Edit MouseWheelZoomModifier Behavior

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;
}
}

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