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:
M,{; xf
6+s&%io4 一、实现方法
b/#<::D ` ~% ]V,-4 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:
TOqxl XCn;<$3w #pragma data_seg("shareddata")
dKchQsgCg HHOOK hHook =NULL; //钩子句柄
:=q9ay UINT nHookCount =0; //挂接的程序数目
I(j{D>v static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
=''*'a-P static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
xTcY& static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
wt_ae|hv static int KeyCount =0;
<A\g*ld static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
\j
we #pragma data_seg()
%>O}bdSf 5*B'e{C 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
<x$fD37 %hBw)3;l 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:
kAxJ#RG F[v^43-^_ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
0q1+5 cKey,UCHAR cMask)
<P Vmr2Jp" {
wlP%
U BOOL bAdded=FALSE;
l,b_'
m@ for(int index=0;index<MAX_KEY;index++){
`\BBdQ#bH if(hCallWnd[index]==0){
k5)IBO hCallWnd[index]=hWnd;
,~K4+
t_ HotKey[index]=cKey;
GsqO^SV HotKeyMask[index]=cMask;
yW"}%)
d bAdded=TRUE;
,zBc-Cm KeyCount++;
]zvOM^l~ break;
p1ER<_fp }
lcoJ1+`C }
sQT,@+JEr return bAdded;
B=%YD"FAv }
Q6[h;lzGV //删除热键
_9/Af1X BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Z>'hNj)ju {
MB.LHIo BOOL bRemoved=FALSE;
kw1Lm1C for(int index=0;index<MAX_KEY;index++){
j8t_-sU9 i if(hCallWnd[index]==hWnd){
D6FG$SV if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
!<>`G0 hCallWnd[index]=NULL;
qMBEJ<o HotKey[index]=0;
\5)
ZI'q HotKeyMask[index]=0;
@oMl^UYM= bRemoved=TRUE;
5pE@Ww KeyCount--;
.Ag)/Xm(? break;
Vf(n }
}-WuHh# }
wmX * n'l }
\FyHIs return bRemoved;
3\P/4GK) }
~^eC?F( ".fnx8v, C2
!F DLL中的钩子函数如下:
vmtmiN8;d LFQPysC LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
DJ NM=v {
16N`xw+{ BOOL bProcessed=FALSE;
Y3luU&' if(HC_ACTION==nCode)
w6k^|." {
Fw"x4w if((lParam&0xc0000000)==0xc0000000){// 有键松开
dC">AW switch(wParam)
'KNUPi| {
?vP}#N!=d case VK_MENU:
!=+hU/e MaskBits&=~ALTBIT;
YW-Ge break;
`&A-m8X case VK_CONTROL:
S3/Z]?o MaskBits&=~CTRLBIT;
EPeV1$ break;
$D#eD. case VK_SHIFT:
)$FwB6^ MaskBits&=~SHIFTBIT;
rAQ3x0 break;
^eqq|(<K default: //judge the key and send message
qI gb;=V break;
UrB{jS? }
5CM]-qbf@ for(int index=0;index<MAX_KEY;index++){
Cx`?}A\% if(hCallWnd[index]==NULL)
&eX^ll continue;
}nNCgH if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
r6`KZ TU {
,tOc+3Qz$ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
J,wpY$93 bProcessed=TRUE;
()@+QE$ }
mv9@Az9 }
q VJC O-K| }
[Q20c<, else if((lParam&0xc000ffff)==1){ //有键按下
2ISnWzq; switch(wParam)
G]fx3= {
knu>{a} case VK_MENU:
q%}54E80 MaskBits|=ALTBIT;
+p)kemJ~ break;
Z <tJ+ case VK_CONTROL:
V8J!8=2 MaskBits|=CTRLBIT;
XiUae{j` break;
>c8EgSZJ case VK_SHIFT:
I78huYAYA MaskBits|=SHIFTBIT;
0SWec7G break;
p%y|w default: //judge the key and send message
}o#6g|"\sY break;
r}])V[V }
Z6r_T for(int index=0;index<MAX_KEY;index++){
rc]`PV if(hCallWnd[index]==NULL)
.^*
.-8q continue;
OLxiY r if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Z&0*\.6S~ {
w#`E;fN' SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
{3=]cLtt bProcessed=TRUE;
:+\B|*T2.L }
