Author: Radikal Q3
I suppose that to somebody it will be he useful this trick.
Have I outlined it to me as a simple exercise of those that you tell yourself to
yourself ' that would happen if? '.
It is that the mouse only works in your application. Neither in the Windows
desktop, neither in the window's taskbar, neither in any
other place that in your form...
Of course, care with him... if you are happened to print something and the driver
of your printer it jumps you with the typical
message ' papaer empty' you won't be able to close the dialogue that it appears...
in short, better you prove it and you see if it is
good you for something:
Answer:
1 function CallBackDelHook(Code: Integer;
2 wParam: WPARAM;
3 lParam: LPARAM
4 ): LRESULT; stdcall;
5
6 var
7 DatosMouse: PMouseHookStruct;
8 Intentos: integer;
9
10 {Esta es la funcion CallBack a la cual llamará el hook.}
11 {This is the CallBack function called by he Hook}
12 begin
13 {Si hay un nuevo evento de raton...}
14 {if there is a new mouse event...}
15 if code = HC_ACTION then
16 begin
17 {Miramos si existe el fichero}
18 {if the mapfile exists}
19 FicheroM := OpenFileMapping(FILE_MAP_READ, False, 'ElReceptor');
20 {Si no existe, no enviamos nada a la aplicacion receptora}
21 {If dont, send nothing to receiver application}
22 if FicheroM <> 0 then
23 begin
24 Compartido := MapViewOfFile(FicheroM, FILE_MAP_READ, 0, 0, 0);
25
26 {Apuntamos hacia los datos del evento del raton}
27 DatosMouse := Pointer(lparam);
28
29 UnmapViewOfFile(Compartido);
30 CloseHandle(FicheroM);
31 end;
32 end;
33 {Llamamos al siguiente hook de la cadena}
34 {call to next hook of the chain}
35 if Compartido^ <> DatosMouse^.hwnd then
36 Result := 1
37 else
38 Result := CallNextHookEx(HookDeMouse, Code, wParam, lParam);
39 end;
40
41 //and the relevant part is this:
42
43 if Compartido^ <> DatosMouse^.hwnd then
44 Result := 1
45 else
46 Result := CallNextHookEx(HookDeMouse, Code, wParam, lParam);
that is to say, if the recipient of the message that has captured the hook is our
application, we call to the following mouse hook that
has installed in the chain, if it is not this way, because we give the message like
treaty, miscarrying this way his processed later for
the application that is...
Well, like in any hook at system level, we will build ourselves first a DLL that is
where anger the procedure CallBack of the hook,
and then an example application that will communicate somehow with the DLL.
Therefore:
Hook's DLL
47 library HookMouse;
48
49 {Demo de Hook de Ratón a nivel de sistema, Radikal.}
50
51 uses Windows, Messages;
52
53 type
54 PCompartido = ^THandle;
55
56 var
57 HookDeMouse: HHook;
58 FicheroM: THandle;
59 Compartido: PCompartido;
60
61 function CallBackDelHook(Code: Integer;
62 wParam: WPARAM;
63 lParam: LPARAM
64 ): LRESULT; stdcall;
65
66 var
67 DatosMouse: PMouseHookStruct;
68 Intentos: integer;
69
70 {Esta es la funcion CallBack a la cual llamará el hook.}
71 {This is the CallBack function called by he Hook}
72 begin
73 {Si hay un nuevo evento de raton...}
74 {if there is a new mouse event...}
75 if code = HC_ACTION then
76 begin
77 {Miramos si existe el fichero}
78 {if the mapfile exists}
79 FicheroM := OpenFileMapping(FILE_MAP_READ, False, 'ElReceptor');
80 {Si no existe, no enviamos nada a la aplicacion receptora}
81 {If dont, send nothing to receiver application}
82 if FicheroM <> 0 then
83 begin
84 Compartido := MapViewOfFile(FicheroM, FILE_MAP_READ, 0, 0, 0);
85
86 {Apuntamos hacia los datos del evento del raton}
87 DatosMouse := Pointer(lparam);
88
89 UnmapViewOfFile(Compartido);
90 CloseHandle(FicheroM);
91 end;
92 end;
93 {Llamamos al siguiente hook de la cadena}
94 {call to next hook of the chain}
95 if Compartido^ <> DatosMouse^.hwnd then
96 Result := 1
97 else
98 Result := CallNextHookEx(HookDeMouse, Code, wParam, lParam);
99 end;
100
101 procedure HookOn; stdcall;
102 {Procedure que instala el hook}
103 {procedure for install the hook}
104 begin
105 HookDeMouse := SetWindowsHookEx(WH_MOUSE, @CallBackDelHook, HInstance, 0);
106 end;
107
108 // stops this type of watch
109
110 procedure HookOff; stdcall;
111 begin
112 {procedure para desinstalar el hook}
113 {procedure to uninstall the hook}
114 UnhookWindowsHookEx(HookDeMouse);
115 end;
116
117 exports
118 {Exportamos las procedures...}
119 {Export the procedures}
120 HookOn,
121 HookOff;
122
123 begin
124 end.
