Bug 14020 – [GDK] Jumbled text during initial load of a large page

• Component: New Bugs
• Status: RESOLVED FIXED

[Alp Toker]

Visiting http://planet.gnome.org/

Some of the text content seems to get rendered in a very small area near the top left of the window, overlapping previous text output.

This happens during the first half a second or so of page loading, after which the page is re-rendered, correctly this time.

This causes some slowdown on mobile devices, though it can be easily observed on desktop systems. Other ports are reported not to suffer from this issue.

[Alp Toker]

Created attachment 14892 [details]
Screenshot of the bad rendering

This screenshot was taken in the split second during which the rendering is jumbled during initial page load.

[Alp Toker]

It's worth noting that this issue happens on other pages too, not just the site mentioned.

[Holger Freyther]

I have observed this as well. Currently I'm tempted to blame CURL. What we could try is to save the website+resources as files (adjust the html to refer to the images relative) and see if we have this rendering issue as well.
I will add this to my agenda but feel free to beat me.

My hypothesis is: The CURL ResourceHandleManager is not loading fast enough and we have some sort of partial layouting+rendering. By trying file based loading we could partly confirm this.

[Holger Freyther]

This is due ScrollView::resizeContent generating an expose event which will draw the incomplete site. The fix would disable generating expose signals..

[Holger Freyther]

Created attachment 15523 [details]
Update the scrollbars once when ScrollView::update gets called

Fix jumbled text by updating the scrollbars on ScrollView::update. The theory is we will generate less expose events, so FrameGdk.cpp will less often paint and we don't force the RenderTree to layout.

[Maciej Stachowiak]

Comment on attachment 15523 [details]
Update the scrollbars once when ScrollView::update gets called

Tiny nitpicks:

"lead to less often layouting" - there's no such word as layouting in English, layout is only a noun, not a verb. "lead to laying out less often" would be the way to say it.


+    if (m_data->scrollBarsNeedUpdate) {
+        updateScrollbars();
+    }

Shouldn't be braces here.

You can fix these before committing, otherwise r=me.

[Holger Freyther]

Landed in r24321.