在 WPF 中使用实时图表将数据绑定到 CartesianChart 而无需设置数据上下文

Question

When I set up datacontext like this then everything works fine. My backend code

public partial class ucMyGraph : UserControl
{
    public ucMyGraph()
    {
        InitializeComponent();
        DataContext = this;
    }
    public ChartValues<decimal> ChartValues
    {
        get { return (ChartValues<decimal>)GetValue(ChartValuesProperty); }
        set { SetValue(ChartValuesProperty, value); }
    }
    public static readonly DependencyProperty ChartValuesProperty =
        DependencyProperty.Register("ChartValues", typeof(ChartValues<decimal>), typeof(ucWatchlistGraph),
            new PropertyMetadata(new ChartValues<decimal> { 1816.59m, 1818.85m, 1820.71m, 1821.03m, 1824.32m, 1825.62m, 1825.58m, 1826.71m, 1825.62m, 1824.76m, 1825.05m,
        1823.71m, 1824.66m, 1825.54m, 1824.67m, 1826.1m, 1820.66m, 1822.35m, 1822.06m, 1822.22m }));
}

And here is the xmal

 <lvc:CartesianChart Height="60" Width="120"  Margin="0" Padding="0" x:Name="cartesianChart" 
                            AnimationsSpeed="0:0:0.5" Hoverable="False" 
                            DataTooltip="{x:Null}">
        <lvc:CartesianChart.Series>
            <lvc:LineSeries Values="{Binding ChartValues}" 
                            PointGeometry="{x:Null}" 
                            LineSmoothness="0.1"
                            StrokeThickness="1"                                 
                            Stroke="#43A047">
            </lvc:LineSeries>
        </lvc:CartesianChart.Series>
    </lvc:CartesianChart>

When I erase this line DataContext = this form the constractor and try to bind ChartValues using relative resource like this ( Binding RelativeSource={RelativeSource AncestorType={x:Type local:ucMyGraph}}, Path=ChartValues ) it doesn't work. I'm wondering why it is important to set datacontext for showing the live chart graph. I'm new in this topic so I need your help. I want to show the graph without initialize datacontext. How do I achieve this?

Answer 1

DataContext is use for store data to display to UI(User Interface). If you set Values="{Binding ChartValues}", it will understand that you are binding ChartValues of DataContext. In the constructor ucMyGraph() you assigned DataContext = this (ucMyGraph), which mean the "Values" will display the value of property ChartValues of this(ucMyGraph). If the DataContext you assigned doesn't have the property ChartValues, the binding will not work.