ionSlideDidChange and ionSlidePrevEnd handlers are not fired after zoom of ion-slides

i am using ion-slides in ionic 4.in the home.html in ion-slides html element, i attach some handlers:

(ionSlideNextEnd)=“loadNext()”
(ionSlidePrevEnd)=“loadPrev()”
(ionSlideDidChange)=“onSlideChanged()”

They are called fine. However ,after i pinch , using hammerjs

//Inside the hammer events,calculates the new scale
if (ev.type == “pinch”) {
scale = Math.max(.999,
Math.min(last_scale * (ev.scale), 4));
}

if(ev.type == “pinchend”){
last_scale = scale;
}

//applies this change to the ion-slides component
transform =
“translate3d(” + posX + “px,” + posY + "px, 0) " +
“scale3d(” + scale + ", " + scale + “, 1)”;
if (transform) {
el.style.webkitTransform = transform;
}

They are not called anymore. I tried attaching them programmatically ,like that:

//I tried to call this method after zoom, but nothing changed.
this.mySlider.ionSlideDidChange.subscribe(progress =>
this.onSlideChanged());
but nothing is changed. I was wondering if you could help me on this,please? Thank you in advance.