----- Original Message -----
From: Ross Levis
To: Multiple recipients of list delphi
Sent: Saturday, July 26, 2003 8:53 AM
Subject: [DUG]: windows class name
>I want to tell from a D5 app if another D5 app is currently running. Is
the class name the same as >the main forms Name or is this set somewhere
else?
>
>Thanks,
>Ross.
You can modify this example, which doesn't allow multiple copies of your
program to run:
// Making only one instance of the application
// and sending ParamStr parameters from second instance to the first
// before closing the second instance.
// This is declaration of main form of the project.
// The name of form class must be unique. "TForm1" or "TfrmMain" is
// not very apropriate because you will find the form by it's class name.
interface
type
TfrmYourApplicationMainForm = class(TForm)
MainMenu1: TMainMenu;
File1: TMenuItem;
// .........
// .... etc...
procedure FormShow(Sender: TObject); // OnShow event.
private
{ Private declarations }
// .........
// .... etc...
// Insert this in private section.
procedure WMCopyData(var msg:TWMCopyData); message WM_COPYDATA;
public
{ Public declarations }
// .........
// .... etc...
end;
implementation
procedure TfrmYourApplicationMainForm.WMCopyData(var msg: TWMCopyData);
var i,imax:integer;
s:string;
begin
// Here I am using 2 string manipulating functions from
// unit StrUtils of the RxLib library:
// WordCount and ExtractWord.
// If you don't use this excelent library, you may use the source of this
// functions from the end of this file.
s := PChar(msg.CopyDataStruct.lpData);
imax := WordCount(s,[#$0d]);
Application.BringToFront;
for i:= 1 to imax do
// You can use some your function here...
OpenNewWindow(ShortToLongPath(ExtractWord(i,s,[#$0d])));
end;
// This is processing of the parameters when the first instance opens.
// Assign to the OnShow event of the main form...
procedure TfrmYourApplicationMainForm.FormShow(Sender: TObject);
var i:integer;
begin
for i:=1 to ParamCount do
// You can use some your function here...
OpenNewWindow(ShortToLongPath(ParamStr(i)));
end;
end.
// The following text is from .dpr file of the application:
uses
Windows, messages;
var handle: THandle;
cds: TCopyDataStruct;
fMutex: THandle;
s:string;
i:integer;
begin
// This is check for opened instance of the application.
// The mutex name must be specific for this application.
fMutex := CreateMutex(nil,false,'YourMutexName'); // <-- change mutex
name.
if ( GetLastError() = ERROR_ALREADY_EXISTS ) or
( WaitForSingleObject(fMutex,100) = WAIT_TIMEOUT ) or
( fMutex = 0 ) then
begin
// Another instance opened;
// Find main window handle...
handle := FindWindow('TfrmYourApplicationMainForm',nil); // <-- Use
the class name of your main form.
// If found send ParamStr.
if handle <> 0 then
begin
// Making one string from all Params.
s := '';
for i:= 1 to ParamCount do
s:=s+ParamStr(i)+#$0d;
with cds do
begin
dwData := 0;
cbData := length(s);
lpData := PChar(s);
end;
// Sending parameters to the other instance of the application.
SendMessage(handle,WM_COPYDATA,Application.Handle,integer(@cds));
exit;
end;
end;
// This is Delphi generated source...
Application.Initialize;
Application.HelpFile := '';
Application.CreateForm(TfrmYourApplicationMainForm,
frmYourApplicationMainForm);
Application.Run;
end.
// OPTIONAL... ;-)
// Here is 3 functions from unit StrUtils of RxLib library.
// if you don't use this library, you must include this functions
// somewhere in your source.
// If you have installed RxLib, simply include "uses StrUtils" in your
// main form of the project.
type
TSysCharSet = set of Char;
function WordCount(const S: string; const WordDelims: TSysCharSet): Integer;
var
SLen, I: Cardinal;
begin
Result := 0;
I := 1;
SLen := Length(S);
while I <= SLen do begin
while (I <= SLen) and (S[I] in WordDelims) do Inc(I);
if I <= SLen then Inc(Result);
while (I <= SLen) and not(S[I] in WordDelims) do Inc(I);
end;
end;
function WordPosition(const N: Integer; const S: string;
const WordDelims: TCharSet): Integer;
var
Count, I: Integer;
begin
Count := 0;
I := 1;
Result := 0;
while (I <= Length(S)) and (Count <> N) do begin
{ skip over delimiters }
while (I <= Length(S)) and (S[I] in WordDelims) do Inc(I);
{ if we're not beyond end of S, we're at the start of a word }
if I <= Length(S) then Inc(Count);
{ if not finished, find the end of the current word }
if Count <> N then
while (I <= Length(S)) and not (S[I] in WordDelims) do Inc(I)
else Result := I;
end;
end;
function ExtractWord(N: Integer; const S: string; const WordDelims:
TSysCharSet): string;
var
I: Integer;
Len: Integer;
begin
Len := 0;
I := WordPosition(N, S, WordDelims);
if I <> 0 then
{ find the end of the current word }
while (I <= Length(S)) and not(S[I] in WordDelims) do begin
{ add the I'th character to result }
Inc(Len);
SetLength(Result, Len);
Result[Len] := S[I];
Inc(I);
end;
SetLength(Result, Len);
end;
Cheers,
Nicholas Sherlock
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