[Bug 1834636] Re: Import selection rectangle leaves trails visible in screenshot

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: imagemagick (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1834636

Title:
  Import selection rectangle leaves trails visible in screenshot

Status in imagemagick package in Ubuntu:
  Confirmed

Bug description:
  Under Kubuntu 18.04.2 LTS, the import tool leaves remnants of the
  selection rectangle in the captured screenshot.  Those are also
  visible in real-time when moving the mouse to adjust the size of the
  selection rectangle, as if the old-sized rectangle is not always
  erased before the new-sized rectangle is drawn.  There also seems to
  be some kind of double buffering going on (in the KDE compositor?) so
  that the display alternates between multiple sets of rectangle
  remnants.  Speculating a bit, perhaps the double buffering is also the
  root cause for the problem - maybe the old-sized rectangle *is* erased
  but in the wrong buffer.

  The standard screenshot tool in KDE (accessed using the PrtScr key)
  does not exhibit the problem using its equivalent mode (rectangular
  selection).

  
  Output from lsb_release -rd: 

  Description:    Ubuntu 18.04.2 LTS
  Release:        18.04

  
  Output from apt-cache policy imagemagick-6.q16:

  imagemagick-6.q16:
    Installed: 8:6.9.7.4+dfsg-16ubuntu6.7
    Candidate: 8:6.9.7.4+dfsg-16ubuntu6.7
    Version table:
   *** 8:6.9.7.4+dfsg-16ubuntu6.7 500
          500 http://se.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
          500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
          100 /var/lib/dpkg/status
       8:6.9.7.4+dfsg-16ubuntu6 500
          500 http://se.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

  
  What I expected to happen:

  Obtaining a clean screenshot of the region corresponding to the
  selection rectangle (as in attachment "emacs_screenshot_kde.png").

  
  What happened instead:

  Obtained a screenshot including remnants from the selection rectangle
  (see attachment "emacs_screenshot_imagemagick.png").

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