Revert "Refactor trimming logic for read/writePixels()"

This reverts commit 977f64cbfad1ecd7fd4b1231c694c7e828fda1f0.

Reason for revert: Triggering nanobench asserts

Original change's description:
> Refactor trimming logic for read/writePixels()
> 
> (1) Move trimming logic into Bitmap/Pixmap level for
>     raster.  Everything goes through here, so we'll
>     only do the work once.
> (2) This means it also goes to GPU level.
> (3) Always use SkReadPixelsRec rather than inlining
>     the logic.
> (4) Create an SkWritePixelsRec to encapsulate write
>     trimming.
> (5) Disabled kIndex8 as a dst - always.
> 
> BUG=skia:6021
> 
> Change-Id: I748f50c3b726f7c6de5462e2b1ccb54bc387a510
> Reviewed-on: https://skia-review.googlesource.com/7326
> Reviewed-by: Mike Reed <reed@google.com>
> Commit-Queue: Matt Sarett <msarett@google.com>
> 

TBR=msarett@google.com,brianosman@google.com,reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:6021

Change-Id: If9aacc6ce8b20e3dfe8a0f22ebca653f28356175
Reviewed-on: https://skia-review.googlesource.com/7379
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/core/SkImageInfoPriv.h b/src/core/SkImageInfoPriv.h
index f04acc5484..151de82632 100644
--- a/src/core/SkImageInfoPriv.h
+++ b/src/core/SkImageInfoPriv.h
@@ -39,7 +39,8 @@ static inline bool SkImageInfoIsValid(const SkImageInfo& info) {
 /**
  *  Returns true if Skia has defined a pixel conversion from the |src| to the |dst|.
  *  Returns false otherwise.  Some discussion of false cases:
- *      We will not convert to kIndex8.  Do we overwrite the input color table?
+ *      We will not convert to kIndex8 unless |src| is kIndex8.  This is possible only
+ *      in some cases and likley inefficient.
  *      We do not convert to kGray8 when the |src| is not kGray8.  We may add this
  *      feature - it just requires some work to convert to luminance while handling color
  *      spaces correctly.  Currently no one is asking for this.
@@ -56,7 +57,7 @@ static inline bool SkImageInfoValidConversion(const SkImageInfo& dst, const SkIm
         return false;
     }
 
-    if (kIndex_8_SkColorType == dst.colorType()) {
+    if (kIndex_8_SkColorType == dst.colorType() && kIndex_8_SkColorType != src.colorType()) {
         return false;
     }