Background(You can read the proposal below by skipping it if you are only interested in the proposal part itself)
A year ago, David Baron mentioned that at a discussion in the CSS WG someone raised the issue that people are hesitant to use vertical writing-mode at the top level of the page(and I think all the horizontally scrollable contents also suffer, regardless of whether it's vertical writing and whether it's at the top level) as most of the users only have a single-direction wheel in their pointing device.
This is a realistic problem we are facing, more than ten years have passed since the first standardized writing-mode came out, but in practical it's still very hard for us to see ANY SINGLE website which uses vertical writing-mode at the its pages' top level. Why? I don't think we can conclude that people aren't interested in vertical writing pages(Think about it: there are about a quarter of the population in the world whose native languages are traditionally vertical writing), I think it's the incovinent horizontal scrolling UX in almost of all browsers which makes the reality.
Unfortunately there is difficulty to solve this kind of issue by browsers themselves without no any standard involving:
Earlier on, I implemented an experimental feature called auto-dir scrolling in Gecko, it's mostly used to horizontalize a vertical wheel scroll to a horizontal scroll when the hovering target only has a horizontal scrollbar but no vertical scrollbar. But the opinions on the feature turned out to vary from person to person, there are people favouring the feature, and there are also people finding it erratic. So, the solution overall doesn't seem to be any better. Part of the reason of the varied thoughts is personal preference, and the more important reason I think is that the necessities of convinent horizontal scrolling are different in different senarios: there are overflowed horizontal contents which are not important and don't need to be read carefully, and there are also overflowed horizontal contents which are very important to be read without which people are unable to comprehend the whole content. For example, the classcial former senario could be some Latin text with lots of lines, and just very few long lines of the text overflowed in the horizontal direction; the classcial latter senario could be some lengthy vertical writing CJK text, and several paragraphs are completely overflowed in the horizontal direction. So it's hard for browsers to distinguish complicated senarios, a standard needs to come out so that the responsibility can handed off to the web developers, so with code, developers would be able to tell the browser how important the convinent horizontal scrolling would be for an element.
Proposal
Given the above background, I propose to add major-scroll-direction property in CSS.
The property has the following values:
none
both
vertical
horizontal
auto
The values have the following meanings:
none: This value doesn't give any hint to the user agent as to which direction scrolling is eager for convenience. So no sepcial treatment for scroll input. This value typically indicates the traditional way just as we already have in all browsers.
Take a mouse wheel for example, if the default action of the wheel event scroll is a scroll event, then a vertical wheel is treated as a vertical scroll event, and a horizontal wheel is treated as a horizontal scroll event.
both: This value gives a hint to the user agent that scrollings in either direction are eager for convenience. The user agent should always try its best to provide convenience for the scrolling in either direction when possible.
Take a mouse wheel for example, when the default action of a wheel event scroll is a scroll event, then the behaviour of this value is recommended to be implemented in this way:
- If the element is only scrollable in one direction, then the default action of any wheel scroll(no matter it's vertical or horizontal) is a scroll event in the only scrollable direction.
- If the element is scrollable or unscrollable in both directions, then the behaviour is the same as
none.
The auto-dir feature mentioned in the Background section above is pretty much the implementation of this value.
horizontal: This value gives a hint to the user agent that scrolling in the horizontal direction is eager for convenience. The user agent should always try its best to provide convenience for the scrolling in horizontal direction when possible.
Take a mouse wheel for example, when the default action of a wheel event scroll is a scroll event, then the behaviour of this value is recommended to be implemented in this way:
- If the element is only scrollable in the horizontal direction, then the default action of any wheel scroll(no matter it's vertical or horizontal) is a scroll event in the horizontal direction.
- If the element is scrollable or unscrollable in both directions, or is only scrollable in the vertical direction, then the behaviour is the same as
none.
vertical: This value gives a hint to the user agent that scrolling in the vertical direction is eager for convenience. The user agent should always try its best to provide convenience for the scrolling in vertical direction when possible.
Take a mouse wheel for example, when the default action of a wheel event scroll is a scroll event, then the behaviour of this value is recommended to be implemented in this way:
- If the element is only scrollable in the vertical direction, then the default action of any wheel scroll(no matter it's vertical or horizontal) is a scroll event in the vertical direction.
