[poppler] splash output improvement

[Albert Astals Cid]

A Dijous 10 Novembre 2005 19:17, Carlos Fangmeier va escriure:
> Hi,
Hi

> I'm using the evince pdf reader, who use the poppler lib to do the 
> render. I notice that the render of poppler ( using the splash output )
> is much slower than xdf. Maybe runing evince on a desktop pc isn'tt a
> big deal, but runing evince on a Zaurus C860 is to slow.
> Using valgrind-cachegrind on my pc I find out that most of the cpu used
> for rendering a pdf, was spend in the constructor
> SplashScreen::SplashScreen  ( almost 38% ), so I decided to do some
> litle improvement. After my changes the cpu spend on this constructor
> dropped to 0.1%. With this improvement the evince response was much
> better than before.
> Attachedt to this mail is the patch with my changes, maybe they aren't
> 100% acording with your develope, but it could  be a good idea.
> Basically I implemented a cache for all possible threshold matrix.

Hmm, this is C++, so i think having 

SplashCoord **cache_mat;
int cache_count;

as static members of SplashScreen would be better, what do you think?

Also, i don't seem to understand the caching method much, let's say we first 
call that contructor with 100, we would get 

size2 = sizeA >> 1  // size2 = 50
size = size2 << 1; // size = 100

size1 = size +1; // size1 = 101
if( cache_count <  size1 ) // true because cache_count stats at 0
{
	// create a 101 SplashCoord * array
}
........
// end up using only the 100 position of that array, all else is empty

So would be better to just use a GooHash and not loose the other positions?

My other concern would be cache growing too much as you never seem to empty it 
and that making it take too much mem but 

$ grep -ri "new SplashScreen" *
splash/SplashScreen.h:  SplashScreen *copy() { return new 
SplashScreen(this); }
splash/SplashState.cc:  screen = new SplashScreen(10);

says that we always use 10 as size for the SplashScreen so the cache is always 
going to be of 1 element :-D

So can you try to rewrite the patch using a static GooHash as SplashScreen 
member and see if it still works/gives you the same quickness?

Thanks.

Albert


>
> Best regards
>
>
> Carlos Fangmeier
>
>
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