Using Dynamic Images in PDF Reports

One question about the PDF printing feature in APEX keeps popping up: how to include images in a PDF report. For static images, that's pretty straightforward. Just place them into your RTF layout using MS Word and BI Publisher Desktop. For dynamic images, that's a little more complicated, so here's how to do that:

When talking about dynamic images, what I mean are images that are stored in BLOB columns in database tables, like for example product images. To include those images in a PDF report, two things are needed: the image needs to be included in the generated XML representation of the report data and the RTF report layout needs to include instructions on what to do with the image information stored in the XML data. To get the BLOB values to be included in the XML data, they need to be base64 encoded. And in the RTF report layout an XSL-FO expression can be used to reference the image:

<fo:instream-foreign-object content-type="image/jpg">
<xsl:value-of select="IMAGE_ELEMENT"/>
</fo:instream-foreign-object>

To enter such a XSL-FO, edit your RTF layout in Word and then use the field-browser of the BI Publisher plug-in to edit the report column attributes.


I setup a sample application that illustrates how this works on apex.oracle.com, you can try it out here:

http://apex.oracle.com/pls/otn/f?p=50930:1 (logon as demo/demo123)

You can also download this application to try it out on your local instance or your own apex.oracle.com workspace. The download is available here:

Download PDF Image Demo Application

The application comes packaged with a table containing a BLOB column and a PL/SQL function that encodes the BLOB to base64. A sample RTF layout with the required XSL-FO snipped for the image transformation is also included. Once the application is installed in your own workspace, just upload a few images and try it out. One issue, which we'll address in the next version of Application Express, is the 32k limit on report columns. For this scenario, this means that only fairly small images are currently supported when using this technique with report queries or report regions. If the XML data is generated by some other way, and the PDF rendering is done using the print API, then the use of larger images would be possible as well.