Revert "Respect full precision for RGB16 PNGs"

This reverts commit 7a090c403da1dad6a2e19f2011158bd894a62d91.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Respect full precision for RGB16 PNGs
> 
> BUG=skia:
> 
> CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD
> 
> Change-Id: If58d201daae97bce2f8efbc453c2ec452e682493
> Reviewed-on: https://skia-review.googlesource.com/7085
> Commit-Queue: Matt Sarett <msarett@google.com>
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Reviewed-by: Leon Scroggins <scroggo@google.com>
> Reviewed-by: Mike Reed <reed@google.com>
> 

TBR=mtklein@chromium.org,mtklein@google.com,msarett@google.com,scroggo@google.com,reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:
CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD

Change-Id: Ibd9879bc4f65ca0c2457dd0bfb5eb008d9a8f672
Reviewed-on: https://skia-review.googlesource.com/7183
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>

1 files changed, 9 insertions, 29 deletions

diff --git a/src/codec/SkPngCodec.cpp b/src/codec/SkPngCodec.cpp
index 468b0b8731..9f5c8e6906 100644
--- a/src/codec/SkPngCodec.cpp
+++ b/src/codec/SkPngCodec.cpp
@@ -420,12 +420,8 @@ void SkPngCodec::allocateStorage(const SkImageInfo& dstInfo) {
             // be created later if we are sampling.  We'll go ahead and allocate
             // enough memory to swizzle if necessary.
         case kSwizzleColor_XformMode: {
-            const int bitsPerPixel = this->getEncodedInfo().bitsPerPixel();
-
-            // If we have more than 8-bits (per component) of precision, we will keep that
-            // extra precision.  Otherwise, we will swizzle to RGBA_8888 before transforming.
-            const size_t bytesPerPixel = (bitsPerPixel > 32) ? bitsPerPixel / 8 : 4;
-            const size_t colorXformBytes = dstInfo.width() * bytesPerPixel;
+            const size_t bpp = (this->getEncodedInfo().bitsPerPixel() > 32) ? 8 : 4;
+            const size_t colorXformBytes = dstInfo.width() * bpp;
             fStorage.reset(colorXformBytes);
             fColorXformSrcRow = fStorage.get();
             break;
@@ -434,13 +430,10 @@ void SkPngCodec::allocateStorage(const SkImageInfo& dstInfo) {
 }
 
 static SkColorSpaceXform::ColorFormat png_select_xform_format(const SkEncodedInfo& info) {
-    // We use kRGB and kRGBA formats because color PNGs are always RGB or RGBA.
-    if (16 == info.bitsPerComponent()) {
-        if (SkEncodedInfo::kRGBA_Color == info.color()) {
-            return SkColorSpaceXform::kRGBA_U16_BE_ColorFormat;
-        } else if (SkEncodedInfo::kRGB_Color == info.color()) {
-            return SkColorSpaceXform::kRGB_U16_BE_ColorFormat;
-        }
+    // We always use kRGBA because color PNGs are always RGB or RGBA.
+    // TODO (msarett): Support kRGB_U16 inputs as well.
+    if (16 == info.bitsPerComponent() && SkEncodedInfo::kRGBA_Color == info.color()) {
+        return SkColorSpaceXform::kRGBA_U16_BE_ColorFormat;
     }
 
     return SkColorSpaceXform::kRGBA_8888_ColorFormat;
@@ -1097,22 +1090,9 @@ bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& opt
         return false;
     }
 
-    // If SkColorSpaceXform directly supports the encoded PNG format, we should skip format
-    // conversion in the swizzler (or skip swizzling altogether).
-    bool skipFormatConversion = false;
-    switch (this->getEncodedInfo().color()) {
-        case SkEncodedInfo::kRGB_Color:
-            if (this->getEncodedInfo().bitsPerComponent() != 16) {
-                break;
-            }
-
-            // Fall through
-        case SkEncodedInfo::kRGBA_Color:
-            skipFormatConversion = this->colorXform();
-            break;
-        default:
-            break;
-    }
+    // If the image is RGBA and we have a color xform, we can skip the swizzler.
+    const bool skipFormatConversion = this->colorXform() &&
+            SkEncodedInfo::kRGBA_Color == this->getEncodedInfo().color();
     if (skipFormatConversion && !options.fSubset) {
         fXformMode = kColorOnly_XformMode;
         return true;