Preference for zoom scaling

[j-jasz]

With multitude of display resolutions and hardware options like flying mouse wheels (MX Master for example) and future mobile version of Graphite it would be good to have more control of how viewport zoom levels behave.

This is a known issue in other 2D applications as well: https://krita-artists.org/t/smooth-zoom-with-mouse-wheel/31011
In the above example of Krita it was solved by adding to the preference an option to set multiplier for zoom steps.
For version 5.2.9 it can be set in: Settings -> Configure Krita -> General -> Tools -> Zoom steps between powers of 2

[0HyperCube]

Thanks for reporting @j-jasz. Using ctrl + scroll works by a multiplier of the scroll delta reported to us by the browser from the WheelEvent's deltaY.

Graphite/editor/src/messages/portfolio/document/navigation/navigation_message_handler.rs

Lines 235 to 236 in 85fac63

	let scroll = ipp.mouse.scroll_delta.scroll_delta();
	let mut zoom_factor = 1. + scroll.abs() * VIEWPORT_ZOOM_WHEEL_RATE;

I am not familiar with the «MX Master». However I assume that your browser is rounding the scroll delta. I'm not sure if there is a way to avoid this. To confirm that this is the case, please try the wheel event demo from mdn and check if you still see the rounded deltas.

An alternative approach to zoom smoothly is to use the navigate tool and drag the mouse up and down.

I'll close this since I don't really see any way that Graphite could better deal with this.

[j-jasz]

Fair enough. If the interaction is decided by a browser limitation, then I get why its not possible.
Perhaps this could be revisited in the more distant future with the desktop app?

By the way MX Master is a mouse from Logitech. It is widely used by digital creators and it has flying wheel that allows for scrolling really, really fast without intermediate snapping. I believe this function is also in different mouse models.

[0HyperCube]

If we end up writing a native desktop app then I guess that would avoid any modifications done by the browser to the scroll delta.

In the meantime I guess we could allow the user to customise the VIEWPORT_ZOOM_WHEEL_RATE to change the zoom rate. Would you find that useful @j-jasz?

[j-jasz]

Yes that would be fantastic! As long as this would not impact other areas outside of the viewport where the scrolling is used.
I was thinking about simple multiplication by a value between 0-1 in the preferences?
Also this is a pure 'quality of life' feature from my perspective so I understand completely if you have more important things to work on.