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unit AppInstanceMgmt;
interface
uses Windows, SysUtils, Forms, TntMenus, Classes;
type
PAppInstanceInfo = ^TAppInstanceInfo;
TAppInstanceInfo = packed record
AppHandle: THandle;
ConnectionString: Array [0 .. 100] of Char;
ApplicationCaption: Array [0 .. 100] of Char;
end;
PAppInstances = ^TAppInstances;
TAppInstances = packed record
InstanceCount: Integer;
Instances: Array [0..100] of TAppInstanceInfo;
end;
TDataMenuItem = class(TTntMenuItem)
constructor Create(AOwner: TComponent; AppHandle: THandle); reintroduce;
private
FAppHandle: THandle;
public
procedure Click; reintroduce; override;
property AppHandle: THandle read FAppHandle;
end;
function RegisterApplication(App: TApplication; ConnectionString: WideString;
AllowOnlyOneInstance: Boolean = False): Boolean;
procedure UnregisterApplication(App: TApplication);
procedure BuildRegisterApplicationMenuItems(MenuItem: TTntMenuItem);
//----------------------------------------------------------------------------------------------------------------------
implementation
uses
AuxFuncs, gnugettext;
var
MappingHandle: THandle; // Central handle for file mapping used for instance management.
//----------------------------------------------------------------------------------------------------------------------
constructor TDataMenuItem.Create(AOwner: TComponent; AppHandle: THandle);
begin
inherited Create(AOwner);
FAppHandle := AppHandle;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure TDataMenuItem.Click;
begin
inherited;
if (IsIconic(FAppHandle)) then
ShowWindow(FAppHandle, SW_RESTORE);
SetForegroundWindow(FAppHandle);
end;
//----------------------------------------------------------------------------------------------------------------------
function RegisterApplication(App: TApplication; ConnectionString: WideString; AllowOnlyOneInstance: Boolean): Boolean;
var
AppInstances: PAppInstances;
S: string;
I: Integer;
LastError: Cardinal;
begin
Result := True;
if MappingHandle = 0 then
begin
MappingHandle := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, SizeOf(TAppInstances),
'MySQLGuiInstanceManagement');
if MappingHandle = 0 then
begin
LastError := GetLastError;
// An access denied error appears if the file mapping was already created but under a differen user account.
// In this case can continue but don't have the running applications list in the menu (which is not
// a really severe limitation).
if LastError <> ERROR_ACCESS_DENIED then
RaiseLastOSError;
end;
end;
if MappingHandle <> 0 then
begin
LastError := GetLastError;
AppInstances := MapViewOfFile(MappingHandle, FILE_MAP_ALL_ACCESS, 0, 0, SizeOf(TAppInstances));
if Assigned(AppInstances) then
begin
if LastError <> ERROR_ALREADY_EXISTS then
AppInstances.InstanceCount := 1
else //already runing
begin
if AllowOnlyOneInstance then
begin
for I := 0 to AppInstances.InstanceCount - 1 do
if (WideSameText(UTF8Decode(AppInstances^.Instances[I].ApplicationCaption), App.Title)) then
begin
if (IsIconic(AppInstances.Instances[I].AppHandle)) then
ShowWindow(AppInstances.Instances[I].AppHandle, SW_RESTORE);
SetForegroundWindow(AppInstances^.Instances[I].AppHandle);
Result := False;
Exit;
end;
end;
Inc(AppInstances.InstanceCount);
end;
AppInstances.Instances[AppInstances.InstanceCount - 1].AppHandle := App.Handle;
S := UTF8Encode(App.Title);
// Add one char to overall length (to write the terminating #0).
StrMove(AppInstances.Instances[AppInstances.InstanceCount - 1].ApplicationCaption, PChar(S), Length(S) + 1);
AppInstances.Instances[AppInstances.InstanceCount - 1].ConnectionString[0] := #0;
S := UTF8Encode(ConnectionString);
StrMove(AppInstances^.Instances[AppInstances.InstanceCount - 1].ConnectionString, PChar(S), Length(S) + 1);
UnmapViewOfFile(AppInstances);
end;
end
end;
//----------------------------------------------------------------------------------------------------------------------
procedure UnregisterApplication(App: TApplication);
var
AppInstances: PAppInstances;
I: Integer;
J: Integer;
begin
if MappingHandle <> 0 then
begin
AppInstances := MapViewOfFile(MappingHandle, FILE_MAP_ALL_ACCESS, 0, 0, SizeOf(TAppInstances));
// Find current application.
for I := 0 to AppInstances.InstanceCount - 1 do
if (AppInstances.Instances[I].AppHandle = App.Handle) then
begin
// Move down all other instances.
for J := AppInstances.InstanceCount - 1 downto I + 1 do
AppInstances.Instances[J - 1] := AppInstances.Instances[J];
break;
end;
Dec(AppInstances.InstanceCount);
UnmapViewOfFile(AppInstances);
end;
end;
//----------------------------------------------------------------------------------------------------------------------
procedure BuildRegisterApplicationMenuItems(MenuItem: TTntMenuItem);
var
I: Integer;
AppInstances: PAppInstances;
AppMenuItem: TTntMenuItem;
LastCount: Integer;
begin
// In order to keep the menu operating we must first add the new items then delete the old ones .
// If we not keep at least one item then the new subitems will never show. Strange bug IMO.
LastCount := MenuItem.Count;
if MappingHandle <> 0 then
begin
AppInstances := MapViewOfFile(MappingHandle, FILE_MAP_ALL_ACCESS, 0, 0, SizeOf(TAppInstances));
// Find current application.
for I := 0 to AppInstances.InstanceCount - 1 do
begin
AppMenuItem := TDataMenuItem.Create(MenuItem.Owner, AppInstances.Instances[I].AppHandle);
AppMenuItem.Caption := UTF8Decode(AppInstances.Instances[I].ApplicationCaption);
if AppInstances.Instances[I].ConnectionString <> '' then
AppMenuItem.Caption := AppMenuItem.Caption + ' - ' + UTF8Decode(AppInstances.Instances[I].ConnectionString);
AppMenuItem.OnAdvancedDrawItem := MenuItem.OnAdvancedDrawItem;
AppMenuItem.OnMeasureItem := MenuItem.OnMeasureItem;
MenuItem.Add(AppMenuItem);
end;
MenuItem.Enabled := True;
UnmapViewOfFile(AppInstances);
end;
for I := 0 to LastCount - 1 do
MenuItem.Delete(0);
end;
//----------------------------------------------------------------------------------------------------------------------
initialization
finalization
if MappingHandle <> 0 then
CloseHandle(MappingHandle);
end.
|
