Question

问题：我有一个带有TextBlocks的ListBox，其中Text属性绑定到不同的属性。我希望将TextBlock拖到OxyPlot上，并让绘图创建一个新的LineSeries，其集合应绑定到与TextBlock相同的绑定（这有意义吗？）

我从TextBlock派生了一个类来处理OnMouseMove事件，如下所示：

    protected override void OnMouseMove(MouseEventArgs e)
    {
        base.OnMouseMove(e);
        if (CanDrag && (e.LeftButton == MouseButtonState.Pressed))
        {
            // Make sure we have a data binding
            BindingExpression binding = GetBindingExpression(TextProperty);
            if(binding == null)
            { return; }
            // Package the data.
            DataObject data = new DataObject();
            data.SetData("DragListText.Binding", binding);

            // Inititate the drag-and-drop operation.
            DragDrop.DoDragDrop(this, data, DragDropEffects.Copy);
        }
    }

我还从Oxy.Plot派生了一个处理OnDrop的类：

protected override void OnDrop(DragEventArgs e)
    {
        base.OnDrop(e);
        // DataObject must contain a DragListText.Binding object
        if (e.Data.GetDataPresent("DragListText.Binding"))
        {
            BindingExpression binding = e.Data.GetData("DragListText.Binding") as BindingExpression;
            AddSeries(binding);
        }
        e.Handled = true;
    }

AddSeries函数执行以下操作：

public void AddSeries(BindingExpression binding)
    {
        plot1 = new PlotCollection();

        LineSeries newSeries = new LineSeries();
        newSeries.ItemsSource = plot1.Collection;

        Series.Add(newSeries);
    }

最后，PlotCollection定义为：

public class PlotCollection : DependencyObject
{
    public ObservableCollection<DataPoint> Collection;

    public static DependencyProperty ValueProperty = DependencyProperty.Register("Value", typeof(double), typeof(PlotCollection), new PropertyMetadata(0.0, new PropertyChangedCallback(OnValueChanged)));

    private static void OnValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    { ((PlotCollection)d).AddLast(); }

    public double Value
    {
        get { return (double)GetValue(ValueProperty); }
        set { SetValue(ValueProperty, value); }
    }

    public PlotCollection()
    {
        Collection = new ObservableCollection<DataPoint>();
    }
    protected void AddLast()
    {
        Collection.Add(new DataPoint(OxyPlot.Axes.DateTimeAxis.ToDouble(DateTime.Now), Value));
    }
}

所以我的问题是：如何在PlotCollection.Value上创建一个与TextBlock.Text匹配的绑定？

Answer 1

在AddSeries方法中，尝试添加以下代码行：

BindingOperations.SetBinding(plot1, PlotCollection.ValueProperty, binding.ParentBinding);

Answer 2

发现问题，

我需要将PropertyChangedCallback添加到ValueProperty声明中，如下所示：

public static DependencyProperty ValueProperty = DependencyProperty.Register("Value", typeof(double), typeof(DynamicSeries), new PropertyMetadata(0.0, OnValueChanged));

然后在回调方法中处理属性更改：

private static void OnValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        PlotCollection ds = (PlotCollection)d;
        ds.AppendValue((double)e.NewValue);
    }

我想我误解了Value属性是如何工作的？！

感谢您抽出宝贵时间尝试帮助我......

在WPF中，如何将绑定从TextBlock复制到自定义集合？

2 个答案: