trunk/runtime/IBEvents.pas

{************************************************************************}
{                                                                        }
{       Borland Delphi Visual Component Library                          }
{       InterBase Express core components                                }
{                                                                        }
{       Copyright (c) 1998-2000 Inprise Corporation                      }
{                                                                        }
{    InterBase Express is based in part on the product                   }
{    Free IB Components, written by Gregory H. Deatz for                 }
{    Hoagland, Longo, Moran, Dunst & Doukas Company.                     }
{    Free IB Components is used under license.                           }
{                                                                        }
{    The contents of this file are subject to the InterBase              }
{    Public License Version 1.0 (the "License"); you may not             }
{    use this file except in compliance with the License. You            }
{    may obtain a copy of the License at http://www.Inprise.com/IPL.html }
{    Software distributed under the License is distributed on            }
{    an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either              }
{    express or implied. See the License for the specific language       }
{    governing rights and limitations under the License.                 }
{    The Original Code was created by InterBase Software Corporation     }
{       and its successors.                                              }
{    Portions created by Inprise Corporation are Copyright (C) Inprise   }
{       Corporation. All Rights Reserved.                                }
{    Contributor(s): Jeff Overcash                                       }
{                                                                        }
{************************************************************************}

unit IBEvents;

interface

uses
  SysUtils, Windows, Messages, Classes, Graphics, Controls,
  Forms, Dialogs, DB, IBHeader, IBExternals, IB, IBDatabase;

const
  MaxEvents = 15;
  EventLength = 64;

type

  TEventAlert = procedure( Sender: TObject; EventName: string; EventCount: longint;
                           var CancelAlerts: Boolean) of object;

  TEventBuffer = array[ 0..MaxEvents-1, 0..EventLength-1] of char;

  TIBEvents = class(TComponent)
  private
    FIBLoaded: Boolean;
    FEvents: TStrings;
    FOnEventAlert: TEventAlert;
    FQueued: Boolean;
    FRegistered: Boolean;
    Buffer: TEventBuffer;
    Changing: Boolean;
    CS: TRTLCriticalSection;
    EventBuffer: PChar;
    EventBufferLen: integer;
    EventID: ISC_LONG;
    ProcessingEvents: Boolean;
    RegisteredState: Boolean;
    ResultBuffer: PChar;
    FDatabase: TIBDatabase;
    procedure SetDatabase( value: TIBDatabase);
    procedure ValidateDatabase( Database: TIBDatabase);
    procedure DoQueueEvents;
    procedure EventChange( sender: TObject);
    procedure UpdateResultBuffer( length: short; updated: PChar);
  protected
    procedure HandleEvent;
    procedure Loaded; override;
    procedure Notification( AComponent: TComponent; Operation: TOperation); override;
    procedure SetEvents( value: TStrings);
    procedure SetRegistered( value: boolean);
    function  GetNativeHandle: TISC_DB_HANDLE;

  public
    constructor Create( AOwner: TComponent); override;
    destructor Destroy; override;
    procedure CancelEvents;
    procedure QueueEvents;
    procedure RegisterEvents;
    procedure UnRegisterEvents;
    property  Queued: Boolean read FQueued;
  published
    property  Database: TIBDatabase read FDatabase write SetDatabase;
    property Events: TStrings read FEvents write SetEvents;
    property Registered: Boolean read FRegistered write SetRegistered;
    property OnEventAlert: TEventAlert read FOnEventAlert write FOnEventAlert;
  end;

implementation

uses
  IBIntf;

function TIBEvents.GetNativeHandle: TISC_DB_HANDLE;
begin
  if assigned( FDatabase) and FDatabase.Connected then
    Result := FDatabase.Handle
  else result := nil;
end;

procedure TIBEvents.ValidateDatabase( Database: TIBDatabase);
begin
  if not assigned( Database) then
    IBError(ibxeDatabaseNameMissing, [nil]);
  if not Database.Connected then
    IBError(ibxeDatabaseClosed, [nil]);
end;

