Fix SkSwizzler bug

Fix SkSwizzler bug

Now, that we are subsetting, fX0 is not necessarily less than
fSrcWidth (since fSrcWidth is really the subset width).

Ex: We may want a 10 pixel subset starting twenty pixels from the
left edge.  In that case, fX0=20 and fSrcWidth=10.

Let's rename the width as fSubsetWidth to avoid confusion
and remove the check.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/80803ff615e4293e8af2dc5d094a1f4fa81ec396

[msarett, 2015-10-13 22:02:26]

Patchset #2 (id:20001) has been deleted

[msarett, 2015-10-13 22:03:29]

msarett@google.com changed reviewers:
+ scroggo@google.com

[msarett, 2015-10-13 22:03:30]

Sorry, I meant to commit this with the partial scanlines CL.

[scroggo, 2015-10-14 14:20:24]

> Now, that we are subsetting, fX0 is not necessarily greater than
> fSrcWidth.

I think you mean "not necessarily less than"?

> Ex: We may want a 10 pixel subset starting twenty pixels from the
> left edge.  In that case, fX0=20 and fSrcWidth=10.

These names are a little confusing now. It seems like fSrcWidth is not really
the source width anymore, which is why this assert is no longer valid. fSrcWidth
is now the width of the subset.

Does the MaskSwizzler have this same issue?

[msarett, 2015-10-15 21:43:13]

On 2015/10/14 14:20:24, scroggo wrote:
> > Now, that we are subsetting, fX0 is not necessarily greater than
> > fSrcWidth.
> 
> I think you mean "not necessarily less than"?
> 

You are correct, I have fixed this.

> > Ex: We may want a 10 pixel subset starting twenty pixels from the
> > left edge.  In that case, fX0=20 and fSrcWidth=10.
> 
> These names are a little confusing now. It seems like fSrcWidth is not really
> the source width anymore, which is why this assert is no longer valid.
fSrcWidth
> is now the width of the subset.

Yes, let's rename the width as fSubsetWidth.

> 
> Does the MaskSwizzler have this same issue?

Yes, nice catch.  Fixing the mask swizzler as well.

[scroggo, 2015-10-16 13:36:17]

Can you add a test for this? Otherwise, lgtm

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzle...
File src/codec/SkMaskSwizzler.cpp (right):

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzle...
src/codec/SkMaskSwizzler.cpp:380: // check that fX0 is less than original width
This comment no longer applies

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzler.h
File src/codec/SkMaskSwizzler.h (right):

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzle...
src/codec/SkMaskSwizzler.h:59: SkMaskSwizzler(int width, SkMasks* masks, RowProc
proc);
subsetWidth?

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkSwizzler.h
File src/codec/SkSwizzler.h (right):

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkSwizzler.h#...
src/codec/SkSwizzler.h:185: SkSwizzler(RowProc proc, const SkPMColor* ctable,
int deltaSrc, int srcWidth);
subsetWidth*

[msarett, 2015-10-16 17:35:33]

Patchset #3 (id:60001) has been deleted

[msarett, 2015-10-16 17:36:52]

PTAL

Sorry about the rebase.  Somehow the branch I was on was so old that it didn't
even have partial scanline decodes.

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzle...
File src/codec/SkMaskSwizzler.cpp (right):

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzle...
src/codec/SkMaskSwizzler.cpp:380: // check that fX0 is less than original width
On 2015/10/16 13:36:16, scroggo wrote:
> This comment no longer applies

Done.

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzler.h
File src/codec/SkMaskSwizzler.h (right):

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkMaskSwizzle...
src/codec/SkMaskSwizzler.h:59: SkMaskSwizzler(int width, SkMasks* masks, RowProc
proc);
On 2015/10/16 13:36:16, scroggo wrote:
> subsetWidth?

Done.

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkSwizzler.h
File src/codec/SkSwizzler.h (right):

https://codereview.chromium.org/1407603003/diff/40001/src/codec/SkSwizzler.h#...
src/codec/SkSwizzler.h:185: SkSwizzler(RowProc proc, const SkPMColor* ctable,
int deltaSrc, int srcWidth);
On 2015/10/16 13:36:17, scroggo wrote:
> subsetWidth*

Done.

[scroggo, 2015-10-16 17:42:44]

LGTM

[msarett, 2015-10-16 17:44:31]

The CQ bit was checked by msarett@google.com

[commit-bot: I haz the power, 2015-10-16 17:44:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1407603003/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1407603003/80001

[commit-bot: I haz the power, 2015-10-16 17:54:15]

Committed patchset #3 (id:80001) as
https://skia.googlesource.com/skia/+/80803ff615e4293e8af2dc5d094a1f4fa81ec396