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:
OMgFp |^
R~TzZ(Ah] 一、实现方法
)(V|d$n .dM4B'OA? 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
%xv } j
N":9+F #pragma data_seg("shareddata")
&m<:&h& b HHOOK hHook =NULL; //钩子句柄
di$\\ Ah UINT nHookCount =0; //挂接的程序数目
HG
kL6o= static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
h\dq]yOl static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
lrrNyaFn static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
3msb"|DG static int KeyCount =0;
hq+j8w}<- static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
Esx"nex #pragma data_seg()
^k{b8-)W< r Z)?uqa 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。
\zOo[/-< ~gZ"8frl 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:
K{DsGf, noI>Fw<V BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
d7(g=JK< cKey,UCHAR cMask)
uknX py)) {
W5a7HkM BOOL bAdded=FALSE;
'$nm~z,V for(int index=0;index<MAX_KEY;index++){
&}}UdJ` if(hCallWnd[index]==0){
fib#)KE hCallWnd[index]=hWnd;
% \N52 HotKey[index]=cKey;
8);G'7O HotKeyMask[index]=cMask;
iwM$U(
9 bAdded=TRUE;
J[ 0o6 KeyCount++;
.: dy d break;
H 5\k`7R }
hJ|zX }
uUmkk return bAdded;
-]hk2Q0 }
vT1StOx<V //删除热键
iG+hj:5 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
=*2_B~` {
*z852@ BOOL bRemoved=FALSE;
^W8kt for(int index=0;index<MAX_KEY;index++){
zH)M,+P if(hCallWnd[index]==hWnd){
qK=uSLo\+ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
nev@ykP6 hCallWnd[index]=NULL;
{"e)Jj_= HotKey[index]=0;
V7~tIhuJH HotKeyMask[index]=0;
+q<G%PwbV bRemoved=TRUE;
E]@$,)nC KeyCount--;
R V@'$`Q break;
,76xa%k(U| }
)SjhOvm }
- 2DvKW$ }
+wPXDN#R return bRemoved;
cpLlkR O }
JJE?!Yvc <A~a|A-QFR r3OR7f[ DLL中的钩子函数如下:
A [c1E[ `PoFKtVXM LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
-6KNMk {
r%=} e++^% BOOL bProcessed=FALSE;
PoB-:G6 if(HC_ACTION==nCode)
,y>Sq + {
Z.QgL= if((lParam&0xc0000000)==0xc0000000){// 有键松开
r3;@ switch(wParam)
:o"9x, {
mZG)#gW[ case VK_MENU:
G>@KX MaskBits&=~ALTBIT;
;URvZ! {/Z break;
#S4lRVt5 case VK_CONTROL:
WWBm*?U MaskBits&=~CTRLBIT;
HP,sNiw break;
Q%T[&A}3B case VK_SHIFT:
#OMFv. MaskBits&=~SHIFTBIT;
k.5(d.*( break;
I,8f{T!O@" default: //judge the key and send message
Ez)hArxns break;
w ag^Sk }
R"2wop for(int index=0;index<MAX_KEY;index++){
%$Smei if(hCallWnd[index]==NULL)
fV(WUN+ continue;
nY)H-u^ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
ko-,l6E {
; <NK SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
'((pW bProcessed=TRUE;
B=d
:r }
mxPzB#t4 }
>))f;$D= }
/XVjcD66c else if((lParam&0xc000ffff)==1){ //有键按下
y3+iADo.p switch(wParam)
L^E#"f {
QKB*N)%6 case VK_MENU:
Y?'Krw ` MaskBits|=ALTBIT;
tEam6xNf, break;
KkJrh@lk case VK_CONTROL:
93[&' MaskBits|=CTRLBIT;
*DUP$@}k break;
=:"wU case VK_SHIFT:
UE\Z]t! MaskBits|=SHIFTBIT;
RW4,j&) break;
%a\L^w)Xn default: //judge the key and send message
G(;hJ'LT break;
`uh+d }
,wYA_1$$H for(int index=0;index<MAX_KEY;index++){
BN>t"9XpW if(hCallWnd[index]==NULL)
qP k`e}D continue;
`k;MGs)& if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
ou\M}C`E {
b/soU2?^ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
\?_M_5Nb bProcessed=TRUE;
o)2KQ$b>Q }
umo<9Y }
eYQPK?jo }
7cQFH@SC if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
ks|c'XQb for(int index=0;index<MAX_KEY;index++){
Z<IN>:l if(hCallWnd[index]==NULL)
x@LNjlP continue;
"tF#]iQQ
u if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
/?Y]wY SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
t6C2DHh7$ //lParam的意义可看MSDN中WM_KEYDOWN部分
GoUsB|-\ }
[X"pOz }
e0:[,aF` }
%o return CallNextHookEx( hHook, nCode, wParam, lParam );
4Q17vCC*n }
"$krK7Z ]tx/t^&/\u 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:
YAP,#a HD_ #-M BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
$n=w BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
Y/<`C XVfw0-O 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
l.Q.G<ol
NIh?2w"\ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
S
Rb-eDk' {
5q,ZH6\
{ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
s1>d)2lX {
M .oH,Kd6 //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
&WKAg:^k) SaveBmp();
8G )O,F7z return FALSE;
Ud& '*, }
^61;0 …… //其它处理及默认处理
wx*03(|j; }
/<VR-yr _Kwp8_kTr 5ktFL<^5T 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
]|_UpP8EP =/e$Rp 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。
1k0*WCfZ :|a$[g5
二、编程步骤
I~F]e|Ehqr [x{Ai(
/T^ 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";
g#%Egb1 4DgH/Yo 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
]%2y`Jrl^W f=hT
o!i 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;
VOSq%hB eq(1'?7]`G 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;
uGpLh0 GS&I6 5、 添加代码,编译运行程序。
-2B3 xIZJ }eAV8LU 三、程序代码
><xJQeW eb>jT: ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
lOy1vw' #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
(Xl+Zi>\{ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
$1y8X K7r #if _MSC_VER > 1000
9]%2Yb8SC #pragma once
1]a\uq} #endif // _MSC_VER > 1000
kB9@
&t+ #ifndef __AFXWIN_H__
43,baeG #error include 'stdafx.h' before including this file for PCH
7g>|e #endif
h?Lp9VF #include "resource.h" // main symbols
*.
