Using the hook function [5]

Bo friend "Peng" letter to discuss the problem of hooks, the core difficulty is: The data in the DLL how to pass out. This question is discussed in the next two examples.

This example establishes a global mouse hook and then passes the information about the mouse through a custom GetInfo function to the calling hook program.

To facilitate testing, provide a source download bar: Http://files.cnblogs.com/del/MouseHook_1.rar

This example effect chart:

DLL file:

Library Myhook

uses
Sysutils,
Windows,
Messages,
Classes;

{$R *.res}

var
hook:hhook;
Info:string;

function Getinfo:pchar;
Begin
Result: = Pchar (info),
end;

function Mousehook (ncode:integer; Wparam:wparam lparam:lparam): lresult; stdcall;
Begin
Case WParam of
Wm_mousemove:info: = ' mouse position ';
Wm_lbuttondown:info: = ' press ';
Wm_lbuttonup:info: = ' let go ';
End;
Info: = Format ('%s:%d,%d ', [info, pmousehookstruct (lParam) ^.pt. X, Pmousehookstruct (LParam) ^.pt. Y]);
{This information can be extracted externally from the GetInfo function}

Result: = CallNextHookEx (hooks, ncode, WParam, LParam);
End;

function Sethook:boolean; stdcall;　
Const
WH_MOUSE_LL = 14;　{Delphi gave two constants less: WH_KEYBOARD_LL = 13;　Wh_mouse_ll = 14;　Define yourself when needed
begin
Hook: = SetWindowsHookEx (Wh_mouse_ll, @MouseHook, hinstance, 0); {Wh_mouse is only a thread-level}
Result: = Hook <> 0;
End;　

Function Delhook:boolean;stdcall;
Begin
Result: = UnhookWindowsHookEx (Hook),
end;

Exports Sethook, Delhook, Mousehook, GetInfo;
Begin
End.

Test code:

unit Unit1;

Interface

uses
Windows, Messages, sysutils, variants, Classes, Graphics, Controls, Forms,
Dialogs, S Tdctrls, Extctrls;

Type
TForm1 = Class (Tform)
Button1:tbutton;
Button2:tbutton;
Timer1:ttimer;
Procedure formcreate (sender:tobject);
Procedure Button1Click (sender:tobject);
Procedure Button2click (sender:tobject);
Procedure Timer1timer (sender:tobject);
Procedure Formdestroy (sender:tobject);
End;

function Sethook:boolean; stdcall
function Delhook:boolean; stdcall;
function Getinfo:pchar; stdcall ;

var
form1:tform1;

Implementation

{$R *.DFM}

function sethook; external ' MyHook.dll ';
function delhook; external ' MyHook.dll ';
function GetInfo; external ' MyHook.dll ';

Procedure Tform1.button1click (sender:tobject);
begin
Sethook;
timer1.enabled: = True;
End;

Procedure Tform1.button2click (SendeR:tobject);
Begin
Timer1.enabled: = False;
Delhook;
End;

Procedure tform1.formcreate (sender:tobject);
Begin
Button1.caption: = ' install hook ';
Button2.caption: = ' load unload hook ';
Timer1.interval: = 100;
Timer1.enabled: = False;　
Formstyle: = Fsstayontop; {To test, keep the window in front}
End;

Procedure Tform1.formdestroy (sender:tobject);
Begin
Delhook
End;

Procedure Tform1.timer1timer (sender:tobject);
Begin
Text: = GetInfo
End;

End.