Android 高效图片压缩的实现

export PATH=/home/study/cmake-3.18.2/bin:$PATH

#!/bin/bash
 
# 源码目录
MY_SOURCE_DIR=/home/study/libjpeg-turbo-2.0.5
 
NDK_PATH=/home/study/android-ndk-r21b
TOOLCHAIN=clang
ANDROID_VERSION=21
 
 
build_bin() {
  echo "-------------------star build $1-------------------------"
  ANDROID_ARCH_ABI=$1  # armeabi-v7a 
	
  # 最终编译的安装目录
  PREFIX=${MY_SOURCE_DIR}/android/${ANDROID_ARCH_ABI}/
  HOST=$2
  
  cmake -G"Unix Makefiles" \
	 -DANDROID_ABI=$ANDROID_ARCH_ABI \
	 -DANDROID_ARM_MODE=arm \
	 -DANDROID_PLATFORM=android-${ANDROID_VERSION} \
	 -DANDROID_TOOLCHAIN=${TOOLCHAIN} \
	 -DCMAKE_ASM_FLAGS="--target=${HOST}${ANDROID_VERSION}" \
   -DCMAKE_TOOLCHAIN_FILE=${NDK_PATH}/build/cmake/android.toolchain.cmake \
   -DCMAKE_INSTALL_PREFIX=${PREFIX} 
 
  make clean
  make
  make install
 
 
  echo "-------------------$1 build end-------------------------"
}
 
#build armeabi-v7a
build_bin armeabi-v7a arm-linux-androideabi

cmake_minimum_required(VERSION 3.4.1)
 
# 引入头文件
include_directories(${CMAKE_SOURCE_DIR}/include)
# 设置静态库路径
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -L${CMAKE_SOURCE_DIR}/libs/${CMAKE_ANDROID_ARCH_ABI}")
 
add_library(
    native-lib
    SHARED
    native-lib.cpp)
 
 
find_library(
    log-lib
    log)
 
target_link_libraries(
    native-lib
    turbojpeg
    ${log-lib})

#include <jni.h>
#include <string>
#include <jpeglib.h>
#include <android/bitmap.h>
 
 
void write_jpeg_file(uint8_t *temp, int w, int h, jint q, const char *path) {
  // 1. 创建jpeg压缩对象
  jpeg_compress_struct jcs;
  // 错误回调
  jpeg_error_mgr errorMgr;
  jcs.err = jpeg_std_error(&errorMgr);
  // 创建压缩对象
  jpeg_create_compress(&jcs);
 
  // 2. 指定存储文件
  FILE *file = fopen(path, "wb");
  jpeg_stdio_dest(&jcs, file);
 
  // 3. 设置压缩参数
  jcs.image_width = w;
  jcs.image_height = h;
  // bgr
  jcs.input_components = 3;
  jcs.in_color_space = JCS_RGB;
  jpeg_set_defaults(&jcs);
  // 开启哈夫曼功能
  jcs.optimize_coding = true;
  jpeg_set_quality(&jcs, q, 1);
 
  // 4. 开始压缩
  jpeg_start_compress(&jcs, 1);
 
  // 5. 循环写入每一行数据
  int row_stride = w * 3;
  JSAMPROW row[1];
  while (jcs.next_scanline < jcs.image_height) {
    // 取出一行数据
    uint8_t *pixels = temp   jcs.next_scanline * row_stride;
    row[0] = pixels;
    jpeg_write_scanlines(&jcs, row, 1);
  }
 
  // 6 压缩完成
  jpeg_finish_compress(&jcs);
 
  // 7 释放内存
  fclose(file);
  jpeg_destroy_compress(&jcs);
}
 
extern "C"
JNIEXPORT void JNICALL
Java_com_lx_libjpeg_utils_ImageCompressUtils_native_1compress(JNIEnv *env, jobject thiz,
                               jobject bitmap, jint q,
                               jstring path) {
  // TODO: implement native_compress()
 
  const char *jni_path = env->GetStringUTFChars(path, 0);
  // 从bitmap中获取argb数据
  // 创建AndroidBitmapInfo对象
  AndroidBitmapInfo info;
  // 获取bitmap中的信息
  AndroidBitmap_getInfo(env, bitmap, &info);
  // 得到图片中的像素信息
  uint8_t *pixels; 
  AndroidBitmap_lockPixels(env, bitmap, (void **) &pixels);
  // jpeg argb中去掉他的a ===》 grg
  int w = info.width;
  int h = info.height;
  int color;
  // 申请一块内存用来存储rgb信息
  uint8_t *data = (uint8_t *) malloc(w * h * 3);
  memset(data, 0, w * h * 3);
  uint8_t *temp = data;
  uint8_t r, g, b;
  // 循环取出图片的每一个像素
  for (int i = 0; i < h;   i) {
    for (int j = 0; j < w;   j) {
      color = *(int *) pixels;
      // 取出rgb
      r = (color >> 16) & 0xFF;
      g = (color >> 8) & 0xFF;
      b = color & 0xFF;
      // 存放 以前的主流格式jpeg bgr
      *data = b;
      *(data   1) = g;
      *(data   2) = r;
      data  = 3;
      // 指针跳过4个字节
      pixels  = 4;
    }
  }
 
  // 把得到的新的图片的信息存放入一个新文件中
  write_jpeg_file(temp, w, h, q, jni_path);
 
  // 释放内存
  free(temp);
  AndroidBitmap_unlockPixels(env, bitmap);
  env->ReleaseStringUTFChars(path, jni_path);
 
}

 public void compress() {
    File input = new File("storage/emulated/0/original.jpg");
    Bitmap inputBitmap = BitmapFactory.decodeFile(input.getAbsolutePath());
    originalImage.setImageBitmap(inputBitmap);
    imageCompressUtils.compress(inputBitmap, 30, "storage/emulated/0/original_1.jpg");
    Toast.makeText(this, "执行完成", Toast.LENGTH_SHORT).show();
    compressImage.setImageBitmap(BitmapFactory.decodeFile("storage/emulated/0/original_1.jpg"));
  }