Re: [css3-writing-modes] horizontal-bt writing mode

John Daggett wrote:
> David Hyatt wrote:
> 
>> There is really no reason to leave it out.  Once you've abstracted
>> your engine, horizontal-bt just comes along for free.
> 
> In terms of initial implementation sure, but you still have to have
> someone make tests for those extra values, and run those tests each time
> a test suite is run.  Running a minor test a zillion times means a real
> cost.


How many test are required for this. One?


> Although the current CSS3 Writing Mode spec says nothing about this,
> writing-mode affects UI interactions.


It sure does affect UI interactions. Block progression proceeds 
leftwards instead of downwards. This is why I proposed a 'block 
progression context' [1].


> For example, in vertical-rl mode
> IE8 alters the default viewport and how the mouse scroll wheel interacts
> with it, scrolling the wheel "down" scrolls left in the vertical case. 
> Oddly, the page-up/page-down/home/end keys are all "logicalized" but
> up/down/left/right arrow keys are not.


This really is quite sensible for MS to consider and implement this.

The reason that the up and down arrow keys do not work is because none 
of the elements overflow the height of the viewport. Add this style,

body h1 {height:150%;}

and the up and down keys work.


> To see this, view the examples below.  The Flash example mimics the IE
> UI behavior:
> 
> Testcase for IE:
> 
>   http://nadita.com/murakami/tests/wagahaiwanekodearu-vert-1.html
> 
> Nice example layout using Flash:
>  
>   http://macromarionette.com/#/p/25
> 
> So in the horizontal-bt case what happens?  Using the model above the
> viewport would be set to the bottom left/right and
> page-up/page-down/home/end would all be reversed.


Yes, that sounds right.


> That's consistent and
> simple to implement but some poor tester in Beijing is going to have to
> test this each time some test suite is run.  Why waste people's time
> this way?


It could just be one test.


> I don't see any reason that "completeness" justifies additional testing
> and maintenance costs for a feature that has no use case other than
> effects than can be achieved in other ways.
> 
> John Daggett


I disagree since implementing this can help analyze problems with 
writing-mode, CSS layout and visual formating in CSS2.1.


1. <http://lists.w3.org/Archives/Public/www-style/2010Oct/0737.html>


-- 
Alan http://css-class.com/

Armies Cannot Stop An Idea Whose Time Has Come. - Victor Hugo

Received on Wednesday, 27 October 2010 03:41:39 UTC