Bug 49377 – [Qt][WK2] Implement BackingStore

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit2

[Balazs Kelemen]

Fill stubbed BackingStore with implmentation!

[Balazs Kelemen]

I have a weird problem with implementing this method:
PassOwnPtr<GraphicsContext> BackingStore::createGraphicsContext()
I need to create a QImage and a QPainter on heap to create the GraphicsContext.
Our GC implementation does not own the painter so this would cause a leak.
I took a look at the CoreGraphics and Cairo implementation of GC and those
owns the platform specific data. Unfortunately we cannot tweak the GC to
behave like those because:
1. in some cases we get the painter from the user so we are not allowed to
   own that
2. there is no way to create a copy from an active painter
   (active = begin has been called)

So what I did in the change that will be uploaded is adding a way to explicitly
take off ownership of the painter and the paint device to the GC.

[Balazs Kelemen]

Created attachment 73601 [details]
Patch

[Andreas Kling]

Comment on attachment 73601 [details]
Patch

r=me

[Balazs Kelemen]

Comment on attachment 73601 [details]
Patch

Clearing flags on attachment: 73601

Committed r71821: <http://trac.webkit.org/changeset/71821>

[Balazs Kelemen]

All reviewed patches have been landed.  Closing bug.

[Balazs Kelemen]

Noam, could you take a post review on the patch? Maybe it should be tweaked for
performance (maybe the QImage format).

[Noam Rosenthal]

Post review looks good!

[Andreas Kling]

One thing we might want to look at later is letting QImage align its scanlines on 32-bit boundaries (the default behavior) instead of using the cramped W*H*4 format.

It basically just means overriding UpdateChunk::size() and removing the stride (width * 4) arguments to QImage constructors.