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  1. Qt
  2. QTBUG-66036

QTextLayout draw() rendering issues with "some" font sizes

    Details

    • Type: Bug
    • Status: Reported
    • Priority: P2: Important
    • Resolution: Unresolved
    • Affects Version/s: 5.10.0
    • Fix Version/s: None
    • Component/s: GUI: Painting
    • Labels:
      None
    • Environment:

      Can be reproduced with latest Qt on at least X11 and macOS (you just need to zoom in your text document, you surely will hit some font size that is bad)

      Description

      Different applications using the QTextLayout mechanism to render text have the same rendering glitches with some font sizes.

      You will get horizontal or vertical "non-filled" pixels in your textlines.

      E.g. If you have some "white" background and paint over text with some different background, you sometimes will get small "gaps" in the painted text.

      This happens e.g. on X11 or macOS.

      Example bug in Kate/KWrite (that uses QTextLayout directly without QTextDocument) can be seen here (horizontal lines, the same can happen vertically):

       

      https://bugs.kde.org/show_bug.cgi?id=379727

      https://bugsfiles.kde.org/attachment.cgi?id=105445

       

      Effect with QtCreator using 5.10.0 on macOS:

       

       

      Given two totally different code bases have the same issue (and QtCreator uses QTextDocument), I think this is some rendering issue in Qt.

        Attachments

        For Gerrit Dashboard: QTBUG-66036
        # Subject Branch Project Status CR V

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            People

            • Assignee:
              sletta Gunnar Sletta
              Reporter:
              cullmann Christoph Cullmann
            • Votes:
              6 Vote for this issue
              Watchers:
              6 Start watching this issue

              Dates

              • Created:
                Updated:

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