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:
VO] Jvf
>*(4evU 一、实现方法
f50qA;7k ~Z!xS 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:
O`~G'l&@T Po'yr] pr #pragma data_seg("shareddata")
yw^t6E HHOOK hHook =NULL; //钩子句柄
gV1&b
(h UINT nHookCount =0; //挂接的程序数目
l~!Tnp\M static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
#Z;ziM: static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
"(PJh\S>S static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
QDYS}{A:V static int KeyCount =0;
58,_ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
tuo'4%]i #pragma data_seg()
UeV2`zIg` Ck8`$x&t 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
rVowHP q{@j$fMt0 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:
rpu9 767xCP BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
.%_scNP cKey,UCHAR cMask)
G,9osTt/ {
5|f[evQj<S BOOL bAdded=FALSE;
.",E}3zn for(int index=0;index<MAX_KEY;index++){
b2u_1P\ if(hCallWnd[index]==0){
';us;xR# hCallWnd[index]=hWnd;
{LYA?w^GT HotKey[index]=cKey;
..V6U"/ HotKeyMask[index]=cMask;
\!j{&cJ bAdded=TRUE;
28JWQ%- KeyCount++;
wcUf?`21, break;
ke_Dd? }
Q<B=m6~ }
G 5w: return bAdded;
}C!N$8d, }
&MsnQP //删除热键
#X'!wr|- BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
o7S,W?;=5
{
Zm& X $U BOOL bRemoved=FALSE;
li;Np5P for(int index=0;index<MAX_KEY;index++){
GV#"2{t
j if(hCallWnd[index]==hWnd){
(.4mX
t if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
W4Rs9NA} hCallWnd[index]=NULL;
b/cc\d < HotKey[index]=0;
5BR9f3} HotKeyMask[index]=0;
0][PL%3Z bRemoved=TRUE;
,!_$A}@0
^ KeyCount--;
]f#ZU{A'mt break;
VeeQmR?u- }
Ic/D!J{Y }
fvK):eCo }
}md[hi J return bRemoved;
K.4t*-<`[ }
J[2c[|[- zC#[ <x@brXA DLL中的钩子函数如下:
<o,]f E[ yM>:,T S LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
@N,dA# {
pYIm43r H BOOL bProcessed=FALSE;
'bVDm m). if(HC_ACTION==nCode)
4^\5]d! {
5D9I;L{ if((lParam&0xc0000000)==0xc0000000){// 有键松开
Lb;:< switch(wParam)
oG~a`9N%C {
Uu
~BErEC case VK_MENU:
=EwC6+8*M MaskBits&=~ALTBIT;
Wm\HZ9PN break;
}bIbMEMn case VK_CONTROL:
gBb+Q, MaskBits&=~CTRLBIT;
89ivyv;]U break;
qE?*:$ case VK_SHIFT:
vpu20?E>5z MaskBits&=~SHIFTBIT;
`7$0H]*6 break;
5/4N Y default: //judge the key and send message
l2Z!;Wm( break;
W@U<GF1 }
TY}9;QL: for(int index=0;index<MAX_KEY;index++){
e<o{3*%p) if(hCallWnd[index]==NULL)
[)UL}vAO\q continue;
wh8h1I
if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
7 -yf {
)Zud|%L SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
t;X
!+ bProcessed=TRUE;
1}nrVn[B9 }
W&>ONo6ki }
%GS^=Qr }
{ ]Tb else if((lParam&0xc000ffff)==1){ //有键按下
,SQmQ6h switch(wParam)
A'Q=DoE {
S%J $.ge case VK_MENU:
b.HfxYt( MaskBits|=ALTBIT;
sk*AlSlM break;
Hw[(v[v case VK_CONTROL:
m/}(dT; MaskBits|=CTRLBIT;
}i,LP1R break;
k~
Z9og case VK_SHIFT:
W~(4t:hp MaskBits|=SHIFTBIT;
V`:iun^f break;
cb|cY Co5 default: //judge the key and send message
qy@v,a break;
%T9'dcM }
J3/2>N]/} for(int index=0;index<MAX_KEY;index++){
xZ2^lsY if(hCallWnd[index]==NULL)
2^Y@e=^A continue;
`Hj{XIOx if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
|ci1P[y {
e'%"G{(D SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
.CU~wB@h bProcessed=TRUE;
j;%RV)e }
E(t:F^z&D }
2Cy">Exl }
Py?EA*(d# if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
4-ijuqjN for(int index=0;index<MAX_KEY;index++){
7,vvL8\NHu if(hCallWnd[index]==NULL)
}<G"w5.< continue;
4n1-@qTPF~ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
p\xi5z SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
#Z%?lx"Q0 //lParam的意义可看MSDN中WM_KEYDOWN部分
9hoTxWpmy }
f(=3'wQ }
