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c#axismousewheeloxyplot

oxyplot axis locking center when mouse wheel

I'm new to wpf and oxyPlot. Now, I want create a dynamic line chart like an oscilloscope, but I don't know how to lock the axis on a value when mouse wheel zooms.

Example:

enter image description here

The red point is mouse location. In normal, zoom A -> B, zoom C -> D. now, I want to zoom C ->E, like mouse location at 0 center.

Solution

  • I've found a solution that works for blocking an axis zoom center. You have to create a custom LinearAxis to achieve this:

    public class FixedCenterLinearAxis : LinearAxis
{
    double center = 0;
    public FixedCenterLinearAxis() : base(){}

    public FixedCenterLinearAxis(double _center) : base()
    {
        center = _center;
    }

    public override void ZoomAt(double factor, double x)
    {
        base.ZoomAt(factor, center);
    }
}

    You have to use it like that:

    var bottomAxis = new FixedCenterLinearAxis(0.5) //specify the center value here
{
    Position = AxisPosition.Bottom,
};

plotModel.Axes.Add(bottomAxis);

    If you dont specify a value on the constructor, center value will be 0.