On Fri, Apr 4, 2014 at 7:17 PM, Levente Kurusa <le...@linux.com> wrote: > Hi, > > On 04/04/2014 05:15 PM, Jason Cooper wrote: >> On Thu, Apr 03, 2014 at 01:57:04PM -0700, David Lang wrote: >>> On Tue, 1 Apr 2014, Jason Cooper wrote: >>> >>>>> Now I guess we need to think how to make it work without a >>>>> framebuffer. I already suggested using the ASCII characters, >>>>> but seeing the resolution of this QR code for example (147x147), >>>>> made me realize that we can't shuffle that into a 80x25 textmode >>>>> display. Any ideas how to fix that or should we just simply depend >>>>> on a framebuffer being present? >>>> >>>> I think depending on the framebuffer being present (via kconfig) is >>>> sane. Folks running old systems know what they're in for, like missing >>>> shiny new features. ;-) >>> >>> First get it working and into acceptable form, but after that, take >>> a look at the various ASCII-art tools out there. While the display >>> may be limited to 80x25, that's not a hard requirement (and I'd >>> happily run systems with a smaller text console if this was an >>> option), and then you can look at the possibility of using >>> characters that represent more than one pixel per character. While >>> this may not be able to render everything perfectly, remember that >>> qr codes can include redundancy to correct for bad pixels, you may >>> be able to get something working. > > I am not sure depending on the error recovery is good practice. > We also have to take into account that scanners themselves also > create noise and may not be perfect. Better reserve the error > recovery for those details instead of messing the QR code with > characters...
You do have the option of error recovery for up to 30% recovery (H level), but that means the space you get for storing is smaller. > >> >> I'm not sure this will work. The screen space allocated to a single >> character isn't square. However, the QR pixels are square. I see a lot >> of fragile complexity ahead... >> > > ... not to mention this as well. > > > IMHO supporting textmode is just not worth the effort. Besides, > what would we gain from it? Supporting those devices without > a framebuffer? Do devices like that even exist anymore? In fact, > even to make this you need a screen, and AFAIK most screens come > with some kind of a framebuffer to drive them. Guys, first things first is cleaning the library up. I haven't managed to do anything yet as I am working on my thesis (bachelor's degree, yay!). I will do some this weekend and that is removing the kanji mode support. So, Levente, pleaso do that parameter thing you mentioned. Merging that with the cleanup shouldn't be a problem. :-) I think writing the QR to the frame buffer is the way to do it for now. Doing a QR in text mode (as in displaying it, not as previously mentioned idea with the link base64 encoding &/ compression) would mean that for each square you get an ASCII character filling up your screen. To get an idea of how the QR looks on the frame buffer I've made a screenshot. That's the whole Oops message being encoded and compressed. [0] The problem with frame buffer is that I currently implemented it using the generic frame buffer API. There are some issues as mentioned in the first post of this RFC [1]. Would making it work with KMS be better? Any opinions? Thanks, -- Teodora [0] http://swarm.cs.pub.ro/~teobaluta/QR_code_fb.jpg [1] https://lkml.org/lkml/2014/3/17/525 > > -- > Regards, > Levente Kurusa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
