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Simplest PDF Generating API for JPEG Image Content

, 19 Dec 2008 CPOL
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An article on how to generate PDF file based on JPEG file as page content


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:

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 */
    /* 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.


  • 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.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Hao Hu
Software Developer
United States United States
No Biography provided

Comments and Discussions

GeneralHow to display image in original size PinmemberDenny Mathew18-Dec-14 2:26 
Questionwhy you only supports less than 256 Images? Pinmemberveeta23-Nov-14 21:20 
QuestionExcellent PinmemberT800G27-Sep-14 11:57 
Questionpatches done: keep images's aspect ratio & automatic page rotate for best fit Pinmemberdab1826-Aug-11 7:55 
QuestionRemove the max 250 pages limitation? Pinmembermonday200015-Mar-11 2:54 
AnswerRe: Remove the max 250 pages limitation? PinmemberHao Hu15-Mar-11 8:15 
QuestionHow to get DPI from JPEG? Pinmembermonday200011-Mar-11 6:22 
AnswerRe: How to get DPI from JPEG? PinmemberHao Hu11-Mar-11 6:39 
GeneralRe: How to get DPI from JPEG? Pinmembermonday200011-Mar-11 11:09 
General PinmemberHao Hu26-Aug-10 13:27 
GeneralRe: Pinmembermonday200012-Mar-11 22:20 
QuestionWhat about the XMP manipulation? [modified] Pinmembermonday200018-Aug-10 0:11 
AnswerRe: What about the XMP manipulation? PinmemberHao Hu18-Aug-10 7:09 
GeneralDesired enhancements Pinmembermonday200014-Aug-10 1:09 
GeneralRe: Desired enhancements PinmemberHao Hu14-Aug-10 16:12 
GeneralRe: Desired enhancements Pinmembermonday200015-Aug-10 20:44 
GeneralI made my program based on this one Pinmembermonday200013-Aug-10 2:12 
GeneralRe: I made my program based on this one Pinmembermonday200016-Mar-11 23:03 
GeneralRe: I made my program based on this one PinmemberHao Hu18-Mar-11 21:16 
GeneralBug found Pinmembermonday200013-Aug-10 2:08 
GeneralRe: Bug found [modified] PinmemberHao Hu13-Aug-10 6:43 
Thanks for your message.
However, I think the place you point out is not right. The issue is within the test code.
Basically, when calling Jpeg2PDF_GetFinalDocumentAndCleanup(), I want user to pass in
their buffer size to avoid the situation of overflow. So the *outPDFSize should be initialized
in the caller as the size of the outPDF buffer. Later, I'll change that value and let caller
know the exact byte size that has been used. This is a very common way for API to get then set
a buffer size.
It seems complicate for me to update this article right now. (codeproject ask to submit my change to their editor for the update, which is much more complicate than before)
So what should been done is in the testMain.c:
Just remove the declaration of: pdfFinalSize and replace all pdfFinalSize with pdfSize.
So pdfSize will be a In/Out variable.
In: Caller let the jpeg2pdf know the byte size of pdfBuf
Out: jpeg2pdf let the caller know the actual byte size that has been used.

modified on Saturday, August 14, 2010 4:26 AM

QuestionMay I re-use your code under the "GPL 2 and later" license? Pinmembermonday20002-Jul-10 2:32 
AnswerRe: May I re-use your code under the "GPL 2 and later" license? PinmemberHao Hu2-Jul-10 8:33 
GeneralMy vote of 5 Pinmembermonday20002-Jul-10 0:06 
GeneralBmp 2 pdf function PinmemberJunson_Feng13-May-10 21:32 

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