1S
class CHookApp : public CWinApp
LeV";=_n {
7/zaf public:
k&9[}a* CHookApp();
0at['zw // Overrides
wx8Qz,Z // ClassWizard generated virtual function overrides
}R!t/8K //{{AFX_VIRTUAL(CHookApp)
4Opf[3] public:
4I8QM&7 virtual BOOL InitInstance();
/'a\$G"%6 virtual int ExitInstance();
w0X})&,{`m //}}AFX_VIRTUAL
cD t|v~ //{{AFX_MSG(CHookApp)
12@Ge] // NOTE - the ClassWizard will add and remove member functions here.
k$|g)[RE // DO NOT EDIT what you see in these blocks of generated code !
Y|6gg //}}AFX_MSG
?c<uN~fC= DECLARE_MESSAGE_MAP()
SUDvKP };
fTt\@"V LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
VVbFn9+V BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Van=dzG BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
wGw<z[:f BOOL InitHotkey();
op($+Q BOOL UnInit();
VCzb[. #endif
G
2`hEX% . @0@Y //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
9-Z? #include "stdafx.h"
!l5@L\ #include "hook.h"
E9\u^"GVO #include <windowsx.h>
lnGg1/ #ifdef _DEBUG
D*/fY=gK #define new DEBUG_NEW
g:s|D
hE[ #undef THIS_FILE
A=sz8?K+` static char THIS_FILE[] = __FILE__;
[!#}# #endif
G-| #define MAX_KEY 100
67Ev$a_d" #define CTRLBIT 0x04
D?FmlDTr[ #define ALTBIT 0x02
cTQ._|M #define SHIFTBIT 0x01
ITy/h]0 #pragma data_seg("shareddata")
?pWda<& HHOOK hHook =NULL;
N/eus"O; UINT nHookCount =0;
" {X0& static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
@&x'.2[nv static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
`!xI!Y\ static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
hka%!W5 static int KeyCount =0;
07]9VJa static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
>abpse #pragma data_seg()
L2c\i HINSTANCE hins;
A;k#8&; void VerifyWindow();
.u'MMe>^ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
D&x.io //{{AFX_MSG_MAP(CHookApp)
L|nFN}da // NOTE - the ClassWizard will add and remove mapping macros here.
?Y 5Vje[^ // DO NOT EDIT what you see in these blocks of generated code!
