[webkit-dev] WebKit Wishes

[noam.rosenthal at nokia.com]

On 2/3/13 7:46 PM, "ext Maciej Stachowiak" <mjs at apple.com> wrote:

>If you're asking about phasing it out entirely, we don't have any
>immediate plans to deprecate or remove the WebKit1 mac API. There are
>quite a few Apple and third-party apps using it, and WebKit2 is not even
>public API on Mac OS X currently.
>
>As for implementing aspects of the WebKit1 API in a less efficient but
>less WebCore-intrusive way, we could probably start doing that now, on a
>case-by-case basis. Do you have any specific constraints you're concerned
>about?
Maybe the problem is less about the WK1 API layer and more about
WebCore/platform.
In many other projects, there is a common pattern of "platform adaptation
layer", where there is a clear semi-public and stable interface exposed by
the middleware, which allows platform adaptations to occur with less
intrusive dependencies. WebKit doesn't really have that notion, making it
impossible to "port" webkit without either participating in trunk or
forking.

Platform adaptations bring a lot of benefit since they allow flexibility,
but they come with the cost of not being able to always achieve the most
straightforward vertical integration.
Accelerated compositing is, in my view, a successful example of a platform
adaptation layer. GraphicsContext is perhaps less successful.
A successful platform adaptation is measured by how much access is needed
to the underlying platform-specific implementation. For GraphicsContext,
for example, we call platformContext() inside rendering code way too much.

I suggest that a good (but difficult) starting point to separating WebCore
and the platform adaptation is to remove all or most calls to
GraphicsContext::platformContext(), adding the appropriate functionality
as public interface to GraphicsContext, making the rendering code truly
platform agnostic, and perhaps later externalized as a true platform
adaptation interface.
But I would let others say whether this is feasible/desirable :)