\*$''`b)j }
skn];%[v\ }
o%=OBTh_ if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
TW?A/GoXI for(int index=0;index<MAX_KEY;index++){
Ny)!uqul* if(hCallWnd[index]==NULL)
cYp]zn+6 continue;
V@Fj!/ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
2AI~Jm# SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
M2e_)f:
//lParam的意义可看MSDN中WM_KEYDOWN部分
'IroQ M }
ojZvgF }
yGtGhP8 }
=;^#5dpt$ return CallNextHookEx( hHook, nCode, wParam, lParam );
ue{0X\[P< }
r%~/y ?Dk&5d^d 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:
u>o2lvy8 }*I:0"WH BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
0 lsX~d'W BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
o72G oUfs WfE,U=e* 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:
\>*B ril4*$e7^\ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
zDO`w0N {
StJ&YYdD if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
YYUWBnf30G {
0(!D1G{ul //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
;y"quJ'O SaveBmp();
A296f( return FALSE;
?4,e?S6,[ }
ZkZTCb`/l …… //其它处理及默认处理
48 `k"Uy }
!B &%!06 B'Ll\<mq@ +
\AiUY 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。
{\+!@? R3SAt-IE 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。
8Yq_6 EpCsJ08K 二、编程步骤
..xg4V/ "eiZZSz 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";
%;|^*?!J0 B&E qd 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
?tLBEoUmKT y9OxPq.Cy 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;
0HRLTgIC *u4h+P 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;
_Hn-bp[?> nT.2HQ((Xg 5、 添加代码,编译运行程序。
$($26g ~]_gq;bG 三、程序代码
d)&}%
2ku pO.+hy ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
s*k[Fbi #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
3"Y
|RSy #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
N>S_Vgk} #if _MSC_VER > 1000
nDvj*lZF #pragma once
X)^kJ` #endif // _MSC_VER > 1000
-kVt_ #ifndef __AFXWIN_H__
:NJ(QkTZv #error include 'stdafx.h' before including this file for PCH
xM3T7PV9 #endif
ny:4L{) #include "resource.h" // main symbols
7]w]i5 class CHookApp : public CWinApp
mPy=,xYyC {
G92Ya^` public:
JC6Bs`=s~ CHookApp();
Q^qdm5}UkW // Overrides
R7)2@;i // ClassWizard generated virtual function overrides
&xG>"sJ //{{AFX_VIRTUAL(CHookApp)
i+)9ItZr public:
dd +%d virtual BOOL InitInstance();
1 U|IN= virtual int ExitInstance();
VgHVj)ir //}}AFX_VIRTUAL
Ne)H*DT //{{AFX_MSG(CHookApp)
\/Z?QBFvz // NOTE - the ClassWizard will add and remove member functions here.
'<.@a"DnJ // DO NOT EDIT what you see in these blocks of generated code !
D.hj9 //}}AFX_MSG
al9L+ruR DECLARE_MESSAGE_MAP()
#R<ErX)F };
478gl
o LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
0T{Z'3^= BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
U&uop$/Cq BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
1d4?+[)gUv BOOL InitHotkey();
j~d<n_ BOOL UnInit();
jU~
!*] #endif
([y 2x.kd Ydw04WEJ //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
_<`j?$P #include "stdafx.h"
QN!$4 1A?{ #include "hook.h"
HD1+0< #include <windowsx.h>
#@QZ #ifdef _DEBUG
^Gc#D:zU #define new DEBUG_NEW
s%K9;(RWI #undef THIS_FILE
h7iI=[_V static char THIS_FILE[] = __FILE__;
Gf(|?"
