Check libpng directly into third_party/

cmake/CMakeLists.txt

 # Boilerplate.
 cmake_minimum_required (VERSION 3.1)   # First version with CMAKE_CXX_STANDARD.
 project (skimake)
 set (CMAKE_CXX_STANDARD 11)
 
 # Default to Release mode.  We're mainly targeting Skia users, not Skia developers.
 if (NOT CMAKE_BUILD_TYPE)
     set (CMAKE_BUILD_TYPE Release)
 endif ()
 
@@ skipping 17 matching lines @@
 list (REMOVE_ITEM public_includes ${private_includes})  # Easiest way to exclude private.
 file (GLOB default_include_config "../include/config")
 list (REMOVE_ITEM public_includes ${default_include_config})
 set (userconfig_directory ${CMAKE_BINARY_DIR}/include)
 list (APPEND public_includes ${userconfig_directory})
 
 # These guys are third_party but provided by a Skia checkout.
 list (APPEND srcs             ../third_party/etc1/etc1.cpp ../third_party/ktx/ktx.cpp)
 list (APPEND private_includes ../third_party/etc1          ../third_party/ktx)
 
+list (APPEND private_includes ../third_party/libpng)

[scroggo, 2016/06/02 16:15:10]

I know very little of CMake, and I'm still working on setting it up. Does this
look right? It is based on the code around it. I also skipped the intel
optimizations for now; do I need to set PNG_ARM_NEON_OPT?

[msarett, 2016/06/02 16:35:33]

Looks right, I think, though I haven't done too much with CMake either.

Looks like you're skipping arm and intel opts (arm opts are in a arm/
directory).  I think that's right thing to do right now.

You might actually want to set PNG_ARM_NEON_OPT to 0, so it doesn't try to
automatically detect arm support (and then fail when we fail to compile the
files).

If you have any issues setting up CMake, the trybots may be useful for testing.

[scroggo, 2016/06/02 17:03:27]

Done.
Which trybot? I don't see one for CMake.

[msarett, 2016/06/02 17:10:36]

The CMake trybots actually run automatically in the commit queue when you modify
this file.  They are:
Build-Ubuntu-GCC-x86_64-Release-CMake-Trybot
Build-Mac-Clang-x86_64-Release-Trybot

+file (GLOB libpng_srcs ../third_party/libpng/*.c)
+foreach (src ${libpng_srcs})
+    list (APPEND srcs ${src})
+endforeach()
+
 function (remove_srcs)
     file (GLOB_RECURSE to_remove ${ARGN})
     list (REMOVE_ITEM srcs ${to_remove})
     set (srcs ${srcs} PARENT_SCOPE)
 endfunction()
 
 # This file is empty and is only used to trick GYP.
 remove_srcs (../src/core/SkForceCPlusPlusLinking.cpp)
 # Chrome only?
 remove_srcs (../src/ports/SkFontHost_fontconfig.cpp
@@ skipping 93 matching lines @@
 find_path (OSMESA_INCLUDE_DIRS "GL/osmesa.h")
 find_library(OSMESA_LIBRARIES "OSMesa")
 
 if (UNIX AND NOT APPLE)
     find_package (Freetype)
     # Same deal for fontconfig.
     find_path (FONTCONFIG_INCLUDE_DIRS "fontconfig/fontconfig.h")
     find_library (FONTCONFIG_LIBRARIES fontconfig)
     find_package (GIF)
     find_package (JPEG)
-    find_package (PNG)
 endif()
 
 # Do not compile SkRawCodec.
 remove_srcs(../src/codec/*Raw*.cpp)
 
 # TODO: macro away this if (found) ... else() ... endif() stuff.
 
 if (EXPAT_FOUND)
     list (APPEND private_includes ${EXPAT_INCLUDE_DIRS})
     list (APPEND libs             ${EXPAT_LIBRARIES})
@@ skipping 19 matching lines @@
     remove_srcs(../src/codec/*Jpeg*)
 endif()
 
 if (LUA_FOUND)
     list (APPEND private_includes ${LUA_INCLUDE_DIR})
     list (APPEND libs             ${LUA_LIBRARIES})
 else()
     remove_srcs(../src/utils/*Lua*)
 endif()
 
-if (PNG_FOUND)
-    list (APPEND private_includes ${PNG_INCLUDE_DIRS})
-    list (APPEND libs             ${PNG_LIBRARIES})
+# PNG
     add_definitions(-DPNG_SKIP_SETJMP_CHECK)

[scroggo, 2016/06/02 16:15:10]

I did not see this or PNG_SKIP_SKIA_OPTS anywhere in libpng or Skia. (Actually,
this one is mentioned in a change-log, so I'm guessing it got removed.) Safe to
delete?

[msarett, 2016/06/02 16:35:33]

I believe that they are both safe to delete.

nit: outdent this text

[scroggo, 2016/06/02 17:03:27]

Removed.
Done.

     add_definitions(-DPNG_SKIP_SKIA_OPTS)
     add_definitions(-DSK_HAS_PNG_LIBRARY)
-else()
-    remove_srcs(../src/images/*PNG*)
-    remove_srcs(../src/codec/*Png*)
-    remove_srcs(../src/codec/*Ico*)
-endif()
 
 if (ZLIB_FOUND)
     list (APPEND private_includes ${ZLIB_INCLUDE_DIRS})
     list (APPEND libs             ${ZLIB_LIBRARIES})
     remove_srcs(../src/pdf/SkDocument_PDF_None.cpp)
 else()
     remove_srcs(../src/pdf/*.cpp)
     set (srcs ${srcs} ../src/pdf/SkDocument_PDF_None.cpp)
 endif()
 
@@ skipping 136 matching lines @@
         file (APPEND ${skia_h_path} "#include \"${filename_component}\"\n")
       endif ()
     endforeach()
   endif()
 endforeach()
 file(APPEND ${skia_h_path} "\n#endif  // skia_DEFINED\n")
 
 # Now build a simple example app that uses Skia via libskia.so.
 add_executable(example example.cpp)
 target_link_libraries(example skia ${OPENGL_LIBRARIES})