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:
(Dl$k Gn
s1NKLt 一、实现方法
Hx*;jpy(2 tEK my7'# 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
G) 7;; TbGn46!: #pragma data_seg("shareddata")
Dg?70v<a HHOOK hHook =NULL; //钩子句柄
JB`\G=PiL UINT nHookCount =0; //挂接的程序数目
Q/_f
zg static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
`-l6S static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
x+x40!+\ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
HO%wHiv1X static int KeyCount =0;
\cUNsB5 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
4/1d&Sg #pragma data_seg()
R0vI bFwj 5Z\#0":e 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
ws|;` L>%o[tS DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
e5B Qr$j m{uxIza BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
)3w@]5j cKey,UCHAR cMask)
% !>I*H {
#+5pgD2C BOOL bAdded=FALSE;
aL%AQB, for(int index=0;index<MAX_KEY;index++){
muZ~*kMc if(hCallWnd[index]==0){
DRgTe&+ hCallWnd[index]=hWnd;
ul2")HL]; HotKey[index]=cKey;
&twf,8 HotKeyMask[index]=cMask;
ayD}r#7 bAdded=TRUE;
k
|%B?\m KeyCount++;
}J1tdko# break;
.CU5}Tv- }
YmgLzGk` }
?5cI' return bAdded;
mvZw }
J<maQ6p //删除热键
>U*T0FL7 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
? 1$fJ3 {
$UCAhG$ BOOL bRemoved=FALSE;
!@'6)/ for(int index=0;index<MAX_KEY;index++){
oMTf"0EIW if(hCallWnd[index]==hWnd){
JJ'.(( if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
`~;rblo; hCallWnd[index]=NULL;
@reeO= HotKey[index]=0;
C@W"yYt HotKeyMask[index]=0;
aKuSd3E@# bRemoved=TRUE;
h{p=WWK KeyCount--;
>ByXB!Wi+ break;
aZ'Lx:)R }
mB9r3[ }
}S$@ Ez6 }
BWuqo return bRemoved;
OYmR<x5y/ }
4NG?_D5& ux3<l +jv^ wG<(F}VX DLL中的钩子函数如下:
:!b'Vk `poE6\ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
LLXVNO@e+ {
P2'DD 3 BOOL bProcessed=FALSE;
!0C^TCuG if(HC_ACTION==nCode)
sWblFvHqrU {
SD$h@p=!= if((lParam&0xc0000000)==0xc0000000){// 有键松开
eI:C{0p= switch(wParam)
J6G(_(d {
E7)=`kSl case VK_MENU:
_Bp1co85MQ MaskBits&=~ALTBIT;
.h5[Q/*h break;
.]7Qu;L case VK_CONTROL:
09kt[
MaskBits&=~CTRLBIT;
h!:~f-@j4 break;
]U7KLUY>: case VK_SHIFT:
(BfgwC) MaskBits&=~SHIFTBIT;
/2Bi@syxK break;
?6jkI2w default: //judge the key and send message
'hv k break;
qt^T6+faaQ }
ZMLg;-T.&4 for(int index=0;index<MAX_KEY;index++){
3UQ;X**F if(hCallWnd[index]==NULL)
jSuL5|Gui continue;
cEd+MCN if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
9n5<]Q( {
Eb>78k(3I) SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
!G}+E2fDA bProcessed=TRUE;
Y.U[wL> }
T%n2$ }
Xy &uZ }
V-r3-b else if((lParam&0xc000ffff)==1){ //有键按下
#\ n8M switch(wParam)
0#*#a13 {
]
0m&(9 case VK_MENU:
3lq Mucr MaskBits|=ALTBIT;
JA_BKA break;
4bJZmUb case VK_CONTROL:
Mz;[ +p MaskBits|=CTRLBIT;
]B]*/ break;
]$\|ktY! case VK_SHIFT:
j$Je6zq0x MaskBits|=SHIFTBIT;
4[-*~C|W5 break;
p6XtTx default: //judge the key and send message
xvSuPP4 m break;
&gE 75B }
(?! ,p^ for(int index=0;index<MAX_KEY;index++){
"a/ Q%.P if(hCallWnd[index]==NULL)
u@%r continue;
BEgV^\u if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
:C8$Xi_i} {
^T,Gu-2> SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
H'UR8% bProcessed=TRUE;
T,OwM\`.X{ }
-tI'3oT1 }
fiN3xP]V
}
d/e|'MPX if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
LJTQaItdqJ for(int index=0;index<MAX_KEY;index++){
d{de6 ` if(hCallWnd[index]==NULL)
3#45m+D continue;
e=QK}gzX if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
uH;-z_Wpn! SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
D'hW| //lParam的意义可看MSDN中WM_KEYDOWN部分
D\YE^8/ }
!GQ\"Ufs> }
vuFBET, }
|s)?cpb return CallNextHookEx( hHook, nCode, wParam, lParam );
