# Re: TODO list

From: Henning Meier-Geinitz (hmg-ml@gmx.de)
Date: Wed Nov 08 2000 - 09:58:22 PST

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  Hi,

  On Wed, Nov 08, 2000 at 09:46:09AM +0800, kwlee wrote:
  > well, i need a API which frontend can query backend the warm up remaining
  > time.

  I think that is possible at the moment. Just define an option that
  includes this time. The problem is that this option won't be polled
  every x seconds by the frontend.

  But why should the frontend know about this scanner internal warm-up
  time at all? Wouldn't it be possible to start the warm-up in sane_init
  (or sane_open), if necessary in the background? And then, if the user
  chooses to scan immediately, just wait for the scanner to be ready? In
  this case the frontend will block until start_scan is finished. It
  would be nicer if the frontend printed out a message like "wait for
  warmup" but I don't think it's really necessary.

  > humm this is necessary for no-cpu(or firmware) CCD scanner(not for CIS one)
  > drivers have to check the lamp is warming up enough.
  > this behavior is only necessary for user the first time connect the power,
  > if the lamp always turn-on, there is no need to check warm up remain time...

  But shouldn't this be done in the backend completely? Why should the
  frontend know about the warm-up time? Is it so long that the user
  kills the frontend because he thinks it's frozen?

  > OK! the jpeg data coming from scanner, some manufactures use this mode
  > to speed-up scanning, for example A4 600 dpi color can be achieved
  > around 1.5 minutes, so scanning with jpeg mode, and decompress by driver.
  > In SANE, the decompressing can be done by backend or frontend! but
  > in my opnion, there could be more & more H/W jpeg supported scanners,
  > so better there has API can support this kind of decompression

  So ypou want to have an sanei_ function to decompress jpeg? The SANE
  API itsself deals mainly with transfering information between the
  frontend and the backend. So if one of the standard frame types is
  used the decompression will be done in the backend. If a jpeg frame
  type is used (when it will be available) it's done in the frontend (at
  least if the file isn't saved directly to the disk).

  > I'm junior about SANE, so i need your help:)
  > i have no idea about the differences on desc & projects files:( the detail
  > descriptions of my problems on anothe new 1.04 backend.

  PROJECTS is a summary of backends and other parts of SANE that are not
  included until now. These may be programs that are already finished,
  in alpha state or just an idea/concept. If there is a backend that
  already works we can add a description file (.desc) to SANE. This will
  make sure that the backend is listed on the SANE website. So in your
  case we should make both.

  Bye,
  Henning

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