{ TIBEvents }

procedure HandleEvent( param: integer); stdcall;
begin
  { don't let exceptions propogate out of thread }
  try
    TIBEvents( param).HandleEvent;
  except
    Application.HandleException( nil);
  end;
end;

procedure IBEventCallback( ptr: pointer; length: short; updated: PChar); cdecl;
var
  ThreadID: DWORD;
begin
  { Handle events asynchronously in second thread }
  EnterCriticalSection( TIBEvents( ptr).CS);
  TIBEvents( ptr).UpdateResultBuffer( length, updated);
  if TIBEvents( ptr).Queued then
    CloseHandle( CreateThread( nil, 8192, @HandleEvent, ptr, 0, ThreadID));
  LeaveCriticalSection( TIBEvents( ptr).CS);
end;

constructor TIBEvents.Create( AOwner: TComponent);
begin
  inherited Create( AOwner);
  FIBLoaded := False;
  CheckIBLoaded;
  FIBLoaded := True;
  InitializeCriticalSection( CS);
  FEvents := TStringList.Create;
  with TStringList( FEvents) do
  begin
    OnChange := EventChange;
    Duplicates := dupIgnore;
  end;
end;

destructor TIBEvents.Destroy;
begin
  if FIBLoaded then
  begin
    UnregisterEvents;
    SetDatabase( nil);
    TStringList(FEvents).OnChange := nil;
    FEvents.Free;
    DeleteCriticalSection( CS);
  end;
  inherited Destroy;
end;

procedure TIBEvents.CancelEvents;
begin
  if ProcessingEvents then
    IBError(ibxeInvalidCancellation, [nil]);  
  if FQueued then
  begin
    try
      { wait for event handler to finish before cancelling events }
      EnterCriticalSection( CS);
      ValidateDatabase( Database);
      FQueued := false;
      Changing := true;
      if (isc_Cancel_events( StatusVector, @FDatabase.Handle, @EventID) > 0) then
        IBDatabaseError;
    finally
      LeaveCriticalSection( CS);
    end;
  end;
end;

procedure TIBEvents.DoQueueEvents;
var
  callback: pointer;
begin
  ValidateDatabase( DataBase);
  callback := @IBEventCallback;
  if (isc_que_events( StatusVector, @FDatabase.Handle, @EventID, EventBufferLen,
                     EventBuffer, TISC_CALLBACK(callback), PVoid(Self)) > 0) then
    IBDatabaseError;
  FQueued := true;
end;

procedure TIBEvents.EventChange( sender: TObject);
begin
  { check for blank event }
  if TStringList(Events).IndexOf( '') <> -1 then
    IBError(ibxeInvalidEvent, [nil]);
  { check for too many events }
  if Events.Count > MaxEvents then
  begin
    TStringList(Events).OnChange := nil;
    Events.Delete( MaxEvents);
    TStringList(Events).OnChange := EventChange;
    IBError(ibxeMaximumEvents, [nil]);
  end;
  if Registered then RegisterEvents;
end;

procedure TIBEvents.HandleEvent;
var
  Status: PStatusVector;
  CancelAlerts: Boolean;
  i: integer;
begin
  try
    { prevent modification of vital data structures while handling events }
    EnterCriticalSection( CS);
    ProcessingEvents := true;
    isc_event_counts( StatusVector, EventBufferLen, EventBuffer, ResultBuffer);
    CancelAlerts := false;
    if assigned(FOnEventAlert) and not Changing then
    begin
      for i := 0 to Events.Count-1 do
      begin
        try
        Status := StatusVectorArray;
        if (Status[i] <> 0) and not CancelAlerts then
            FOnEventAlert( self, Events[Events.Count-i-1], Status[i], CancelAlerts);
        except
          Application.HandleException( nil);
        end;
      end;
    end;
    Changing := false;
    if not CancelAlerts and FQueued then DoQueueEvents;
  finally
    ProcessingEvents := false;
    LeaveCriticalSection( CS);
  end;
end;

procedure TIBEvents.Loaded;
begin
  inherited Loaded;
  try
    if RegisteredState then RegisterEvents;
  except
    if csDesigning in ComponentState then
      Application.HandleException( self)
    else raise;
  end;
end;

