Mega Code Archive
One application instance
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Title: One application instance
Question: It is possible to work with only one instance of your applications?
Take a loock to this source code, and try it
IT WORKS.
Answer:
var
MH,
Hwnd2 : THandle;
implementation
{$R *.DFM}
function ReadAppHandle : Integer;
begin
Result := 0;
with TRegistry.Create do
begin
RootKey := HKEY_LOCAL_MACHINE;
if OpenKey('APP_INSTANCES\' + Application.Title, True) then
Result := ReadInteger('HandleID');
CloseKey;
end;
end;
procedure WriteAppHandle;
begin
with TRegistry.Create do
begin
RootKey := HKEY_LOCAL_MACHINE;
if OpenKey('APP_INSTANCES\' + Application.Title, True) then
WriteInteger('HandleID',Application.Handle);
CloseKey;
end;
end;
Initialization
// Create the mutex
MH := CreateMutex(nil, false, PChar(Application.Title));
if (MH NULL) and (GetLastError = ERROR_ALREADY_EXISTS) then
begin
//read handle from reg.
Hwnd2 := ReadAppHandle;
if (IsIconic(Hwnd2)) then
begin
ShowWindow(Hwnd2,SW_RESTORE);
Halt;
end
else
begin
SetForeGroundWindow(Hwnd2);
BringWindowToTop(Hwnd2);
Halt;
end;
end
else
WriteAppHandle;
end.
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