在图表上选择特定值 [英] Selecting specific values on a Chart

问题描述

我试图创建一个复制和粘贴功能与我的图形上的数据，我想知道是否有任何方法来获得图表上点的x位置，当它被点击？

I'm trying to create a sort of copy and paste function with the data on my graph and I was wondering if there was any way to get the x position of a point on the chart when it is clicked?

基本上，这个想法是能够点击图形的一部分并拖动以选择一个区域，然后我将相应地处理。

Basically, the idea is to be able to click a portion of the graph and drag to select an area, which I will then process accordingly.

所以，我需要知道用户在图表上点击的位置，以确定所选区域的第一个点。

So, I need to be able to figure out where on the graph the user has clicked to determine the what the first point of the selected area will be.

我通过图表API，但我似乎找不到任何有用的这种类型的问题。

I looked through the chart API, but I couldn't seem to find anything useful for this type of problem..

推荐答案

要直接点击 DataPoint ，您可以执行 HitTest 。

For directly clicking on a DataPoint you can do a HitTest. But for tiny points or for a selection of a range this will not work well.

必要的函数隐藏在 Axes 方法。

The necessary functions are hidden in the Axes methods.

此解决方案使用常规橡皮圈矩形选择捕获的点：

This solution uses a regular rubber-band rectangle to select the points caught:

Point mdown = Point.Empty;
List<DataPoint> selectedPoints = null;

private void chart1_MouseDown(object sender, MouseEventArgs e)
{
    mdown = e.Location;
    selectedPoints = new List<DataPoint>();
}

private void chart1_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == System.Windows.Forms.MouseButtons.Left)
    {
        chart1.Refresh();
        using (Graphics g = chart1.CreateGraphics())
            g.DrawRectangle(Pens.Red, GetRectangle(mdown, e.Location));
    }
}

private void chart1_MouseUp(object sender, MouseEventArgs e)
{
    Axis ax = chart1.ChartAreas[0].AxisX;
    Axis ay = chart1.ChartAreas[0].AxisY;
    Rectangle rect = GetRectangle(mdown, e.Location);

    foreach (DataPoint dp in chart1.Series[0].Points)
    {
        int x = (int)ax.ValueToPixelPosition(dp.XValue);
        int y = (int)ay.ValueToPixelPosition(dp.YValues[0]);
        if (rect.Contains(new Point(x,y))) selectedPoints.Add(dp);
    }

    // optionally color the found datapoints:
    foreach (DataPoint dp in chart1.Series[0].Points)
        dp.Color = selectedPoints.Contains(dp) ? Color.Red : Color.Black;
}

static public Rectangle GetRectangle(Point p1, Point p2)
{
    return new Rectangle(Math.Min(p1.X, p2.X), Math.Min(p1.Y, p2.Y),
        Math.Abs(p1.X - p2.X), Math.Abs(p1.Y - p2.Y));
}

注意，这将适用于 Line，FastLine和点图表。对于其他类型，您必须调整选择标准！

Note that this will work for Line, FastLine and Point charts. For other types you would have to adapt the selection criterium!

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