Hi! Though I am unsure how well it works, as I have not tried it myself, in theory cairo should support rotated text. There exists a DirectFB backend for cairo. Image rotation should also be possible via cairo.
Richard Unger > -----Ursprüngliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von > Phil Endecott > Gesendet: Freitag, 29. Dezember 2006 18:28 > An: [email protected] > Betreff: [directfb-users] Rotate JPEGs or text? Limit on > amount of videomemory? > > Dear All, > > I am developing a digital picture frame using DirectFB. It > is progressing well. > > One problem that I have not yet found a solution to it > rotating JPEGs, and possibly also text. There are a couple > of reasons why I might want to do this. Firstly, I may know > from the EXIF metadata in a JPEG that it was taken with the > camera held in portrait orientation but the data has not been > rotated. Secondly, I may make it possible to physically > rotate the picture frame to better display portrait-format > images. In the latter case I need to render text rotated as > well as rotated JPEGs. > > I can think of several points in the system where rotation > could occur (for JPEGs; text rendering is similar): > > - The raw JPEG data could be transformed; I believe that this > can be done losslessly quite cheaply (e.g. the jpegtran program). > > - The rotation could be performed as the JPEG is decoded. > > - The blit from the output of the decoder onto the screen > could do the rotation. > > - The rasterisation of the framebuffer could be re-ordered to > effect the rotation. > > However, I can't see any existing support for any of these > things. I suspect that the easiest place to add support for > rotation is in the JPEG image provider; any thoughts? Is > there any hardware support anywhere for rotation? > > > My code provides a pan/zoom user interface for photo > browsing. To provide good performance without excessive > memory use I cache surfaces containing decoded JPEGs. I > presume that video memory is used for these surfaces. In a > PC with a plug-in video card this video memory is discrete > and of a finite size; is there a way that a directfb > application can know how much video memory is available, and > how much a surface has used? On the other hand, in my > picture frame I'm using a simple nano-itx board with no > separate video memory. In this case, can I use all of my > main memory for surfaces without penalty? Or is some portion > of the main memory dedicated to video? Can I change this? > > > Many thanks, > > Phil. > > > > > > > _______________________________________________ > directfb-users mailing list > [email protected] > http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-users > _______________________________________________ directfb-users mailing list [email protected] http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-users
