- From: Rik Cabanier <cabanier@gmail.com>
- Date: Tue, 18 Dec 2012 20:39:11 -0800
- To: robert@ocallahan.org
- Cc: Vladimir Vukicevic <vladimir@pobox.com>, Kevin Gadd <kevin.gadd@gmail.com>, Justin Novosad <junov@chromium.org>, whatwg@lists.whatwg.org, Jeff Muizelaar <jmuizelaar@mozilla.com>, Ian Hickson <ian@hixie.ch>
On Tue, Dec 18, 2012 at 1:14 PM, Robert O'Callahan <robert@ocallahan.org>wrote: > On Wed, Dec 19, 2012 at 4:17 AM, Kevin Gadd <kevin.gadd@gmail.com> wrote: > >> Sorry, upon reading over the ImageBitmap part of the spec again I'm >> confused: Why is constructing an ImageBitmap asynchronous? I thought >> any decoding isn't supposed to happen until drawImage, so I don't >> really understand why this operation involves a callback and a delay. >> Making ImageBitmap creation async means that you *cannot* use this as >> a replacement for drawImage source rectangles unless you know all >> possible source rectangles in advance. This is not possible for many, >> many use cases (scrolling through a bitmap would be one trivial >> example). >> > > I think this is a real problem. > > It seems to me a synchronous constructor that creates an ImageBitmap for a > subimage of another ImageBitmap (but not other kind of source!) will be > needed. > > Did you mean to say a synchronous constructor? Reading the new spec ( http://www.whatwg.org/specs/web-apps/current-work/#imagebitmap), I still fail to see how this is better than a drawimage with dx=dy=0 and dw/dy=canvas width/height
Received on Wednesday, 19 December 2012 04:39:38 UTC