在Windows操作系统中,当用户按下"PrintScreen"按钮后,Windows自动将当前屏幕的图像拷贝到系统剪贴板中,这时可以通过"画笔"这个小程序将剪贴板中的内容保存成图像文件,可以看出,如果需要将当前屏幕保存下来还是比较麻烦的,能否可以自己编写一个应用程序,自动将当前屏幕的内容保存到一个图像文件中去呢?这个答案是肯定的,本实例应用程序就是利用通用的热键管理DLL库实现的热键功能,在收到热键通知后截取屏幕的内容并保存到bmp文件中。例如我们设置图片保存路径为c:\,热键为F9 + Control,然后按Change按钮设置好热键,那么当我们按下CTRL+F9后,当前界面将以BMP图像文件的格式被保存在C:\目录下。程序编译运行后的界面效果如图一所示:
d`9%:2qE
;w";s$ 一、实现方法
[#S[=% fT1/@ 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
<A?- * ]5W|^% #pragma data_seg("shareddata")
.s-X%%e\ HHOOK hHook =NULL; //钩子句柄
2lNZwV7 UINT nHookCount =0; //挂接的程序数目
c?oNKqPzg static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
|fX
@o0H static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
6$-Ex static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
0<"4W: static int KeyCount =0;
``?]13XjK static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
3u +A/ #pragma data_seg()
WVDkCo@ E0QrByr_ 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
=Tv;?U C xu9K\/{7 DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
z0[_5Cm/ u|prVzm\m BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
3>FeTf#: cKey,UCHAR cMask)
QiBo]`)% {
?,8|K B BOOL bAdded=FALSE;
.Bxv|dji for(int index=0;index<MAX_KEY;index++){
?B>
{rj if(hCallWnd[index]==0){
)U0`?kD hCallWnd[index]=hWnd;
TtA6N8G HotKey[index]=cKey;
tow0/Jt HotKeyMask[index]=cMask;
.OI&Zm- bAdded=TRUE;
l1*qDzb KeyCount++;
!p$z8~ break;
\q9wo*A }
Y'tPD#|r }
i>Wsc? return bAdded;
?K9&ye_rgw }
hUy"XXpr //删除热键
82ay("ZY BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
HD^ Ou5YB {
f5p>oXo4b BOOL bRemoved=FALSE;
Pi|WOE2 for(int index=0;index<MAX_KEY;index++){
#
+OEO if(hCallWnd[index]==hWnd){
Q/'jwyj_ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
K,f*}1$qM hCallWnd[index]=NULL;
;tK%Q~To HotKey[index]=0;
tQz =_;jy HotKeyMask[index]=0;
98 dl -? bRemoved=TRUE;
t[$C r; KeyCount--;
n.+%eYM< break;
XV)<Oav s }
h/`]=kCl }
=[]V$<G'w{ }
o@SL0H-6| return bRemoved;
fyYHwG }
\@IEqm6 f|U;4{k s|*0cK!K^ DLL中的钩子函数如下:
)IN!CmpN &/XRiK1"0 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
GQ=Zp3[ {
OCR`1 BOOL bProcessed=FALSE;
~<[$.8* if(HC_ACTION==nCode)
byALM {
H?-Byi if((lParam&0xc0000000)==0xc0000000){// 有键松开
8:* switch(wParam)
%eK=5Er jx {
Sg#$
B#g case VK_MENU:
&>Zm gz MaskBits&=~ALTBIT;
1%Yd ] 1c( break;
-*`7Q'}% case VK_CONTROL:
)Fe6>tE MaskBits&=~CTRLBIT;
GWb=X cx break;
&<??,R14 case VK_SHIFT:
']Q4SB"q MaskBits&=~SHIFTBIT;
&Pk #v break;
uY 6]rt_#a default: //judge the key and send message
X/< zxM break;
~SKV% }
'OrGt_U for(int index=0;index<MAX_KEY;index++){
7 'T3Wc if(hCallWnd[index]==NULL)
(i..7B: continue;
c*>8VW> if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
}STTDq4 {
>4 n\ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
^,W;dM2 bProcessed=TRUE;
5UWj#|t }
-"Mq<XO&51 }
?w^MnK0U) }
c?ZM<Y" else if((lParam&0xc000ffff)==1){ //有键按下
EJAk'L+nuH switch(wParam)
H?]%b!gQG {
il8n
K case VK_MENU:
>* Ag0.Az MaskBits|=ALTBIT;
<Zb~tYp break;
eyM<#3\\S case VK_CONTROL:
/x2-$a:< MaskBits|=CTRLBIT;
l\f
/(&, break;
Nuc;Y case VK_SHIFT:
\mK;BWg) MaskBits|=SHIFTBIT;
+Tf4SJ break;
%XF>k) default: //judge the key and send message
*'?aXS -'r break;
$<NrJgQ }
kZb #k# for(int index=0;index<MAX_KEY;index++){
_?VMSu if(hCallWnd[index]==NULL)
g:dtfa/] continue;
8Pb~`E/ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
K_SURTys {
3@}rO~ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
z D "n7; bProcessed=TRUE;
qdW"g$fW }
*'i9 }
{[I]pm~n }
ey/{Z<D if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
_%R]TlL for(int index=0;index<MAX_KEY;index++){
{l0[`"EF if(hCallWnd[index]==NULL)
:P'M|U continue;
Z]~) ->=} if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
%XC3V7 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
