Re: [E-devel] [Patch] Implement scale down decoding feature of bmp loader

[Jiyoun P. <jy0...@sa...>]

I modified bmp loader file according to your advice.

(remove white space and reduce if/else statement)

I added down scale feature to 1,2,4,8 bit BMP type and each compression
mode.
In compression mode, I set buffer size to compressed image file size
because it is not possible to use row skip.
Not compression mode, I used row skip method. 

Last week, you recommended inline method if I didn't use row skip using
seek. 
Could you tell me more detail? 
I have trouble to reduce conditional case. :)

Thanks. 


-----Original Message-----
From: "Carsten Haitzler"<ra...@ra...>
To: "Enlightenment developer list"<enl...@li...urceforge.
net>
Cc: 
Sent: 11-10-13(목) 16:30:00
Subject: Re: [E-devel] [Patch] Implement scale down decoding feature of bmp
loader On Sun, 02 Oct 2011 21:37:02 +0900 Jiyoun Park
<jy0...@sa...> said:
got a few whitespace issues like:
+ if(ie->load_opts.scale_down_by > 1)
and:
+ if (scale_ratio == 1)
+ {
 if (fread(buffer, image_size, 1, f) != 1) goto close_file;
+ }
+ else
you could simplify the code a fair bit. too. for example:
 if (scale_ratio > 1)
 p += 2 * scale_ratio;
 else
 p += 2;
could be just
 p += 2 * scale_ratio;
you could even avoid the multiply with pre-calculating the step count:
int step;
...
step = 2; // for 16bpp, 3 for 24bpp, 4 for 32bpp etc.
step *= scale_ratio;
also you don't handle less than 16bpp bmps... which should really be done
given your argument that scaling down bmp is important. after some more
looking i realize it's a bit nasty to try and make the downscale and
rowskip more generic so it kind of has to be inlined. is it possible to
reduce the if () cases more to have fewer special-case code inlined? i
guess not if u want to row skip via seeks...
so
1. spacing
2. you can reduce if cases to make the changes simpler 3. depths less than
16bpp need support. :)
> 
> Hello~~
> 
> I implement scale down decoding feature of bmp loader using down 
> sample algorithm.
> Desktop have low risk to go wrong memory problem during big image 
> decoding, but mobile device is different.
> 
> Raster said it is life (meet memory problem during big image 
> decoding), and it is enough to return decoding fail.
> 
> But I think it seems a bit harsh,
> because 2 or 3 bmp image (5000X5000 size: for example) can cause 
> application close because of memory lack.
> 
> I only deal with 16,24,32 bit count type of bmp(related with scale 
> down), because Bmp file size of this bit count is more big than 1,2,4 
> or 8 bit count file size.
> It is take so much time to deal with all bit count type, so I'll deal 
> with small bit count later(after adding scale down feature to png and 
> gif file type).
> 
> I attach sample code test scale down feature.
> [Usage]
> #hello [file name] [scale num(option: default=8)]
> 
> Thanks. 
> 
> ----------------------------------------------
> Jiyoun Park
> 
> Mobile S/W Platform Lab
> DMC R&D Center
> SAMSUNG ELECTRONICS CO. ,LTD
> 
> TEL: +82-31-279-0619
> Mobile: +82-10-9871-0703
> jy0...@sa...
> ----------------------------------------------
> 
> 
> 
> 
--
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