Solved TD-23229 : WM_EraseBackground causes terrible flickering

Post found bugs and possible workarounds.
Dave Rabelink
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TD-23229 : WM_EraseBackground causes terrible flickering

Post by Dave Rabelink » 10 Mar 2017, 07:44

Seen on TD 7.0 RTM x86 and x64.

OpenText ticked has been created:
OTCS Ticket 2861652 : WM_EraseBackground causes terrible flickering
TD-23229 :TD7 increased WM_EraseBackground causes bad app flickering



It seems that there are a lot more WM_EraseBackground messages processed by TD 7.0 compared to TD 6.3.
On a normal default form with normal default objects, on simple actions like clicking on the form canvas or editing fields (eg multiline) will cause the form to process a lot of WM_EraseBackground actions.
This causes default objects like frames, groupboxes, pictures and mostly other objects to flicker.

(WM_EraseBackground wil normally completely repaint the form and child objects on each request).

On our GUI's the result is unbearable. Objects which have custom painting or complex forms having a lot of objects flicker when normally used.
On more complex screens, the flickering increases such that they can be used as stroboscope.

Testcase source.
On a form several objects in different colors. The colors do not matter, even normal objects show flickering.

Case 1:
Click on the canvas of the form. Do this repeatedly. See that a lot of WM_EraseBackground msg are processed. This causes objects to repaint and in even a simple case it is clearly visible.
Case 2:
Edit the multiline field. See the increase in processed msg

The same test application on TD6.3 does not show this amount of msg sprayed and does not have the severe flickering.

EraseBackground.zip
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Regards,
Dave Rabelink

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Dave Rabelink
Founder/Site Admin
Founder/Site Admin
Netherlands
Posts: 275
Joined: 24 Feb 2017, 09:12
Location: Gouda, The Netherlands

Re: TD-23229 : WM_EraseBackground causes terrible flickering

Post by Dave Rabelink » 10 Mar 2017, 07:45

To follow up on this story...

The issue that the form is repainted when just left clicking on the form canvas seems to be solved in the upcoming TD 7.0 UPD1 release.

But there is more:

Handling just one object causes forms to repaint, depending on the type of object and the action.

Till now I have identified these objects:

- background text (labels)
- checkbox
- radiobutton
- groupbox

When you perform one of these actions on it:

- Enable/Disable
- Set text color or back color
- Set the value (TRUE/FALSE) or the value text

It will repaint the complete form.
When more of these objects are on a form, the flickering will increase
When more other type of objects are on one screen, the flickering will increase

I have created a case and Gupta has identified the issues as:

Ticket # 2901279: TD-23294 WM_EraseBackground/WM_Paint on usage checkboxes & radiobuttons

Use the testcase provided and watch the video.

These issues are present in all TD UNICODE versions, but on my system, TD 7 seems to flicker even more.

EraseBackground_V3_TD63.zip
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Regards,
Dave Rabelink

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Dave Rabelink
Founder/Site Admin
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Posts: 275
Joined: 24 Feb 2017, 09:12
Location: Gouda, The Netherlands

Re: TD-23229 : WM_EraseBackground causes terrible flickering

Post by Dave Rabelink » 10 Mar 2017, 07:48

Mike Vandine OpenText support wrote:Hi,

The defect that you've reported in this ticket has been fixed with the TD 7.0 Update 1 release.

OTCS Ticket 2861652 : TD-23229: WM_EraseBackground causes terrible flickering
OTCS Ticket 2901279 : WM_EraseBackground/WM_Paint on usage checkboxes & radiobuttons

You can pick up this release from the OpenText Knowledge Center:

https://knowledge.opentext.com/knowledg ... n/62156116

You will find the release notes in the same location.

I will be closing this ticket. If you find that you still have a problem after installing this release, a new ticket can be opened.


Regards,

Mike Vandine
OpenText Support Team
Regards,
Dave Rabelink

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Dave Rabelink
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Location: Gouda, The Netherlands

Re: TD-23229 : WM_EraseBackground causes terrible flickering

Post by Dave Rabelink » 20 Sep 2017, 11:30

This defect has been fixed in TD 7.0.3
Regards,
Dave Rabelink

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