ehLn+tg //}}AFX_MSG_MAP
-p"}K~lt: END_MESSAGE_MAP()
SmAii}-jf kQp*+ras CHookApp::CHookApp()
>2v<;. {
X|yVRQ?F` // TODO: add construction code here,
6n|][! f // Place all significant initialization in InitInstance
_S,UpR~2W }
Gx*B(t]4y k;K-6<^h CHookApp theApp;
0+k..l LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
+R7pdi {
6E2#VT>@/ BOOL bProcessed=FALSE;
|h\A5_0_ if(HC_ACTION==nCode)
T
oT(' {
KAi_+/]K_ if((lParam&0xc0000000)==0xc0000000){// Key up
=sso )/3 switch(wParam)
R?y_tho4A {
`dWnu3r; case VK_MENU:
5LZs_%# MaskBits&=~ALTBIT;
P@Fx6 break;
BC5R$W.e case VK_CONTROL:
q VavP6I MaskBits&=~CTRLBIT;
HA0F'k break;
[E+J=L.l case VK_SHIFT:
&-!$qUli MaskBits&=~SHIFTBIT;
,M:[GuXD< break;
3dJiu default: //judge the key and send message
$inKI break;
j\NCoos }
z "z for(int index=0;index<MAX_KEY;index++){
Mf !S'\ if(hCallWnd[index]==NULL)
vY"I continue;
o2;Eti if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
*^Ro I {
%&0/Ypp= SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
DL d~ bProcessed=TRUE;
=nO:R, U }
4`ZoAr-5| }
\T!,Z;zK }
%zo
6A1Q; else if((lParam&0xc000ffff)==1){ //Key down
[mj=m?j switch(wParam)
cB_9@0r[S {
!E|R3eX_ case VK_MENU:
Z78i7k } MaskBits|=ALTBIT;
Sy]W4% break;
wn|;Li case VK_CONTROL:
#s' `bF^ MaskBits|=CTRLBIT;
2bG92 break;
.l|29{J case VK_SHIFT:
!? H:? MaskBits|=SHIFTBIT;
!1K.HdK break;
NJmx(!Xsh default: //judge the key and send message
E(wS6 break;
K4o']{:U }
LK!sk5/ for(int index=0;index<MAX_KEY;index++)
Efoy]6P\ {
qu!x#OY+ if(hCallWnd[index]==NULL)
m%UF{I, continue;
^6Zx-Mf\ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
wp'[AR} {
lHPnAaue@ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
WncHgz bProcessed=TRUE;
f,|;eF-Z }
\Ui8gDJ8y5 }
)T? BO }
,7 m33Pv* if(!bProcessed){
_\8E/4zh for(int index=0;index<MAX_KEY;index++){
X"mPRnE330 if(hCallWnd[index]==NULL)
W7(5z continue;
X-Ev>3H if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
:fnJp9c SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
.JTRFk{W }
}D`ZWTjDay }
Ui-Y` }
4=`1C-v?q return CallNextHookEx( hHook, nCode, wParam, lParam );
t=My=pG }
V|F/ynJfA s&+`> BOOL InitHotkey()
q(WGvl^r {
tOte[~, if(hHook!=NULL){
|eg8F$WU nHookCount++;
E2z=U return TRUE;
W$Xr:RU }
X\w["!B else
f="Zpl W hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
E{QjmlXQ< if(hHook!=NULL)
65VTKlDD nHookCount++;
OoRg:"9{# return (hHook!=NULL);
q&O9W?E8dG }
J_j4Zb% K BOOL UnInit()
>e(@!\ x {
MxUQ F?@6 if(nHookCount>1){
/?0|hi<_$ nHookCount--;
Wb#<ctM> return TRUE;
L>&{<M_ }
pAqPHD= BOOL unhooked = UnhookWindowsHookEx(hHook);
8kr$w$=q if(unhooked==TRUE){
8|$g"?CU nHookCount=0;
)~S`[jV5 hHook=NULL;
1(*+_TvZ }
TKbfZw return unhooked;
Tr4\ `a-i }
Yt{Z+.;9OI n5efHJU BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
L?P[{Ohh/ {
H3pZfdh?w BOOL bAdded=FALSE;
g;OR{ for(int index=0;index<MAX_KEY;index++){
@MoCEtt if(hCallWnd[index]==0){
:cIPX%S hCallWnd[index]=hWnd;
.wTb/x HotKey[index]=cKey;
;Xqi;EA HotKeyMask[index]=cMask;
PR AP~P&^ bAdded=TRUE;
[3ggJcUgW> KeyCount++;
K6)IBV; break;
I>w|80%% }
'vZy-qHrV }
9eE
FX7 return bAdded;
;PqC*iz }
sFvYCRw
/ 0"N4WH O BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
__uk/2q {
ar'VoL} BOOL bRemoved=FALSE;
Sj*W|n\gj for(int index=0;index<MAX_KEY;index++){
M0e&GR8<z> if(hCallWnd[index]==hWnd){
kmlO}0 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
u[4h|*'"| hCallWnd[index]=NULL;
^5>W`vwp HotKey[index]=0;
>HzTaXCR[ HotKeyMask[index]=0;
3j[<nBsn. bRemoved=TRUE;
/qq*"R KeyCount--;
|%rRALIY break;
u*oP:!s }
.lI.I }
y]!mN }
=%u=ma; return bRemoved;
yFDt%&*n^ }
naeppBo X3XTB* void VerifyWindow()
onS4ZE3B {
*13-)yfd
for(int i=0;i<MAX_KEY;i++){
M0)ZJti if(hCallWnd
!=NULL){ Fa </
if(!IsWindow(hCallWnd)){ OU^I/TU
hCallWnd=NULL; &sXk!!85:
HotKey=0; #"H<k(-Cz
HotKeyMask=0; %RzkP}1>E
KeyCount--; Lm0q/d2|\X
} `d
x.<R#,
} qjf4G[]!
} O -p^S
} V4W(>g
WS1Y maV
BOOL CHookApp::InitInstance() V.yDZ"
{ nn">
AFX_MANAGE_STATE(AfxGetStaticModuleState()); qA25P<