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:
3,8>\yf`
^+zF;Q' 一、实现方法
}fW@8ji\ s[|sfqB1` 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:
2*6b{}yJH /jQW4eW0 #pragma data_seg("shareddata")
y K~;LV HHOOK hHook =NULL; //钩子句柄
LYPjdp2>"o UINT nHookCount =0; //挂接的程序数目
W'2|hP static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
0/d+26lR static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
/s3AZ j9 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
m$xL#omD static int KeyCount =0;
}g:y!pk static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
nz:I\yA #pragma data_seg()
(&4aebkZO q/Dc*Qn
m 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
hPhNDmL#3 `MAluu+b DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
r5XG$:$8\ i DV.L BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
%D|27gh cKey,UCHAR cMask)
(MiEXU~v {
j?ihUNY!+ BOOL bAdded=FALSE;
jN:!V t for(int index=0;index<MAX_KEY;index++){
Ycypd\q/ if(hCallWnd[index]==0){
4oT1<n`r+ hCallWnd[index]=hWnd;
PW"G]G, HotKey[index]=cKey;
xQX,1NbH5 HotKeyMask[index]=cMask;
7a Fvj bAdded=TRUE;
zhbp"yju7 KeyCount++;
9WsPBzi"T break;
Ep/4o<N( }
s5T$>+
a }
`#&pB0.y return bAdded;
&B\tcF }
F gM<2$h //删除热键
Q}~of}h/ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
LuQ4TT {
1>OfJc(K BOOL bRemoved=FALSE;
$Scb8< for(int index=0;index<MAX_KEY;index++){
RwMK%^b if(hCallWnd[index]==hWnd){
hM")DmvB4 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
vr<6j/ty hCallWnd[index]=NULL;
$}0q=Lg%wv HotKey[index]=0;
%"~\Pu*> HotKeyMask[index]=0;
"Zd4e2>{M\ bRemoved=TRUE;
B#'TF?HUEn KeyCount--;
Tx%6whd/' break;
&K5wCNX1 }
8Czy<}S<G }
;hi+.ng_ }
r-
0BLq]~{ return bRemoved;
i|PQNhUe }
6k"'3AKaR /w0l7N O;c;>x_dA DLL中的钩子函数如下:
Q.Hy"~ nYG$V)iCb LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
l\7N R {
'+1<7jl&I BOOL bProcessed=FALSE;
K2,oP )0.Y if(HC_ACTION==nCode)
EotZ$O= {
(#FWA<o if((lParam&0xc0000000)==0xc0000000){// 有键松开
,@ A1eX} switch(wParam)
sXp>4MomV {
Mi&,64< case VK_MENU:
)NJD+yQ% MaskBits&=~ALTBIT;
z5-vx ` break;
Z.+-MN WV case VK_CONTROL:
6>ZUx}vYj MaskBits&=~CTRLBIT;
<d~P;R(@ break;
8MgoAX,p case VK_SHIFT:
)tGeQXVhbJ MaskBits&=~SHIFTBIT;
XYIZ^_My break;
[8AGW7_ default: //judge the key and send message
9,=3D2x& break;
Y<M,/Y_ ! }
J
>Zd0Dn for(int index=0;index<MAX_KEY;index++){
[=079UN-X if(hCallWnd[index]==NULL)
O1IR+"0 continue;
= M^4T?{T if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
=8S*t5 {
=,&PD(. SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
j(mbUB* bProcessed=TRUE;
`#B|l+baq }
#4"(M9kf }
$6w[h7 }
!qPVC\l else if((lParam&0xc000ffff)==1){ //有键按下
Cw]&B switch(wParam)
{LfVV5? {
<CIJg* case VK_MENU:
ko\VDyt, MaskBits|=ALTBIT;
v'0A$`w` break;
Ovh
case VK_CONTROL:
z?`&HU Nf MaskBits|=CTRLBIT;
P.mz$M break;
-o*IJQ_ case VK_SHIFT:
"1>I/CM MaskBits|=SHIFTBIT;
AFO g*{1 break;
}z6@Z#%q default: //judge the key and send message
