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Re: Reading image bytes to a PNG in a typed array

From: Kyle Huey <me@kylehuey.com>
Date: Wed, 16 Jan 2013 07:56:49 -0800
Message-ID: <CAP045AqK3B3yjvexQBqL6Gth7eW+VipmeSNi0SSg_8oecOEhZg@mail.gmail.com>
To: Glenn Maynard <glenn@zewt.org>
Cc: Florian Bösch <pyalot@gmail.com>, Webapps WG <public-webapps@w3.org>
On Wed, Jan 16, 2013 at 7:50 AM, Glenn Maynard <glenn@zewt.org> wrote:

> On Wed, Jan 16, 2013 at 9:40 AM, Florian Bösch <pyalot@gmail.com> wrote:
>
>> Perhaps we should think of a better scheme to export data than toFoo().
>> Maybe toData('url'), toData('arraybuffer') toData('blob') or perhaps
>> toData(URL), toData(ArrayBuffer) or toData(Blob). I tend to think that if
>> you're starting to write toA, toB, toC, toX methods on an object, you've
>> not thought this really trough what's a parameter, and what's a method.
>>
>
> We should be avoiding the need to return data in a bunch of different
> interfaces in the first place.  If the data is large, or takes a long or
> nondeterministic amount of time to create (eg. something that would be
> async in the UI thread), return a Blob; otherwise return an ArrayBuffer.
>  The user can convert from there as needed.
>

Well, the problem is that we fundamentally screwed up when we specced
Blob.  It has a synchronous size getter which negates many of the
advantages of FileReader extracing data asynchronously.  For something like
image encoding (that involves compression), where you have to perform the
operation to know the size, Blob and ArrayBuffer are effectively
interchangeable from the implementation perspective, since both require you
to perform the operation up front.

- Kyle
Received on Wednesday, 16 January 2013 15:57:20 GMT

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