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Re: [whatwg] CanvasRenderingContext2D with addPath, currentPath

From: Dirk Schulze <dschulze@adobe.com>
Date: Mon, 4 Nov 2013 10:36:48 -0800
To: Glenn Maynard <glenn@zewt.org>
CC: Rik Cabanier <cabanier@gmail.com>, "whatwg@whatwg.org" <whatwg@whatwg.org>, "public-canvas-api@w3.org" <public-canvas-api@w3.org>, "Robert O'Callahan" <robert@ocallahan.org>
Message-ID: <32412330-DA6A-4EF0-AE7E-8548CC618D15@adobe.com>

On Nov 3, 2013, at 3:22 PM, Glenn Maynard <glenn@zewt.org> wrote:

> On Sat, Nov 2, 2013 at 9:03 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> 
>>> Does this mean that ctx.currentPath != ctx.currentPath?
>> 
>> Yes
>> 
>>> That's bad!
>> 
>> Why would it be bad (apart from being different)?
>> 
> 
> It's strange to say "foo.bar.baz = 1" (ctx.currentPath.baz = 1), and for
> foo.bar.baz to not be 1 the next time you look.  It's also confusing if you
> use it as a Map key.

I think the problem that the UA would be focused with is the following:

var path = ctx1.currentPath;
ctx2.currentPath = path;

or simply

ctx2.currentPath = ctx1.currentPath

Both contexts could manipulate the same path and both can have different CTMs which also change independent of each other. Mixing that up could cause a huge mess.

That is one of the reasons why WebKit creates copies.

Greetings,
Dirk
Received on Monday, 4 November 2013 18:37:25 UTC

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