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  1. Qt
  2. QTBUG-131923

QPainter::drawImage with CompositionMode_Source into non-alpha image format produces transparent pixels

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    • All
    • 68d001150 (dev), 1e605b6e0 (6.10), d3c5bfbf6 (tqtc/lts-6.8), 0899651c8 (dev), d2c8fcb75 (6.10), 2b4959e69 (tqtc/lts-6.5)

      QPainter paints transparent pixels white on macOS with composition mode CompositionMode_Source and image format QImage::Format_RGBX64 (as shown in macos.png). On Windows the pixels are painted black (windows.png).

      The attached example can be used to reproduce the issue.

        1. macos.png
          278 kB
          Titta Heikkala
        2. windows.png
          33 kB
          Titta Heikkala
        3. sourceComposition.zip
          43 kB
          Titta Heikkala
        4. iconcol.zip
          1.0 kB
          Eirik Aavitsland
        5. iconcol_linux.png
          15 kB
          Eirik Aavitsland
        6. image-2025-10-09-13-20-36-486.png
          313 kB
          Tor Arne Vestbø
        7. image-2025-10-09-13-21-53-506.png
          345 kB
          Tor Arne Vestbø
        8. image-2025-10-09-13-24-46-086.png
          251 kB
          Tor Arne Vestbø
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            allan.jensen Allan Sandfeld Jensen
            tiheikka Titta Heikkala
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            1 Vote for this issue
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              Created:
              Updated:
              Resolved: