I forgot to mention that this application might be equally interesting for Batik. And now that I thought about this, I remember that Batik does image comparison. Maybe something could be borrowed from there.
On 17.06.2005 15:43:20 Jeremias Maerki wrote: > I've just found a bug in our renderers that causes nested > block-containers to be painted in the wrong position (vertically). The > area tree is fine, so it doesn't make sense to write a layout engine > test case. Now would be the time for visual comparison. With the bitmap > renderer we could do that very easily but that would only test the > Java2D renderer, not the others. In the example I attached the PDF and > Java2D renderers actually render the document differently, but both > wrong. :-) > > We really need that visual comparator which consists of: > - Generic JUnit TestCase implementation that does visual checks similar > to how I implemented the layout engine tests. > - Converters from PDF, PS etc. to bitmaps (for example, calling > GhostScript externally) [1] > - Component that compares two bitmaps and creates a "diff bitmap". > - Helper application (with GUI) which makes it possible to quickly go > through many test results. For each test it would show the reference > bitmap, the actual bitmap and the diff bitmap side by side. Possibly, it > could even show a reference bitmap from a different FOP version or even > a different FO implementation. > > This helper application doesn't even necessarily have to be inside FOP > because visually testing the formatting results could be interesting for > other people, too (including possibly the XSL WG). To simplify calling > different FO processors my general FO processing API could be a great > helper here. I should simply find the time to publish the latest version. > > Anyone out there who would like to do such a nice little project? > > [1] has the potential problem of license issues because of the GPL. > However, we would only call GhostScript via command-line but it could > still be an unproper linking. Maybe the AFPL would be less problematic. > We'd have to find out. > > Jeremias Maerki Jeremias Maerki
