Qt
  1. Qt
  2. QTBUG-59360

qt_getCanonicalFontNames takes a huge amount of time

    Details

    • Type: Bug Bug
    • Status: Reported
    • Priority: P1: Critical P1: Critical
    • Resolution: Unresolved
    • Affects Version/s: 5.8.0
    • Fix Version/s: None
    • Component/s: GUI: Font handling
    • Labels:
      None
    • Environment:

      Windows 10, MSVC 2015.

      Description

      Text {
          text: "foobar"
      }
      

      Profiling this code on Windows shows that qt_getCanonicalFontNames takes about 60% of the total execution time. Specifically, 48% was spent in GetFontData. This appears to be the single biggest regression for QML compared to 5.6.

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        Activity

        Hide
        Allan Sandfeld Jensen added a comment -

        How did you measure this?

        Show
        Allan Sandfeld Jensen added a comment - How did you measure this?
        Hide
        Allan Sandfeld Jensen added a comment -

        Trying with the textedit widget example in qtbase, I got a total of 7-10% of the startup spend in populating the fontdatabse, ~4% in qt_getCanonicalFontNames, but only 0.2% in GetFontData.

        Show
        Allan Sandfeld Jensen added a comment - Trying with the textedit widget example in qtbase, I got a total of 7-10% of the startup spend in populating the fontdatabse, ~4% in qt_getCanonicalFontNames, but only 0.2% in GetFontData.

          People

          • Assignee:
            Allan Sandfeld Jensen
            Reporter:
            Erik Verbruggen
          • Votes:
            9 Vote for this issue
            Watchers:
            14 Start watching this issue

            Dates

            • Created:
              Updated:

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