Re: devtools highlighter

On 3/23/14, 10:22 PM, Ehsan Akhgari wrote:
> On 2014-03-23, 6:07 AM, Robert O'Callahan wrote:
>> On Fri, Mar 21, 2014 at 9:55 PM, Patrick Brosset 
>> <[email protected]>wrote:
>>
>>> We're struggling with a limitation related to the devtools highlighter
>>> (the outline you see in this video:
>>> https://www.youtube.com/watch?v=zBYEg40ByCM).
>>> Today, the highlighter is created with XUL nodes that are appended 
>>> in the
>>> browser XUL markup, in one of the parent elements of the page currently
>>> being inspected. These XUL nodes are absolutely positioned over the 
>>> element
>>> being highlighted.
>>>
>>> This technique has served us well until we wanted our devtools to 
>>> work on
>>> Fennec, Fxos and E10S mode. In these cases, the page being inspected
>>> doesn't have a reachable parent element that we can use to append our
>>> highlighter elements, and appending it inside the content page 
>>> itself isn't
>>> really a viable option because we don't want to impact the content 
>>> in any
>>> way.
>>>
>>
>> I think you need an API to add anonymous content to the root element 
>> of the
>> page. We don't have such an API at the moment but it might not be 
>> hard to
>> add.
>
> Bug 924692 is making the canvas frame have a native anonymous content. 
> If that is where you would like to stick that element in, then art of 
> the frame constructions bits is being done in that bug.
>
> Cheers,
> Ehsan
Bug 924692 landed yesterday so I thought this would be a good time to 
revive this thread.

So with this bug, there's now a way to insert anonymous content in the 
canvas frame, which is awesome.
 From what I understood looking at the bug and code, I can see 2 things 
potentially missing for the devtools highlighter use case:

- the code that creates the anonymous content seems pretty specifically 
tied to the touch caret and it doesn't seem possible as of now to insert 
any content,
- I don't think this can be accessed by privileged JS code yet.

I wanted to file a bug to address these 2 points, but wanted to check 
here first.

Cheers,
Patrick