路径绘制和数据绑定 [英] Path drawing and data binding

问题描述

我正在寻找一种方法，能够使用 wpf Path 元素来绘制将在地图上表示路线的路径.我有包含顶点集合的 Route 类，并希望将其用于绑定.我什至不知道如何开始..有什么提示吗?

I am looking for a way to be able to use the wpf Path element to draw a path that will represent a route on the map. I have the Route class that contains a collection of vertices and would like to use it for binding. I don't really know how to even start.. Any hints?

推荐答案

绑定所需的主要内容是一个转换器，可将您的点转换为 Geometry，路径需要为 Geometrycode>Data，这是我从 System.Windows.Point-array 到 Geometry 的单向转换器的样子:

The main thing you'll need for the binding is a converter that turns your points into Geometry which the path will need as Data, here is what my one-way converter from a System.Windows.Point-array to Geometry looks like:

[ValueConversion(typeof(Point[]), typeof(Geometry))]
public class PointsToPathConverter : IValueConverter
{
    #region IValueConverter Members

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Point[] points = (Point[])value;
        if (points.Length > 0)
        {
            Point start = points[0];
            List<LineSegment> segments = new List<LineSegment>();
            for (int i = 1; i < points.Length; i++)
            {
                segments.Add(new LineSegment(points[i], true));
            }
            PathFigure figure = new PathFigure(start, segments, false); //true if closed
            PathGeometry geometry = new PathGeometry();
            geometry.Figures.Add(figure);
            return geometry;
        }
        else
        {
            return null;
        }
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotSupportedException();
    }

    #endregion
}

现在真正剩下的就是创建它的一个实例并将其用作绑定的转换器.它在 XAML 中的样子:

Now all that is really left is to create an instance of it and use it as the converter for the binding. What it might look like in XAML:

<Grid>
    <Grid.Resources>
        <local:PointsToPathConverter x:Key="PointsToPathConverter"/>
    </Grid.Resources>
    <Path Data="{Binding ElementName=Window, Path=Points, Converter={StaticResource ResourceKey=PointsToPathConverter}}"
          Stroke="Black"/>
</Grid>

如果您需要自动更新绑定，您应该使用依赖属性或接口，例如 INotifyPropertyChanged/INotifyCollectionChanged

希望有帮助:D

If you need the binding to update automatically you should work with dependency properties or interfaces like INotifyPropertyChanged/INotifyCollectionChanged

Hope that helps :D

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