Append Multiple Images to a PDF in C/C++

Recently we posted about how to convert PDF to JPEG and converting multi-page TIFF to PDF. A customer recently asked how one might add multiple images to a PDF. Luckily, LEADTOOLS supports more than 150 raster, vector, and document file formats including SVG, JPEG, PNG and more. So let's dive in and show you how simple it is!

    // Create file with first page
    try {
      BITMAPHANDLE page1 = { 0 };
      L_INT return_code = L_LoadBitmap(page1_file, &page1, sizeof BITMAPHANDLE, 24, ORDER_BGR, NULL, NULL);
      if(return_code < 1) throw(return_code);

      page1.XResolution = page1.YResolution = BITMAPHEIGHT(&page1) / 11; //set the DPI to cause 11 inch height.
      
      return_code = L_SaveBitmap(outputPdf_file, &page1, FILE_RAS_PDF_LZW, 24, 0, NULL);
      if(return_code < 1) throw(return_code);

      L_FreeBitmap(&page1);
    }
    catch (L_INT err) {
      cout << "Error Code: " << err;
    }
    

If you wish to append or replace pages using L_SaveBitmap(), the existing PDF file must be a raster-based PDF similar to the output of L_SaveBitmap() itself. L_SaveBitmap() also returns a success or error code to aid debugging.

Next, load an image and append it as a second page to the same PDF file:

    // Append second page
    try {
      BITMAPHANDLE page2 = { 0 };
      L_INT return_code = L_LoadBitmap(page2_file, &page2, sizeof BITMAPHANDLE, 24, ORDER_BGR, NULL, NULL);
      if(return_code < 1) throw(return_code);

      SAVEFILEOPTION SaveOptions = { 0 };

      return_code = L_GetDefaultSaveFileOption(&SaveOptions, sizeof SAVEFILEOPTION);
      if(return_code < 1) throw(return_code);

      SaveOptions.PageNumber = 2;
      page2.XResolution = page2.YResolution = BITMAPHEIGHT(&page2) / 11; //set the DPI to cause 11 inch height.

      return_code = L_SaveBitmap(outputPdf_file, &page2, FILE_RAS_PDF_LZW, 24, 0, &SaveOptions);
      if(return_code < 1) throw(return_code);
      
      L_FreeBitmap(&page2);
    }
    catch (L_INT err) {
      cout << "Error Code: " << err;
    }
    

Finally, load two images, combine them into one image, and replace the first page with the image combined from the newly loaded 2 images:

    BITMAPHANDLE page2_1 = { 0 }, page2_2 = { 0 };
    // Load 2 images for one page
    try {
      L_INT return_code = L_LoadBitmap(page2_1_file, &page2_1, sizeof BITMAPHANDLE, 24, ORDER_BGR, NULL, NULL);
      if(return_code < 1) throw(return_code);

      return_code = L_LoadBitmap(page2_2_file, &page2_2, sizeof BITMAPHANDLE, 24, ORDER_BGR, NULL, NULL);
      if(return_code < 1) throw(return_code);

      L_UINT w = max(BITMAPWIDTH(&page2_1), BITMAPWIDTH(&page2_2));
      L_UINT h = BITMAPHEIGHT(&page2_1) + BITMAPHEIGHT(&page2_2);
      BITMAPHANDLE combinedPage = { 0 };

      // Create empty bitmap
      return_code = L_CreateBitmap(&combinedPage, sizeof BITMAPHANDLE, TYPE_CONV, w, h, 24, ORDER_BGR, NULL, BOTTOM_LEFT, NULL, 0);
      if(return_code < 1) throw(return_code);
      
      // Copy the first image into the empty bitmap
      return_code = L_CombineBitmap(&combinedPage, 0, 0, BITMAPWIDTH(&page2_1), BITMAPHEIGHT(&page2_1), &page2_1, 0, 0, CB_DST_0 | CB_OP_ADD | CB_RAWCOMBINE, 0);
      if(return_code < 1) throw(return_code);
      
      L_FreeBitmap(&page2_1);

      // Copy the second image below the first image
      return_code = L_CombineBitmap(&combinedPage, 0, BITMAPHEIGHT(&page2_1), BITMAPWIDTH(&page2_2), BITMAPHEIGHT(&page2_2), &page2_2, 0, 0, CB_DST_0 | CB_OP_ADD | CB_RAWCOMBINE, 0);
      if(return_code < 1) throw(return_code);
      
      L_FreeBitmap(&page2_2);

      SaveOptions.PageNumber = 1;
      SaveOptions.Flags |= ESO_REPLACEPAGE; // add the replace flag to put the combined image instead of the old page1
      combinedPage.XResolution = combinedPage.YResolution = BITMAPHEIGHT(&combinedPage) / 11; //set the DPI to cause 11 inch height.

      return_code = L_SaveBitmap(outputPdf_file, &combinedPage, FILE_RAS_PDF_LZW, 24, 0, &SaveOptions);
      if(return_code < 1) throw(return_code);
      
      L_FreeBitmap(&combinedPage);
    }
    catch (L_INT err) {
      cout << "Error Code: " << err;
    }    
    

For more information see the documentation for PDFFile class and PDFDocument class.

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