save jpg file with libjpeg-tubo

libjpeg-turbo-demo.c

#include <string.h>
#include <stdio.h>
#include "libjpeg-turbo/turbojpeg.h"

#pragma comment(lib, "turbojpeg.lib") 

bool savejpg(const char* filename,const unsigned char* pData,int width,int height, int nchannels);

int main(int argc, char **argv)
{
	int width = 352, height = 288;
	unsigned char *img_data = new unsigned char[width * height * 4];
	memset(img_data, 0, width * height * 4);
	savejpg("a.jpg", img_data, width, height, 4);
}

bool savejpg(const char* filename,const unsigned char* pData,int width,int height, int nchannels)
{
	const int JPEG_QUALITY = 100;
	const int COLOR_COMPONENTS = nchannels;
	long unsigned int size = 0;
	unsigned char* output = nullptr;
	unsigned char *buffer = new unsigned char[width*height*nchannels];
	memcpy(buffer, pData, width*height*nchannels);

	tjhandle handleCompress = tjInitCompress();
	tjCompress2(handleCompress, buffer, width, 0, height, TJPF_BGRA, // 注意这里可以直接压缩rgba数据
		&output, &size, TJSAMP_444, JPEG_QUALITY,
		TJFLAG_FASTDCT);
	
	FILE * file = fopen(filename, "wb");
	if (!file) {
		fprintf(stderr, "open file %s failed!\n", filename);
		delete buffer;
		return false;
	}

	fwrite (output, 1, size, file);
	fclose(file);

	tjDestroy(handleCompress);
	tjFree(output);

	delete buffer;
	return true;
}