GN: more optional components: jpeg, pdf, png, xml

src/codec/SkPngCodec.h

 /*
  * 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 "SkColorSpaceXform.h"
 #include "SkColorTable.h"
 #include "SkPngChunkReader.h"
 #include "SkEncodedFormat.h"
 #include "SkImageInfo.h"
 #include "SkRefCnt.h"
 #include "SkSwizzler.h"
 
-#include "png.h"
+// Instead of including png.h here, forward declare the few types we refer to.

[msarett, 2016/08/24 16:41:51]

This should work.  I believe we've had issues in the past because old versions
of libpng used different names for these structs.

We are working towards requiring 1.6 now.

Might want to use CMake trybots though.

+struct png_struct_def;
+struct png_info_def;
+typedef png_struct_def png_struct;
+typedef png_info_def png_info;
 
 class SkStream;
 
 class SkPngCodec : public SkCodec {
 public:
     static bool IsPng(const char*, size_t);
 
     // Assume IsPng was called and returned true.
     static SkCodec* NewFromStream(SkStream*, SkPngChunkReader* = NULL);
 
@@ skipping 12 matching lines @@
     SkSampler* getSampler(bool createIfNecessary) override {
         SkASSERT(fSwizzler);
         return fSwizzler;
     }
     void allocateStorage();
 
     virtual int readRows(const SkImageInfo& dstInfo, void* dst, size_t rowBytes, int count,
                          int startRow) = 0;
 
     SkPngCodec(const SkEncodedInfo&, const SkImageInfo&, SkStream*, SkPngChunkReader*,
-            png_structp, png_infop, int, int);
+               png_struct*, png_info*, int, int);
 
     SkAutoTUnref<SkPngChunkReader>     fPngChunkReader;
-    png_structp                        fPng_ptr;
-    png_infop                          fInfo_ptr;
+    png_struct*                        fPng_ptr;
+    png_info*                          fInfo_ptr;
 
     // These are stored here so they can be used both by normal decoding and scanline decoding.
     SkAutoTUnref<SkColorTable>         fColorTable;    // May be unpremul.
     SkAutoTDelete<SkSwizzler>          fSwizzler;
     std::unique_ptr<SkColorSpaceXform> fColorXform;
     SkAutoTMalloc<uint8_t>             fStorage;
     uint8_t*                           fSwizzlerSrcRow;
     uint32_t*                          fColorXformSrcRow;
     size_t                             fSrcRowBytes;
 
     const int                          fNumberPasses;
     int                                fBitDepth;
 
 private:
     bool createColorTable(const SkImageInfo& dstInfo, int* ctableCount);
     void destroyReadStruct();
 
     typedef SkCodec INHERITED;
 };