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  1. Qt
  2. QTBUG-94201

QImageWriter Makes Large PNG

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: P1: Critical
    • Resolution: Invalid
    • Affects Version/s: 5.15.3
    • Fix Version/s: None
    • Component/s: Image formats
    • Labels:
      None
    • Platform/s:
      macOS

      Description

      The attached example program writes a PNG file that should be 100KB, but QImageWriter writes a large 118MB file that doesn't seem compressed.  QImage::save does the right thing. Qt 5.9.6 works fine, but 5.15.3 is broken.  QImageWriter::setQuality does nothing.  To be consistent with QImage::save, I would expect:

      "The quality factor must be in the range 0 to 100 or -1. Specify 0 to obtain small compressed files, 100 for large uncompressed files, and -1 (the default) to use the default settings."

        Attachments

        1. terminal.png
          terminal.png
          34 kB
        2. badPngCompression.zip
          37 kB
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          Activity

            People

            Assignee:
            vgt Eirik Aavitsland
            Reporter:
            remik Remik Ziemlinski
            Votes:
            5 Vote for this issue
            Watchers:
            5 Start watching this issue

              Dates

              Created:
              Updated:
              Resolved:

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