Question

我使用此方法将Line绑定到两个ScatterViewItems的中心：

private void BindLineToScatterViewItems(Shape line, ScatterViewItem origin, ScatterViewItem destination)
        {
            // Bind line.(X1,Y1) to origin.ActualCenter
            BindingOperations.SetBinding(line, Line.X1Property, new Binding { Source = origin, Path = new PropertyPath("ActualCenter.X") });
            BindingOperations.SetBinding(line, Line.Y1Property, new Binding { Source = origin, Path = new PropertyPath("ActualCenter.Y") });

            // Bind line.(X2,Y2) to destination.ActualCenter
            BindingOperations.SetBinding(line, Line.X2Property, new Binding { Source = destination, Path = new PropertyPath("ActualCenter.X") });
            BindingOperations.SetBinding(line, Line.Y2Property, new Binding { Source = destination, Path = new PropertyPath("ActualCenter.Y") });
        }

但是现在我想将它从底部从一个ScatterViewItem绑定到另一个ScatterViewItem的顶部： enter image description here

我怎样才能做到这一点？

Answer 1

你可以：

使用带有视图项的边界矩形的IValueConverter和转换器参数来指定计算中心的边。

public enum MidpointSide { None, Left, Top, Right, Bottom }

public class MidpointConverter : IValueConverter
{
    private bool returnY;
    public MidpointConverter(bool returnY)
    {
        this.returnY = returnY;
    }

    public object Convert(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        var scatter = value as ScatterViewItem;
        var side = (MidpointSide)parameter;
        var center = scatter.ActualCenter;
        var halfW = scatter.ActualWidth / 2.0;
        var halfH = scatter.ActualHeight / 2.0;

        Point point = null;
        switch (side)
        {
        case MidpointSide.Left:
            point = new Point(center.X - halfW, center.Y);
            break;
        case MidpointSide.Top:
            point = new Point(center.X, center.Y - halfH);
            break;
        case MidpointSide.Right:
            point = new Point(center.X + halfW, center.Y);
            break;
        case MidpointSide.Bottom:
            point = new Point(center.X, center.Y + halfH);
            break;
        default:
            return null;
        }

        return this.returnY ? point.Y : point.X;
    }

    public object ConvertBack(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

您将使用的转换器是：

var x = new MidpointConverter(false), y = MidpointConverter(true);

BindingOperations.SetBinding(line, Line.X1Property,
    new Binding { Source = origin, Converter = x, ConverterParameter = MidpointSide.Bottom });
BindingOperations.SetBinding(line, Line.Y1Property,
    new Binding { Source = origin, Converter = y, ConverterParameter = MidpointSide.Bottom });

// Definitely more heavyweight than just changing the `ZIndex`
// You run into the problem that you can't bind the 'start' and 'end'
// of a line, only X1/Y1 and X2/Y2 making this converter involved

保持相同的ActualCenter绑定，但使该行的ZIndex低于矩形的行。{1}}。使用这种方法可能使您不必检测一个ScatterViewItem是否以需要更改转换器中使用的一侧的方式移动。

Answer 2

  BindingOperations.SetBinding(line, Line.X1Property, new Binding { Source = origin, Path = new PropertyPath("ActualCenter.X"),Converter=converter });

是否有理由设置转换器？

WPF：如何将行绑定到UI元素？

2 个答案: