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  1. Qt
  2. QTBUG-23359

Spurious bounding box edges drawn by QPainter::drawPolyLine for Windows printer when pen colour has alpha != 255

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Reported
    • Priority: P4: Low
    • Resolution: Unresolved
    • Affects Version/s: 4.8.0
    • Fix Version/s: None
    • Labels:
      None
    • Environment:
      Windows 7 Professional SP1 32-bit
      Samsung CLP-310N printer

      Description

      I'm drawing an irregular polyline with a 'highlighter pen' effect by using alpha blending. On screen and when printing in Linux, this works perfectly, but when printing in Windows (Win7 32-bit), one or more of the edges of the polyline bounding box are drawn as solid black lines. The thickness of the lines varies, and as does exactly which edges are drawn (it may be that all are drawn but some are zero pixels wide). If I set alpha=255 for the pen colour, the problem goes away again, but any other value (including zero, so the polyline itself doesn't show at all) brings it back.

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              Assignee:
              Unassigned Unassigned
              Reporter:
              steveren Steve Rencontre
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                Dates

                Created:
                Updated:

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