Adding png scanline decoding to kIndex8

src/codec/SkCodecPriv.h

 /*
  * Copyright 2015 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCodecPriv_DEFINED
 #define SkCodecPriv_DEFINED
 
+#include "SkColorTable.h"
 #include "SkImageInfo.h"
 #include "SkSwizzler.h"
 #include "SkTypes.h"
+#include "SkUtils.h"
 
 /*
  *
  * Helper routine for alpha result codes
  *
  */
 #define INIT_RESULT_ALPHA                       \
     uint8_t zeroAlpha = 0;                      \
     uint8_t maxAlpha = 0xFF;
 
 #define UPDATE_RESULT_ALPHA(alpha)              \
     zeroAlpha |= (alpha);                       \
     maxAlpha  &= (alpha);
 
 #define COMPUTE_RESULT_ALPHA                    \
     SkSwizzler::GetResult(zeroAlpha, maxAlpha);
 
 /*
  *
+ * Copy the codec color table back to the client when kIndex8 color type is requested
+ *
+ */
+static inline void copy_color_table(const SkImageInfo& dstInfo, SkColorTable* colorTable,
+        SkPMColor* inputColorPtr, int* inputColorCount) {
+    if (kIndex_8_SkColorType == dstInfo.colorType()) {
+        SkASSERT(NULL != inputColorPtr);
+        SkASSERT(NULL != inputColorCount);
+        SkASSERT(NULL != colorTable);
+        sk_memcpy32(inputColorPtr, colorTable->readColors(), *inputColorCount);
+    }
+}
+
+/*
+ *
  * Compute row bytes for an image using pixels per byte
  *
  */
 static inline size_t compute_row_bytes_ppb(int width, uint32_t pixelsPerByte) {
     return (width + pixelsPerByte - 1) / pixelsPerByte;
 }
 
 /*
  *
  * Compute row bytes for an image using bytes per pixel
@@ skipping 62 matching lines @@
 #endif
 }
 
 #ifdef SK_PRINT_CODEC_MESSAGES
     #define SkCodecPrintf SkDebugf
 #else
     #define SkCodecPrintf(...)
 #endif
 
 #endif // SkCodecPriv_DEFINED