SendMessage with Linux
lazarus / 32-Linux

----------------------------------------------------------------------
Iniw · 2021-07-21 14:01

Hello,

with lazarus-2.0.12-fpc-3.2.0-win64, I can move a Form by clicking on
its background [and on its TControl]
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if Msg =
LM_MOUSEMOVE then    begin      ReleaseCapture();     
SendMessage(Self.Handle, LM_NCLButtonDown, HTCaption, 0);    end;The
same code in Linux has no effect [even if no compilation error
appears].
Is SenMessage inoperative on Linux or am I doing it wrong ?

Best regards. IW

----------------------------------------------------------------------
MarkMLl · 2021-07-21 16:20

The documentation suggests to me that it's not intended to work on any
OS other than Windows: are you absolutely certain that those message
numbers are portable?

MarkMLl

----------------------------------------------------------------------
Iniw · 2021-07-21 16:36

Hello,
i suspected it doesn't work with linux or mac os.  But I had not found
the documentation specifying it..
So I'll use the classic onMouseDown and co in a less elegant way.
Best regards. IW

----------------------------------------------------------------------
howardpc · 2021-07-21 17:07

I think on Linux the LM_NCLMouseButtonDown message is not interpreted 
by window managers in the same way as on Windows.
For cross-platform use you have to do some variation on this sort of
thing:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.ApplicationProperties1UserInput(Sender: TObject; Msg:
cardinal);var  pt: TPoint;begin  case Msg of    LM_LBUTTONDOWN: begin 
                    if not bPotentiallyMoving then                   
   bPotentiallyMoving := True;                      Cursor := crDrag; 
                  end;    LM_LBUTTONUP: begin                   
bPotentiallyMoving := False;                    Cursor := crDefault; 
               end;    LM_MOUSEMOVE: if bPotentiallyMoving then      
            begin                      pt :=
ScreenToClient(Mouse.CursorPos);                      Left :=
ClientOrigin.X + pt.X;                      Top := ClientOrigin.Y +
pt.Y;                    end;  end;end;

----------------------------------------------------------------------
MarkMLl · 2021-07-21 17:41

Quote from: IniWo on July 21, 2021, 06:36:42 pmHello,
i suspected it doesn't work with linux or mac os.  But I had not found
the documentation specifying it..
So I'll use the classic onMouseDown and co in a less elegant way.
Best regards. IW

Out of curiosity: you've said it doesn't work but is that code
successfully executed (i.e. if you put a debugger on that
SendMessage())?

The documentation is phrased as though it's intended to be used if
you're recompiling something which works on Delphi on the same
platform. I am by no means an LCL expert, and responded primarily to
make sure your question remained visible in the "Recent" list...
grepping the sources it looks as though LM_NCLBUTTONDOWN is defined
but literally never used.

OTOH LM_MOUSEMOVE appears in the code for all the widget sets.

MarkMLl