恢复当前窗口的程序，由于当前进程有可能在全屏模式下运行，所以需要通过指定特定的热键使程序窗口消失，且不出现在任务栏上。下面介绍如何用Delphi实现。主要需要解决两个问题，即隐藏窗口和设定热键。
一.隐藏窗口
通过API函数GETACTIVEWINDOW获取当前窗口；函数ShowWindow(HWND,nCmdShow)的参数nCmdShow取SW_HIDE时将之隐藏，取SW_SHOW时将之显示。例如：showwindow(getactivewindow,sw_hide)。隐藏好窗体后，须记住窗体句柄以便恢复。
二.键盘监控
为了实现键盘监控须用到钩子。
以下是程序的源文件：
---HKHide.pas---
unit HKHide;
interface
uses
Windows, Messages, sysutils;
var
hNextHookHide: HHook;
HideSaveExit: Pointer;
hbefore:longint;
function KeyboardHookHandler(iCode: Integer;wParam: WPARAM;
lParam: LPARAM): LRESULT; stdcall; export;
function EnableHideHook: BOOL; export;
function DisableHideHook: BOOL; export;
procedure HideHookExit; far;
implementation
function KeyboardHookHandler(iCode: Integer;wParam: WPARAM;
lParam: LPARAM): LRESULT; stdcall; export;
const _KeyPressMask = $80000000;
var
f:textfile;
temp:string;
begin
Result := 0;
If iCode < 0 Then
begin
Result := CallNextHookEx(hNextHookHide, iCode, wParam, lParam);
Exit;
end;
// 侦测 Ctrl + Alt + F12 组合键
if ((lParam and _KeyPressMask) = 0) //按下时生效
and (GetKeyState(vk_Control) < 0)
and (getkeystate(vk_menu)<0) and (wParam = vk_F12) then
begin
Result := 1;
//文件不存在则创建
if not fileexists(c:\test.txt) then
begin
assignfile(f,c:\test.txt);
rewrite(f);
writeln(f,0);
closefile(f);
end
else begin
assignfile(f,c:\test.txt);
reset(f);
readln(f,temp);
hbefore:=strtoint(temp);
begin
hbefore:=getactivewindow;
temp:=inttostr(hbefore);
rewrite(f);
writeln(f,temp);
closefile(f);
ShowWindow(hbefore, SW_HIDE);
end
else begin
showwindow(hbefore,sw_show);
rewrite(f);
writeln(f,0);
closefile(f);
end;
end;
end;
end;
function EnableHideHook: BOOL; export;
begin
Result := False;
if hNextHookHide <> 0 then Exit;
// 挂上 WH_KEYBOARD 这型的 HOOK, 同时, 传回值必须保留下
// 来, 免得 HOOK 呼叫链结断掉
hNextHookHide := SetWindowsHookEx(WH_KEYBOARD,
KeyboardHookHandler,HInstance,0);
Result := hNextHookHide <> 0;
end;
function DisableHideHook: BOOL; export;
begin
if hNextHookHide <> 0 then
begin
Result:=True;
UnhookWindowshookEx(hNextHookHide); // 解除 Keyboard Hook
hNextHookHide:=0;
end
else
Result:=False;
end;
procedure HideHookExit;
begin
// 如果忘了解除 HOOK, 自动代理解除的动作
if hNextHookHide <> 0 then DisableHideHook;
ExitProc := HideSaveExit;
end;
end.
---HKPHide.dpr---
library HKPHide;
uses
HKHide in HKHide.pas;
exports
EnableHideHook,
DisableHideHook;
begin
hNextHookHide := 0;
hbefore:=0;
HideSaveExit := ExitProc;
ExitProc := @HideHookExit;
end.
文件制作好后选Build All编译成HKPHide.dll。
新建一个工程Project1
---Unit1.pas---
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
function EnableHideHook: BOOL; external HKPHide.DLL;
function DisableHideHook: BOOL; external HKPHide.DLL;
procedure TForm1.Button1Click(Sender: TObject);
begin
if EnableHideHook then
ShowMessage(HotKey Testing...);
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
if DisableHideHook then
ShowMessage(HotKey Testing..., DONE!!);
end;
end.
运行程序按Button1后启动钩子，这时运行其他程序，按Ctrl+Alt+F12可将之隐藏，再按一下则恢复。以下程序在Delphi 4下通过。