Um4$. BKD }
&+"-'7 return CallNextHookEx( hHook, nCode, wParam, lParam );
,UOAGu<_gb }
47]?7GU, 42 6l:>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:
LHy-y%?i OXT'$]p.* BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
lawjGI BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
bBwMx{iNNz }vzZWe 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
J2tD).G <|qh5Scp LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
">$.>sn{ {
/K+GM8rtE if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Y@&1[Z {
4[q'1N6- //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
Mv\odf\] SaveBmp();
*^h$%<QI return FALSE;
s#f6qj }
N\Nw mx …… //其它处理及默认处理
4VPJv>^ }
'a&( r; _6Ex}`fyJ
FrPpRe %! 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
]g}Tqf/N% kaKV{;UM 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
0/r\#"+XT S`N_}, 二、编程步骤
(YOp |.8lS3C 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
T[$! ^WT f;Cu@z{b 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
^N{Lau M@R_t(&= 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;
]yR0"<W^xO lDBn3U&z> 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;
w-[A"M]I ^+v6?%m 5、 添加代码,编译运行程序。
rXortK#\% zAr@vBfC% 三、程序代码
n\U3f M>N WJB/X"J ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
|l*#pN&L #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
#fF~6wopV #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
uU7s4oJ| #if _MSC_VER > 1000
ao@"j}c #pragma once
ISp'4H7R+N #endif // _MSC_VER > 1000
=*ZQGM 3w #ifndef __AFXWIN_H__
9PpPAF #error include 'stdafx.h' before including this file for PCH
ZO`{t1 #endif
btQDG #include "resource.h" // main symbols
N*dO'ol class CHookApp : public CWinApp
m/2LwN {
9`3%o9V9Y public:
#D{jNSB CHookApp();
!jV}sp<Xp // Overrides
R0 g- // ClassWizard generated virtual function overrides
0cd`. ZF //{{AFX_VIRTUAL(CHookApp)
3L;GfYr0 public:
b IS3 virtual BOOL InitInstance();
%B;e7
UJ virtual int ExitInstance();
.x
1& //}}AFX_VIRTUAL
iMr Np //{{AFX_MSG(CHookApp)
`ViFY
// NOTE - the ClassWizard will add and remove member functions here.
9c/&+j // DO NOT EDIT what you see in these blocks of generated code !
K):MT[/" //}}AFX_MSG
/& qN yo DECLARE_MESSAGE_MAP()
Tug}P K };
QasUgZ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
aNqhxvwf BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Z#n!=kTTm BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
q#8$@*I BOOL InitHotkey();
?5%0zMC BOOL UnInit();
Z+mesj?. #endif
F?+K~['i Sdc
yL%6! //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
GzJ("RE0)v #include "stdafx.h"
o6 FSSKM #include "hook.h"
-^y$RJC #include <windowsx.h>
sT. :"Pj$ #ifdef _DEBUG
CB<i #define new DEBUG_NEW
Ol }^'7H #undef THIS_FILE
-SZW[T<N" static char THIS_FILE[] = __FILE__;
[OH9/" #endif
LX4*3c|i, #define MAX_KEY 100
\'rh7!v-u #define CTRLBIT 0x04
Ab]`*h\U #define ALTBIT 0x02
4FmT.P #define SHIFTBIT 0x01
rtl|zCst #pragma data_seg("shareddata")
ZDmBuf
q HHOOK hHook =NULL;
[V\0P,l UINT nHookCount =0;
0>uMR{ # static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
/$'R!d5r static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
[Rz9Di ; static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
{b|:q>Be8 static int KeyCount =0;
B2QC#R static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
<X7x #pragma data_seg()
(GLd"Zq HINSTANCE hins;
{8NnRnzU void VerifyWindow();
1-@[th BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
+V"t't7 //{{AFX_MSG_MAP(CHookApp)
e 1W9Z $m // NOTE - the ClassWizard will add and remove mapping macros here.
