Trap WM_COPYDATA from component.

[Gome206]

Hi!

I'm trying to write a component, to send string messages between applications by WM_COPYDATA.
I'd like trap the WM_COPYDATA, but isn't work like this:


TMyMessage = class(TComponent)
private
{ Private declarations }
…
protected
{ Protected declarations }
…
procedure WMCopyData(var Msg : TMessage); message WM_COPYDATA;
…
end;

Searching Google a lot, found some reference using wndproc. I tried it, but isn't working too.

TMyMessage = class(TComponent)
…
protected
{ Protected declarations }
…
procedure WMCopyData(var Msg : TMessage); message WM_COPYDATA;
procedure WndProc(var Msg: TMessage);
…
end;
…
procedure TMyMessage.WndProc(var Msg: TMessage);
var
p: PCopyDataStruct;
begin
//inherited;
if Msg.Msg = WM_COPYDATA then
WMCopyData(Msg);
end;

Please help, what is wrong?

Göme206

[lexdean]

thier is a project on torry pages on your subject
except windows is not good at handling delphi objects

Lex Dean

[Kambiz]

Do not override WndProc. Delphi automatically calls WMCopyData, it doesn't need to be called manually inside the WndProc.

[lexdean]

I made my self such a Component
its has a server /terminal arrangement.
The component removes most the code from the form's code.

It transports a ID integer and a reference with ether:-
a string and integer for data
or a stream and transport pictures between programs

The ID integer is to remove broadcast copy messages from being received

I have made a execute and wait for the EXE to be installed

It’s on Tory pages.

[arhangelsoft]

WM_ messages could be handled only by windows.
Your component need to create a window and organize message cycle for it and fork with it.

See my example:

Code: Select all

uses windows, messages;

var   
  wndClass: TWndClassEx;
  wndMain: HWND;
  wndMC: TMsg; //Message for my windows messages cycle


//Message handler
function WindowProc(wnd:HWND; Msg : Integer; Wparam:Wparam; Lparam:Lparam):Lresult;
 stdcall;
Begin

case msg of
wm_destroy :
  Begin
   PostQuitMessage(0); Exit;
   Result:=0;
  End;

  else Result:=DefWindowProc(wnd,msg,wparam,lparam);
end;

End;

var xPos,yPos,nWidth,nHeight : Integer;

begin
wndClass.cbSize:=sizeof(TWndClassEx);
wndClass.style:=cs_hredraw or cs_vredraw;
wndClass.lpfnWndProc:=@WindowProc;
wndClass.cbClsExtra:=0;
wndClass.cbWndExtra:=0;
wndClass.hInstance:=HInstance;
wndClass.hIcon:=LoadIcon(0,idi_application);
wndClass.hCursor:=LoadCursor(0,idc_arrow);
wndClass.hbrBackground:=COLOR_BTNFACE+1;
wndClass.lpszMenuName:=nil;
wndClass.lpszClassName:='TMP: Window';

RegisterClassEx(wndClass);


xPos:=100;
yPos:=150;
nWidth:=400;
nHeight:=250;


wndMain:=CreateWindowEx(0,'TMP: Window','Window',ws_overlappedwindow,xPos,yPos,nWidth,nHeight,0, 0,Hinstance,nil);
ShowWindow(MwndMain,CmdShow);

//message cycle
While GetMessage(wndMC,0,0,0) do
begin
  TranslateMessage(wndMC);
  DispatchMessage(wndMC);
end;

end.


Only what is need.
Description of used functions you can found on MSDN WinAPI reference

Why you don't use Memory Mapped Files? Window doesn't need it.

[lexdean]

go to about.com WM_COPYDATA
and start from scrach

[dejavu.cucud]

simply, you can use SendMessage to send string into any destination window (on same application or different application). fill the wParam with any TEdit.Handle or another Text Control's handle.

const
{ User-defined message }
WM_EXCHANGE_TEXT = WM_USER + 2;

SendMessage(hWndDestination, Edit1.Handle, 0);

on the destination window, create a custom message method to catch the message. use GetWindowText() function, and fill HWND/handle parameter with wParam.

private
procedure ExchangeText(var Msg: TMessage); message WM_EXCHANGE_TEXT;

procedure TFormDest.ExchangeText(var Msg: TMessage);
var data: PChar;
begin
GetMem(data, 1024);
GetWindowText(Msg.wParam, data, 1024);
ShowMessage(StrPas(data));
FreeMem(data);
end;