Programmatically creating PDF files

January 24, 2012

by Cardiff Creative

Scenario

One of our clients is a Philatelic Auctioneer based in Cardiff, South Wales and sells items to a world-wide audience. Auctions run in Lots of almost 1000 items at a time. We were asked if it would be possible to create a PDF version of the Auction Catalogue both for the website and to send to the printers for hard copy versions for those clients who don’t use the internet. The catalogue is comprised of Images and Text. The source file was Excel and the images could optionally come from both the internet or locally.

Of course, anything is possible and we set about writing a custom application to fulfil the request.

Challenges along the way included:

Calculating the size of a paragraph of text and how to stop it running off the edge of the page.
Splicing, rotating and glueing images together on-the-fly.
Stopping text and images running off the end of the page by calculating where page breaks were needed in advance.

If your company has a similar requirement, why not contact us ?

Below is some technical detail for anyone with programming experience who is looking into doing something similar.

Tools used:

Dusted of our copy of Visual Basic 6, it’s getting on a bit now but we still love it…

We did some research into components and code that would be needed for creating PDF files, manipulating images and downloading files. The following were used and are well documented:

Downloading Files or Images from the Internet using Visual Basic

Code

Private Declare Function URLDownloadToFile Lib "urlmon" Alias "URLDownloadToFileA" _
 (ByVal pCaller As Long, ByVal szURL As String, ByVal szFileName As String, _
  ByVal dwReserved As Long, ByVal lpfnCB As Long) As Long
 
Public Function DownloadFile(URL As String, LocalFilename As String) As Boolean
  Dim lngRetVal As Long
  lngRetVal = URLDownloadToFile(0, URL, LocalFilename, 0, 0)
  If lngRetVal = 0 Then DownloadFile = True
End Function

Processing and Manipulating Images in Visual Basic

David Crowell has very generously made his ActiveX component ‘PhotoTrue’ available as freeware. It is a powerful control that was solid and easy to use.

Image processing functions include: Rotate, Crop, Flip, Adjust Gamma, Adust brightness and contrast, Make greyscale, Blur, Overlay one image on another, Quick resize, Re-sample (higher quality resize), Drawing lines and text, Swap colour channels.