我有一个LineSeries的图表。通过 series.IsSelectionEnabled = TRUE; 当我将鼠标移动到该点，我可以选择的节点。但是，我怎么能做到这一点，当鼠标不完全结束点，但是当它旁边有（之上或之下）？谢谢你。

I have a LineSeries chart. By series.IsSelectionEnabled = true; when I move the mouse over the points, I can select that node. But how can I do it when the mouse is not exactly over the point but when it's near it (above or under)? Thanks.

PS： 还有一件事。我怎样才能改变列的颜色，当鼠标滑过它使用户可以告诉列，他/她会选择哪一个。

PS: One more thing. How can I change the color of the column when the mouse is over it so the user can tell which one of the columns he/she is going to select.

推荐答案

我所创建的图表跟单的例子供LineSeries 。您可以点击任何地方的情节和最近的点会被选中。

I have created the example of the chart with the single LineSeries. You can click anywhere at the plot and the nearest point will be selected.

XAML（更改的ItemsSource 财产和其他财产，以你的）：

XAML (Change the ItemsSource property and other properties to yours):

    <Charting:Chart MouseLeftButtonDown="Chart_MouseLeftButtonDown">
        <Charting:Chart.Series>
            <Charting:LineSeries IsSelectionEnabled="True" ItemsSource="..." ... />
        </Charting:Chart.Series>
    </Charting:Chart>

code-背后：

Code-behind:

    private void Chart_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        var chart = sender as Chart;
        //In my example the line series is the first item of the chart series
        var line = (LineSeries)chart.Series[0];

        //Find the nearest point on the LineSeries
        var newPoint = e.GetPosition(line);
        var selectIndex = this.FindNearestPointIndex(line.Points, newPoint);

        if (selectIndex != null)
        {
            //Select a real item from the items source
            var source = line.ItemsSource as IList;
            line.SelectedItem = source[selectIndex.Value];
        }
    }

    private int? FindNearestPointIndex(PointCollection points, Point newPoint)
    {
        if (points == null || !points.Any())
            return null;

        //c^2 = a^2+b^2
        Func<Point, Point, double> getLength = (p1, p2) => Math.Sqrt(Math.Pow(p1.X - p2.X, 2) + Math.Pow(p1.Y - p2.Y, 2));

        //Create the collection of points with more information
        var items = points.Select((p,i) => new { Point = p, Length = getLength(p, newPoint), Index = i });
        var minLength = items.Min(item => item.Length);

        //Uncomment if it is necessary to have some kind of sensitive area
        //if (minLength > 50)
        //    return null;

        //The index of the point with min distance to the new point
        return items.First(item => item.Length == minLength).Index;
    }

正如我所说的这个图表将选择最近的点，即使你在很远的地方，从任何排行榜中一点点击。如果未预期的行为，则可以取消这些线和设置任何数目的像素：

As I said this chart will select the nearest point even if you click at a great distance away from any chart point. If it isn't intended behavior, you can uncomment these lines and set any number in pixels:

//Uncomment if it is necessary to have some kind of sensitive area
if (minLength > 50)
    return null;

我已经写了评论，但是如果事情是不明确的，你可以问，我会解释。

I have written comments, but if something isn't clear you can ask and I will explain.