SignaturePad and <ion-scroll> canvas

Hello. I create simply canvas view with Signature Pad from ( I would like to zooming the canvas. The problem is when I change the zoom, signature pad reads wrong position of my finger and draw line in another place.
Here’s my html code
<ion-scroll zooming="true" id="myCanvas" min-zoom="0.5" max-zoom="2" direction="xy" delegate-handle="canvas" overflow-scroll="false" style="width: 90%; display: block; margin: 0 auto; max-width: 1240px; border: 1px solid black; background-color: #fff;"> <canvas height="1754" width="1240" id='signatureCanvas'></canvas> </ion-scroll>
Thanks for help.