当鼠标在点上时查看图表点的值 [英] see values of chart points when the mouse is on points

问题描述

我有一个图表，希望用户将指针放在点上时看到这些值. 通过使用页面在页面中找到digEmAll的帮助，图表，我可以编写以下代码:

I have a chart and I want the user to see the values when the pointer is on the points. By using digEmAll's help in the page finding the value of the points in a chart ,I could write the following code:

Point? prevPosition = null; 
ToolTip tooltip = new ToolTip();  

void chart1_MouseMove(object sender, MouseEventArgs e) 
{     
    var pos = e.Location;     
    if (prevPosition.HasValue && pos == prevPosition.Value)         
        return;     
    tooltip.RemoveAll();     
    prevPosition = pos;     
    var results = chart1.HitTest(pos.X, pos.Y, false, ChartElementType.PlottingArea);     
    foreach (var result in results)     
    {         
        if (result.ChartElementType == ChartElementType.PlottingArea)         
        {            
            chart1.Series[0].ToolTip = "X=#VALX, Y=#VALY";          
        }    
    } 
} 

通过上述代码，当指针位于序列附近时，用户可以看到值.但是现在，我如何让用户仅当指针位于时看到值?点上? 我替换了

by the above code,the user can see the values when the pointer is near to a series.But now How can I let the user to see the values only when the pointer is on the points? I replaced

int k = result.PointIndex;
if (k >= 0)
{
    chart1.Series[0].Points[k].ToolTip = "X=#VALX, Y=#VALY";
}

代替

chart1.Series[0].ToolTip = "X=#VALX, Y=#VALY";

解决我的问题.但这没用.

to solve my problem.But It wasn't usefull.

推荐答案

您应按以下方式修改代码:

You should modify the code in this way:

Point? prevPosition = null;
ToolTip tooltip = new ToolTip();

void chart1_MouseMove(object sender, MouseEventArgs e)
{
    var pos = e.Location;
    if (prevPosition.HasValue && pos == prevPosition.Value)
        return;
    tooltip.RemoveAll();
    prevPosition = pos;
    var results = chart1.HitTest(pos.X, pos.Y, false,
                                    ChartElementType.DataPoint);
    foreach (var result in results)
    {
        if (result.ChartElementType == ChartElementType.DataPoint)
        {
            var prop = result.Object as DataPoint;
            if (prop != null)
            {
                var pointXPixel = result.ChartArea.AxisX.ValueToPixelPosition(prop.XValue);
                var pointYPixel = result.ChartArea.AxisY.ValueToPixelPosition(prop.YValues[0]);

                // check if the cursor is really close to the point (2 pixels around the point)
                if (Math.Abs(pos.X - pointXPixel) < 2 &&
                    Math.Abs(pos.Y - pointYPixel) < 2)
                {
                    tooltip.Show("X=" + prop.XValue + ", Y=" + prop.YValues[0], this.chart1,
                                    pos.X, pos.Y - 15);
                }
            }
        }
    }
}

这个想法是要检查鼠标是否非常靠近该点，例如在其周围2像素(因为实际上不太可能精确到该点)，并在这种情况下显示工具提示.

The idea is to check if the mouse is very close to the point e.g. 2 pixels around it (because is really unlikely to be exactly on the point) and show the tooltip in that case.

这是一个完整的工作示例.

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