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:
!*JE%t
sq1Z;l31" 一、实现方法
a"ZBSg( -L<''2t 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:
-b'93_ZTu: XMzL\Edo #pragma data_seg("shareddata")
Z\Qa6f! HHOOK hHook =NULL; //钩子句柄
ky*-THS UINT nHookCount =0; //挂接的程序数目
6P@3UQ)}s static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
8#b>4Dx static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
5:ca6H static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
tai static int KeyCount =0;
1<g,1TR static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
/|v:$iH,C #pragma data_seg()
z'FD{xdf T"ors]eI 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
s2s}5b3 j<[+vrj DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
4|i.b?" rN* ,U\q BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
H%2Y8} cKey,UCHAR cMask)
yv2BbrYyy {
}H2<w-,+ BOOL bAdded=FALSE;
5[NF for(int index=0;index<MAX_KEY;index++){
kH$)0nK if(hCallWnd[index]==0){
?L.c~w;l hCallWnd[index]=hWnd;
XoI,m8A HotKey[index]=cKey;
CtItzp HotKeyMask[index]=cMask;
/4w"akB|P bAdded=TRUE;
a:nMW '! KeyCount++;
3N%%69JN) break;
-OY[x|0 }
~&) }
Rf7*Ut
wVr return bAdded;
2pa:
3O }
tS!|#h-J //删除热键
RDX".'`(= BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
m<]b]FQ {
^}nz^+R BOOL bRemoved=FALSE;
96M?tTa for(int index=0;index<MAX_KEY;index++){
% heX06 if(hCallWnd[index]==hWnd){
[;O 6)W if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
'Y`.0T[& hCallWnd[index]=NULL;
QI\ &D)
HotKey[index]=0;
Z[+H$ =$% HotKeyMask[index]=0;
eyPh^c]?`8 bRemoved=TRUE;
gHCk;dmq81 KeyCount--;
ODE9@]a break;
eLC}h % }
NY]`1yy }
=FZt }
eq>E<X#< return bRemoved;
r[2N;U }
GWP;;x% X2ShxD| %) A-zzj DLL中的钩子函数如下:
d3
h^L X[pk9mha LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
qSj$0Hq5XI {
doJ\7c5uU BOOL bProcessed=FALSE;
MN|8(f5Gs if(HC_ACTION==nCode)
z>_jC+ {
P8#;a if((lParam&0xc0000000)==0xc0000000){// 有键松开
SVvR]T&_ switch(wParam)
?9<byEO%M {
{-X8MisI case VK_MENU:
P=ARttT`( MaskBits&=~ALTBIT;
^"Y5V5 break;
K&{*sa r case VK_CONTROL:
3PS(1 MaskBits&=~CTRLBIT;
q r12"H break;
5tyr$P! N case VK_SHIFT:
:{pJ MaskBits&=~SHIFTBIT;
i7^_y3dG break;
7=jeq|&kN default: //judge the key and send message
5~WMb6/ break;
Q{9#Am^6w }
\W73W_P&g for(int index=0;index<MAX_KEY;index++){
# f~,8<K if(hCallWnd[index]==NULL)
G(piq4D continue;
UMe@[E= if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
gwFHp.mE {
Gx75EQ2 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
%trtP bProcessed=TRUE;
TRQX#))B }
F[ca4_lK }
RU`m|< }
iRwqt-WZ else if((lParam&0xc000ffff)==1){ //有键按下
g2
dvs switch(wParam)
-#XNZy!// {
imE5$; case VK_MENU:
XO |U4#ya MaskBits|=ALTBIT;
r{~K8!=oU] break;
GdN'G case VK_CONTROL:
^s'ozCk 0 MaskBits|=CTRLBIT;
2+G_Y> break;
XWo=?(iA case VK_SHIFT:
<fY<.X MaskBits|=SHIFTBIT;
%dXf C! break;
/?b<}am default: //judge the key and send message
L|DSEth break;
V0p@wG3 }
hM*T{|y for(int index=0;index<MAX_KEY;index++){
'WH@Zk/l if(hCallWnd[index]==NULL)
@Bfwb?& continue;
}<Y3jQnl if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
AuZ?~I1 {
n*\AB=|X SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
:z=/z!5:j bProcessed=TRUE;
4i'2~w{/ }
a.F6!? }
/wIev1Z!Y }
1a{~B# if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
C._I\:G^ for(int index=0;index<MAX_KEY;index++){
6"Tr$E if(hCallWnd[index]==NULL)
64s9Dy@%F continue;
~g2ColFhu if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
~mUP!f SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
|L{<=NNs:D //lParam的意义可看MSDN中WM_KEYDOWN部分
GXaCH))TO }
htg+V-, }
LyA=(h6 }
