Get Minimize, Maximize and Close button width of a Tform

[FabDev 6]

Hello,

 

I would like to show a  StayOnTop form on the left of the Minimize, Maximize and Close button (Top right of tittle bar) of a TForm.

 

To do it I need to compute width of these button, so I have tried this :

 

var

  TitleInfo       : TTitleBarInfo;

  NonClientWidth, ButtonWidth: Integer;


begin

        NonClientWidth := Width - ClientWidth;

         SendMessage(Handle, WM_GETTITLEBARINFOEX, 0,NativeInt(@TitleBarInfoEx));//   LPARAM(@TitleBarInfoEx));

         ButtonWidth := TitleBarInfoEx.rgrect[5].Right - TitleBarInfoEx.rgrect[2].Left + 2 * NonClientWidth - 2 * BorderWidth;

....

Following this :

https://learn.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-titlebarinfo

 

 

But  TitleBarInfoEx.rgrect[5].Right return me wrong value like not initialized :

 

So how to get it ?

 

 

 

Edited April 13, 2023 by FabDev

[dwrbudr 8]

Inspect Delphi's VCL.Forms.pas -> TTitleBar.GetCaptionButtonsRect -> DwmGetWindowAttribute

[Remy Lebeau 1260]

7 hours ago, FabDev said:

To do it I need to compute width of these button, so I have tried this :

...
But  TitleBarInfoEx.rgrect[5].Right return me wrong value like not initialized

Your code snippet is declaring a variable named TitleInfo, but you are sending WM_GETTITLEBARINFOEX with a pointer to a variable named TitleBarInfoEx instead. Also, make sure you initialize the TTitleBarInfo/Ex.cbSize member before sending WM_GETTITLEBARINFOEX.

 

https://learn.microsoft.com/en-us/windows/win32/menurc/wm-gettitlebarinfoex

Quote

lParam

A pointer to a TITLEBARINFOEX structure. The message sender is responsible for allocating memory for this structure. Set the cbSize member of this structure to sizeof(TITLEBARINFOEX) before passing this structure with the message.

https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-gettitlebarinfo

Quote

[in, out] pti

Type: PTITLEBARINFO

A pointer to a TITLEBARINFO structure to receive the information. Note that you must set the cbSize member to sizeof(TITLEBARINFO) before calling this function.

So, try this instead:

var
  TitleInfo : TTitleBarInfoEx;
  ...
begin
  ...
  TitleInfo.cbSize := SizeOf(TitleInfo); // <-- ADD THIS!
  SendMessage(Handle, WM_GETTITLEBARINFOEX, 0, LPARAM(@TitleInfo));
  ...
end;

 

[KodeZwerg 54]

Beside the WinAPI way, you could make your day easier by following the Vcl way of doing and playing with the Titlebar.

[FabDev 6]

5 hours ago, KodeZwerg said:

Beside the WinAPI way, you could make your day easier by following the Vcl way of doing and playing with the Titlebar.

Thank you that was a nice idea but I use DevExpress (Bar/Ribbon and Skin) which is not compatible with the native Titlebar.

[FabDev 6]

23 hours ago, Remy Lebeau said:

So, try this instead:

 

Thank you Remy it's work fine !