how to convert pdf to jpg.Any code sniplet?

I know how to convert jpg to pdf. but how the reverse is possible?
is there any way to get the size of Pdf? any native c++/c code?
please help?

There is nothing Qt to read and manipulate PDF files.
Here are some open source libraries that do various things with PDFs: Poppler and PoDoFo
Of course, Adobe offer such tools also.

Hi, did you find anything else that does the pdf-to-image conversion?
As for converting pdf to jpg, I've used an open source project a while back to turn uploaded pdfs into images for use in an online catalog. Not sure whether it helps. You may have a check.

Code:

---

import org.icepdf.core.exceptions.PDFException;
import org.icepdf.core.exceptions.PDFSecurityException;
import org.icepdf.core.pobjects.Document;
import org.icepdf.core.pobjects.Page;
import org.icepdf.core.util.GraphicsRenderingHints;
 
 
public byte[][] convert(byte[] pdf, String format) {
 
    Document document = new Document();
    try {
        document.setByteArray(pdf, 0, pdf.length, null);
 
    } catch (PDFException ex) {
        System.out.println("Error parsing PDF document " + ex);
    } catch (PDFSecurityException ex) {
        System.out.println("Error encryption not supported " + ex);
    } catch (FileNotFoundException ex) {
        System.out.println("Error file not found " + ex);
    } catch (IOException ex) {
        System.out.println("Error handling PDF document " + ex);
    }
    byte[][] imageArray = new byte[document.getNumberOfPages()][];
    // save page captures to bytearray.
    float scale = 1.75f;
    float rotation = 0f;
 
    // Paint each pages content to an image and write the image to file
    for (int i = 0; i < document.getNumberOfPages(); i++) {
        BufferedImage image = (BufferedImage)
                document.getPageImage(i,
                                      GraphicsRenderingHints.SCREEN,
                                      Page.BOUNDARY_CROPBOX, rotation, scale);
       try {
            //get the picture util object
            PictureUtilLocal pum = (PictureUtilLocal) Component
            .getInstance("pictureUtil");
            //load image into util
            pum.loadBuffered(image);
 
            //write image in desired format
            imageArray[i] = pum.imageToByteArray(format, 1f);
 
            System.out.println("\t capturing page " + i);
 
        } catch (IOException e) {
            e.printStackTrace();
        }
        image.flush();
    }
    // clean up resources
    document.dispose();
    return imageArray;
}

---

How is this non-C++ (Java?) code related to Qt?

A c++ based open source library is xpdf: http://www.foolabs.com/xpdf/ and its free UI based software: http://pdf-to-jpg-convert.en.softonic.com