[webkit-dev] Table hit testing

Fady Samuel fsamuel at google.com
Wed Jun 2 13:40:29 PDT 2010

So I have completed all the following things locally:

* First fix the grid to record all the cells at a given position.  This
fixes a repaint bug.
* Then change the hit-testing to work just like painting.  This makes hit
testing more efficient and ensures hit testing and painting agree.
* Then optimize hit-testing to binary-search if there are no overflowing
cells.  (And optimize painting similarly)
* Fix a table layout bug
* created a bunch of additional simple table layout tests

I did all the pieces locally first to make sure I understand how all the
parts of table rendering fit together. However, I intend to get the pieces
of this work out in in smaller patches to simplify the review process for

While I still have some more work to do testing, and splitting my work up
into the suggested pieces, please expect bug reports and proposed patches to
begin appearing shortly (within the next couple of days or so).


Fady Samuel

On Wed, Jun 2, 2010 at 7:34 AM, Fady Samuel <fsamuel at google.com> wrote:

> Ohh, I see, thanks Roland.
> Fady
> On Wed, Jun 2, 2010 at 3:25 AM, Roland Steiner <rolandsteiner at google.com>wrote:
>> AFAICT you could have an arbitrary number up to the width or height of the
>> table, whichever is smaller, by combining row- and colspans - e.g. with 3
>> ([v]aligns just to emphasize the overlapping):
>> <table border=1><tbody>
>> <tr><td>R1C1</td><td>R1C2</td><td rowspan=3 valign=bottom>\\\\\\</td></tr>
>> <tr><td>R2C1</td><td rowspan=2 colspan=2 align=right
>> valign=bottom>//////</td></tr>
>> <tr><td colspan=3 align=right>----</td></tr>
>> </tbody></table>
>> - Roland
>> On Wed, Jun 2, 2010 at 8:58 AM, Fady Samuel <fsamuel at google.com> wrote:
>>> Hi David,
>>> Just so I'm certain, there's no way for more than two cells to overlap in
>>> a single grid slot, is there?
>>> Thanks,
>>> Fady Samuel
>>> On Thu, May 20, 2010 at 4:43 PM, David Hyatt <hyatt at apple.com> wrote:
>>>> On May 20, 2010, at 3:38 PM, Fady Samuel wrote:
>>>> > So what are the rules for stacking here? do the cells stack in the
>>>> order in which they appear in the HTML?
>>>> >
>>>> Correct, although note that backgrounds paint behind foregrounds, and
>>>> hit testing works the same way, so it's not as simple as saying that cell 7
>>>> is always above cell 5.  They're interleaved, so from bottom to top:
>>>> Cell 5 background
>>>> Cell 7 background
>>>> Cell 5 foreground (the number "5" in this example)
>>>> Cell 7 foreground (the number "7" in this example)
>>>> That's why if you hover over the actual number 5 in that example it will
>>>> light up, but if you're in the background area overlap, the number 7 will
>>>> light up.
>>>> http://www.w3.org/TR/CSS21/zindex.html
>>>> Therefore you do have to know about all the cells at the position, since
>>>> when you're in the "foreground" phase of hit testing, cell 7 will say "Nope,
>>>> you're not inside my foreground", and so you then need to check cell 5,
>>>> which will say "Yes, you are inside my foreground."
>>>> The grid structure just isn't expressive enough.  It needs to be patched
>>>> to track all cells in a given row/column instead of just the first one.
>>>> dave
>>>> (hyatt at apple.com)
>>> _______________________________________________
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>>> webkit-dev at lists.webkit.org
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