[Lazarus] How to hide pop-up menu before taking a screen snapshot?

[Andrey Sobol]

Try to call

Application.ProcessMessages();
after disable a popup menu.

Andrey.

On 07.02.2021 17:09, Bo Berglund via lazarus wrote:
> On Sun, 7 Feb 2021 14:01:46 +0000, Denis Kozlov via lazarus
> <lazarus at lists.lazarus-ide.org> wrote:
> 
>>
>> I had a similar experience with taking a screenshot programmatically.
>> Simply waiting or processing application messages after hiding the form
>> often doesn't help, and results in a form being a part of the screenshot
>> anyway.
>>
>> I managed to work around it by forcing Windows to repaint everything on
>> the desktop by broadcasting WM_PAINT message, like so:
>>
>> SendMessageTimeout(HWND_BROADCAST, WM_PAINT, 0, 0, SMTO_ABORTIFHUNG,
>> 1000, MsgResult);
>>
>> You might also need to disable transition effects (fade-in and fade-out)
>> by setting the DWMWA_TRANSITIONS_FORCEDISABLED flag on the form before
>> hiding it, and then unsetting it when showing the form again.
>>
>> DwmSetWindowAttribute(AForm.Handle, DWMWA_TRANSITIONS_FORCEDISABLED,
>> @dwAttribute, SizeOf(dwAttribute));
>>
>> Good luck,
>> Denis
> 
> Thanks for the suggestion!
> 
> It turned out that (from a suggestion on the Lazarus forum) I could use a
> sleep(300) right before the call to the CopyScreenRect() instead of the other
> failed tests.
> 
> Apparently the menu item is subject to Windows "animation" when it is closed...
> 
> So this is now the code and it does work:
> 
> procedure TfrmMain.miCopyImageClick(Sender : TObject);
> begin
>    Sleep(300);
>    CopyScreenRect;
> end;
> 
> procedure TfrmMain.CopyScreenRect;
> var
>    MyCapture : TBgraBitmap;
>    Clip: TRect;
> begin
>    try
>      Clip := Bounds(Self.Left, Self.Top, Self.Width, Self.Height);
>      Self.Visible := false; //To remove the capture frame from image
>      MyCapture := TBgraBitmap.Create();
>      try
>        MyCapture.TakeScreenShot(Clip);
>        Self.Visible := true;
>        Clipboard.Assign(MyCapture.Bitmap);
>      finally
>        MyCapture.Free;
>      end;
>    except
>      on E: exception do
>        Clipboard.AsText := E.Message;
>    end;
> end;
> 
> I tried various values for the sleep time and settled for 300, 200 does not
> quite fix it - a faded shadow image still remains.
> 
> 


-- 
Andrey