Rewrite nine piece image painting code

Rewrite nine piece image painting code

Introduce a NinePieceImageGrid class responsible for computing the
nine piece image drawing information. The NinePieceImageGrid is
oblivious to painting details and only operates on the border image
properties (through NinePieceImage), image size and border image area.

Functionally, it shouldn't introduce any significant changes and
nothing web exposed should change at all.

Since computing drawing information is now self-contained, supply unit
tests for verifying it does the correct thing in the common and not so
common cases.

BUG=496033
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197805

[davve, 2015-06-24 11:39:48]

davve@opera.com changed reviewers:
+ chrishtr@chromium.org, fs@opera.com

[davve, 2015-06-24 11:39:49]

I originally refactored this code to ease fixing

http://code.google.com/p/chromium/issues/detail?id=492485

That bug (and spec change) seems to have stalled but I thought I should still
finish through with the refactor anyway. PTAL.

[fs, 2015-06-24 13:19:11]

LGTM w/ nits

https://codereview.chromium.org/1180053009/diff/90001/Source/core/core.gypi
File Source/core/core.gypi (right):

https://codereview.chromium.org/1180053009/diff/90001/Source/core/core.gypi#n...
Source/core/core.gypi:3937: 'paint/NinePieceImageGridTest.cpp',
N < T

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
File Source/core/paint/NinePieceImageGrid.cpp (right):

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.cpp:72: static FloatRect subrect(IntRect
rect, float offsetX, float offsetY, float width, float height)
Maybe a short comment on the behavior of this function?

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.cpp:155: static IntSize subsize(const
IntSize& size, int horizontalInset, int verticalInset)
I think there's an operator overload for this (if phrasing the "insets" as
IntSize). Maybe with a better name it might be useful still.

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
File Source/core/paint/NinePieceImageGrid.h (right):

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.h:19: class IntSize;
FloatSize, IntRect and IntSize are used in class definitions below, so forward
declaring them is a bit misleading.

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.h:85: bool draw() const { return slice > 0
&& width > 0; }
isDrawable? (or any for of query sounding name)

[davve, 2015-06-24 13:35:26]

https://codereview.chromium.org/1180053009/diff/90001/Source/core/core.gypi
File Source/core/core.gypi (right):

https://codereview.chromium.org/1180053009/diff/90001/Source/core/core.gypi#n...
Source/core/core.gypi:3937: 'paint/NinePieceImageGridTest.cpp',
On 2015/06/24 13:19:10, fs wrote:
> N < T

Done.

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
File Source/core/paint/NinePieceImageGrid.cpp (right):

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.cpp:72: static FloatRect subrect(IntRect
rect, float offsetX, float offsetY, float width, float height)
On 2015/06/24 13:19:10, fs wrote:
> Maybe a short comment on the behavior of this function?

Done.

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.cpp:155: static IntSize subsize(const
IntSize& size, int horizontalInset, int verticalInset)
On 2015/06/24 13:19:10, fs wrote:
> I think there's an operator overload for this (if phrasing the "insets" as
> IntSize). Maybe with a better name it might be useful still.

Nice, I like the operator overload.

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
File Source/core/paint/NinePieceImageGrid.h (right):

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.h:19: class IntSize;
On 2015/06/24 13:19:10, fs wrote:
> FloatSize, IntRect and IntSize are used in class definitions below, so forward
> declaring them is a bit misleading.

Done.

Removed some unused ones as well.

https://codereview.chromium.org/1180053009/diff/90001/Source/core/paint/NineP...
Source/core/paint/NinePieceImageGrid.h:85: bool draw() const { return slice > 0
&& width > 0; }
On 2015/06/24 13:19:10, fs wrote:
> isDrawable? (or any for of query sounding name)

Yep, that's better.

[davve, 2015-06-25 06:29:01]

The CQ bit was checked by davve@opera.com

[davve, 2015-06-25 06:29:02]

The patchset sent to the CQ was uploaded after l-g-t-m from fs@opera.com
Link to the patchset: https://codereview.chromium.org/1180053009/#ps110001
(title: "Address review comments")

[commit-bot: I haz the power, 2015-06-25 09:00:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1180053009/110001

[commit-bot: I haz the power, 2015-06-25 09:08:26]

Committed patchset #7 (id:110001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197805