[texworks] zoom devours memory

Stefan Löffler st.loeffler at gmail.com
Mon Sep 19 15:34:08 CEST 2011


On 2011-09-19 14:53, Arno Trautmann wrote:
> I have some trouble with the built-in pdf viewer: When I zoom, it 
> works, great. But the largest and second-to-largest zoom steps take a 
> very long time to proceed (~ 30s on a document that has just “\TeX” in 
> it). Also, the memory consumption during this time (rendering time?) 
> goes up dramatically, up to 50% of my 1GB RAM. But when it's finished, 
> memory drops, the machine goes on working and scrolling etc. is very 
> fast again, also the zoom lense doesn't make any problems.
> So – is this known? Is it a bug or just the way the renderer works? 
> Can it be improved?

Yes, it is a known problem 
(http://code.google.com/p/texworks/issues/detail?id=86). It is just the 
way the poppler library (which does the page rendering) works - 30s are 
quite normal for high magnifications. The actual content indeed seems 
irrelevant. It might be that (part of) the problem lies in the internal 
handling of images by Qt, as even copying a large image from one 
variable to another takes noticeably long (maybe a second or two).

The principle problem that it takes a long time can't be solved by us. 
But Charlie and I are currently working on an overhaul of the pdf 
previewer, which among other things should increase the response time of 
the application (by rendering in the background and displaying a scaled 
image until that is finished).


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