Edit MouseWheelZoomModifier Behavior

Hi Ben,

We discussed your inquiry.
To change the zooming direction you can override the OverrideKeyboardAction() method and change ActionTypeProperty and XyDirectionProperty values.
Please find the default OverrideKeyboardAction() method implementation below:

        protected virtual void OverrideKeyboardAction(MouseModifier modifier)
    {
        if (ExecuteWhen == MouseModifier.None)
        {
            if (modifier == MouseModifier.Ctrl)
            {
                this.SetCurrentValue(ActionTypeProperty, ActionType.Pan);
                this.SetCurrentValue(XyDirectionProperty, XyDirection.YDirection);
            }
            else if (modifier == MouseModifier.Shift)
            {
                this.SetCurrentValue(ActionTypeProperty, ActionType.Pan);
                this.SetCurrentValue(XyDirectionProperty, XyDirection.XDirection);
            }
        }
    }

With best regards,
Lex S., MSEE
SciChart Technical Support Engineer

Hi Lex,

Eventually there was another requirement that “Shift” modifier will produce an X-axis pan, “Ctrl” modifier will produce Y-axis zoom, and “Alt” modifier will produce XY-axes zoom.

Therefore I eventually concluded that it would be easier to inherit “RelativeZoomModifierBase” and override “OnModifierMouseWheel” method.

public class XAxisZoomWithModifiers : RelativeZoomModifierBase
{
public XAxisZoomWithModifiers()
{
GrowFactor = .1;
}

public override void OnModifierMouseWheel(ModifierMouseArgs e)
{
base.OnModifierMouseWheel(e);
e.Handled = true;
if ((ExecuteWhen != MouseModifier.None) && ExecuteWhen != e.Modifier)
{
return;
}

SetZoomState(ZoomStates.UserZooming);
using IUpdateSuspender updateSuspender = ParentSurface.SuspendUpdates();

double arg = -e.Delta / 120.0;
if (e.Modifier == MouseModifier.Shift)
{
foreach (var axis in XAxes)
{
axis.Scroll(arg * GrowFactor * GetAxisSize(axis), ClipMode.None);
}
return;
}

var point = GetPointRelativeTo(e.MousePoint, base.ModifierSurface);

XyDirection = e.Modifier switch
{
MouseModifier.None => XyDirection.XDirection,
MouseModifier.Ctrl => XyDirection.YDirection,
_ => XyDirection.XYDirection,
};
PerformZoom(point, arg, arg);
}

protected virtual double GetAxisSize(IAxis axis)
{
double num = axis.IsHorizontalAxis ? axis.Width : axis.Height;
if (Math.Abs(num) < double.Epsilon && (ParentSurface != null) && (ParentSurface.RenderSurface != null))
{
num = axis.IsHorizontalAxis ? ParentSurface.RenderSurface.ActualWidth : ParentSurface.RenderSurface.ActualHeight;
}

if (axis.IsPolarAxis)
{
num /= 2.0;
}

return num;
}
}