procedure TIBEvents.Notification( AComponent: TComponent;
                                        Operation: TOperation);
begin
  inherited Notification( AComponent, Operation);
  if (Operation = opRemove) and (AComponent = FDatabase) then
  begin
    UnregisterEvents;
    FDatabase := nil;
  end;
end;

procedure TIBEvents.QueueEvents;
begin
  if not FRegistered then
    IBError(ibxeNoEventsRegistered, [nil]);
  if ProcessingEvents then
    IBError(ibxeInvalidQueueing, [nil]);
  if not FQueued then
  begin
    try
      { wait until current event handler is finished before queuing events }
      EnterCriticalSection( CS);
      DoQueueEvents;
      Changing := true;
    finally
      LeaveCriticalSection( CS);
    end;
  end;
end;

procedure TIBEvents.RegisterEvents;
var
  i: integer;
  bufptr: pointer;
  eventbufptr: pointer;
  resultbufptr: pointer;
  buflen: integer;
begin
  ValidateDatabase( Database);
  if csDesigning in ComponentState then FRegistered := true
  else begin
    UnregisterEvents;
    if Events.Count = 0 then exit;
    for i := 0 to Events.Count-1 do
      StrPCopy( @Buffer[i][0], Events[i]);
    i := Events.Count;
    bufptr := @buffer[0];
    eventbufptr :=  @EventBuffer;
    resultBufPtr := @ResultBuffer;
    asm
      mov ecx, dword ptr [i]
      mov eax, dword ptr [bufptr]
      @@1:
      push eax
      add  eax, EventLength
      loop @@1
      push dword ptr [i]
      push dword ptr [resultBufPtr]
      push dword ptr [eventBufPtr]
      call [isc_event_block]
      mov  dword ptr [bufLen], eax
      mov eax, dword ptr [i]
      shl eax, 2
      add eax, 12
      add esp, eax
    end;
    EventBufferlen := Buflen;
    FRegistered := true;
    QueueEvents;
  end;
end;

procedure TIBEvents.SetEvents( value: TStrings);
begin
  FEvents.Assign( value);
end;

procedure TIBEvents.SetDatabase( value: TIBDatabase);
begin
  if value <> FDatabase then
  begin
    UnregisterEvents;
    if assigned( value) and value.Connected then ValidateDatabase( value);
    FDatabase := value;
  end;
end;

procedure TIBEvents.SetRegistered( value: Boolean);
begin
  if (csReading in ComponentState) then
    RegisteredState := value
  else if FRegistered <> value then
    if value then RegisterEvents else UnregisterEvents;
end;

procedure TIBEvents.UnregisterEvents;
begin
  if ProcessingEvents then
    IBError(ibxeInvalidRegistration, [nil]);
  if csDesigning in ComponentState then
    FRegistered := false
  else if not (csLoading in ComponentState) then
  begin
    CancelEvents;
    if FRegistered then
    begin
      isc_free( EventBuffer);
      EventBuffer := nil;
      isc_free( ResultBuffer);
      ResultBuffer := nil;
    end;
    FRegistered := false;
  end;
end;

procedure TIBEvents.UpdateResultBuffer( length: short; updated: PChar);
var
  i: integer;
begin
  for i := 0 to length-1 do
    ResultBuffer[i] := updated[i];
end;