5>Kk>[|. //lParam的意义可看MSDN中WM_KEYDOWN部分
_^%DfMP3i\ }
-- >q=hlA }
T]_]{%z }
"26=@Q^Y return CallNextHookEx( hHook, nCode, wParam, lParam );
R$|"eb5 }
yg@8&;bP` o=zr]vv 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
}srmG|@: {sOW DM5 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
E|,RM;7 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
ur$=%3vM MlKSjKl" ! 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
^RI&`5g #ETy#jKL LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
-~_[2u^3 {
,K WIuCU; if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
7oy}<9 {
Tr@|QNu //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
wU}%]FqtZ= SaveBmp();
&7J-m4BI return FALSE;
@sdHB./ }
+0l-zd\ …… //其它处理及默认处理
zJ*(G_H }
9$q35e ''Y'ZsQ; `R!%k]$ 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
L*#W?WMM
v VbI$#;:[7 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
|Cm6RH$( o#K*-jOfiH 二、编程步骤
,{C
hHnJ%# <B&vfKO^h 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
2MU$OI0| \1ncr4 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
`B$rr4_ $Ph#pM( 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
6 h%,% Tlm::S
4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
j 06mky V(5*Dn84 5、 添加代码,编译运行程序。
}?)U`zF)7} hLICu[LC? 三、程序代码
0FcG;i+ <kCOg8<y
: ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
@P)2ZGG #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
Di"Tv<RlQ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
koa-sy )#L #if _MSC_VER > 1000
yZV Y3<] #pragma once
r"|UgCc #endif // _MSC_VER > 1000
5AbY 59 #ifndef __AFXWIN_H__
#&}j'oD|N #error include 'stdafx.h' before including this file for PCH
XW.k%H4@ #endif
Nu;?})tF #include "resource.h" // main symbols
^M)+2@6 class CHookApp : public CWinApp
7G+E+A5o& {
m:D0O]2 public:
6r.#/' " CHookApp();
A2.GNk // Overrides
~s{
V!)0 // ClassWizard generated virtual function overrides
w9w=2 * //{{AFX_VIRTUAL(CHookApp)
Sq SiuO.D public:
` 7P%muY. virtual BOOL InitInstance();
9e*o$)j_ virtual int ExitInstance();
m-2!r*(zt //}}AFX_VIRTUAL
nX_w F`n" //{{AFX_MSG(CHookApp)
%x-`Y[ // NOTE - the ClassWizard will add and remove member functions here.
dczq,evp // DO NOT EDIT what you see in these blocks of generated code !
Oz4vV_a&' //}}AFX_MSG
0j :u.x DECLARE_MESSAGE_MAP()
6rMXv0) };
"Q`Le{ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
Ay6]vU BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
ZmDM=qN BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
D(WdI BOOL InitHotkey();
9~J#> C0} BOOL UnInit();
m}(M{^\| #endif
DkEf;P 0|DyYu //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
qjsEyro$- #include "stdafx.h"
" ?Ux\)* #include "hook.h"
y(wb?86#W5 #include <windowsx.h>
_;,"!'R`f #ifdef _DEBUG
xpJ=yxO #define new DEBUG_NEW
m
al?3*x/ #undef THIS_FILE
H]}mg='kI static char THIS_FILE[] = __FILE__;
mX%T"_^ #endif
'=`af>Nc #define MAX_KEY 100
-(},%!-_ #define CTRLBIT 0x04
cGyR_8:2cv #define ALTBIT 0x02
Nwo*tb: #define SHIFTBIT 0x01
\UP=pT@ #pragma data_seg("shareddata")
2fgYcQ8` HHOOK hHook =NULL;
Zb7%$1)L~ UINT nHookCount =0;
>K<cc#Aa static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
H;seT XL static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Qv<p$Up6 static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
9PUobV_^Wo static int KeyCount =0;
mT/^F{c static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
^3ai}Ei3 #pragma data_seg()
^#t6/fY.# HINSTANCE hins;
CXBFR>" void VerifyWindow();
h[;DRD!Z BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
)KY4BBc //{{AFX_MSG_MAP(CHookApp)
M.\XG}RR // NOTE - the ClassWizard will add and remove mapping macros here.
Y!`pF // DO NOT EDIT what you see in these blocks of generated code!