?5m[Qc(< return CallNextHookEx( hHook, nCode, wParam, lParam );
'{EBK }
tYt/m6h ]2Aqqy 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:
;F@dN,Y Kb%j;y BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
YW"?Fy BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
;8sEE?C$g o?P(Fuf 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
hB:R8Y^?H Fs:l"5~>1 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
_:om(gL {
zk]6|i$!I if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
~S Js2-2 {
di6A.N5A //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
BzH7E[R49 SaveBmp();
9s)YPlDz return FALSE;
UC*<] }
2vKnxK+ 5 …… //其它处理及默认处理
FE1dr_i }
kl[bDb1p DSix(bs9 7<{Zq8) 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。
6<A\U/ zx{\SU 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。
Qwx}e\= hD\C[C, 二、编程步骤
Cm}ZeQ 5}e-~- 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";
lqPRUkin 9&}qie, 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
NW=j>7 LJZEM;;} 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;
{Z;W|w1t :i*JlKHJd 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;
cd}TDd(H% ]\P 5、 添加代码,编译运行程序。
?"AcK"v ,%dn)gt7 三、程序代码
;BoeE3*
6 V&KH{j/P ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
xPqpNs-, #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
n2-R[W^ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
=}7wpTc, #if _MSC_VER > 1000
fE)+9! #pragma once
s4SR6hBO #endif // _MSC_VER > 1000
vE?qF9I{$0 #ifndef __AFXWIN_H__
?Z!itB~ #error include 'stdafx.h' before including this file for PCH
oq]KOj[ #endif
gzzPPd,hd #include "resource.h" // main symbols
}W<]fK class CHookApp : public CWinApp
sr#,S(p {
_?Jm.nT public:
!0`ZK-nA6 CHookApp();
4$.UVW\ // Overrides
) !ZA.sx // ClassWizard generated virtual function overrides
-$WiB //{{AFX_VIRTUAL(CHookApp)
txr!3-Ne'! public:
$if(`8 virtual BOOL InitInstance();
)'%L#
virtual int ExitInstance();
oG@P M+{ //}}AFX_VIRTUAL
ZH:#~Zyj //{{AFX_MSG(CHookApp)
21 cB_" // NOTE - the ClassWizard will add and remove member functions here.
G`|mP:T:o // DO NOT EDIT what you see in these blocks of generated code !
KUH&_yCRB //}}AFX_MSG
+cy(}Vp DECLARE_MESSAGE_MAP()
zGZe|- };
biGaP#"0 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
GLc+`,. BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
?h>mrj BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
1Sz5&jz BOOL InitHotkey();
>!? f6
{\| BOOL UnInit();
xNxIqq<k #endif
%XG X( RWA|%/L //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
,O
a) #include "stdafx.h"
/q='~t #include "hook.h"
s'\"%~nF< #include <windowsx.h>
F$F5N1< #ifdef _DEBUG
~>}BDsM #define new DEBUG_NEW
Bb:jy!jq_ #undef THIS_FILE
*N'B(j/ static char THIS_FILE[] = __FILE__;
j-
F=5)A #endif
$BH0W{S #define MAX_KEY 100
0?,EteR #define CTRLBIT 0x04
.M:,pw"S] #define ALTBIT 0x02
+$},Hu69j #define SHIFTBIT 0x01
"
I`YJEv #pragma data_seg("shareddata")
(a7IxW HHOOK hHook =NULL;
w #(XiH* UINT nHookCount =0;
GUat~[lUrj static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
|Z 3POD"9 static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
vn}Vb+@R static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
^@X
=v`C static int KeyCount =0;
JpS:}yyJ>N static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
Pn 7oQA\ #pragma data_seg()
`5 e#9@/e HINSTANCE hins;
NqqLRgMOR' void VerifyWindow();
z8z U3? BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
C?x //{{AFX_MSG_MAP(CHookApp)
uc7np]Z // NOTE - the ClassWizard will add and remove mapping macros here.
jIdhmd* $z // DO NOT EDIT what you see in these blocks of generated code!
