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
