Fix YUV horizontal and vertical sampling checks

src/codec/SkJpegCodec.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 "SkCodec.h"
 #include "SkMSAN.h"
 #include "SkJpegCodec.h"
@@ skipping 550 matching lines @@
     // The definition of samp_factor is kind of the opposite of what SkCodec
     // thinks of as a sampling factor.  samp_factor is essentially a
     // multiplier, and the larger the samp_factor is, the more samples that
     // there will be.  Ex:
     //     U_plane_width = image_width * (U_h_samp_factor / max_h_samp_factor)
     //
     // Supporting cases where the samp_factors for U or V were larger than
     // that of Y would be an extremely difficult change, given that clients
     // allocate memory as if the size of the Y plane is always the size of the
     // image.  However, this case is very, very rare.
-    if (!(1 == dinfo->comp_info[1].h_samp_factor) &&
-         (1 == dinfo->comp_info[1].v_samp_factor) &&
-         (1 == dinfo->comp_info[2].h_samp_factor) &&
-         (1 == dinfo->comp_info[2].v_samp_factor)) {
+    if  (!((1 == dinfo->comp_info[1].h_samp_factor) &&

[msarett, 2016/03/04 00:34:01]

A couple characters makes a big difference :).

Whew I really needed an easy bug!

[mtklein, 2016/03/04 13:23:27]

This may indicate we should De Morgan the logic?

if (1 != dinfo->comp_info[1].h_samp_factor ||
    1 != dinfo->comp_info[1].v_samp_factor ||
    1 != dinfo->comp_info[2].h_samp_factor ||
    1 != dinfo->comp_info[2].v_samp_factor) {
   return false;
} 

[msarett, 2016/03/04 13:42:51]

Yeah I think that's clearer.

+           (1 == dinfo->comp_info[1].v_samp_factor) &&
+           (1 == dinfo->comp_info[2].h_samp_factor) &&
+           (1 == dinfo->comp_info[2].v_samp_factor))) {
         return false;
     }
 
     // Support all common cases of Y samp_factors.
     // TODO (msarett): As mentioned above, it would be possible to support
     //                 more combinations of samp_factors.  The issues are:
     //                 (1) Are there actually any images that are not covered
     //                     by these cases?
     //                 (2) How much complexity would be added to the
     //                     implementation in order to support these rare
@@ skipping 139 matching lines @@
 
         JDIMENSION linesRead = jpeg_read_raw_data(dinfo, yuv, numRowsPerBlock);
         if (linesRead < remainingRows) {
             // FIXME: Handle incomplete YUV decodes without signalling an error.
             return kInvalidInput;
         }
     }
 
     return kSuccess;
 }