Changing the text and background color of a PDF file

Question

I\'d like to change the background color and text color programmatically in PDF documents so that they\'re nicer to read at night (kinda like in Adobe Reader: Edit -> Prefer

Answer 1

As you asked for an API, I'll throw one additional possibility in the mix. It is actually possible to write a plug-in for Adobe Acrobat (should be possible for Adobe Reader too, but Reader plug-ins are more difficult) that interferes with display.

A long time ago I wrote code for Enfocus PitStop to implement a wireframe rendering mode for PDF files inside of Adobe Acrobat. Click a button and the display changes to wireframe, click again and you have your normal view. This works because you can (as a plug-in) modify the display list (the list of objects) drawn by Acrobat.

This means that to draw your special display mode you could create a new display list (or modify the existing one) so that it has a rectangle at the very back in the color that you want and then modify the color of all objects in the display list to suit your needs.

This is relatively complex as it is, what makes it more complex is that - if you don't want your changes to affect the PDF file on disk, you have to intercept a myriad of Acrobat notifications and undo your changes. For example, if the user attempts to save the PDF document while viewing in your display mode, you have to make sure you are warned about that and undo the changes during the save. Adobe Acrobat makes this possible because it sends you notifications before and after the save process but it's still a serious job to make sure nothing gets screwed up.

But it's a absolutely cool and very flexible way to implement what you were after. Just make sure you have more than a couple of weeks to implement it :)