Android PDFium 编译

一、PDFium 简介

Pdfium是一个由Google开发的开源PDF渲染库，可以用来显示、处理PDF文档。它是Google Chrome浏览器中用于处理PDF文档的核心引擎。该库不只限于Chrome浏览器使用，其他开发者也可在自己的项目中使用Pdfium库。Pdfium提供了丰富的特性，如文本提取、搜索、注解、表单填充等，且性能高、稳定性好、兼容性强，被许多第三方项目所使用。

二、编译环境

1. Docker unbuntu 22.04

2. Dockerfile

FROM ubuntu:22.04

RUN apt-get update
RUN apt-get install -y  build-essential git subversion pkg-config python3 libtool cmake glib2.0-dev libatspi2.0-dev wget nano

RUN mkdir /pdfium_build
WORKDIR /pdfium_build
RUN git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
ENV PATH=/pdfium_build/depot_tools:${PATH}
RUN gclient config --unmanaged https://pdfium.googlesource.com/pdfium.git@9eec95782c4ecdae50cd8c8e9f88d3f8941db1cd
RUN echo "target_os = [ 'android' ]" >> .gclient
RUN gclient sync
# 可根据需要指定不同版本
RUN mv pdfium.git\@9eec95782c4ecdae50cd8c8e9f88d3f8941db1cd/ pdfium

# working dir
WORKDIR /app

3. build.sh

#!/bin/bash

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"

set -e

build() {
  local ARCH="$1"
  shift
  local OUT="$DIR/../libpdfsdk/jniLibs/$ARCH/libpdfsdk.so"
  local OUT_UNSTRIPPED="$DIR/../libpdfsdk/jniLibs/$ARCH/libpdfsdk_unstripped.so"
  [ -e "$OUT" ] && return
  echo "building $OUT"
  gn gen out --args="target_os=\"android\" pdf_bundle_freetype=true pdf_is_standalone=false is_component_build=false pdf_enable_xfa=false pdf_enable_v8=false is_debug=false is_official_build=true $*"
  ninja -C out pdfsdk
  mkdir -p $(dirname "$OUT") && cp out/libpdfsdk.so "$OUT" && cp out/lib.unstripped/libpdfsdk.so "$OUT_UNSTRIPPED"
}

build armeabi-v7a target_cpu=\"arm\" arm_version=7
build arm64-v8a target_cpu=\"arm64\"
build x86 target_cpu=\"x86\"
build x86_64 target_cpu=\"x64\"

mkdir -p "$DIR"/../libpdfsdk/jniLibs/include/ && cp "$DIR"/public/*.h "$DIR"/../libpdfsdk/jniLibs/include/

三、编译步骤

1. mkdir pdf & cd pdf

2. 将 build.sh 放入 pdf 目录

3. 将 Dockerfile 放入 pdf/docker 目录下

4. 创建docker image

docker build -t pdfium-android -f ./docker

5. 运行docker并进入bash

docker run -v ${PWD}:/app -it pdfium-android /bin/bash

6. 在docker的bash中进入目录

cd /pdfium_build/pdfium/

7. 编辑BUILD.gn

将

config("pdfium_common_config") {
  cflags = []
  cflags_cc = []
  ldflags = []
  include_dirs = [ "." ]
  defines = [
  ]

改为

config("pdfium_common_config") {
  cflags = [ "-fvisibility=default" ]
  cflags_cc = []
  ldflags = []
  include_dirs = [ "." ]
  defines = [
     "PNG_PREFIX",
     "PNG_USE_READ_MACROS",
     "FPDFSDK_EXPORTS"
  ]

找到 component("pdfium") 节，在这节之后添加

shared_library("pdfsdk") {
  deps = [":pdfium"]
  if (target_os == "android") {
    configs -= [ "//build/config/android:hide_all_but_jni_onload" ]
  }
}

8. 修改 build_overrides/build.gni

将以下三行注释掉

if (current_cpu == "arm") {
  arm_use_neon = true
}

变为

#if (current_cpu == "arm") {
#  arm_use_neon = true
#}

9. 将build.sh拷贝至此

copy /app/build.sh .

10. 运行build.sh

11. 完成后结果会输出在

/pdfium_build/libpdfsdk

12. 将结果copy到app目录。这样就可以在宿主机使用了。

cp -r /pdfium_build/libpdfsdk /app

See Also

https://github.com/benjinus/android-support-pdfium
https://github.com/benjinus/android-support-pdfium