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wm_copydata how to use it

Posted on 2002-03-23
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Last Modified: 2012-06-27
hi,

i was wondering what wm_copydata and copydatastruct does can anyone give me an example?

cheers
classic_gaming
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Question by:classic_gaming
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Expert Comment

by:robert_marquardt
ID: 6891000
Not an example at hand, but it is easy.
The whole data block is copead by Windows from the address space of the sending apllication to the address space of the receiving application.
So all data has to be in a single block of memory and you have to state the length of the data.
This means no Pascal strings among other things.
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Accepted Solution

by:
inthe earned 100 total points
ID: 6891012
hi,
you use WM_COPYDATA  to send data to another app,for
an example make 2 projects:

put a edit in the first and the following ( listener ) :


  public
    { Public declarations }
    procedure WMCopyData(var Msg: TWMCopyData); message WM_COPYDATA;
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.WMCopyData(var Msg: TWMCopyData);
begin
 Edit1.Text := PChar(Msg.CopyDataStruct^.lpData);
end;



in the second project ( the sender ) put a button and a edit and the following :

procedure TForm1.Button1Click(Sender: TObject);
var
 copydata: TCopyDataStruct;
begin
 with copydata do
  begin
   dwData := 0;
   cbData := Length(Edit1.Text) + 1;
   GetMem(lpData, cbData);
   StrCopy(lpData, PChar(Edit1.Text));
  end;
SendMessage(HWND_BROADCAST,WM_COPYDATA,WPARAM(Form1.Handle),LParam(@copydata));
 FreeMem(copydata.lpData);
end;



clicking the button on app2 will send the edits data to the edit on app 1.
hopefully that is of some use :)

Regards Barry
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Author Comment

by:classic_gaming
ID: 7211067
sorry i kept it so long forgot about it :)

cheers
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