Re: Intent to implement: Frames timing functions

[Boris Chiou]

OK, sure. I will add a pref to protect it. Thanks for suggestion.

On Sat, Feb 25, 2017 at 12:09 AM,  wrote:

> On Thursday, February 23, 2017 at 9:09:58 AM UTC-6, Boris Chiou wrote:
> > *Preference behind which this will be implemented*: I'm not sure. I think
> > we don't need it because it is just a variant of the step timing
> function,
> > and so it is safe to turn it on. If there is any other concerns, I can
> add
> > a preference for this.
>
> Given our (and all browsers') painful history with people finding novel
> ways to bypass security by abusing any and all timers we expose, I would
> feel much better if this had a pref.
>
> -tom
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Re: Intent to implement: Frames timing functions

[Brian Birtles]

On Sat, Feb 25, 2017 at 1:09 AM,   wrote:
> On Thursday, February 23, 2017 at 9:09:58 AM UTC-6, Boris Chiou wrote:
>> *Preference behind which this will be implemented*: I'm not sure. I think
>> we don't need it because it is just a variant of the step timing function,
>> and so it is safe to turn it on. If there is any other concerns, I can add
>> a preference for this.
>
> Given our (and all browsers') painful history with people finding novel ways 
> to bypass security by abusing any and all timers we expose, I would feel much 
> better if this had a pref.

As Boris mentioned, adding a pref is no problem, but I'm curious to
learn about the specific security concern here. This doesn't expose
any new timing information. It's just a variation on the steps timing
function. Perhaps the 'frames' name suggests something about exposing
the browser's animation frames, but there's no connection between
frames() and actual animation frames in the browser.
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Re: Intent to implement: Frames timing functions

[tritter]

On Thursday, February 23, 2017 at 9:09:58 AM UTC-6, Boris Chiou wrote:
> *Preference behind which this will be implemented*: I'm not sure. I think
> we don't need it because it is just a variant of the step timing function,
> and so it is safe to turn it on. If there is any other concerns, I can add
> a preference for this.

Given our (and all browsers') painful history with people finding novel ways to 
bypass security by abusing any and all timers we expose, I would feel much 
better if this had a pref.

-tom
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Re: Intent to implement: Frames timing functions

[Brian Birtles]

On Fri, Feb 24, 2017 at 12:35 AM, Jeff Muizelaar  wrote:
> The linked bug suggests that Chrome implements this but this email suggests
> it doesn't. What's the truth?

There used to be a steps-middle timing function which is what the
linked bug originally covered. Chrome implemented it and shipped it
(but exposed it only to the Web Animations API, I believe). We
implemented it in that bug, but before we shipped it the standards
discussion progressed and revealed that steps-middle didn't really
solve the problem authors were facing, and as a result we decided on
creating a frames() timing function instead.

I spoke with Chrome engineers in January this year and they wanted to
remove steps-middle but were reluctant to do so without providing a
replacement. That's why I went ahead and specced frames() (and dropped
steps-middle at the same time). In Bugzilla we just morphed the
steps-middle bug into the frames() bug, hence the confusion.

On Fri, Feb 24, 2017 at 12:35 AM, Jeff Muizelaar  wrote:
> The linked bug suggests that Chrome implements this but this email suggests
> it doesn't. What's the truth?
>
> -Jeff
>
> On Thu, Feb 23, 2017 at 2:45 AM, Boris Chiou  wrote:
>>
>> *Summary*:
>> A frames timing function is a type of timing function that divides the
>> input time into a specified number of intervals of equal length, each of
>> which is associated with an output progress value of increasing value. The
>> difference between a frames timing function and a step timing function is
>> that a frames timing function returns the output progress value 0 and 1
>> for
>> an equal portion of the input progress value in the range [0, 1]. This
>> makes it suitable for using in animation loops where the animation should
>> display the first and last frame of the animation for an equal amount of
>> times as each other frame during each loop.
>>
>> *Bug*: https://bugzilla.mozilla.org/show_bug.cgi?id=1248340
>>
>> *Link to standard*: FPWD:
>> https://www.w3.org/TR/css-timing-1/#frames-timing-functions
>>
>> *Platform coverage*: All platform.
>>
>> *Estimated or target release*: Not yet determined.
>>
>> *Preference behind which this will be implemented*: I'm not sure. I think
>> we don't need it because it is just a variant of the step timing function,
>> and so it is safe to turn it on. If there is any other concerns, I can add
>> a preference for this.
>>
>> *DevTools bug*: Not sure.
>>
>> *Do other browser engines implement this?* No
>>
>> *Tests* - web-platform/tests/timing-functions/frames-timing-functions
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Re: Intent to implement: Frames timing functions

[Jeff Muizelaar]

The linked bug suggests that Chrome implements this but this email suggests
it doesn't. What's the truth?

-Jeff

On Thu, Feb 23, 2017 at 2:45 AM, Boris Chiou  wrote:

> *Summary*:
> A frames timing function is a type of timing function that divides the
> input time into a specified number of intervals of equal length, each of
> which is associated with an output progress value of increasing value. The
> difference between a frames timing function and a step timing function is
> that a frames timing function returns the output progress value 0 and 1 for
> an equal portion of the input progress value in the range [0, 1]. This
> makes it suitable for using in animation loops where the animation should
> display the first and last frame of the animation for an equal amount of
> times as each other frame during each loop.
>
> *Bug*: https://bugzilla.mozilla.org/show_bug.cgi?id=1248340
>
> *Link to standard*: FPWD:
> https://www.w3.org/TR/css-timing-1/#frames-timing-functions
>
> *Platform coverage*: All platform.
>
> *Estimated or target release*: Not yet determined.
>
> *Preference behind which this will be implemented*: I'm not sure. I think
> we don't need it because it is just a variant of the step timing function,
> and so it is safe to turn it on. If there is any other concerns, I can add
> a preference for this.
>
> *DevTools bug*: Not sure.
>
> *Do other browser engines implement this?* No
>
> *Tests* - web-platform/tests/timing-functions/frames-timing-functions
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Intent to implement: Frames timing functions

[Boris Chiou]

*Summary*:
A frames timing function is a type of timing function that divides the
input time into a specified number of intervals of equal length, each of
which is associated with an output progress value of increasing value. The
difference between a frames timing function and a step timing function is
that a frames timing function returns the output progress value 0 and 1 for
an equal portion of the input progress value in the range [0, 1]. This
makes it suitable for using in animation loops where the animation should
display the first and last frame of the animation for an equal amount of
times as each other frame during each loop.

*Bug*: https://bugzilla.mozilla.org/show_bug.cgi?id=1248340

*Link to standard*: FPWD:
https://www.w3.org/TR/css-timing-1/#frames-timing-functions

*Platform coverage*: All platform.

*Estimated or target release*: Not yet determined.

*Preference behind which this will be implemented*: I'm not sure. I think
we don't need it because it is just a variant of the step timing function,
and so it is safe to turn it on. If there is any other concerns, I can add
a preference for this.

*DevTools bug*: Not sure.

*Do other browser engines implement this?* No

*Tests* - web-platform/tests/timing-functions/frames-timing-functions
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