YG , break;
3RG*:9 }
;$Q`JN= for(int index=0;index<MAX_KEY;index++){
Lbk?( TL if(hCallWnd[index]==NULL)
3a #2 } continue;
?WE#%W7U if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
n[ip'*2L {
V8ka*VJ(B SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
;n_ |t/= bProcessed=TRUE;
Gqq%q!k&1 }
f.acH]p }
PPO*&=!] }
a5jc8S> if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
Pn|A>.)z for(int index=0;index<MAX_KEY;index++){
B}_*0D if(hCallWnd[index]==NULL)
uu L"o continue;
89T xd9X if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
XB*)d
9'8 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
3wK{? //lParam的意义可看MSDN中WM_KEYDOWN部分
x!GHUz*:uz }
(hej
3;W }
U 2am1} }
@qk$
6X return CallNextHookEx( hHook, nCode, wParam, lParam );
P3X;&iT }
!'uL V(Ll]g/T_; 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:
b,"gBg - &u]B$ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
yq+'O&+
BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
h`n,:Y^++P (c;F%m| 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:
-Yx'qz@ gSQq LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
}&A!h {
$5kb3x<W if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
vgY )
L {
a^_\ #,} //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
=.`(KXT SaveBmp();
.lnyn|MVb return FALSE;
a@:(L"Or }
:VpRpj4f …… //其它处理及默认处理
734)s }
d_s=5+Yj 94 58.!3 +{U0PI82 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
#DK@&Gv ^\=<geEj 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
)
=-$>75Z vYQ0e:P 二、编程步骤
$SAq/VHI1] ;8\w$SPP 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";
_b8&$\> A;ip
V :) 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
pw|f4c7AH B1)gudP` 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
+(n&>75 ?O3E.!Q| 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
q5C(/@)^ ~L\KMB/9e= 5、 添加代码,编译运行程序。
#MkXio; h -7E)u 三、程序代码
"TW%-67 y#F`yXUj ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
pu#h:nb>88 #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
02B *cz_K #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
D2N| A #if _MSC_VER > 1000
K8[vJ7(!| #pragma once
3!E*h0$} #endif // _MSC_VER > 1000
ZL/iX~}a' #ifndef __AFXWIN_H__
<q@/Yy32 #error include 'stdafx.h' before including this file for PCH
#1fT\aP #endif
t;005]'Mp #include "resource.h" // main symbols
BfZAK0+*$ class CHookApp : public CWinApp
3
RB+ {
>np!f8+d"q public:
)!SA]>- CHookApp();
'fpm] *ig // Overrides
|f5WN&c // ClassWizard generated virtual function overrides
32h}+fd //{{AFX_VIRTUAL(CHookApp)
dH:z_$Mg public:
<u "xHl8Io virtual BOOL InitInstance();
4<%(Y-_sF virtual int ExitInstance();
Y%<y`]I //}}AFX_VIRTUAL
eS(hLXE!7 //{{AFX_MSG(CHookApp)
`pr$l // NOTE - the ClassWizard will add and remove member functions here.
7#/->Y // DO NOT EDIT what you see in these blocks of generated code !
