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  1. Qt
  2. QTBUG-40546

QPainter does not honor Qt::SmoothPixmapTransform render hint

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Not Evaluated
    • Resolution: Out of scope
    • Affects Version/s: 5.3.1
    • Fix Version/s: None
    • Component/s: GUI: Painting
    • Labels:
      None
    • Environment:
      Linux 3.7.10-110.gbe6d65b-desktop #1 SMP PREEMPT Thu Jun 5 06:35:30 UTC 2014 (be6d65b) x86_64 x86_64 x86_64 GNU/Linux

      Description

      When using a QPainter to draw a scaled image, the result is really poor even with the Qt::SmoothPixmapTransform render hint turned on. It looks like it does not make any difference is the hint is enabled or not.

      Scaling with QImage::scaled(..., Qt::SmoothTransformation) first and then painting the scaled image results in a superior rendering.

      I attached an example project that displays an image at it's original size (128x128) and then scaled down to 20x20 pixels via the painter and via QImage::scaled().

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            Assignee:
            sletta Gunnar Sletta
            Reporter:
            mlangen Marc Langenbach
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              Dates

              Created:
              Updated:
              Resolved:

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