Re: [boost] [gil io_new review] Reading images fromin-memory sources

Subject: Re: [boost] [gil io_new review] Reading images fromin-memory sources
From: Domagoj Saric (domagoj.saric_at_[hidden])
Date: 2010-12-08 08:45:49

"Phil Endecott" <spam_from_boost_dev_at_[hidden]> wrote in message 
news:1291755767785_at_dmwebmail.dmwebmail.chezphil.org...
> You're always reading 4 lines and asserting that rec_outbuf_height is not 
> greater than this (as the docs say it will be).  This is not unreasonably, 
> but it's not exactly what I meant; in my code, I explicitly read exactly 
> rec_outbuf_height lines.

Hmm, yes, this passage is definitely missing an implementation note :)
The assert is actually to be read the other way around, it is verifying that 
I am providing enough scanlines for optimal reading (as recommended by the 
documentation)...And the code does not actually read 4 lines, rather it 
provides LibJPEG with the space to read up to 4 lines if it can/wants...it 
is up to LibJPEG to decide how much to read...There is no need to read/use 
the rec_outbuf_height value (unless you plan to dynamically allocate the 
small scanlines buffer which would be self defeating) if the documentation 
guarantees it will be between 1 and 4...

-- 
"What Huxley teaches is that in the age of advanced technology, spiritual
devastation is more likely to come from an enemy with a smiling face than
from one whose countenance exudes suspicion and hate."
Neil Postman