,PN>,hFL //}}AFX_MSG_MAP
Kq!n`@ END_MESSAGE_MAP()
DU1,i&( ` S85i* CHookApp::CHookApp()
mg >oB/,'Z {
&2?kD{ // TODO: add construction code here,
zP=J5qOZ8 // Place all significant initialization in InitInstance
TqbKH08i/ }
SKRD{MRsux d G:=tf&1R CHookApp theApp;
>b*Pd
*f LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Fd'Ang6" {
8a?V h^ BOOL bProcessed=FALSE;
<Bu*: O if(HC_ACTION==nCode)
$$qhX]^~ {
>Ckb9A if((lParam&0xc0000000)==0xc0000000){// Key up
$ HUCp9 switch(wParam)
3v0)oK {
Nt/*VYUn case VK_MENU:
<j,7Z>Rk\x MaskBits&=~ALTBIT;
OgfQGGc break;
p3^7Hr case VK_CONTROL:
>{GC@Cw MaskBits&=~CTRLBIT;
lBh {8a|2W break;
O4$:
xjs case VK_SHIFT:
u%*;gu"2 MaskBits&=~SHIFTBIT;
=}c~BHT break;
SKG_P)TnO default: //judge the key and send message
P$4?-AZ break;
9@vY(k k }
|y'q`cY for(int index=0;index<MAX_KEY;index++){
VCc4nn# if(hCallWnd[index]==NULL)
_'j>xK continue;
M>I}^Zp! if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
+%gh? {
>)S
a#w; SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
]Uxx_1$, bProcessed=TRUE;
PVtQ&m$y }
.+[[m$J }
HmX(=Y }
;UPw;' else if((lParam&0xc000ffff)==1){ //Key down
:EA,0 , switch(wParam)
OB$A"XGAEV {
EKoCm)}d case VK_MENU:
NU
6P MaskBits|=ALTBIT;
QT-rb~ break;
N+}yw4lb case VK_CONTROL:
3rR(>}:[V MaskBits|=CTRLBIT;
$V\xN(Ed break;
BwBv'p+n case VK_SHIFT:
, H[o.r= MaskBits|=SHIFTBIT;
VJ1`& break;
bt
j\v[D default: //judge the key and send message
9Xm"kVqd/ break;
VNytK_F0P }
}l[t0C
t for(int index=0;index<MAX_KEY;index++)
e dD(s5 {
TS1k'<c? if(hCallWnd[index]==NULL)
&$+yXN continue;
1y?TyUP if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Y,&)%Eo< {
Z3#3xG5pl SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Tp0Tce/ bProcessed=TRUE;
92} ,A`= }
ZGp8$Y>r }
7`WK1_rR\ }
IPT}JX' if(!bProcessed){
St(7@)gvY for(int index=0;index<MAX_KEY;index++){
s}HTxY; if(hCallWnd[index]==NULL)
zizrc.g/Yg continue;
0q62 {p7 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
WnIh (
0 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
E26ZVFg }
myJsRb5 }
fitm* }
% l5J return CallNextHookEx( hHook, nCode, wParam, lParam );
* |,V$ }
2oq>tnYyV[ {(aJrSE<z BOOL InitHotkey()
%OzxR9 {
8"S0E(,mu if(hHook!=NULL){
Ajq<=y`NzV nHookCount++;
) I5f`r=Ry return TRUE;
a{)"KA P }
9h9Y:i*Gh5 else
#~ >0Dr hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
Y*7.3 +# if(hHook!=NULL)
Kk/qd)nk nHookCount++;
hy6px return (hHook!=NULL);
&i!.6M2 }
Mv;7kC7] BOOL UnInit()
*.~M#M 9c {
:z^c<KFX if(nHookCount>1){
KD#ip3 nHookCount--;
\GPWC}V\s return TRUE;
Cjwg1?^RZ }
F!Nx^M1 BOOL unhooked = UnhookWindowsHookEx(hHook);
:/1WJG:! if(unhooked==TRUE){
IXC: Q
nHookCount=0;
g/T`4"p[H hHook=NULL;
+i
K.+B }
t(s']r return unhooked;
5$9j&&R }
pRYt.}/K e+&/Tq'2 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
aFl(K\ {
,>e<mphM BOOL bAdded=FALSE;
&{7%VsTB for(int index=0;index<MAX_KEY;index++){
W}T$ Z if(hCallWnd[index]==0){
[z Y9"B<3 hCallWnd[index]=hWnd;
(s\Nm_j HotKey[index]=cKey;
Lo !kv* HotKeyMask[index]=cMask;
7j@TW%FmV\ bAdded=TRUE;
o 0fsM;K KeyCount++;
R2r0'Yx break;
q`qbaX\J3 }
=NlAGzv!w }
RJSNniYr7 return bAdded;
n!f@JHL }
.Z9Bbab: %40|7O BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
`XI1,&Wp7 {
^#_@Kq%th BOOL bRemoved=FALSE;
zR]l2zL3 for(int index=0;index<MAX_KEY;index++){
1tfm\/V}ho if(hCallWnd[index]==hWnd){
R|5w :+=z if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
+VzR9ksJj hCallWnd[index]=NULL;
i\N,4Fdor HotKey[index]=0;
sdrE4-zd HotKeyMask[index]=0;
HhIa=,VY bRemoved=TRUE;
tn:tM5m KeyCount--;
M|e@N break;
$ABW|r }
r1t TY? }
c!6.D }
HbV[L)zYG return bRemoved;
QCMt4`%'u }
Q?Q!D+~mND ^gD&Nb