1007574 - [b2g] Receive two "getScreenshot" request with size 1x1 when open an application

Status: RESOLVED FIXED

(Firefox OS Graveyard :: Gaia::System::Window Mgmt, defect)

Description

[Peter Chang[:pchang]]

Open any application, I always see two "getScreenshot" requests happened and the requested size of screenshot is 1x1.

I would expect no "getScreenshot" request when app goes to foreground.

I/Gecko   (31921): BrowserElementChild - Received getScreenshot message: (req_10)
I/Gecko   (31921): BrowserElementChild - Taking a screenshot: maxWidth=1, maxHeight=1, mimeType=image/jpeg, domRequestID=req_10.
I/Gecko   (31921): BrowserElementChild - Received setVisible message: (true)
I/Gecko   (31921): BrowserElementChild - Received getScreenshot message: (req_11)
I/Gecko   (31921): BrowserElementChild - Got afterpaint event: app://communications.gaiamobile.org/contacts/index.html
I/Gecko   (31921): BrowserElementChild - Taking a screenshot: maxWidth=1, maxHeight=1, mimeType=image/jpeg, domRequestID=req_11.
I/Gecko   (31921): BrowserElementChild - Received setVisible message: (true)

Comment 1

[Tim Guan-tin Chien [:timdream] (please needinfo)]

This is done as a hack to ensure the frame is already painted, sine |setVisible()| does not return anything. Alive can verify. 

What kind of trouble we are in if we keep this?

Comment 2

[(inactive after 6/18) Alive Kuo [:alive]]

Yes, this is to make sure we have the iframe painted.

Comment 3

[Peter Chang[:pchang]]

(In reply to Tim Guan-tin Chien [:timdream] (MoCo-TPE) (please ni?) from comment #1)
> This is done as a hack to ensure the frame is already painted, sine
> |setVisible()| does not return anything. Alive can verify. 
> 
> What kind of trouble we are in if we keep this?
Compare to painting task, this should be small overhead.
I just notice this during debugging.

Alive, why do I see the requests happen twice when open an app?
But I only saw once after unlock screen from suspend.

Comment 4

[(inactive after 6/18) Alive Kuo [:alive]]

The first request is to force it to be repainted before doing opening transition.
The second request is to make sure before we remove the screenshot layer it's repainted.

What's the problem is, if we always have screenshot on top the app we don't need the first check but sometimes we have sometimes we don't.

If this really matters(two requests) I will try to fix it.

Comment 5

[(inactive after 6/18) Alive Kuo [:alive]]

Attachment: patch for master

v1: If the app window is already protected by screenshot layer, be ready right away.

Comment 6

[(inactive after 6/18) Alive Kuo [:alive]]

https://github.com/mozilla-b2g/gaia/commit/2e8f91f13a17f4d8b5c2851f20e5bd5ac67ba304

Comment 7

[Ivan Tsay (:ITsay)]

Hi Alive,

Does this one affect v1.4?

Comment 8

[(inactive after 6/18) Alive Kuo [:alive]]

Yes I think so.