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  1. Qt
  2. QTBUG-27637

[Regression Qt4 to Qt5] QScrollBar usages 5% CPU on idle

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Not Evaluated
    • Resolution: Cannot Reproduce
    • Affects Version/s: 5.0.0 Beta 1
    • Fix Version/s: 5.0.0 Beta 2
    • Labels:
      None
    • Environment:
      Mac OS X 10.7, Clang

      Description

      Creating a QScrollBar will eat 5% of the CPU when the application is doing absolutely nothing. 0% CPU usage is expected when the application is doing nothing.

      The following code will reproduce the issue. The code works as expected in Qt 4.8.1.

      #include <QApplication>
      #include <QScrollBar>
      
      int main(int argc, char *argv[])
      {
          QApplication a(argc, argv);
      
          QScrollBar* scrollbar = new QScrollBar();
          scrollbar->show();
      
          return a.exec();
      }
      

      If you install an event filter (installEventFilter()) on a QScrollBar, it'll produce a never ending stream of paint events.

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            Assignee:
            Unassigned Unassigned
            Reporter:
            vpicaver Philip Schuchardt
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              Dates

              Created:
              Updated:
              Resolved:

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