Hi Leo ,
Currently there is no built in support to call the Resetbuttons click event when the chart is zoomed in. However you can use the ZoomOutIncrement property to chage the ZoomOut factor, when the user click on the reset button.
this.ChartWebControl1.ZoomOutIncrement = 1;
Please refer to the attached sample. In this sample the ZoomOutIncrement is set to 1. Here you can completely reset the chart zooming with single click on the reset button.
http://www.syncfusion.com/Product/uploads/Chart_Zooming_28f29758.zipPlease refer to it and let me know if this helps.
Thanks,
Nagaraj