+        <lvc:CartesianChart x:Name="chart" Series="{Binding SeriesCollection}" LegendLocation="Left" 
+                            DisableAnimations="True" Hoverable="False" DataTooltip="{x:Null}">
+
+            <lvc:CartesianChart.AxisX>
+                <lvc:Axis MinValue="{Binding XMin}" MaxValue="{Binding XMax}"></lvc:Axis>
+            </lvc:CartesianChart.AxisX>
+            <lvc:CartesianChart.AxisY>
+                <lvc:Axis Title="Sold Apps" LabelFormatter="{Binding Formatter}"></lvc:Axis>
+            </lvc:CartesianChart.AxisY>
+        </lvc:CartesianChart>
+        <StackPanel Orientation="Vertical" HorizontalAlignment="Left" Background="#08000000" VerticalAlignment="Top">
+            <StackPanel Orientation="Horizontal" Margin="5">
+                <TextBlock Text="XMin"/>
+                <TextBox Text="{Binding XMin}"/>
+            </StackPanel>
+            <StackPanel Orientation="Horizontal" Margin="5">
+                <TextBlock Text="XMax"/>
+                <TextBox Text="{Binding XMax}"/>
+            </StackPanel>
+            <StackPanel Orientation="Horizontal" Margin="5">
+                <TextBlock Text="运行中"/>
+                <TextBlock Text="{Binding IsRunning,Mode=OneWay}"/>
+            </StackPanel>
+            <Button Content="定时更新" Width="80" Padding="5" Click="Button_Click"/>
+            <Button Content="清空" Width="80" Padding="5" Click="ButtonClear_Click"/>
+            <Button Content="GC" Width="80" Padding="5" Click="ButtonGC_Click"/>
+        </StackPanel>
+    </Grid>
+</Window>
\ No newline at end of file

WpfApp1/Column2Example.xaml.cs

+using LiveCharts;
+using LiveCharts.Configurations;
+using LiveCharts.Defaults;
+using LiveCharts.Wpf;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Shapes;
+using System.Windows.Threading;
+
+namespace WpfApp1
+{
+    /// <summary>
+    /// Window1.xaml 的交互逻辑
+    /// </summary>
+    public partial class Column2Example : Window
+    {
+        Column2ExampleViewModel viewModel;
+        public Column2Example()
+        {
+            InitializeComponent();
+            viewModel = new Column2ExampleViewModel();
+            viewModel.Init();
+            this.DataContext = viewModel;
+        }
+
+        private void Button_Click(object sender, RoutedEventArgs e)
+        {
+            if (viewModel.IsRunning)
+                viewModel.Stop();
+            else
+                viewModel.Start();
+        }
+
+        private void ButtonGC_Click(object sender, RoutedEventArgs e)
+        {
+            GC.Collect();
+        }
+
+
+        private void ButtonClear_Click(object sender, RoutedEventArgs e)
+        {
+            viewModel.Values.Clear();
+        }
+    }
+    public class Column2ExampleViewModel : INotifyPropertyChanged
+    {
+        DispatcherTimer timer;
+
+
+        public SeriesCollection SeriesCollection { get; set; }
+        public Func<double, string> Formatter { get; set; }
+
+        public double XMin { get; set; } = double.NaN;
+        public double XMax { get; set; } = double.NaN;
+        public bool IsRunning { get; private set; }
+        List<double> datas = new List<double>();
+        
+        public ChartValues<double> Values = new ChartValues<double>();
+
+        public void Update()
+        {
+
+            Random random = new Random();
+            double[] datas2 = new double[datas.Count()];
+            for (int i = 0; i < datas.Count(); i++)
+            {
+                datas2[i] = datas[i] + (random.NextDouble() - 0.5) * 1;
+            }
+            //把其中一部分数据变为无效
+            int null_value_pos = random.Next(datas.Count());
+            for (int i = 0; i < datas.Count()/10; i++)
+            {
+                int index = null_value_pos - datas.Count() / 20 + i;
+                if (index < 0)
+                    index += datas2.Count();
+                else if (index >= datas2.Count())
+                    index -= datas2.Count();
+
+                datas2[index] = double.NaN;
+            }
+
+
+
+           // if (SeriesCollection.Count() > 0)
+           //     SeriesCollection.Clear();
+
+
+            Values.Clear();
+            
+            Values.AddRange(datas2);
+
+
+
+
+        }
+        public void Init()
+        {
+            //-----------------------------------------------------------
+            //模拟数据
+            double target = 150;
+            double tolerance = 2;
+
+            Random random = new Random();
+            for (int i = 0; i < 100; i++)
+            {
+                double d = Math.Sin(Math.PI * 2 * i / 35) * tolerance + (random.NextDouble() - 0.5) * 0.3 + target;
+                datas.Add(d);
+            }
+
+
+
+            SeriesCollection = new SeriesCollection();
+
+
+            SeriesCollection.Add(
+                new Column2Series
+                {
+                Title = "Column2",
+                Values = Values,
+                StrokeThickness = 1,
+                Stroke = new SolidColorBrush(System.Windows.Media.Colors.DarkRed),
+                Fill = new SolidColorBrush(System.Windows.Media.Color.FromArgb(0x80, 0xff, 0, 0)),
+                
+                YAxisCrossing = 150,
+                Configuration = Mappers.Xy<double>()
+                .X((v,index)=>index)
+                .Y(v => v)
+                });
+
+
+            Formatter = value => value.ToString("N");
+            XMin = 100;
+            XMax = 900;
+
+            //-----------------------------------------------------------
+            //转显示数据
+            Update();
+
+            timer = new DispatcherTimer();
+            timer.Interval = TimeSpan.FromSeconds(0.1);
+            timer.Tick += Timer_Tick;
+        }
+        public void Start()
+        {
+            IsRunning = true;
+            timer.Start();
+        }
+        public void Stop()
+        {
+            IsRunning = false;
+            timer.Stop();
+        }
+        
+        private void Timer_Tick(object sender, EventArgs e)
+        {
+            Update();
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+    }
+
+}

WpfApp1/WpfApp1.csproj

@@ -62,9 +62,16 @@
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </ApplicationDefinition>
+    <Compile Include="Column2Example.xaml.cs">
+      <DependentUpon>Column2Example.xaml</DependentUpon>
+    </Compile>
     <Compile Include="ColumnRangeExample.xaml.cs">
       <DependentUpon>ColumnRangeExample.xaml</DependentUpon>
     </Compile>
+    <Page Include="Column2Example.xaml">
+      <Generator>MSBuild:Compile</Generator>
+      <SubType>Designer</SubType>
+    </Page>
     <Page Include="MainWindow.xaml">
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>

WpfView/Points/ColumnPointView.cs

@@ -184,7 +184,8 @@ namespace LiveCharts.Wpf.Points
             chart.View.RemoveFromDrawMargin(Rectangle);
             chart.View.RemoveFromDrawMargin(DataLabel);
             //feng
-            DataLabel.Content = null;
+            if(DataLabel!=null)
+                DataLabel.Content = null;
 
         }