Can anyone explain mousewheel.default.delta_multiplier?

[patrickjdempsey]

I just saw this post from Phil:
viewtopic.php?p=12196871#p12196871

I use both: mousewheel.withnokey.sysnumlines and mousewheel.withnokey.numlines in my extension to revert the hyper-fast page scrolling that has become standard in Firefox. Anyone have ANY idea how those relate to this delta_multiplier mess? How does it relate to LINES OF TEXT scrolled? Or has that been thrown out the window?

[TheVisitor]

I don't know much about code, but I suspect that https://bugzilla.mozilla.org/show_bug.cgi?id=719320 gutted most of the mousewheel settings / controls in a what appears to me to be a total-rewrite of scrolling.

I could be way off base here..

[patrickjdempsey]

Yeah that's exactly what has happened. I'm just extremely confused as to how a "delta_multiplier" relates to "numlines" or if it's not even quantifiable.

[Groovy Gregor]

It's exactly what it says it is, a delta multiplier (in percentage). If default settings scroll 150 pixels, changing that pref to 200 will cause firefox to scroll 300 pixels, and changing it to 50 will cause it to scroll 75 pixels.

[patrickjdempsey]

That sounds like it will be dramatically different from OS to OS and even different based on OS scroll settings. Which would make it non-quantifiable. Brilliant work there.

[patrickjdempsey]

It's exactly what it says it is, a delta multiplier (in percentage).

Also, I'm not an idiot, but I'm also not a mathematician. If this is an improvement, it certainly isn't in usability.

[KWierso]

https://wiki.mozilla.org/Gecko:Mouse_Wh ... ult_action

[patrickjdempsey]

Yeah I read that. No clue what it means.

Edit: I went to art school.

[patrickjdempsey]

What especially makes no sense to me is that recently they changed Firefox to scroll twice as fast as it used to... from 3 lines to 6. I just want to disable that and revert to the slower (more readable) scrolling. It used to be simple:

mousewheel.withnokey.sysnumlines: false
mousewheel.withnokey.numlines: 3

Any ideas on how to adjust the new settings or which ones to change (since they replaced the already verbose 3 dozen settings with 4 dozen).

[KWierso]

You'd probably need to post to moz.dev.platform or hop on #developers on IRC to figure out what the equivalent values would be.
I only have touchpads and touch mice at the moment, so I can't play around with a mousewheel.

[patrickjdempsey]

After mucking about with it, I think I've found it:

mousewheel.system_scroll_override_on_root_content.enabled;false

Which is equivalent of:

mousewheel.system_scroll_override_on_root_content.horizontal.factor;100
mousewheel.system_scroll_override_on_root_content.vertical.factor;100

I found it because those values were set to 200... so twice the scrolling. *facepalm* What I don't know, and have no way of confirming, is whether or not that is true on other OS's.

[rclick]

Looking at all.js, the override seems to be enabled on Windows and disabled everywhere else. There's also a comment about the prefs at http://mxr.mozilla.org/mozilla-central/source/modules/libpref/src/init/all.js#1371.

Code: Select all

// Prefs for override the system mouse wheel scrolling speed on the root
// content of the web pages.  When
// "mousewheel.system_scroll_override_on_root_content.enabled" is true and the system
// scrolling speed isn't customized by the user, the root content scrolling
// speed is multiplied by the following factors.  The value will be used as
// 1/100.  E.g., 200 means 2.00.
// NOTE: Even if "mousewheel.system_scroll_override_on_root_content.enabled" is
// true, when Gecko detects the user customized the system scrolling speed
// settings, the override isn't executed.
pref("mousewheel.system_scroll_override_on_root_content.vertical.factor", 200);
pref("mousewheel.system_scroll_override_on_root_content.horizontal.factor", 200);

[patrickjdempsey]

Hmm. So I'm wondering if on other OS's the scroll distance is greater natively, or if they are low and Windows is the only OS Mozilla wanted to bugger with.

[wworonick]

I have discovered a way to restore the mouse wheel scrolling from 6 lines back to 3, that works for Firefox 22.0, Windows 7 Professional, and a Lenovo Mouse. Change mousewheel.default.delta_multiplier_z from 100 to 50. This changes both vertical, and horizontal. After making the change, I noticed that changing mousewheel.default.delta_multiplier_x from anywhere from 33 to 200 will not make any difference, but only changing mousewheel.default.delta_multiplier_y. Values of mousewheel.default.delta_multiplier_y below 100, changes the mouse wheel scrolling to 1 line; changing mousewheel.default.delta_multiplier_y to 200, changes the scrolling lines back to 6. So, it looks like if you change mousewheel.default.delta_multiplier_z, you will have to live with changes to both vertical, and horizontal scrolling.

[LIMPET235]

Locking due to old age.