\r_-gn'1b // DO NOT EDIT what you see in these blocks of generated code!
93zoJiLRf //}}AFX_MSG_MAP
k<mfBNvuo END_MESSAGE_MAP()
I}5#!s< {& UjNe0jt%s CHookApp::CHookApp()
%R%e0|a {
Vb0((c%& // TODO: add construction code here,
pw^$WK // Place all significant initialization in InitInstance
l{:7*U{d }
G(LGa2;Zg `0@onDQVc= CHookApp theApp;
HPGMR4=ANS LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
faqOGAb {
:iWW2fY BOOL bProcessed=FALSE;
icq!^5BzL if(HC_ACTION==nCode)
%P!6cyQS {
z(sfX}% if((lParam&0xc0000000)==0xc0000000){// Key up
?a~59!u switch(wParam)
ac8+?FpK # {
}9w?[hXW" case VK_MENU:
WJefg MaskBits&=~ALTBIT;
IMaa#8, break;
?0%yDq1_ case VK_CONTROL:
Te%2(w,B MaskBits&=~CTRLBIT;
un{LwZH break;
[TUy><Z case VK_SHIFT:
]a4rA+NFLB MaskBits&=~SHIFTBIT;
L : hEt break;
~x:\xQti default: //judge the key and send message
.>4Zt'gCt break;
ZWZRG-:&H }
K`|%-k+D for(int index=0;index<MAX_KEY;index++){
cG)i: if(hCallWnd[index]==NULL)
#t.)4$ continue;
Ns ?8N": if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
{Kn:>l$*7 {
)%8 ;C]G; SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
T%GdvtmS> bProcessed=TRUE;
2Zf}t }
A*;I}F }
xcBV,[E{ }
84xA/BR W else if((lParam&0xc000ffff)==1){ //Key down
<m;idfn switch(wParam)
x|>N {
C%hMh/Li; case VK_MENU:
}.j<kmd MaskBits|=ALTBIT;
6Fp}U break;
+;Yd<~!c Z case VK_CONTROL:
j<H5i} MaskBits|=CTRLBIT;
>LvQ&fAo break;
M4MO)MYJ case VK_SHIFT:
|?zFm
mh MaskBits|=SHIFTBIT;
ZbmBwW_ 7 break;
R#D>m8&}3 default: //judge the key and send message
]: VR3e"H break;
R07 7eX }
1y\-Iz^ for(int index=0;index<MAX_KEY;index++)
TR@*tfS {
teRK#: .P if(hCallWnd[index]==NULL)
Fjq~^_8 continue;
"x;|li3; if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
wH?r522`c {
XTzz/.T;Z SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
h'Gs$o7#P bProcessed=TRUE;
58TH|Rj+I }
N*Is_V\R }
w(>mP9Cb }
oP[R?zN if(!bProcessed){
/UwB6s( for(int index=0;index<MAX_KEY;index++){
GJpQcse% if(hCallWnd[index]==NULL)
tc.`P]R
continue;
FLWQY, if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
bSK> p3 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
rsr}%J }
,CGq_>Z }
M/!5r }
#Cj$;q{! return CallNextHookEx( hHook, nCode, wParam, lParam );
3Ryae/Nk }
8eAc 5by o@o0V BOOL InitHotkey()
&:]ej6V'[ {
.ty^ k@J|] if(hHook!=NULL){
z8MKGM nHookCount++;
F.N4Q'2Z return TRUE;
@<^_ _." }
CLQE@kF; else
aPELAU- hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
am+'j5`Ys if(hHook!=NULL)
p3e_:5k nHookCount++;
TbK;_pg return (hHook!=NULL);
A2C|YmHk }
Ym]Dlz,o BOOL UnInit()
m VSaC {
+{eZ@ if(nHookCount>1){
@bkZ< Gq nHookCount--;
