GNOME Bugzilla – Bug 756832
Page thumbnails disappear while scrolling
Last modified: 2016-09-28 18:47:57 UTC
When you have a PDF with many objects and large images, the thumbnail generation can be slow and inefficient as described in #34110 and #691448. But even if thumbnail generation is slow, evince shows white placeholder pages, so you see appearing content, not appearing pages. When thumbnail generation is slow it can happen that even these placeholder pages appear and disappear which produces a quite unpleasant flickering. Here a video: https://imgrush.com/2UvU1oEmEoWW
I'm seeing something similar. When you scroll or even press space to go page by page, all the thumbnails disappear and sometimes reappear.
Sorry, it's too big to post to bugzilla. Here's a link: http://mitchenerg.people.cofc.edu/Slide-Show.pdf
I can see the same behaviour in a smaller document (186 pages, 1.6MB), whose render does not take that long. It looks like the the thumbnail area needs to be repainted. For example, when I can reproduce the issue, I can pass the mouse over a "hidden" thumbnail and it will be drawn, if I move the scrollbar a little, all of them will appear.
I am sorry to say.. this bug has been there since 3.0... The issue is that the way we modify the model in the IconView invalidates the whole view. Therefore, the IconView triggers a relayout which is very slow... During this relayout there are chances the thumbnails will become invisible. The solution is to move away from the IconView or use another type of custom model... In the previous versions this problem only became apparent with very big documents... Now it seems is reproducible more easily....
I remember that after an update (probably of GTK+) I perceived the thumbnail sidebar slower. It may be related with that. I think I commented it, but I don't remember whether in a bug or somewhere else.
Meh, it was already pointed here: Bug 691448 :-) Then, it is a duplicated.
*** This bug has been marked as a duplicate of bug 691448 ***