5,pEJ>dDD3 //}}AFX_MSG_MAP
pD!j#suMA END_MESSAGE_MAP()
<=Saf. 'jXJ!GFw CHookApp::CHookApp()
f_Hh"Vh {
8!b>[Nsc // TODO: add construction code here,
!+z&] S3s // Place all significant initialization in InitInstance
D~FIv }
V|TD+7.`QB jNI9 .45y CHookApp theApp;
w9StW94p LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
DL#y_;#3_ {
1*e7NJ/., BOOL bProcessed=FALSE;
dlA0&;}z if(HC_ACTION==nCode)
Xf{9rZ+ {
IR{XL\WF if((lParam&0xc0000000)==0xc0000000){// Key up
[ahwJ F#r switch(wParam)
K^",LCJA {
53$;ZO3 case VK_MENU:
5|7<ZL3 MaskBits&=~ALTBIT;
k(M"k!M break;
O)ose?Z
case VK_CONTROL:
\<hHZS MaskBits&=~CTRLBIT;
+4p=a [ break;
* H~=dPC case VK_SHIFT:
[%P[ x]- MaskBits&=~SHIFTBIT;
f1S%p break;
B6j/"x6N15 default: //judge the key and send message
]4r&Q4d>O break;
Kf6D)B 26 }
)W6l/ for(int index=0;index<MAX_KEY;index++){
<(_Tanx9Q if(hCallWnd[index]==NULL)
{6O}E9 continue;
P @J)S ? if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
|N}* {
;Ea8> SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
#]Lodo9rS\ bProcessed=TRUE;
|&@`~OBa }
(J?_~(,`" }
U%0|LQk5 }
Xy. /1`X else if((lParam&0xc000ffff)==1){ //Key down
4\ |/S@. switch(wParam)
z7z9lDS {
,@fx[5{ case VK_MENU:
>4q6 MaskBits|=ALTBIT;
`EfFyhG$ break;
=7#"}%4Q case VK_CONTROL:
'(SivD MaskBits|=CTRLBIT;
yeMe2Zx break;
jo1z#!|Yw} case VK_SHIFT:
UCup {pDp MaskBits|=SHIFTBIT;
l8J2Xd @ break;
ei>iXDt default: //judge the key and send message
zC*dJXt@ break;
?~IdPSY }
cv1PiIl for(int index=0;index<MAX_KEY;index++)
4e?bkC {
H DD)AM&p if(hCallWnd[index]==NULL)
&EYoviFp continue;
5wdKu,nq if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
P_b!^sq9 {
p5py3k SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
ho)JY
$#6 bProcessed=TRUE;
i`Qa7 }
GY %$7 }
@4Zkkjc4b }
H |7XfM if(!bProcessed){
*_d N9 for(int index=0;index<MAX_KEY;index++){
x4MTE?hT if(hCallWnd[index]==NULL)
4<vi@,s continue;
I(WIT=Wi< if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
{;th~[ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
=}@1Z~
}
%!AzFL
J|Z }
Vugb;5Vl }
#qUGc` return CallNextHookEx( hHook, nCode, wParam, lParam );
uix/O*^ }
Q, "8Ty pr1bsrMuL BOOL InitHotkey()
)pe17T1| {
$pKegK;'z if(hHook!=NULL){
xX9snSGz nHookCount++;
r&Qa;-4Pl return TRUE;
#d<|_ }
|H]0pbC)w else
h@'CmIZc hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
34[TM 3L]. if(hHook!=NULL)
*-(o. !#1 nHookCount++;
>]%$lSCW\D return (hHook!=NULL);
WbBd<^Q }
+V9xKhR;x BOOL UnInit()
:bi(mX7t {
WRA(k if(nHookCount>1){
/u_9uJ"-K( nHookCount--;
l]#=I7 6 return TRUE;
l!KPgRw }
kj.9\ BOOL unhooked = UnhookWindowsHookEx(hHook);
NZ0 ?0* if(unhooked==TRUE){
_<DOA:'v nHookCount=0;
qJf\,7mi hHook=NULL;
h{H*k#> }
-'L~Y~'. return unhooked;
~R~.D }
~)`\j <3/_'/C BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
GD'Z"rhI {
~t/i0pKq. BOOL bAdded=FALSE;
qX; F+~ for(int index=0;index<MAX_KEY;index++){
l(-"rE if(hCallWnd[index]==0){
`@WJ_-$# hCallWnd[index]=hWnd;
Y"r728T`K HotKey[index]=cKey;
z]C=nXbk HotKeyMask[index]=cMask;
3:8p="$F bAdded=TRUE;
>p0,]-.J,r KeyCount++;
WC37=8mA break;
zUNUH^Il }
_h1eW9q }
ZBFn return bAdded;
km][QEXs% }
>}Bcv%zZ L|:CQ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
/#&jF:h {
2"6qg>]-t BOOL bRemoved=FALSE;
^W9O_5\g4a for(int index=0;index<MAX_KEY;index++){
%;R&cSZ