sG-$d\
1d //}}AFX_MSG
8<V6W F`e DECLARE_MESSAGE_MAP()
NGQBOV };
<ZmC8&Uo LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
dy/\>hu BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Jr|"QRC BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
~,#zdm1r@ BOOL InitHotkey();
:
:;YS9e BOOL UnInit();
aumWU{j= #endif
BK>3rjXi>a {jz?LM //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
yM* CA,(c #include "stdafx.h"
TA;r #include "hook.h"
WX.6| #include <windowsx.h>
QuFzj`( #ifdef _DEBUG
VF#2I%R* #define new DEBUG_NEW
o[=h=&@5p #undef THIS_FILE
wJ.?u]f@ static char THIS_FILE[] = __FILE__;
K]c|v
i_D #endif
kyV!ATL1F #define MAX_KEY 100
vh+ '
W #define CTRLBIT 0x04
,uz+/K%OA5 #define ALTBIT 0x02
/G[2
#define SHIFTBIT 0x01
\
a}6NIo #pragma data_seg("shareddata")
~x67v+I HHOOK hHook =NULL;
2;8I0BH*' UINT nHookCount =0;
[l~Gwaul> static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
ng,64(wOY static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
|#OMrP+oi static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
,_SE!iL static int KeyCount =0;
#B_Em$ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
2=R}u-@6p #pragma data_seg()
W=QT-4 HINSTANCE hins;
r.-U=ql void VerifyWindow();
UXs=7H". BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
Cn\5Vyrl //{{AFX_MSG_MAP(CHookApp)
SNLZU%jan // NOTE - the ClassWizard will add and remove mapping macros here.
sd(Yr6~.. // DO NOT EDIT what you see in these blocks of generated code!
jV W .=FK //}}AFX_MSG_MAP
^wnlZ09J END_MESSAGE_MAP()
%w9/gD %IAZU c CHookApp::CHookApp()
?HD
eiJkX {
[Eq7!_3 // TODO: add construction code here,
|A .U~P): // Place all significant initialization in InitInstance
+V2\hq[{ }
%P3|#0yg0 VIIBw CHookApp theApp;
YgiLfz iT LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
<H; z4 {
`5SLo=~ BOOL bProcessed=FALSE;
Z~X \Z. if(HC_ACTION==nCode)
vw.rkAGY {
yM_ta '^$ if((lParam&0xc0000000)==0xc0000000){// Key up
F+!w[}0 switch(wParam)
%#AM }MWIa {
x6n( BMr case VK_MENU:
F,hiKq* MaskBits&=~ALTBIT;
v8{ jEAK break;
Wi;wu* case VK_CONTROL:
B|fh 4FNy MaskBits&=~CTRLBIT;
v d{`*|x break;
c@|!0
U%j case VK_SHIFT:
*|Bu 7nwg MaskBits&=~SHIFTBIT;
to2#PXf]y break;
ejFGeR default: //judge the key and send message
NE~R&ym9 break;
^-wdIu~p? }
#1,"^k^ for(int index=0;index<MAX_KEY;index++){
0c-.h if(hCallWnd[index]==NULL)
6H]rO3[8 continue;
~]w|ULNa3| if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
_ ^2\/@ {
E%.w6- SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
i(Xz3L#( bProcessed=TRUE;
"d5nVO/ }
d:<</ah }
pqT+lai)# }
]3 KMFV} else if((lParam&0xc000ffff)==1){ //Key down
1QA{NAnu& switch(wParam)
Q<c{$o {
SlaHhq3 case VK_MENU:
/r8'stRzv MaskBits|=ALTBIT;
s^&Oh*SP* break;
=/#+, case VK_CONTROL:
{s{bnU MaskBits|=CTRLBIT;
_ArN[]Z break;
/W|=Or2oR case VK_SHIFT:
