public boolean compress(CompressFormat format, int quality, OutputStream stream) {checkRecycled("Can't compress a recycled bitmap");// do explicit check before calling the native methodif (stream == null) {throw new NullPointerException();}if (quality < 0 || quality > 100) {throw new IllegalArgumentException("quality must be 0..100");}return nativeCompress(mNativeBitmap, format.nativeInt, quality,stream, new byte[WORKING_COMPRESS_STORAGE]);}

static bool Bitmap_compress(JNIEnv* env, jobject clazz, SkBitmap* bitmap,int format, int quality,jobject jstream, jbyteArray jstorage) {SkImageEncoder::Type fm;  //创建类型变量//将java层类型变量转换成Skia的类型变量switch (format) {case kJPEG_JavaEncodeFormat:fm = SkImageEncoder::kJPEG_Type;break;case kPNG_JavaEncodeFormat:fm = SkImageEncoder::kPNG_Type;break;case kWEBP_JavaEncodeFormat:fm = SkImageEncoder::kWEBP_Type;break;default:return false;}//判断当前bitmap指针是否为空bool success = false;if (NULL != bitmap) {SkAutoLockPixels alp(*bitmap);if (NULL == bitmap->getPixels()) {return false;}//创建SkWStream变量用于将压缩后的图片数据输出SkWStream* strm = CreateJavaOutputStreamAdaptor(env, jstream, jstorage);if (NULL == strm) {return false;}//根据编码类型，创建SkImageEncoder变量，并调用encodeStream对bitmap//指针指向的图片数据进行编码，完成后释放资源。SkImageEncoder* encoder = SkImageEncoder::Create(fm);if (NULL != encoder) {success = encoder->encodeStream(strm, *bitmap, quality);delete encoder;}delete strm;}return success;
}

1 static SkTRegistry<SkImageDecoder*, SkStream*> gDReg(sk_libjpeg_dfactory);
2 static SkTRegistry<SkImageDecoder::Format, SkStream*> gFormatReg(get_format_jpeg);
3 static SkTRegistry<SkImageEncoder*, SkImageEncoder::Type> gEReg(sk_libjpeg_efactory);

    //声明一些在压缩时需要的变量，jerr用于错误控制    struct jpeg_compress_struct cinfo;struct jpeg_error_mgr jerr;cinfo.err = jpeg_std_error(&jerr);jerr.output_message=android_output_message;  //使用自定义的日志输出函数，不是必须的jerr.error_exit=myjpeg_error_exit;  //使用自定义的错误退出函数，不是必须的jpeg_create_compress(&cinfo);  //创建libjpeg的压缩结构体    cinfo.image_width = width;  //设置被压缩图片的宽、高、通道数和色彩空间cinfo.image_height = height;cinfo.input_components = 3;cinfo.in_color_space = JCS_RGB;FILE * outfile;  //创建文件变量用于指定压缩数据的输出目标if ((outfile = fopen(imgPath, "wb")) == NULL) {fprintf(stderr, "can't open %s\n", imgPath);exit(1);}jpeg_set_defaults(&cinfo);  //对cinfo做一些默认设置jpeg_stdio_dest(&cinfo, outfile);  //将之前的outfile作为输出目标jpeg_set_quality(&cinfo,quality,TRUE);  //设置压缩jpeg图片的质量jpeg_start_compress(&cinfo, TRUE);  //开始压缩unsigned char * srcImg=(unsigned char *)imageData;  //逐行的获取图像数据，进行压缩处理while (cinfo.next_scanline < cinfo.image_height) {JSAMPROW row_pointer[1];    /* pointer to JSAMPLE row[s] */row_pointer[0] = srcImg;(void) jpeg_write_scanlines(&cinfo, row_pointer, 1);srcImg+=widthStep;}//压缩保存完毕，对使用到的变量进行销毁jpeg_finish_compress(&cinfo);jpeg_destroy_compress(&cinfo);

LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)
LOCAL_MODULE    := AndroidJpegTest
LOCAL_SRC_FILES := AndroidJpegTest.cpp
LOCAL_LDLIBS :=-llog -ljpeg -ljnigraphics
LOCAL_C_INCLUDES := $(LOCAL_PATH)
LOCAL_CFLAGS += -O3 -fstrict-aliasing -fprefetch-loop-arrays
LOCAL_CFLAGS += -DUSE_ANDROID_ASHMEM
LOCAL_CFLAGS += -DAVOID_TABLES
LOCAL_CFLAGS += -DANDROID_TILE_BASED_DECODE
LOCAL_SDK_VERSION := 17include $(BUILD_SHARED_LIBRARY)

#ifdef __cplusplus
extern "C" {
#endif#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include<android/bitmap.h>
#include<android/log.h>
#include"jpeglib.h"#define TAG "JPEGTEST"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,TAG,__VA_ARGS__)static void myjpeg_error_exit(j_common_ptr jcs)
{jpeg_error_mgr* error = (jpeg_error_mgr*)jcs->err;(*error->output_message) (jcs);jpeg_destroy(jcs);exit(EXIT_FAILURE);
}static void android_output_message(j_common_ptr cinfo) {char buffer[2048];/* Create the message */(*cinfo->err->format_message)(cinfo, buffer);LOGI("%s", buffer);
}JNIEXPORT jint Java_com_example_yuvconv_NativeFunc_convert(JNIEnv *env, jclass thiz, jobject bmpObj,jstring filepath,jint quality)
{const char *imgPath = env->GetStringUTFChars(filepath, 0);AndroidBitmapInfo bmpinfo = {0};if (AndroidBitmap_getInfo(env, bmpObj, &bmpinfo) < 0){LOGI("read failed");return JNI_FALSE;}int width = bmpinfo.width;int height =bmpinfo.height;int widthStep = (width*3+3)/4*4;if(bmpinfo.width <= 0 || bmpinfo.height <= 0 ||bmpinfo.format != ANDROID_BITMAP_FORMAT_RGBA_8888){LOGI("format error");return JNI_FALSE;}void* bmpFromJObject = NULL;if (AndroidBitmap_lockPixels(env,bmpObj,(void**)&bmpFromJObject) < 0){LOGI("lockPixels failed");return JNI_FALSE;}unsigned char*imageData= (unsigned char*)malloc(sizeof(unsigned char)*(width*3+3)/4*4*height);unsigned char* pBuff = (unsigned char*)bmpFromJObject;unsigned char* pImgData = imageData;for (int y = 0; y < height; y++){unsigned char* p1 = pImgData;unsigned char* p2 = pBuff;for (int x = 0; x < width; x++){p1[0] = p2[0];    //Rp1[1] = p2[1];    //Gp1[2] = p2[2];    //Bp1 += 3;p2 += 4;}pImgData +=widthStep;pBuff += bmpinfo.stride;}struct jpeg_compress_struct cinfo;struct jpeg_error_mgr jerr;cinfo.err = jpeg_std_error(&jerr);jerr.output_message=android_output_message;jerr.error_exit=myjpeg_error_exit;jpeg_create_compress(&cinfo);cinfo.image_width = width;cinfo.image_height = height;cinfo.input_components = 3;cinfo.in_color_space = JCS_RGB;FILE * outfile;if ((outfile = fopen(imgPath, "wb")) == NULL) {fprintf(stderr, "can't open %s\n", imgPath);return JNI_FALSE;}jpeg_set_defaults(&cinfo);jpeg_stdio_dest(&cinfo, outfile);jpeg_set_quality(&cinfo,quality,TRUE);jpeg_start_compress(&cinfo, TRUE);unsigned char * srcImg=(unsigned char *)imageData;while (cinfo.next_scanline < cinfo.image_height) {JSAMPROW row_pointer[1];    /* pointer to JSAMPLE row[s] */row_pointer[0] = srcImg;(void) jpeg_write_scanlines(&cinfo, row_pointer, 1);srcImg+=widthStep;}jpeg_finish_compress(&cinfo);jpeg_destroy_compress(&cinfo);env->ReleaseStringUTFChars(filepath, imgPath);return JNI_TRUE;
}#ifdef __cplusplus
}
#endif