W3C home > Mailing lists > Public > www-style@w3.org > January 2014

thoughts about css-snappoints

From: Andrew Fedoniouk <news@terrainformatica.com>
Date: Wed, 29 Jan 2014 22:07:28 -0800
Message-ID: <CALRQH7_dbaVSXJf3f7mFHoNhFqGFHQia08t7Xw5sQe3q-H2qtA@mail.gmail.com>
To: "www-style@w3.org" <www-style@w3.org>
(That is actually not about Snap Points Module[1] per se but rather
similar idea.)

While ago I've implemented similar feature but in more generic fashion
I would say.

In order to define details of scrolling I've added functional value
named `scroll-manner`
that can be used in 'overflow' properties.

Here is an example:

overflow-x:auto scroll-manner( page-animation:true,
step-animation:true, page:100%, step:25% );

(I am using peculiar syntax but concept can be expressed in more standard way)

The above means: if scrolling is needed try to use animated scrolling
for page-scroll and line-scroll events, page step will be of 100% of
scrollable box width of the element, and single step will use
25% of its width. So to scroll view in full it will take four next line clicks.

'page-animation' and 'step-animation' accept: true | false | default,
    default value: default.

'page' and 'step' accept: <length> | <percent> | auto | default
    default value: default;

'auto' value means that scrolling engine shall made an attempt
to use integral stops so scrolling shall end on content boundaries
rather somewhere in between.

'Content boundaries' meaning is different for each layout manager
used by the element. E.g. for horizontal flexbox these are left/right
sides of margin boxes of children. For template/grid layout manager
these are column/rows boundaries. Same is for table rows/columns
and columns in multi-column layout.

To summarize:
1. We should have mechanism of describing animation/discrete
2. We should have a mechanism to define "scroll stops" more
intelligently than just elements.
3. Each layout manager / mechanism shall define concept of
"scroll stops".

[1] http://dev.w3.org/csswg/css-snappoints

Andrew Fedoniouk.

Received on Thursday, 30 January 2014 06:07:58 UTC

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