Simplest PDF Generating API for JPEG Image Content

Introduction

I was working on a project in which I need to wrap a JPEG file into PDF format. The program needs to be done in C, and after searched on the Internet, I could not find anything that I can refer to. Most of the Open Source PDF engine is based on either Java or PHP, and a few C PDF engines are huge and will add a lot of unnecessary code to my project. I decided to write this simple JPEG to PDF wrapper. And it's the result of reverse-engineering of the simplest PDF file that contains one single JPEG file. I just want to share this API so you can grab and use it if you have a similar requirement.

Using the Code

Just give an example to demonstrate how to generate a 2 page PDF file based on 2 JPEG files. Please refer to testMain.c for details. But the idea is:

PJPEG2PDF pPDF;
int pdfByteSize, pdfOutByteSize;
unsigned char *pdfBuf;

pPDF = Jpeg2PDF_BeginDocument(8.5, 11);    
	/* pdfW, pdfH: Page Size in Inch ( 1 inch=25.4 mm ); Letter Size 8.5x11 */

if(NULL != pPDF) {
    
    Loop For All JPEG Files {
        ... Prepare the current JPEG File to be inserted.
        /* You'll need to know the dimension of the JPEG Image, 
	and the ByteSize of the JPEG Image */
        Jpeg2PDF_AddJpeg(pPDF, JPEG_IMGW, JPEG_IMGH, JPEG_BYTE_SIZE, 
		JPEG_DATA_POINTER, IS_COLOR_JPEG);
    } 
    
    /* Call this after all of the JPEG image has been inserted. 
	The return value is the PDF file Byte Size */
    pdfByteSize = Jpeg2PDF_EndDocument(pPDF);
    
    /* Allocate the buffer for PDF Output */
    pdfBuf = malloc(pdfByteSize);
    
    /* Output the PDF to the pdfBuf */
   Jpeg2PDF_GetFinalDocumentAndCleanup(pPDF, pdfBuf, &pdfOutByteSize);
   
   ... Do something you want to the PDF file in the memory.
}

There are several places that you can fine-tune in the Jpeg2PDF.h file:

#define MAX_PDF_PAGES        256     /* Currently only supports less than 256 Images */

#define PDF_TOP_MARGIN        (0.0 * PDF_DOT_PER_INCH)    /* Currently No Top Margin */
#define PDF_LEFT_MARGIN        (0.0 * PDF_DOT_PER_INCH)   /* Currently No Left Margin */

That's it, guys. Enjoy.

History

Updated [2008-12-19] - Added some extra code to auto scan the current folder and automatically obtain the JPEG image dimension from the JPEG file instead of using hard coded value before.
The JPEG image dimension code is borrowed from here.