2',w[I
}
BiZ=${y
z|(+|pV( 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:
ii0Ce}8d~ wB{;bB{ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
/Y2/!mU</ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
F[!ckes<bB xN@Pz)yo 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:
R1W}dRE} c$QX)V LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
M}wXJ8aF? {
5 VA(tzmCt if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
FHPXu59u {
!HJ$UG/\ //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
)I-f U4? SaveBmp();
7 #=}:3c return FALSE;
A=-F,=k(!/ }
DF{Qw@P! …… //其它处理及默认处理
6 Ik,zQL }
leiW4Fj N9rBW M8b4NF_& 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。
@v*/R%rv t 5Fm=/o1 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。
|uH%6&\ Px>va01n 二、编程步骤
`ZaT}#Y M#@aB"@J> 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";
35*\_9/# LN_OD5gZ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
WWZ9._ VNtPKtx\ 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;
,[nm_^R*\ {3Vk p5%l 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;
U\?g* g3%t8O/M 5、 添加代码,编译运行程序。
ro[Y-o5Q0 l#wdpD a{ 三、程序代码
h
!(>7/Gi zK+52jhi ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
OW(&s,|6x #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
<[/%{sUNC #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
ozr9>b>M #if _MSC_VER > 1000
2`=6 %s
#pragma once
:;!\vfZbU #endif // _MSC_VER > 1000
#DkD!dW(l #ifndef __AFXWIN_H__
;bX4(CMe
& #error include 'stdafx.h' before including this file for PCH
H2-28XGc #endif
@lUlY2 #include "resource.h" // main symbols
te4= S
class CHookApp : public CWinApp
VRW]a {
Sb:T*N0gS public:
www`=)A; CHookApp();
BXUF^Hj% // Overrides
mEuHl> // ClassWizard generated virtual function overrides
s2v(=
//{{AFX_VIRTUAL(CHookApp)
yO>V/5` public:
2PSTGG8JV virtual BOOL InitInstance();
7>
Pgc virtual int ExitInstance();
K$REZe //}}AFX_VIRTUAL
XL}<1-} //{{AFX_MSG(CHookApp)
L6i|:D32p // NOTE - the ClassWizard will add and remove member functions here.
%E27.$E_ // DO NOT EDIT what you see in these blocks of generated code !
~-F?Mc //}}AFX_MSG
6bZ[Kt DECLARE_MESSAGE_MAP()
7=*VpX1 };
|H ;+1 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
7XyOB+aQO BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
lg1PE7 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
I2HT2c$ BOOL InitHotkey();
Cj;/Uhs
BOOL UnInit();
rFL$QC2 #endif
UlQQP^Na .%0ne:5 //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
Z]:BYX' #include "stdafx.h"
u&TdWZe #include "hook.h"
$X+u={] #include <windowsx.h>
pyW u9 #ifdef _DEBUG
=<<3Pkv7@ #define new DEBUG_NEW
e"+dTq8W #undef THIS_FILE
hQgN9S5P static char THIS_FILE[] = __FILE__;
S9Yt 1qb #endif
C/v}^#cLD #define MAX_KEY 100
|&hU=J
o #define CTRLBIT 0x04
0D)`2W #define ALTBIT 0x02
Z]-WFU_
N #define SHIFTBIT 0x01
s!6=|SS7 #pragma data_seg("shareddata")
]i8c\UV \ HHOOK hHook =NULL;
xT F=Y_ UINT nHookCount =0;
04y!\ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
CM~MoV[k7e static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
G"S5ki`o static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
Kv+Bfh static int KeyCount =0;
e4qj .b static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
ibF#$&! #pragma data_seg()
]X" / yAn HINSTANCE hins;
LBX%H GH void VerifyWindow();
Wtv#h~jy9 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
<uF [, //{{AFX_MSG_MAP(CHookApp)
_q Tpy)+ // NOTE - the ClassWizard will add and remove mapping macros here.
pX<a2FP // DO NOT EDIT what you see in these blocks of generated code!
