Visual artifacts on HIDPI displays

Docking/MDI for WPF Forum

Posted 3 years ago by Andrei Aliashkevich
Version: 21.1.0
Platform: .NET 5.0
Environment: Windows 10 (64-bit)


I am trying to create a simple application and found a some visual artifacts on HIDPI displays. These artifacts does not appear on Full HD displays.

First artifact appear on Documents Tab Control. When I hover an unselected tab, that tab is highlighted with the specified color, but that color is not solid. There is an strange dark line along the tab perimeter. I have attached a screenshot link because i not found a way how to attach image.

Second artifact appear on ToolWindow Control. Almost whole tool window border looks good but on ToolWindow tabs the border looks blurry.

Tab Visual Articat

ToolWindow Tabs Artifact

Are these really visual artifacts or am I doing something wrong? Do you have any plans to fix them?

Thank you,


[Modified 3 years ago]

Comments (2)

Answer - Posted 3 years ago by Actipro Software Support - Cleveland, OH, USA

Hi Andrei,

Which DPI are you at?  When you use DPIs that aren't at proper pixel scale factors (like 150%), it can make lines not always anti-alias on the correct pixel, or sometimes not align exactly where you want.  This issue shouldn't generally show up at full scale factors (like 100%, 200%, 300%, etc.).

Our TabItemBorder control has a two-phase approach for rendering a tab.  It first renders the background, trying to offset the background by the border width.  We do that because when hovering over an unselected tool window tab, we want the background to show but the border for that tab is transparent, and we want the border of the parent tabstrip to show at the top of the tab (since tabs overlay the tabstrip by a pixel).  If we didn't offset the background by the border width, the hover tab's background would render on top of that tabstrip line.  The border (if non-transparent) for the tab is then rendered on top.

The downside of this seems to be in the non-full scale factors where the anti-aliasing of that background combined with the anti-aliasing of the border doesn't yield a solid transition, as in your first screenshot.

That being said, I believe we were able to find a way to improve the rendering of your first scenario to create a solid transition.  This update will be in the next maintenance release.

Actipro Software Support

Posted 3 years ago by Andrei Aliashkevich

Thanks for answer.

My display have 163 DPI. And you are right, I use 150% scale factor.

I am looking forward to updates.

The latest build of this product (v24.1.2) was released 2 months ago, which was after the last post in this thread.

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