win10 下 pdfium编译 VS2017

VS2017 编译pdfium
1、本地创建google目录，进入 
2、下载
mkdir google
cd google
gclient config --unmanaged https://pdfium.googlesource.com/pdfium.git
gclient sync

3、修改DEBUG_LEVEL
在DEBUG模式下编译时，会报：
#error LNK2038: mismatch detected for '_ITERATOR_DEBUG_LEVEL': value '0' doesn't match value '2' 

  buid/config/BUILD.gn
  
  if (is_win) {
    if (!enable_iterator_debugging && !use_custom_libcxx) {
      # Iterator debugging is enabled by default by the compiler on debug
      # builds, and we have to tell it to turn it off.
      #将原来的_HAS_ITERATOR_DEBUGGING=0修改为以下：（确保DEBUG模式时，_ITERATOR_DEBUG_LEVEL为2）
      defines += [ "_HAS_ITERATOR_DEBUGGING=1" ]
      defines += [ "_ITERATOR_DEBUG_LEVEL=2" ]
    }

  修改：pdfium/BUILD.gn

config("pdfium_public_config") {
  defines = []

  if (pdf_enable_v8) {
    defines += [ "PDF_ENABLE_V8" ]

    if (pdf_enable_xfa) {
      defines += [ "PDF_ENABLE_XFA" ]
      if (pdf_enable_xfa_bmp) {
        defines += [ "PDF_ENABLE_XFA_BMP" ]
      }
      if (pdf_enable_xfa_gif) {
        defines += [ "PDF_ENABLE_XFA_GIF" ]
      }
      if (pdf_enable_xfa_png) {
        defines += [ "PDF_ENABLE_XFA_PNG" ]
      }
      if (pdf_enable_xfa_tiff) {
        defines += [ "PDF_ENABLE_XFA_TIFF" ]
      }
      
      if(is_debug){
        #增加debug级别
        defines += ["_DEBUG"]
        defines += ["_HAS_ITERATOR_DEBUGGING=1"]
        defines += ["_ITERATOR_DEBUG_LEVEL=2"] 
      }
    }
  }  

4、生成工程
官方：
#lease refer to Chromium's Visual Studio set up for requirements and instructions on build environment configuration.
#Run set DEPOT_TOOLS_WIN_TOOLCHAIN=0, or set that variable in your global environment.
#Compilation is done through Ninja, not Visual Studio.
use_goma = true  # Googlers only. Make sure goma is installed and running first.
is_debug = true  # Enable debugging features.

# Set true to enable experimental Skia backend.
pdf_use_skia = false
# Set true to enable experimental Skia backend (paths only).
pdf_use_skia_paths = false

pdf_enable_xfa = true  # Set false to remove XFA support (implies JS support).
pdf_enable_v8 = true  # Set false to remove Javascript support.
pdf_is_standalone = true  # Set for a non-embedded build.
is_component_build = false # Disable component build (Though it should work)

clang_use_chrome_plugins = false  # Currently must be false.
For sample applications like pdfium_test to build, one must set pdf_is_standalone = true.

By default, the entire project builds with C++14, because features like V8 support, XFA support, and the Skia backend all have dependencies on libraries that require C++14. If one does not need any of those features, and need to fall back to building in C++11 mode, then set use_cxx11 = true. This fallback is temporary and will go away in the future when PDFium fully transitions to C++14. See this bug for details.

When complete the arguments will be stored in <directory>/args.gn, and GN will automatically use the new arguments to generate build files. Should your files fail to generate, please double-check that you have set use_sysroot as indicated above.
===============
执行：

cd pdfium
set DEPOT_TOOLS_WIN_TOOLCHAIN=0
gn args out/x86
在弹出窗口中，贴：
#Buildargumentsgohere.
#See"gnargs<out_dir>--list"foravailablebuildarguments.

#是否启用goma支持
use_goma=false

#是否编译为Chrome插件
clang_use_chrome_plugins=false

#是否进行编译测试
pdf_is_standalone=true

#是否启用skia支持
pdf_use_skia=false
pdf_use_skia_paths=false

#true编译为debug版本，false编译为release版本
is_debug=true

#true编译为动态库 /MD,/MDd，false编译为静态库 /MT,/MTd
is_component_build=false

#编译为一个独立的静态库（is_component_build必须为false）
#pdf_is_complete_lib为false时，编译为多个静态库，true编译为一个独立的静态库
pdf_is_complete_lib=true

#xfa支持
pdf_enable_xfa=true

#v8支持
pdf_enable_v8=true

#cpu架构；x86、x64可选
target_cpu="x86"

#true将用clang进行编译，false将用VS2017编译
is_clang=false

5、编译pdfium

cd pdfium
ninja -C out/x86 pdfium

编译时间较长，DEBUG结果有900MB以上,RELEASE结果有600M左右