1735319 - Pinch gesture triggers zoom of the viewport instead of zoom inside the webapp

Status: NEW

(Web Compatibility :: Site Reports, defect, P3)

Description

[Karl Dubost💡 :karlcow]

1. Go to https://www.earthcam.net/projects/empirestatebuilding/gigapixelpanorama/2021/
2. wait for the image to load
3. pinch gesture to zoom in

Expected:
Image is being zoomed in and better resolution is loaded. (The surrounding UI stays in place)

Actual:
The full viewport is being zoomed in, instead of zooming in the image. It results in a pixelated image. The webapp didn't receive the pinch gesture.

Go back to step 1.
Instead of pinch gesture, try the two fingers on the trackpad and move up to zoom in.
The image is properly zoomed with better definition.

This is very similar to what was happening in Bug 1721601 (but in the case of double tap).

Comment 1

[Timothy Nikkel (:tnikkel)]

Pinch zoom is distinct from double tap in that there is no way for a webpage to call preventDefault to stop the browser from double tapping but there is for pinch zooming.

Comment 2

[Timothy Nikkel (:tnikkel)]

Inspecting the page that only event handler I've seen that would recieve pinch zoom events is a DOMMouseScroll handler:
function r(a) {
var c = 0;
if (1 != da.disablewheel && (ua(a), bb([277]), x())) {
a.wheelDelta ? c = a.wheelDelta / -120 : a.detail && (c = a.detail, 0 == d.mac && (c /= 3));
var b = c * da.mousefovchange;
da.zoomtocursor ? (Ga = !0, u(a), Ja = H.x, xa = H.y, 0 < b && 0 == da.zoomoutcursor && (Ga = !1)) : Ga = !1;
Ka = !0;
Ma = 0;
Ra += .001 * b;
m.wheeldelta_raw = -c;
m.wheeldelta = 3 * -c;
z([73])
}
}

Not sure if it's firing or not or if it's doing the right then when it fires.

Comment 3

[Timothy Nikkel (:tnikkel)]

I forgot about bug 1705584, might be causing this.