end.
Revision:	1
Committed:	Mon Jul 31 16:43:00 2000 UTC (24 years, 4 months ago) by tony
Content type:	text/x-pascal
File size:	10947 byte(s)
Log Message:	Borland IBX Open Source Release
#	Content
1	{************************************************************************}
2	{ }
3	{ Borland Delphi Visual Component Library }
4	{ InterBase Express core components }
5	{ }
6	{ Copyright (c) 1998-2000 Inprise Corporation }
7	{ }
8	{ InterBase Express is based in part on the product }
9	{ Free IB Components, written by Gregory H. Deatz for }
10	{ Hoagland, Longo, Moran, Dunst & Doukas Company. }
11	{ Free IB Components is used under license. }
12	{ }
13	{ The contents of this file are subject to the InterBase }
14	{ Public License Version 1.0 (the "License"); you may not }
15	{ use this file except in compliance with the License. You }
16	{ may obtain a copy of the License at http://www.Inprise.com/IPL.html }
17	{ Software distributed under the License is distributed on }
18	{ an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either }
19	{ express or implied. See the License for the specific language }
20	{ governing rights and limitations under the License. }
21	{ The Original Code was created by InterBase Software Corporation }
22	{ and its successors. }
23	{ Portions created by Inprise Corporation are Copyright (C) Inprise }
24	{ Corporation. All Rights Reserved. }
25	{ Contributor(s): Jeff Overcash }
26	{ }
27	{************************************************************************}
28
29	unit IBEvents;
30
31	interface
32
33	uses
34	SysUtils, Windows, Messages, Classes, Graphics, Controls,
35	Forms, Dialogs, DB, IBHeader, IBExternals, IB, IBDatabase;
36
37	const
38	MaxEvents = 15;
39	EventLength = 64;
40
41	type
42
43	TEventAlert = procedure( Sender: TObject; EventName: string; EventCount: longint;
44	var CancelAlerts: Boolean) of object;
45
46	TEventBuffer = array[ 0..MaxEvents-1, 0..EventLength-1] of char;
47
48	TIBEvents = class(TComponent)
49	private
50	FIBLoaded: Boolean;
51	FEvents: TStrings;
52	FOnEventAlert: TEventAlert;
53	FQueued: Boolean;
54	FRegistered: Boolean;
55	Buffer: TEventBuffer;
56	Changing: Boolean;
57	CS: TRTLCriticalSection;
58	EventBuffer: PChar;
59	EventBufferLen: integer;
60	EventID: ISC_LONG;
61	ProcessingEvents: Boolean;
62	RegisteredState: Boolean;
63	ResultBuffer: PChar;
64	FDatabase: TIBDatabase;
65	procedure SetDatabase( value: TIBDatabase);
66	procedure ValidateDatabase( Database: TIBDatabase);
67	procedure DoQueueEvents;
68	procedure EventChange( sender: TObject);
69	procedure UpdateResultBuffer( length: short; updated: PChar);
70	protected
71	procedure HandleEvent;
72	procedure Loaded; override;
73	procedure Notification( AComponent: TComponent; Operation: TOperation); override;
74	procedure SetEvents( value: TStrings);
75	procedure SetRegistered( value: boolean);
76	function GetNativeHandle: TISC_DB_HANDLE;
77
78	public
79	constructor Create( AOwner: TComponent); override;
80	destructor Destroy; override;
81	procedure CancelEvents;
82	procedure QueueEvents;
83	procedure RegisterEvents;
84	procedure UnRegisterEvents;
85	property Queued: Boolean read FQueued;
86	published
87	property Database: TIBDatabase read FDatabase write SetDatabase;
88	property Events: TStrings read FEvents write SetEvents;
89	property Registered: Boolean read FRegistered write SetRegistered;
90	property OnEventAlert: TEventAlert read FOnEventAlert write FOnEventAlert;
91	end;
92
93	implementation
94
95	uses
96	IBIntf;
97
98	function TIBEvents.GetNativeHandle: TISC_DB_HANDLE;
99	begin
