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  1. Qt
  2. QTBUG-71162

Layer-backed backingstore flush copies whole backingstore on each flush

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    • macOS
    • 77a4915bf900aac0c96260018c0a4ccfbdd7c094 (qt/qtbase/5.12)
    • Bug Fixing Week Q2/2020

      Painting on a layer-backed window on macOS (which is apparently unavoidable now when building agains the 10.14 SDK?) performs poorly because of QImage::detach copying the image. This is related to QTBUG-63559. The commit message for that issue indicates that it isn't expected to be fixed for layer-backed windows.

      Is there any way to avoid the copy or disable the layer-backed backing store? I tried setting QT_MAC_WANTS_LAYER=0 without success.

        1. detach-in-flush.png
          detach-in-flush.png
          225 kB
        2. layer-backed.png
          layer-backed.png
          199 kB
        3. layer-backed-detach.diff
          1 kB
        4. non-layer-backed.png
          non-layer-backed.png
          245 kB
        5. test.cpp
          0.7 kB
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            vestbo Tor Arne Vestbø
            jasonhaslam Jason Haslam
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              Resolved:

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