Half a year ago, I experimented with gtk+ and cairo to extract a PDF screenshot out of a progam, i.e. a screenshot of the window that is not a table of colored dots as a regular PNG file would be, but rather a vector graphic that scales perfectly and has selectable text. The main use that I see is documentation: A scalable screenshots looks much better in print, and even in an online-PDF-file, having the full-text-search also find the text in the images is useful.

My experiments back then were successful in a proof-of-concept way, but they were very ugly hacks. With the new version 3 of gtk+, though, things become much easier, as only one cairo context is used, instead of each widget creating its own context to draw on.

By now, the first gtk-3 applications have reached Debian unstable, so I thought it would be time to re-do the experiment. And the result is very pleasing: The pdf screenshot program comes as a gtk module that you can load by setting an environment variable before launching a gtk-3 program. The application will run as usual, but there is an additional PDF screenshot button. If you click it, you get a “Save File” dialog (with a nice, live-updated preview of the screenshot, as an additional gimmick) that lets you save a PDF file. Its as easy as that. You can check out the resulting PDF file of gucharmap and a screencast of me creating that file, including copy’n’pasting from the resulting document.

Your browser does not support the video tag, but you can still download and view the screencast with the above link.

PS: I would offer the video as well on YouTube, but it seems it does not accept Ogg Theora videos. I hope all of you can make use of the above links.

Update: By popular demand, I also created a SVG version. It even looks better because the embedded pixmaps have a higher resolution – probably gtk is confused by the resolution of the PDF cairo surface. The code is almost trivially the same. I guess I could add other formats (PNG, PS) as well. Now I just have to find out how to tame GtkFileChooser to offer this feature better.