- If the element is scrollable or unscrollable in both directions, or is only scrollable in the horizontal direction, then the behaviour is the same as
none.
vertical is almost just in theory, actually not of much value in practice. Because the reality is that vertical scrolling is already convinent. But the CSS(as an abstract standard) just doesn't assume the reality. This value is for an imagined pointing device which doesn't support a native convinent vertical scrolling.
auto: If the element is in vertical writing mode(I.e. vertical-rl, vertical-lr, sideways-rl, sideways-lr), the value is computed to horizontal; if the element is in horizontal writing mode(I.e. horizontal-tb), the value is computed to vertical.
major-scroll-direction is an inherited property, and its initial value is none.
I am expecting to hearing from your opinions on this proposal.
Thank you.
Background(You can read the proposal below by skipping it if you are only interested in the proposal part itself)
A year ago, David Baron mentioned that at a discussion in the CSS WG someone raised the issue that people are hesitant to use vertical writing-mode at the top level of the page(and I think all the horizontally scrollable contents also suffer, regardless of whether it's vertical writing and whether it's at the top level) as most of the users only have a single-direction wheel in their pointing device.
This is a realistic problem we are facing, more than ten years have passed since the first standardized writing-mode came out, but in practical it's still very hard for us to see ANY SINGLE website which uses vertical writing-mode at the its pages' top level. Why? I don't think we can conclude that people aren't interested in vertical writing pages(Think about it: there are about a quarter of the population in the world whose native languages are traditionally vertical writing), I think it's the incovinent horizontal scrolling UX in almost of all browsers which makes the reality.
Unfortunately there is difficulty to solve this kind of issue by browsers themselves without no any standard involving:
Earlier on, I implemented an experimental feature called auto-dir scrolling in Gecko, it's mostly used to horizontalize a vertical wheel scroll to a horizontal scroll when the hovering target only has a horizontal scrollbar but no vertical scrollbar. But the opinions on the feature turned out to vary from person to person, there are people favouring the feature, and there are also people finding it erratic. So, the solution overall doesn't seem to be any better. Part of the reason of the varied thoughts is personal preference, and the more important reason I think is that the necessities of convinent horizontal scrolling are different in different senarios: there are overflowed horizontal contents which are not important and don't need to be read carefully, and there are also overflowed horizontal contents which are very important to be read without which people are unable to comprehend the whole content. For example, the classcial former senario could be some Latin text with lots of lines, and just very few long lines of the text overflowed in the horizontal direction; the classcial latter senario could be some lengthy vertical writing CJK text, and several paragraphs are completely overflowed in the horizontal direction. So it's hard for browsers to distinguish complicated senarios, a standard needs to come out so that the responsibility can handed off to the web developers, so with code, developers would be able to tell the browser how important the convinent horizontal scrolling would be for an element.
Proposal
Given the above background, I propose to add
major-scroll-directionproperty in CSS.The property has the following values:
nonebothverticalhorizontalautoThe values have the following meanings:
none: This value doesn't give any hint to the user agent as to which direction scrolling is eager for convenience. So no sepcial treatment for scroll input. This value typically indicates the traditional way just as we already have in all browsers.both: This value gives a hint to the user agent that scrollings in either direction are eager for convenience. The user agent should always try its best to provide convenience for the scrolling in either direction when possible.The auto-dir feature mentioned in the Background section above is pretty much the implementation of this value.
horizontal: This value gives a hint to the user agent that scrolling in the horizontal direction is eager for convenience. The user agent should always try its best to provide convenience for the scrolling in horizontal direction when possible.vertical: This value gives a hint to the user agent that scrolling in the vertical direction is eager for convenience. The user agent should always try its best to provide convenience for the scrolling in vertical direction when possible.auto: If the element is in vertical writing mode(I.e.vertical-rl,vertical-lr,sideways-rl,sideways-lr), the value is computed tohorizontal; if the element is in horizontal writing mode(I.e.horizontal-tb), the value is computed tovertical.major-scroll-directionis an inherited property, and its initial value isnone.I am expecting to hearing from your opinions on this proposal.
Thank you.