[webkit-dev] Adding blending mode to WebKit canvas

[Ilyes Gouta]

Hi,

On Nov 12, 2012 4:39 PM, "Dirk Schulze" <dschulze at adobe.com> wrote:
>
>
> On Nov 11, 2012, at 10:09 PM, "Rik Cabanier" <cabanier at gmail.com> wrote:
>
>>
>>
>> On Sun, Nov 11, 2012 at 9:52 PM, Dirk Schulze <krit at webkit.org> wrote:
>>>
>>>
>>>
>>> On Sunday, November 11, 2012, Rik Cabanier wrote:
>>>>
>>>>
>>>>
>>>> On Sun, Nov 11, 2012 at 8:43 PM, Maciej Stachowiak <mjs at apple.com>
wrote:
>>>>>
>>>>>
>>>>> On Nov 11, 2012, at 6:59 PM, Rik Cabanier <cabanier at gmail.com> wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Wouldn't it be better to add a new property to canvas for blending?
At the beginning, implementations are just require to use different blend
modes in combination with 'source-over'.
>>>>>>
>>>>>>
>>>>>> That could work too.
>>>>>> There was a mailing list conversation about this a couple of months
ago, and people were evenly split on the subject.
>>>>>>
>>>>>> The vast majority of cases will use 'source-over' in combination
with blending so maybe it's best to keep it simple...
>>>>>
>>>>>
>>>>> It doesn't make sense to me for blend mode and composite operator to
be separate in CSS, but combined in Canvas. Either there are valid use
cases for specifying them separately or there are not. I cannot imagine how
this could differ between Canvas and CSS.
>>>
>>>
>>> To be fair, the 'globalCompositOperator' property mixed the compositing
modes with some blend modes already. Which is the fault of the WebKit
implementation. IIRC they have been removed from the Canvas part of the
HTML spec for some time, but were added later again. Now we have multiple
independent implementations that support all currently specified operators.
>>
>>
>> Is this the 'darker' compositing mode or are there others?
>
>
> Lighter and darker, yes.

Is additive blending also specified/supported?

Regards,
-Ilyes

> Greetings
> Dirk
>
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