100	if assigned( FDatabase) and FDatabase.Connected then
101	Result := FDatabase.Handle
102	else result := nil;
103	end;
104
105	procedure TIBEvents.ValidateDatabase( Database: TIBDatabase);
106	begin
107	if not assigned( Database) then
108	IBError(ibxeDatabaseNameMissing, [nil]);
109	if not Database.Connected then
110	IBError(ibxeDatabaseClosed, [nil]);
111	end;
112
113	{ TIBEvents }
114
115	procedure HandleEvent( param: integer); stdcall;
116	begin
117	{ don't let exceptions propogate out of thread }
118	try
119	TIBEvents( param).HandleEvent;
120	except
121	Application.HandleException( nil);
122	end;
123	end;
124
125	procedure IBEventCallback( ptr: pointer; length: short; updated: PChar); cdecl;
126	var
127	ThreadID: DWORD;
128	begin
129	{ Handle events asynchronously in second thread }
130	EnterCriticalSection( TIBEvents( ptr).CS);
131	TIBEvents( ptr).UpdateResultBuffer( length, updated);
132	if TIBEvents( ptr).Queued then
133	CloseHandle( CreateThread( nil, 8192, @HandleEvent, ptr, 0, ThreadID));
134	LeaveCriticalSection( TIBEvents( ptr).CS);
135	end;
136
137	constructor TIBEvents.Create( AOwner: TComponent);
138	begin
139	inherited Create( AOwner);
140	FIBLoaded := False;
141	CheckIBLoaded;
142	FIBLoaded := True;
143	InitializeCriticalSection( CS);
144	FEvents := TStringList.Create;
145	with TStringList( FEvents) do
146	begin
147	OnChange := EventChange;
148	Duplicates := dupIgnore;
149	end;
150	end;
151
152	destructor TIBEvents.Destroy;
153	begin
154	if FIBLoaded then
155	begin
156	UnregisterEvents;
157	SetDatabase( nil);
158	TStringList(FEvents).OnChange := nil;
159	FEvents.Free;
160	DeleteCriticalSection( CS);
161	end;
162	inherited Destroy;
163	end;
164
165	procedure TIBEvents.CancelEvents;
166	begin
167	if ProcessingEvents then
168	IBError(ibxeInvalidCancellation, [nil]);
169	if FQueued then
170	begin
171	try
172	{ wait for event handler to finish before cancelling events }
173	EnterCriticalSection( CS);
174	ValidateDatabase( Database);
175	FQueued := false;
176	Changing := true;
177	if (isc_Cancel_events( StatusVector, @FDatabase.Handle, @EventID) > 0) then
178	IBDatabaseError;
179	finally
180	LeaveCriticalSection( CS);
181	end;
182	end;
183	end;
184
185	procedure TIBEvents.DoQueueEvents;
186	var
187	callback: pointer;
188	begin
189	ValidateDatabase( DataBase);
190	callback := @IBEventCallback;
191	if (isc_que_events( StatusVector, @FDatabase.Handle, @EventID, EventBufferLen,
192	EventBuffer, TISC_CALLBACK(callback), PVoid(Self)) > 0) then
193	IBDatabaseError;
194	FQueued := true;
195	end;
196
197	procedure TIBEvents.EventChange( sender: TObject);
198	begin
199	{ check for blank event }
200	if TStringList(Events).IndexOf( '') <> -1 then
201	IBError(ibxeInvalidEvent, [nil]);
202	{ check for too many events }
203	if Events.Count > MaxEvents then
204	begin
205	TStringList(Events).OnChange := nil;
206	Events.Delete( MaxEvents);
207	TStringList(Events).OnChange := EventChange;
208	IBError(ibxeMaximumEvents, [nil]);
209	end;
210	if Registered then RegisterEvents;
211	end;
212
213	procedure TIBEvents.HandleEvent;
214	var
215	Status: PStatusVector;
216	CancelAlerts: Boolean;
217	i: integer;
218	begin
219	try
220	{ prevent modification of vital data structures while handling events }
221	EnterCriticalSection( CS);
222	ProcessingEvents := true;
223	isc_event_counts( StatusVector, EventBufferLen, EventBuffer, ResultBuffer);
224	CancelAlerts := false;
225	if assigned(FOnEventAlert) and not Changing then
226	begin
227	for i := 0 to Events.Count-1 do
228	begin
229	try
230	Status := StatusVectorArray;
231	if (Status[i] <> 0) and not CancelAlerts then