Demo application
In a clean form, put this code in its unit:
125 unit Unit1;
126
127 interface
128
129 uses
130 Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
131 StdCtrls, ExtCtrls;
132
133 const
134 NombreDLL = 'HookMouse.dll';
135
136 type
137 PCompartido = ^THandle;
138 THookMouse = procedure; stdcall;
139
140 type
141 TForm1 = class(TForm)
142 procedure FormCreate(Sender: TObject);
143 procedure FormDestroy(Sender: TObject);
144 private
145 { Private declarations }
146 FicheroM: THandle;
147 Compartido: PCompartido;
148 HandleDLL: THandle;
149 HookOn,
150 HookOff: THookMouse;
151
152 public
153 { Public declarations }
154 end;
155
156 var
157 Form1: TForm1;
158
159 implementation
160
161 {$R *.DFM}
162
163 procedure TForm1.FormCreate(Sender: TObject);
164 begin
165 HandleDLL := LoadLibrary(PChar(ExtractFilePath(Application.Exename) +
166 NombreDLL));
167 if HandleDLL = 0 then
168 raise Exception.Create('No se pudo cargar la DLL');
169
170 @HookOn := GetProcAddress(HandleDLL, 'HookOn');
171 @HookOff := GetProcAddress(HandleDLL, 'HookOff');
172
173 if not assigned(HookOn) or
174 not assigned(HookOff) then
175 raise Exception.Create('No se encontraron las funciones en la DLL' + #13 +
176 'Cannot find the required DLL functions');
177
178 {Creamos el fichero de memoria}
179 FicheroM := CreateFileMapping($FFFFFFFF,
180 nil,
181 PAGE_READWRITE,
182 0,
183 SizeOf(THandle),
184 'ElReceptor');
185
186 {Si no se creó el fichero, error}
187 if FicheroM = 0 then
188 raise Exception.Create('Error al crear el fichero' +
189 '/Error while create file');
190
191 {Direccionamos nuestra estructura al fichero de memoria}
192 Compartido := MapViewOfFile(FicheroM, FILE_MAP_WRITE, 0, 0, 0);
193
194 {Escribimos datos en el fichero de memoria}
195 Compartido^ := Handle;
196 HookOn;
197 end;
198
199 procedure TForm1.FormDestroy(Sender: TObject);
200 begin
201 {Desactivamos el Hook}
202 {Uninstall the Hook}
203 if Assigned(HookOff) then
204 HookOff;
205
206 {Liberamos la DLL}
207 {Free the DLL}
208 if HandleDLL <> 0 then
209 FreeLibrary(HandleDLL);
210
211 {Cerramos la vista del fichero y el fichero}
212 {Close the memfile and the View}
213 if FicheroM <> 0 then
214 begin
215 UnmapViewOfFile(Compartido);
216 CloseHandle(FicheroM);
217 end;
218 end;
219
220 end.
Note: If you use this technique in an application with several forms, you will put
in ' Compartido' the handle of the form that you will
activate, but it won't receive mouse events. For example, you can make it in the
event OnShow of the form...
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