H #endif
iB =R #define MAX_KEY 100
'+6SkZ #define CTRLBIT 0x04
^{3,ok*Nf #define ALTBIT 0x02
9U[
A #define SHIFTBIT 0x01
BM_hW8&G #pragma data_seg("shareddata")
+}al_. HHOOK hHook =NULL;
Hy _ ( UINT nHookCount =0;
w^e5" og] static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
a9h K8e static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Sl,\<a static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
7$8YBcZ6 static int KeyCount =0;
sOegR5?; static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
h JVy-] #pragma data_seg()
fO+$`r>9 HINSTANCE hins;
1Y2]jz4 void VerifyWindow();
2WK]I1_ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
i$GL]0 //{{AFX_MSG_MAP(CHookApp)
8ug\GlZc // NOTE - the ClassWizard will add and remove mapping macros here.
r~&[Gaw // DO NOT EDIT what you see in these blocks of generated code!
Q Q3a& //}}AFX_MSG_MAP
%|&Wc pQR END_MESSAGE_MAP()
n*UD0U}` -RisZ-n* CHookApp::CHookApp()
5 *8V4ca {
owz6j: // TODO: add construction code here,
?pS,?>J f // Place all significant initialization in InitInstance
sEQA C9M }
ZK1H%&P=R zJhG`iWFw CHookApp theApp;
yMdE[/+3 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
h[|c?\E
z {
q2o`.f+I BOOL bProcessed=FALSE;
i(hI\hD if(HC_ACTION==nCode)
IQ$cLr-S {
|yqL0x0\l if((lParam&0xc0000000)==0xc0000000){// Key up
jea{BhdUr switch(wParam)
I\%a< {
S?ypka"L case VK_MENU:
p~/ MaskBits&=~ALTBIT;
;7jszs.6% break;
}Zs
y&K case VK_CONTROL:
nH6Ny MaskBits&=~CTRLBIT;
ia'eV10 break;
Q{s9{ case VK_SHIFT:
fwe4f MaskBits&=~SHIFTBIT;
>l<`)4*H break;
op\'T;xIu default: //judge the key and send message
7r F )fKW break;
m&o6j>C }
*]
H8X=[x for(int index=0;index<MAX_KEY;index++){
N:"S/G>r ; if(hCallWnd[index]==NULL)
=UGyZV:z5 continue;
S}@J4}*u[" if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
kx6AMx!nX {
k/6Qwb# SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Bu[sSoA bProcessed=TRUE;
}XJA#@ }
M0+xl+c+ }
4 f)B@A- }
g4Y1*`}2f else if((lParam&0xc000ffff)==1){ //Key down
b4Y< switch(wParam)
4=BIYC"Lu {
3PmM+}j3 case VK_MENU:
;\[n{<
MaskBits|=ALTBIT;
_,,w>q6K break;
Rm i4ZPb. case VK_CONTROL:
.uo9VL< MaskBits|=CTRLBIT;
36
&ghx break;
d`}t!]Gg case VK_SHIFT:
_#9F@SCA MaskBits|=SHIFTBIT;
u,E_Ezq break;
,~z*V;y) default: //judge the key and send message
w"A.*8Iu break;
M>eMDCB\ }
b3'U}0Ug for(int index=0;index<MAX_KEY;index++)
,>YW7+kY {
oGtz*AP% if(hCallWnd[index]==NULL)
~Ox !7Lp continue;
/6K9? / if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
2=\} 0 {
Nk#[~$Q-1 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
(hB+DPi bProcessed=TRUE;
})?t:zX#* }
<D_UF1Pk }
?pBQaUl& }
y'$Re if(!bProcessed){
Fv| )[>z0 for(int index=0;index<MAX_KEY;index++){
2LO8SJ# if(hCallWnd[index]==NULL)
QPc4bg\J~t continue;
ZOAHM1ci if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
