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Re: [whatwg] A question about the drawimage() canvas function

From: Robert O'Callahan <robert@ocallahan.org>
Date: Sun, 3 Mar 2013 22:32:18 +1300
Message-ID: <CAOp6jLbAemewfjwGK6NozZo7-Gcg-ByCx=274K6-PUEuc42Vkw@mail.gmail.com>
To: Rik Cabanier <cabanier@gmail.com>
Cc: "Kang-Hao \(Kenny\) Lu" <kanghaol@oupeng.com>, Glenn Maynard <glenn@zewt.org>, 王铁套 <wang.tietao@outlook.com>, WHAT Working Group <whatwg@whatwg.org>
On Sun, Mar 3, 2013 at 10:26 AM, Rik Cabanier <cabanier@gmail.com> wrote:

> On Fri, Mar 1, 2013 at 1:28 PM, Robert O'Callahan <robert@ocallahan.org>wrote:
>
>> I actually just wrote a patch to implement the spec behavior in Firefox.
>>
>> I think changing behavior from "throw" to "not throw" shouldn't have any
>> compatibility concerns. I also think that "not throw" is better here than
>> throwing; it's simpler to not distinguish "finished downloading but
>> decoding failed" from "download in progress (but very slow perhaps)".
>>
>> In fact I question why the spec has us throw for zero-sized canvas source.
>> It would seem to me to be simpler/better to just not draw and not throw in
>> that case also.
>>
>
> Are you going ahead with this patch?
> This will change current behavior. If we agree ignoring the error makes
> more sense, we will have to change ie and wk as well as patch the canvas
> spec more.
>

My patch follows the current spec, not the revised proposal of
https://www.w3.org/Bugs/Public/show_bug.cgi?id=21173. So maybe I shouldn't
go ahead with it.

It would be really simple if we never throw and just paint nothing when we
don't have a valid image or the source has no pixels. Changing cases from
throwing to not throwing is very unlikely to cause compatibility risk. Why
not just do it?

Rob
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Received on Sunday, 3 March 2013 09:33:06 GMT

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