Y^Y1re+} MaskBits|=SHIFTBIT;
w'r?)WW$ break;
R(^2+mV? default: //judge the key and send message
H^d2|E[D break;
#9/^)^k }
@$*LU:[ for(int index=0;index<MAX_KEY;index++)
w;OvZo| {
0[
BPmO6 if(hCallWnd[index]==NULL)
t@#l0lu$ continue;
2 -C*RHRx if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
IG(1h+5R( {
pzcl@ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
o5(~nQ bProcessed=TRUE;
F
]x2;N }
xHpB/P ~ }
Gi+ZI{) }
W2`/z)[*> if(!bProcessed){
Lw1aG;5 for(int index=0;index<MAX_KEY;index++){
):L ; P) if(hCallWnd[index]==NULL)
AY(z9&;6 continue;
SDbR(oV if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Ovhd%qV;Y SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
'JpCS }
e[($rsx }
AE@N:a }
ll^#I/ return CallNextHookEx( hHook, nCode, wParam, lParam );
_!ITCkBj }
>qL-a*w:a f\vy5'' BOOL InitHotkey()
/\wm/Yx?S {
'V`Hp$r if(hHook!=NULL){
dRGgiQO nHookCount++;
'
X9D( ?O return TRUE;
$&ZN%o3 }
X~VJO|k pz else
s#*
DY hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
%+bw2;a6 if(hHook!=NULL)
X4$86 nHookCount++;
1
k\~% return (hHook!=NULL);
U3tA"X.K }
Ve9*>6i&-4 BOOL UnInit()
\s@7pM=( {
; !9-I%e if(nHookCount>1){
gLzQM3{X9 nHookCount--;
,3,(/%=k return TRUE;
LcW:vV|'K }
7Ap==J{a BOOL unhooked = UnhookWindowsHookEx(hHook);
Q~-M B]' if(unhooked==TRUE){
RQ*oTsq nHookCount=0;
w7e+~8| hHook=NULL;
"/g\?Nce }
DlF6tcoI return unhooked;
zf.&E3Sn }
+d289" "V3f"J? BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
[9H986= {
d8Sr,t+ BOOL bAdded=FALSE;
YsA., for(int index=0;index<MAX_KEY;index++){
o/\f+iz7 if(hCallWnd[index]==0){
v2KK%Qy hCallWnd[index]=hWnd;
OaF[t*]D3 HotKey[index]=cKey;
s;Sv@=\ HotKeyMask[index]=cMask;
1=Y pNXX bAdded=TRUE;
G|+naZ KeyCount++;
pRc<U^Z.h break;
C#oH7o+_. }
7f_tH_( }
P>wTp) return bAdded;
)+dd }
~&%&Z f}ES8Hh[ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
nJr:U2d {
\wb0%>
0 BOOL bRemoved=FALSE;
@A1Ohl for(int index=0;index<MAX_KEY;index++){
f2,\B6+ if(hCallWnd[index]==hWnd){
UC*\3:>'n if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
eZvG hCallWnd[index]=NULL;
^b&U0k$R HotKey[index]=0;
( SiwO.TZ HotKeyMask[index]=0;
X775j"<d bRemoved=TRUE;
'nP;IuMP KeyCount--;
Xo/0lT break;
W</\F& }
\agT#tTJ }
Scz/2vNi` }
.?dYY;P return bRemoved;
W_FN*Er }
3v,Bg4[i Br}0dha3E void VerifyWindow()
:&\^r=D {
iT,Ya-9" for(int i=0;i<MAX_KEY;i++){
R.)w
l if(hCallWnd
!=NULL){ ]MaD7q>+R
if(!IsWindow(hCallWnd)){ S*Hv2sl
hCallWnd=NULL; CZ|h` ";P2
HotKey=0; lCxPR'C|
HotKeyMask=0;
R7NE=X4
KeyCount--;
.H7xG'$
} F&)(G\
} x2$Y"b?vz
} <:!;79T\
} kx6-8j3gD7
`\M}~
BOOL CHookApp::InitInstance() 5$<Ozkj(
{ ~(Xzm
AFX_MANAGE_STATE(AfxGetStaticModuleState()); V:>ZSW4,^
hins=AfxGetInstanceHandle(); hw)#TEt
InitHotkey(); O]-s(8Oo3
return CWinApp::InitInstance(); 2/f!{lz ](
} BQF7S<O+
Ek,$XH
int CHookApp::ExitInstance() nv}z%.rRUj
{ mgI 7zJX
VerifyWindow(); _eg&