Being able to put pdfs as the big-image file (with a png/jpg preview image) and then open these to zoom/pan &see additional pages is an unofficially supported use case, but it is extremely useful for me. (showcase)
Pain points with the current implementation:
- To make this work, each tablet has to have the default cleared and set to an app that will open both PDF and raster images.
- Most devices don't have a PDF viewer installed by default so need one installed or the form won't work for PDF files.
- If Acrobat is used, it can render rasters ok but;
- it regularly attempts to convince you to sign in or subscribe with full screen nag overlays that confuse users
- it has a
<--icon at top left which doesn't jump back to the form like the<system navigation icon does, which can disrupt workflow & confuse
I haven't been able to find a free application that will acceptably open all the file types yet, Graphene PDFViewer & MuPDF do not appear in the 'Open with' dialogue after defaults have been cleared, presumably because they can't open rasters. Fileloom can open nearly anything and so can be set as default, however the previously opened files are retained and can be scrolled to at the next opened big image, which is confusing.
The most helpful change that I can think of would be if the MIME type of the big-image file can be determined on open and use that to determine which app is the default to use. Then the device gallery app would be the default for image/* (well, maybe /png, /jpg /webp /heic etc but not /svg+xml!) and a selected app the default for application/pdf.