1209715 - Give DrawResult operators to make it easier to combine different DrawResults

Status: RESOLVED FIXED

(Core :: ImageLib, defect)

Description

[Seth Fowler [:seth] [:s2h]]

Right now we only combine different DrawResults in nsCSSRendering::PaintBackgroundWithSC(), but to fix 1209703 we're going to have to combine them in *many* places, because borders are frequently drawn using loops. This operation is going to be so common that I think operator overloads are justified.

The operators that I think make the most sense to use for this are the bitwise AND operators, because conceptually combining DrawResults works in the same way as bitwise AND: the result is DrawResult::SUCCESS only if both operands are DrawResult::SUCCESS, and otherwise the result is failure. The details are slightly more complicated, because DrawResult::BAD_IMAGE should also be sticky; see the comments in the patch for details.

Comment 1

[Seth Fowler [:seth] [:s2h]]

(In reply to Seth Fowler [:seth] [:s2h] from comment #0)
> DrawResult::BAD_IMAGE should
> also be sticky; see the comments in the patch for details.

Actually I stated this exactly backwards - DrawResult::BAD_IMAGE is explicitly non-sticky, because we want to know if there were any recoverable failures that might go away if we do another paint. So we only want to return DrawResult::BAD_IMAGE if there were no recoverable failures. Unlike comment 0, the comments in the patch get this right. =)

Comment 2

[Seth Fowler [:seth] [:s2h]]

Attachment: Add operator overloads for combining DrawResults

Here's the patch.

Comment 3

[Seth Fowler [:seth] [:s2h]]

Thanks for the review!

Comment 4

[Seth Fowler [:seth] [:s2h]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/4d87d0f8b704

Comment 5

[Wes Kocher (:KWierso)]

https://hg.mozilla.org/mozilla-central/rev/4d87d0f8b704