Add SkEncodedInfo to report properties of encoded image data

src/codec/SkJpegDecoderMgr.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkJpegDecoderMgr.h"
 #include "SkJpegUtility_codec.h"
 
@@ skipping 16 matching lines @@
 bool JpegDecoderMgr::returnFalse(const char caller[]) {
     print_message((j_common_ptr) &fDInfo, caller);
     return false;
 }
 
 SkCodec::Result JpegDecoderMgr::returnFailure(const char caller[], SkCodec::Result result) {
     print_message((j_common_ptr) &fDInfo, caller);
     return result;
 }
 
-SkColorType JpegDecoderMgr::getColorType() {
+SkEncodedInfo::Color JpegDecoderMgr::getEncodedColor() {
     switch (fDInfo.jpeg_color_space) {
         case JCS_GRAYSCALE:
-            return kGray_8_SkColorType;
+            return SkEncodedInfo::kGray_Color;
+        case JCS_YCbCr:
+            return SkEncodedInfo::kYUV_Color;
+        case JCS_RGB:
+            return SkEncodedInfo::kRGB_Color;
+        case JCS_YCCK:
+            return SkEncodedInfo::kYCCK_Color;
+        case JCS_CMYK:
+            return SkEncodedInfo::kInvertedCMYK_Color;
         default:
-            return kN32_SkColorType;
+            return SkEncodedInfo::kYUV_Color;

[scroggo, 2016/03/23 14:48:50]

What types fall into the default case? Why not be explicit?

[msarett, 2016/03/24 16:20:44]

Other JPEG_COLOR_SPACES include RGBA, BGRA, 565 etc. but these should never the
be the encoded color_space.  They would indicate a bug in libjpeg-turbo.

The only other "valid" value would be JCS_UNKNOWN.  And we would get this if
there is a really strange number of components 2, 5, 6...

In this case the decode will fail because we cannot do color conversion (unless
we call jpeg_read_raw_data(), which we won't, because we only use this for YUV
images).

Still I should handle this more clearly and fail faster...

     }
 }
 
 JpegDecoderMgr::JpegDecoderMgr(SkStream* stream)
     : fSrcMgr(stream)
     , fInit(false)
 {
     // Error manager must be set before any calls to libjeg in order to handle failures
     fDInfo.err = jpeg_std_error(&fErrorMgr);
     fErrorMgr.error_exit = skjpeg_err_exit;
@@ skipping 12 matching lines @@
     }
 }
 
 jmp_buf& JpegDecoderMgr::getJmpBuf() {
     return fErrorMgr.fJmpBuf;
 }
 
 jpeg_decompress_struct* JpegDecoderMgr::dinfo() {
     return &fDInfo;
 }