Bug report #1451: High usage of CPU when moving mouse over map canvas - QGIS Application - QGIS Issue Tracking

Bug report #1451

High usage of CPU when moving mouse over map canvas

Added by Martin Dobias almost 16 years ago. Updated about 9 years ago.

Status:	Closed
Priority:	Low
Assignee:	-
Category:	GUI
Affected QGIS version:	master	Regression?:	No
Operating System:	All	Easy fix?:	No
Pull Request or Patch supplied:	No	Resolution:	worksforme
Crashes QGIS or corrupts data:	No	Copied to github as #:	11511

Description

When you move mouse over map canvas (with any tool, e.g. panning), you can see high CPU usage by QGIS application.

The problem is related to updates of coordinates shown in status bar - if extent is being shown instead of coordinates, CPU usage is very low.

I think it has something to do with layout management in status bar...

Using ubuntu, Qt 4.3.4.

History

#1 Updated by Giovanni Manghi over 15 years ago

What is the status of this problem? Since the ticket was posted something changed?

With qgis 1.2 from trunk, Ubuntu 9.04 and a bunch of vectors/raster opened in the project the cpu for the qgis process rarely passed 50 when panning, zooming, etc.

#2 Updated by Steven Mizuno over 15 years ago

It appears that QLabel is doing a lot of work to paint the new values. Perhaps using a QLineEdit control would be better. The CoordinateCapture tool has two such controls, plus it does coordinate transforms, and its CPU utilization isn't any more (actually less in my testing on Windows) than the mouse cursor position control.

#3 Updated by Paolo Cavallini over 13 years ago

Confirmed with f5b1607e (SVN r15261)

#4 Updated by Anne Ghisla over 13 years ago

I can't confirm with f8e10a33 (SVN r15725), qt 4.7.1 on Fedora. CPU usage by QGIS is mainly under 10% while panning and zooming on a medium complex layer, both with coordinates or extent in the status bar.

Is there any other factor that can trigger this CPU consumption?

#5 Updated by Martin Dobias over 13 years ago

The problem is still there. Ubuntu, Qt 4.7.0.

It is not necessary to pan/zoom a layer. This happens even with empty canvas - just moving the mouse over it keeps the processor busy more than one would expect. Still happens only when showing the current coordinates, not the extent.