Strange behavior in CustomEdit controls embedded in a TwwDBGrid . . .

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Columbus Systems

• March 11, 2021 00:27

We've been in the process of migrating an application developed in Delphi 5 with InfoPower 3K to Delphi 10, InfoPower 4K.  At least a couple of CustomEdit controls in a TwwDBGrid control flicker and spike CPU usage at certain junctures in the migrated code, often in association with the creation of new records.  The code in the Delphi 5 version of the project behaves, as always, reasonably.

The grid's CustomEdit controls where I've detected the behavior are a TwwDBLookupCombo and a TwwDBComboBox.  Has anyone else encountered this sort of problem?

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  Roy Woll

  • March 17, 2021 18:47

  Sorry, I missed your message earlier. We are not aware of flickering problems and cpu spikeage in our current versions. Delphi 10 is a little older so it is possible. I recall a problem with Rio where doublebuffered for the grid needed to be set to false to avoid flicker. Could this be your issue?

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  Columbus Systems

  • March 17, 2021 20:59

  I'll experiment a little with it - see what comes up.  I'll let you know.

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  Columbus Systems

  • March 17, 2021 22:02
  • Edited

  OK . . . your suggestion does seem to have some bearing on the matter.  But kind of in the opposite direction: it seems the DoubleBuffered property for the grid had never been set to True (seems not to have been a published property in Delphi 5), and wasn't set to True for the migrated code; however, now that I've set the grid's DoubleBuffered property to True in the migrated code, I'm not seeing the flickering or CPU spiking (not so far anyway).  If that's all there is to the fix, I won't look a gift horse in the mouth - but I am a little curious why it should be an issue.

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  Roy Woll

  • March 18, 2021 02:25

  Actually I don't recommend doublebuffered as true, but not sure why it works for you.  I would retry when you update to more recent versions of InfoPower (such as for Sydney).

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  Columbus Systems

  • March 18, 2021 15:56

  And I don't pretend to understand why the DoubleBuffered property should be linked to the problem at all.  But we do plan to upgrade to Sydney, so it might not be an issue long term.

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