VCL Styles Flickering

[balabuev 102]

Do I understand correctly that a control, which is not a TWinControl (for example, TLabel), has no way to implement flicker free drawing with VCL Styles turned on?

 

It seems that the parent form erases its own background via TFormStyleHook.PaintBackground not excluding child controls. This happens in both: Form.DoubleBuffered = False and Form.DoubleBuffered = True modes.

[David Hoyle 68]

What version of RAD Studio/Delphi are you using?

[aehimself 396]

On 3/29/2023 at 9:59 AM, balabuev said:

Do I understand correctly that a control, which is not a TWinControl (for example, TLabel), has no way to implement flicker free drawing with VCL Styles turned on?

 

It seems that the parent form erases its own background via TFormStyleHook.PaintBackground not excluding child controls. This happens in both: Form.DoubleBuffered = False and Form.DoubleBuffered = True modes.

I had extreme flickering of controls which were placed on TPanels. The solution was to enable ParentBackground of the TPanel when the current is the system style, otherwise set it to false.

Flickering gone down with a huge margin.

[Vincent Parrett 750]

This is a known issue with VCL Styles, there are several threads here where this is discussed. It's gotten slightly better with 11.x but still an issue with some controls. 

 

 

See also - https://quality.embarcadero.com/browse/RSP-30639

 

Edited March 31, 2023 by Vincent Parrett
Added bug report link