J~}%j.QQ7 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
hDn?R}^l{ }
<5 ? }
G\X}gqe(OJ }
(uW$ch@2K return CallNextHookEx( hHook, nCode, wParam, lParam );
"!g}Q* }
|TQ#[9C0 0~/'c0Ho BOOL InitHotkey()
})V^t3 {
4r+@7hnK if(hHook!=NULL){
e&R?9z-* nHookCount++;
S)?V;@p6 return TRUE;
G!G]*p5 }
IonphTcU! else
#YiphR& hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
ZH~=;S-t if(hHook!=NULL)
k_o$ Ci nHookCount++;
Z9)-kRQz=r return (hHook!=NULL);
R^hlfKnt }
><&>JgM BOOL UnInit()
/h(bMb Z {
NFsCq_f if(nHookCount>1){
DN$[rCi7 nHookCount--;
6rP?$mn2 return TRUE;
prk@uYCa = }
io[>`@= BOOL unhooked = UnhookWindowsHookEx(hHook);
uht>@ WSg| if(unhooked==TRUE){
{V7W!0;! nHookCount=0;
qh]D=i hHook=NULL;
l_2B }
nT:F{2 M; return unhooked;
0xEr`]]U }
iaV%* Sc.@u3 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
1_=I\zx( {
"hbCP4 BOOL bAdded=FALSE;
u3G.xlHH[ for(int index=0;index<MAX_KEY;index++){
;%ng])w=; if(hCallWnd[index]==0){
x+Ws lN2a hCallWnd[index]=hWnd;
_+aMP=H HotKey[index]=cKey;
r.JM!x8 HotKeyMask[index]=cMask;
+$;#bw)yH bAdded=TRUE;
]4X08Cm^ KeyCount++;
BwJL)$D<S break;
znkc@8_4 }
Fd1t/B, }
qlNB\~HCe return bAdded;
k9*6`w }
gb^<6BYUG L=_ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
W6A-/;S\ {
%7S{g BOOL bRemoved=FALSE;
yADX^r( for(int index=0;index<MAX_KEY;index++){
nK8IW3fX9) if(hCallWnd[index]==hWnd){
hWz/PK, if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
a
!yBEpMo hCallWnd[index]=NULL;
hU~up a<dD HotKey[index]=0;
^&z3zFTp HotKeyMask[index]=0;
d%~OEq1i" bRemoved=TRUE;
g9.y`o}c KeyCount--;
W[G5+*i break;
e#<A\? }
MwHxn% }
wqasI@vyu }
cD5N'3 return bRemoved;
ev[!:*6P }
mb?r{WCi ) >H11o{& void VerifyWindow()
2)\gIMt% {
u$Wv*;TT% for(int i=0;i<MAX_KEY;i++){
sLOkLz"x if(hCallWnd
!=NULL){ ?Z2_y-
if(!IsWindow(hCallWnd)){ cl{kCSZo.z
hCallWnd=NULL; +UX~TT:
HotKey=0; Htm;N2$d
HotKeyMask=0; qCI0[U@
KeyCount--; #ULzh&yO
} b(Nxk2uv
} peZ'sZ 6
} g/W&Ap;qVL
} Da)H/3ii
n.b_fkZNr
BOOL CHookApp::InitInstance() )~{8C:
{ *?x[pqGq
AFX_MANAGE_STATE(AfxGetStaticModuleState()); VD90JU]X<
hins=AfxGetInstanceHandle(); m5%E1k$=
InitHotkey(); TNF+yj-|X:
return CWinApp::InitInstance(); ,c&%/"i:w
} p_EWpSOt7
8=,?Bh".
int CHookApp::ExitInstance() 3|
F\a|N
{ P_F0lO
VerifyWindow(); }Ryrd!3bY
UnInit(); [l*;+N+
return CWinApp::ExitInstance(); APv&
^\oUH
} Rebo.6rG
G\B:iyKl
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file 1#lH5|XQ
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) "3$P<Q\;l;
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ q!as~{!
#if _MSC_VER > 1000 `s\E"QeZN
#pragma once KN:V:8:J
#endif // _MSC_VER > 1000 m+EtB6r
1UN$eb7
class CCaptureDlg : public CDialog +(m*??TAV
{ *XkgwJq
// Construction Dq<!wtFG[
public: V`_)H
BOOL bTray; jJK@i\bU_
BOOL bRegistered; jMP;$w
BOOL RegisterHotkey(); IQyw>_~]
UCHAR cKey; Q[&CtM
UCHAR cMask; X8 A$&