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Comment by danhardman | Hacker News Reader

Having trouble zooming in and out (ctrl + scroll). The zoom is incredibly sensitive and once I've zoomed one way, I can't get back to normal... Only to the polar opposite.

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Use alt+scroll for less sensitive zoom.

You can also hit "1" to reset your viewport to the origin with no zoom.

It's a bit of an oddity that ctrl + scroll works at all--mac trackpads set the ctrl key bit on the event when you use pinch-to-zoom. At the normal rate, the pinch-to-zoom feels too sluggish, so I speed it up by 10x. Unfortunately, I can't find a way to tell the difference between pinch-to-zoom on a mac trackpad and normal ctrl + scroll.

Would something like this work?

    ontouchstart: scrollMultiplier = 10;
    ontouchend: if(evt.touches.length === 1) scrollMultiplier = 1;

I would have thought it would be a touch event, but it's actually a normal scroll event. The only difference I can see is that it has the ctrl bit flipped.

Here's the stackoverflow answer: http://stackoverflow.com/questions/15416851/catching-mac-tra...

Probably for interoperability for applications that use "standard" ctrl-scroll for zoom.

It's a relatively common shortcut.

I understand that, but do any of the touch events fire in parallel? Like, just before the pinch happens, is there not a touch start even for when the fingers touch the screen? The idea is to change the rate of the normal scroll event only if there are fingers on the screen.

I don't think there are any touch events at all when you're using a trackpad on a mac. For mobile, we can distinguish by the touch events.

Oh, yes, I'm sorry. I completely spaced on what you were saying.

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