?3=D-Xrb return TRUE;
<B3v4f }
zi7>!#( BOOL unhooked = UnhookWindowsHookEx(hHook);
7 3 Oo; if(unhooked==TRUE){
D'nO nHookCount=0;
834E
]2 hHook=NULL;
yf lt2 R }
_0razNk return unhooked;
Qz[4M` M }
sKIpL(_I$ YtQsSU BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
1@i 8ASL {
)P)Zds@F BOOL bAdded=FALSE;
+"~~;J$ for(int index=0;index<MAX_KEY;index++){
31FQ=(K if(hCallWnd[index]==0){
Q?1'
JF!G hCallWnd[index]=hWnd;
Eps2 HotKey[index]=cKey;
r@|{m QOxa HotKeyMask[index]=cMask;
yjq~O~ bAdded=TRUE;
XBTtfl
& KeyCount++;
MO1t0My c break;
9rd7l6$R" }
t V]BcDp }
,hggmzA~ return bAdded;
=}8:zO
2'{ }
2V-zmyJs5 F74^HQ*J BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
2X=
pu.;F {
?6m6 4{M BOOL bRemoved=FALSE;
GD]yP.. for(int index=0;index<MAX_KEY;index++){
*8a8Ng if(hCallWnd[index]==hWnd){
nc0!ag if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
_Di";fe? hCallWnd[index]=NULL;
2#^@awJ ? HotKey[index]=0;
2a\?Q|1C HotKeyMask[index]=0;
hxedQvW bRemoved=TRUE;
[q<Vm- KeyCount--;
oX;D|8f break;
O.9r'n4f }
e*zt;SR }
M?3Nh; }
@N?u{|R:d return bRemoved;
b/yXE)3
X }
~S$\ PG4 1pM"j! void VerifyWindow()
d/m.VnW {
}H>}v/ for(int i=0;i<MAX_KEY;i++){
=Eh~ wm
if(hCallWnd
!=NULL){ {p70(
]v
if(!IsWindow(hCallWnd)){ z-Ndv;:
hCallWnd=NULL; .o&Vu,/H
HotKey=0; o-m9}pV
HotKeyMask=0; YyF=u~l
KeyCount--; 2<
"-
} (;Ad:!9{
} $4&%<'l3I
} E &wz0d;gf
} (PM!{u=
v Mi&0$
BOOL CHookApp::InitInstance() ?JinX'z
{ zj+.MG04
AFX_MANAGE_STATE(AfxGetStaticModuleState()); BbV @ziL
hins=AfxGetInstanceHandle(); &rj)Oh2
InitHotkey(); $U]KIHb
return CWinApp::InitInstance(); 'H]&$AZ;@
} D=0^"7K
:d!qZFln
int CHookApp::ExitInstance() :O~*}7G
{ B F,8[|%#
VerifyWindow(); $&C~Qti|G
UnInit(); @C?.)#
return CWinApp::ExitInstance(); gZ^'hW-{
} iz0GL&<
z+k[HE^S
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file a9"1a'
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) z"vI-~,YU
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ RdirEH*H
#if _MSC_VER > 1000 EV$$wrohQ`
#pragma once qSg=[7XOO
#endif // _MSC_VER > 1000 1c%ee$Q
/4!.G#DLQ
class CCaptureDlg : public CDialog ],3#[n[ m
{ RXbhuI
// Construction W{v{sQg
public: gpe/ dfyJ9
BOOL bTray; :|V`QM
BOOL bRegistered; GlPd)m`
BOOL RegisterHotkey(); NY,ZTl_
UCHAR cKey; &>T7]])
UCHAR cMask; U=G}@Y
void DeleteIcon(); O2n[`9*
void AddIcon(); b)e';M
UINT nCount; icw (y(W
void SaveBmp(); *2(W`m
CCaptureDlg(CWnd* pParent = NULL); // standard constructor r) SG!;X
// Dialog Data Ul`~d
!3zH
//{{AFX_DATA(CCaptureDlg) #j?SdQ
enum { IDD = IDD_CAPTURE_DIALOG }; yt@;yd:OEk
CComboBox m_Key; 6HK
dBW$/
BOOL m_bControl; XP|qY1
BOOL m_bAlt; JR_s-&