S>ugRasZ$ //}}AFX_MSG_MAP
Vf{2dZZ{1 END_MESSAGE_MAP()
Xi~9&ed#$i PX 3 CHookApp::CHookApp()
h}=M^SL {
&P n] // TODO: add construction code here,
Z|`fHO3j // Place all significant initialization in InitInstance
=%h~/, }
S]yvMj_? #Mi|IwL CHookApp theApp;
{~GR8
U LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
WaYO1*= {
FWTx&Ip BOOL bProcessed=FALSE;
1| xN%27> if(HC_ACTION==nCode)
|ft:|/^F& {
2;N@aZX if((lParam&0xc0000000)==0xc0000000){// Key up
d~[UXQC switch(wParam)
9!t4> {
!O\X+#j case VK_MENU:
t>U!Zal" MaskBits&=~ALTBIT;
gEKO128 break;
qB JRS'6'9 case VK_CONTROL:
sA_X<>vAKJ MaskBits&=~CTRLBIT;
kQ }s/* break;
+?e}<#vd'? case VK_SHIFT:
)bYez MaskBits&=~SHIFTBIT;
H%Y%fQ~^ break;
dB`b9)Tk0z default: //judge the key and send message
IH3FK!>6 break;
<-|SIF }
`)tK^[,<W for(int index=0;index<MAX_KEY;index++){
98<zCSe\] if(hCallWnd[index]==NULL)
VC=6uB continue;
`$9L^Yg,4 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
31 ]7z {
4Vx+[8W SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
uiK:*[ bProcessed=TRUE;
!Y%D
9 }
>0T3'/k<H }
fSV5 }
h[l{ 5Z* else if((lParam&0xc000ffff)==1){ //Key down
*o|p)lH switch(wParam)
zH+<bEo=1= {
P|N?OocE case VK_MENU:
FR' b`Xv: MaskBits|=ALTBIT;
s,
-*q} break;
EVSK8T, case VK_CONTROL:
|!5@xs*T MaskBits|=CTRLBIT;
4qBY%1 break;
/.-m}0h|W- case VK_SHIFT:
aL$j/SC MaskBits|=SHIFTBIT;
B*Cb6'Q break;
fMB4xbpD default: //judge the key and send message
6bJ"$ o break;
O<a3DyUa; }
e3rfXhp for(int index=0;index<MAX_KEY;index++)
R1 qMg+ {
AJWLEc4XK if(hCallWnd[index]==NULL)
Vw?P.4 continue;
36i_D6 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
]n1D1 {
7xR|_+%~K SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
t>@yv# bProcessed=TRUE;
D'?]yyrf }
G 4"lZM }
0nT%Slbih }
TA9dkYlE/ if(!bProcessed){
YUS?]~XC7x for(int index=0;index<MAX_KEY;index++){
165WO}(;/ if(hCallWnd[index]==NULL)
s'AQUUrb< continue;
D`fc7m if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Wbs^(iUU} SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
9!S^^;PN& }
*lY+Yy( }
cqHw^{'8 }
vK`S!7x'& return CallNextHookEx( hHook, nCode, wParam, lParam );
oP,RlR }
DoTs9w|5 4Qhx[Hv>( BOOL InitHotkey()
aZC*7AK
{
_3zU,qm+ if(hHook!=NULL){
/W``LK>;? nHookCount++;
}*ODM6 return TRUE;
Z
c<]^QR }
z}mvX.j7 else
I &cX8Tw hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
Cd9t{pQD4 if(hHook!=NULL)
u-1@~Z nHookCount++;
n\
Gg6Y return (hHook!=NULL);
eFes+i( 35 }
5GUH;o1m BOOL UnInit()
o8mo=V4j {
$;ch82UiX if(nHookCount>1){
H WOek"}Z[ nHookCount--;
kEx8+2s=M return TRUE;
\cFAxL( }
i~ROQMN1 BOOL unhooked = UnhookWindowsHookEx(hHook);
$TFTIk*uU if(unhooked==TRUE){
lWIv(%/@ nHookCount=0;
@#1cx hHook=NULL;
r8<JX5zyuo }
{Wr\DVp return unhooked;
dY 6B%V }
B_b8r7Vn` d[yrNB6| BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
r \9:<i8 {
cy9N:MR(c BOOL bAdded=FALSE;
cyDiA(ot& for(int index=0;index<MAX_KEY;index++){
~S!L!qY if(hCallWnd[index]==0){
-aA<.+ hCallWnd[index]=hWnd;
my=*zziN HotKey[index]=cKey;
?!_u,sT HotKeyMask[index]=cMask;
YlG;A\]k bAdded=TRUE;
nO-d"S* KeyCount++;
rkbl/py break;
G)jG!`I }
[6oq## }
IBzHR[#,^ return bAdded;
O5c_\yv= }
EP/&m|o|G 5wy;8a BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Bfu/9ad {
![qRoYpbg8 BOOL bRemoved=FALSE;
fdg[{T4: for(int index=0;index<MAX_KEY;index++){
XlE$. if(hCallWnd[index]==hWnd){
osI- o~#> if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
jg7d7{{SB hCallWnd[index]=NULL;
aYqqq| HotKey[index]=0;
4p*?7g_WVH HotKeyMask[index]=0;
(}VuiNY<