XPDF rendering to jpeg

XPDF rendering to jpeg

#include <stdio.h>
#include <cstdio>
#include <cstdlib>
#include <assert.h>
#include <stdexcept>
extern "C" {
#include <jpeglib.h>
}
//xpdf includes
#include "GlobalParams.h"
#include "xpdf.h"
#include "xpdf/SplashOutputDev.h"
#include "splash/SplashBitmap.h"

//Stuff you'll want to tweak
#define IN_PDF "./input.pdf"
//resolution in DPI
#define RESOLUTION 300
#define OUT_FILE "./out%i.jpeg"
#define JPEG_BASELINE true
//jpeg quality from 0 to 100
#define JPEG_QUALITY 100

void libjpeg_error_exit(j_common_ptr cinfo) {
	printf("TODO:handle jpeg error");
}

void libjpeg_output_message(j_common_ptr cinfo) {
	printf("TODO:libjpeg_output_message");
}

//quick and dirty func to dump a SplashOutputDev to a jpeg file
//You may want to rely on OpenCV or QT for this 
void write_jpeg(SplashOutputDev *dev, char *filename) {
	struct jpeg_compress_struct cinfo;
	struct jpeg_error_mgr jerr;
	SplashBitmap *bmp = dev->getBitmap();
	int width = bmp->getWidth();
	int height = bmp->getHeight();
	unsigned char *dataPtr = bmp->getDataPtr();
	unsigned int stride = width * 3;
	FILE *fp = NULL;
	cinfo.err = jpeg_std_error(&jerr);
	jerr.error_exit = libjpeg_error_exit;
	jerr.output_message = libjpeg_output_message;
	jpeg_create_compress(&cinfo);
	assert(sizeof(JSAMPLE) == 1);
	cinfo.client_data = NULL; //Put anything here you would like to use in jpeg error handling funcs    
	jpeg_set_quality(&cinfo, JPEG_QUALITY, JPEG_BASELINE);
	cinfo.image_width = width;
	cinfo.image_height = height;
	cinfo.input_components = 3;
	cinfo.in_color_space = (J_COLOR_SPACE) JCS_RGB;
	jpeg_set_defaults(&cinfo);
	//eo header
	if ((fp = fopen(filename, "wb")) == NULL)
		throw std::runtime_error("Cannot open jpeg output file");
	jpeg_stdio_dest(&cinfo, fp);
	jpeg_start_compress(&cinfo, true);
	while (cinfo.next_scanline < cinfo.image_height) {
		jpeg_write_scanlines(&cinfo, &dataPtr, 1);
		dataPtr += stride;
	}
	jpeg_finish_compress(&cinfo);
	fclose(fp);
	jpeg_destroy_compress(&cinfo);
}

int main(int argc, char **argv) {
	globalParams = new GlobalParams("");
	globalParams->setupBaseFonts(NULL);
	globalParams->setTextEncoding("UTF-8");
	GString *infile = new GString(IN_PDF);
	GString userpw("");
	PDFDoc *pdoc = new PDFDoc(infile, &userpw);
	if (((PDFDoc*) pdoc)->isOk() == gFalse) {
		printf("Failed to open PDF file %s", IN_PDF);
		delete ((PDFDoc*) pdoc);
		return 2;
	}
	unsigned char defaultPaperColor[] = { 0xFF, 0xFF, 0xFF };
	//I assume yout RGB , you could also choose grayscale or CMYK
	SplashColorMode spColorMode = splashModeRGB8;
	SplashOutputDev *surf = new SplashOutputDev(spColorMode, 1, gFalse,
			&defaultPaperColor[0]);
	surf->startDoc(pdoc->getXRef());
	int numPages = ((PDFDoc*) pdoc)->getNumPages();
	char buf[1024];
	for (int pi = 1; pi <= numPages; pi++) {
		pdoc->displayPage(surf, pi, RESOLUTION, RESOLUTION, 0, 1, 1, 0, 0, 0);
		sprintf(buf, OUT_FILE, pi);
		write_jpeg(surf, buf);

	}
	delete pdoc;
	delete globalParams;
	return 0;
}