http://www.delphi2007.net/DelphiAPI/html/delphi_20061115102712231.html
我想实现一个功能：
安装一个全局消息HOOK，捕获桌面上任意输入框的获得焦点和失去焦点的事件，为了便于测试我先写了一个线程hook做测试，hook自己窗体上的输入框的获得焦点和失去焦点的事件，但是不奏效，请大家帮忙看看哪里有问题
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
type
TForm1 = class(TForm)
Edit1: TEdit;
Edit2: TEdit;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
var
HookHandle: HHOOK;
function TestHookProc(code: Integer; wparam: WPARAM; lparam: LPARAM): LRESULT;stdcall;
begin
if code = HC_ACTION then
if PMsg(lparam)^.Message = WM_SETFOCUS then
begin
ShowMessage('we get it');
end;
Result := CallNextHookEx(HookHandle, Code, WParam, longint(@lparam));
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
HookHandle:=SetWindowsHookEx(Windows.WH_CALLWNDPROC,TestHookProc,0,GetCurrentThreadID);
end;
end.
用WH_SHELL类型的钩子，具体看一下帮助
不对，是WH_CBT
回调函数是这样的
function CBTProc(nCode:integer;wParam:wParam;lParam:lParam):LRESULT;stdcall;
对于nCode的说明：
nCode
Specifies a code that the hook procedure uses to determine how to process the message. This parameter can be one of the following values:
Value Meaning
HCBT_ACTIVATE The system is about to activate a window.
HCBT_CLICKSKIPPED The system has removed a mouse message from the system message queue. Upon receiving this hook code, a CBT application must install a WH_JOURNALPLAYBACK hook procedure in response to the mouse message.
HCBT_CREATEWND A window is about to be created. The system calls the hook procedure before sending the WM_CREATE or WM_NCCREATE message to the window. If the hook procedure returns a nonzero value, the system destroys the window; the CreateWindow function returns NULL, but the WM_DESTROY message is not sent to the window. If the hook procedure returns zero, the window is created normally.
At the time of the HCBT_CREATEWND notification, the window has been created, but its final size and position may not have been determined and its parent window may not have been established. It is possible to send messages to the newly created window, although it has not yet received WM_NCCREATE or WM_CREATE messages. It is also possible to change the position in the Z order of the newly created window by modifying the hwndInsertAfter member of the CBT_CREATEWND structure.
HCBT_DESTROYWND A window is about to be destroyed.
HCBT_KEYSKIPPED The system has removed a keyboard message from the system message queue. Upon receiving this hook code, a CBT application must install a WH_JOURNALPLAYBACK_hook hook procedure in response to the keyboard message.
HCBT_MINMAX A window is about to be minimized or maximized.
HCBT_MOVESIZE A window is about to be moved or sized.
HCBT_QS The system has retrieved a WM_QUEUESYNC message from the system message queue.
HCBT_SETFOCUS A window is about to receive the keyboard focus.
HCBT_SYSCOMMAND A system command is about to be carried out. This allows a CBT application to prevent task switching by means of hot keys.
If nCode is less than zero, the hook procedure must pass the message to the CallNextHookEx function without further processing and should return the value returned by CallNextHookEx.
如果nCode的值为HCBT_SETFOCUS，则表示检测到了焦点消息。这个时候wParam包含了获得焦点的控件的句柄等信息，lParam包含了失去焦点的控件的句柄等信息。
以上信息在DELPHI帮助里面都有，请看帮助