We have recently added support for inserting and retrieving images from headers and footers section of an Excel spreadsheet. To enable this, we needed to parse the HFPicture records, which turned out to be a difficult task, especially due to lacking documentation.

When a user adds a picture to a worksheet header or footer section, there is no change to the HEADER or FOOTER records (except for the addition of the &G or &[Picture] tokens to the text). So how are the pictures added to file, and how are they linked to the specific header or footer section?

Let’s start by examining the HFPicture record – we will find that, oddly enough, the HFPicture record is simply a wrapper around the DGContainer or the DGGContainer. Which of these it is is determined by the HFPicture’s fIsDrawing and fIsDrawingGroup bits, and if this HFPicture record is a continuation of a previous HFPicture (due to the size limit of the records), the bit fContinue will also be set. Therefore, an image in a header/footer section will be represented very much like regular images. Continue reading Excel Binary HFPicture Record: Parsing Pictures in Headers and Footers →