Title: How to communicate between applications
// 1. Define type of your message structure, it could be something like this:
type
TWMMYMessage = record
Msg: Cardinal; // ( first is the message ID )
Handle: HWND; // ( this is the wParam, Handle of sender)
Info: Longint; // ( this is lParam, pointer to our data)
Result: Longint;
end;
// 2. Override your form's DefaultHandler method and add
// method for handling your message, like this
TForm1 = class(TForm)
...public
{ Public declarations }
...procedure DefaultHandler(var Message); override;
procedure WMMYMessage(var Msg: TWMMYMessage);
...end;
// 3. Declare message variable:
var
WM_OURMESSAGE: DWORD;
// 4. Insert realisation of DefaultHandler and our message handler methods:
procedure TForm1.DefaultHandler(var Message);
var
ee: TWMMYMessage;
begin
with TMessage(Message) do
begin
if (Msg = WM_OURMESSAGE) then
begin
ee.Msg := Msg;
ee.Handle := wParam;
ee.Info := lParam;
// Checking if this message is not from us
if ee.Handle Handle then
WMMYMessage(ee);
end
else
inherited DefaultHandler(Message);
end;
end;
procedure TForm1.WMMYMessage(var Msg: TWMMYMessage);
begin
label1.Caption := Format('Our another form handle :%d', [Msg.Handle]);
Label2.Caption := Format('Our another form top :%d', [Msg.Info]);
end;
// 5. Add registration of your message that you could
// 5. Die Message registrieren.
initialization
WM_OURMESSAGE := RegisterWindowMessage('Our broadcast message');
// 6. Add the message sending somewhere:
procedure TForm1.Button1Click(Sender: TObject);
begin
SendMessage(HWND_BROADCAST, WM_OURMESSAGE, Handle, Top);
end;
// 7. Compile and run two copies of your application and test it functionality.