Public bug reported:
The way qpdfview manages the rendering and re-rendering of the document
when (at the current zoom level) the document size exceeds the window
size is very badly wrong; this may not have noticeable effects on very
light documents that get rendered very quickly, but it makes handling
large and "heavy" documents completely unmanageable.
Use case:
1)
- You open a large document, which is a bit costly to render and which exceeds
the current window.
After a reasonable rendering time, the portion of the document that is
contained in the current window becomes visible. So far so good.
- Then you scroll down (or move to any side) EVEN THE SLIGHTEST BIT.
=> the portion of document that comes into the window is now blank, you have to
wait for it to be rendered.
While I do appreciate that qpdfview does not waste cpu time and memory
to render the entire document in advance, it should at least pre-render
a somewhat bigger area than is currently displayed, so that you have a
reasonable margin of movement within which you will see the new piece of
document immediately.
Also, when you are doing nothing and the application is idle (but
focused), it should take advantage of that to pre-render an even wider
region of the document, as much as reasonable memory usage allows.
But the worst has not come yet.
2) Then you scroll back up (or you move back in the opposite direction
to whatever you did before, going back to the same region of the
document that was displayed just a few second before). Now a portion of
document that had already been rendered and displayed is blank, and you
have to wait AGAIN all the time it takes to render it.
This shouldn't happen. When qpdfview has already rendered a piece of
document, it should keep it in memory, and not throw it away until it
runs short of memory.
And by far the worst:
3) You don't scroll nor move at all. You are already seing the portion of
document that fits in the current window.
You switch to another program.
You switch back to qpdfview
Guess what? The page is blank and you have to wait AGAIN until it's re-
rendered.
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: qpdfview 0.4.7-1
ProcVersionSignature: Ubuntu 3.13.0-29.53-generic 3.13.11.2
Uname: Linux 3.13.0-29-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CurrentDesktop: Unity
Date: Wed Jun 18 20:44:25 2014
InstallationDate: Installed on 2013-10-11 (250 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
SourcePackage: qpdfview
UpgradeStatus: Upgraded to trusty on 2014-05-24 (25 days ago)
** Affects: qpdfview (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug trusty
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https://bugs.launchpad.net/bugs/1331689
Title:
Completely unusable with large heavy documents
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