232	FOnEventAlert( self, Events[Events.Count-i-1], Status[i], CancelAlerts);
233	except
234	Application.HandleException( nil);
235	end;
236	end;
237	end;
238	Changing := false;
239	if not CancelAlerts and FQueued then DoQueueEvents;
240	finally
241	ProcessingEvents := false;
242	LeaveCriticalSection( CS);
243	end;
244	end;
245
246	procedure TIBEvents.Loaded;
247	begin
248	inherited Loaded;
249	try
250	if RegisteredState then RegisterEvents;
251	except
252	if csDesigning in ComponentState then
253	Application.HandleException( self)
254	else raise;
255	end;
256	end;
257
258	procedure TIBEvents.Notification( AComponent: TComponent;
259	Operation: TOperation);
260	begin
261	inherited Notification( AComponent, Operation);
262	if (Operation = opRemove) and (AComponent = FDatabase) then
263	begin
264	UnregisterEvents;
265	FDatabase := nil;
266	end;
267	end;
268
269	procedure TIBEvents.QueueEvents;
270	begin
271	if not FRegistered then
272	IBError(ibxeNoEventsRegistered, [nil]);
273	if ProcessingEvents then
274	IBError(ibxeInvalidQueueing, [nil]);
275	if not FQueued then
276	begin
277	try
278	{ wait until current event handler is finished before queuing events }
279	EnterCriticalSection( CS);
280	DoQueueEvents;
281	Changing := true;
282	finally
283	LeaveCriticalSection( CS);
284	end;
285	end;
286	end;
287
288	procedure TIBEvents.RegisterEvents;
289	var
290	i: integer;
291	bufptr: pointer;
292	eventbufptr: pointer;
293	resultbufptr: pointer;
294	buflen: integer;
295	begin
296	ValidateDatabase( Database);
297	if csDesigning in ComponentState then FRegistered := true
298	else begin
299	UnregisterEvents;
300	if Events.Count = 0 then exit;
301	for i := 0 to Events.Count-1 do
302	StrPCopy( @Buffer[i][0], Events[i]);
303	i := Events.Count;
304	bufptr := @buffer[0];
305	eventbufptr := @EventBuffer;
306	resultBufPtr := @ResultBuffer;
307	asm
308	mov ecx, dword ptr [i]
309	mov eax, dword ptr [bufptr]
310	@@1:
311	push eax
312	add eax, EventLength
313	loop @@1
314	push dword ptr [i]
315	push dword ptr [resultBufPtr]
316	push dword ptr [eventBufPtr]
317	call [isc_event_block]
318	mov dword ptr [bufLen], eax
319	mov eax, dword ptr [i]
320	shl eax, 2
321	add eax, 12
322	add esp, eax
323	end;
324	EventBufferlen := Buflen;
325	FRegistered := true;
326	QueueEvents;
327	end;
328	end;
329
330	procedure TIBEvents.SetEvents( value: TStrings);
331	begin
332	FEvents.Assign( value);
333	end;
334
335	procedure TIBEvents.SetDatabase( value: TIBDatabase);
336	begin
337	if value <> FDatabase then
338	begin
339	UnregisterEvents;
340	if assigned( value) and value.Connected then ValidateDatabase( value);
341	FDatabase := value;
342	end;
343	end;
344
345	procedure TIBEvents.SetRegistered( value: Boolean);
346	begin
347	if (csReading in ComponentState) then
348	RegisteredState := value
349	else if FRegistered <> value then
350	if value then RegisterEvents else UnregisterEvents;
351	end;
352
353	procedure TIBEvents.UnregisterEvents;
354	begin
355	if ProcessingEvents then
356	IBError(ibxeInvalidRegistration, [nil]);
357	if csDesigning in ComponentState then
358	FRegistered := false
359	else if not (csLoading in ComponentState) then
360	begin
361	CancelEvents;
362	if FRegistered then
363	begin
364	isc_free( EventBuffer);
365	EventBuffer := nil;
366	isc_free( ResultBuffer);
367	ResultBuffer := nil;
368	end;
369	FRegistered := false;
370	end;
371	end;
372
373	procedure TIBEvents.UpdateResultBuffer( length: short; updated: PChar);
374	var
375	i: integer;
376	begin
377	for i := 0 to length-1 do
378	ResultBuffer[i] := updated[i];
379	end;
380
381	end.