Tag: Custom Zoom Modifier

I’ve verified it steps thru the code as I would expect; however, it only ever zooms in further. The intent of this modifier is to only zoom out when the mouse is dragged up and left. I.e.

Mouse down
Drag up/left
Mouse up

    class ZoomOutModifier : ZoomExtentsModifier
{
    double _x;
    double _y;
    MouseButtons _button = MouseButtons.None;

    public override void OnModifierDoubleClick(ModifierMouseArgs e)
    {
        // do not zoom to extents on a double click
        e.Handled = true;
    }

    public override void OnModifierMouseDown(ModifierMouseArgs e)
    {
        base.OnModifierMouseDown(e);

        // where was the mouse button on the chart surface?            
        _x = e.MousePoint.X;
        _y = e.MousePoint.Y;

        // which button was clicked?  we're only going to zoom 
        // out on a left button click.
        _button = e.MouseButtons;
    }

    public override void OnModifierMouseUp(ModifierMouseArgs e)
    {            
        // are we left and up from where the mouse was clicked?
        if (MouseButtons.Left == _button &&
            e.MousePoint.X < _x &&
            e.MousePoint.Y < _y)
        {
            using (var updater = ParentSurface.SuspendUpdates())
            {
                ParentSurface.ZoomExtents();
                ParentSurface.ResumeUpdates(updater);
            }

            e.Handled = true;
        }
        else
            base.OnModifierMouseUp(e);
    }
}