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:
vp9E}ga
`zvT5=*-# 一、实现方法
u.xA}yVS U%SNROj 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.m.]%URW k%bTs+]* #pragma data_seg("shareddata")
(HP={MrV HHOOK hHook =NULL; //钩子句柄
Ug[F3J|Mu UINT nHookCount =0; //挂接的程序数目
p_kTLNZd9 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
36D,el In static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
r:S5x. P2 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
5D q{"@E static int KeyCount =0;
r0XGGLFuZl static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
>=RHE@ #pragma data_seg()
:[$i~V *TMM:w|1 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
`:^)"#z) [$ Xu 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:
GQc%OQc\ %@,:RA\pm BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
5tbiNm^X cKey,UCHAR cMask)
q=i,'.nS {
h11bK'TIv BOOL bAdded=FALSE;
c+
H)1Dfq for(int index=0;index<MAX_KEY;index++){
n*]x02:LjZ if(hCallWnd[index]==0){
A5J#x6@ hCallWnd[index]=hWnd;
:d/:Ga5v! HotKey[index]=cKey;
wE=8jl* HotKeyMask[index]=cMask;
NIcNL(] bAdded=TRUE;
v(WL 3[y; KeyCount++;
u>-uRz<)t break;
rBL_]\$7} }
hrtN.4p[ }
%>QSeX return bAdded;
e[Ul"pMvS` }
r|sy_Sk/{ //删除热键
@%okaj#IO BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
c9 TkIe {
>5YYij5Aj BOOL bRemoved=FALSE;
TuT= for(int index=0;index<MAX_KEY;index++){
@zpHemdB if(hCallWnd[index]==hWnd){
=?QQb> if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
"nS{
;: hCallWnd[index]=NULL;
Uu<sntyv HotKey[index]=0;
Pp" )hFx HotKeyMask[index]=0;
Szob_IEq, bRemoved=TRUE;
U*#E aL KeyCount--;
A 5\"e^> break;
'"NdT7* + }
JZ*?1S> }
~s^6Q#Z9| }
fTnyCaB return bRemoved;
(5\d[||9g }
/-} p7AM dXr
!_)i MDXQj5s^ DLL中的钩子函数如下:
` G/QJH{I Vf* B1Zb LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
]4pC\0c {
)fcpE,g' BOOL bProcessed=FALSE;
[;\<
2 =H if(HC_ACTION==nCode)
r4qV}-E {
UM;bVf? if((lParam&0xc0000000)==0xc0000000){// 有键松开
Xv;ZA a switch(wParam)
kA$;vbm {
>w'?DV>u| case VK_MENU:
gbi~!S- MaskBits&=~ALTBIT;
*xX0]{49q break;
X([n>w case VK_CONTROL:
/t2<OU9 MaskBits&=~CTRLBIT;
4rCqN.J break;
J*kzJ{vwy* case VK_SHIFT:
SOY#, Zu MaskBits&=~SHIFTBIT;
;Z0cD*Jb break;
j-\^
}K.& default: //judge the key and send message
AZm)$@e) break;
oA^
]x> }
!haXO for(int index=0;index<MAX_KEY;index++){
5|H(N}S_ if(hCallWnd[index]==NULL)
MhXm-<4
continue;
K0bmU(Xxp if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
[75e\=wK {
XsCbJ[Z_?q SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
eh#
(}v bProcessed=TRUE;
- cC(d$y }
Q? |M BTo }
_p^ "! }
w\[*_wQp else if((lParam&0xc000ffff)==1){ //有键按下
h.0&)t\q" switch(wParam)
0hr)tYW,G {
LGue=Hkp case VK_MENU:
&Fr68HNmj MaskBits|=ALTBIT;
fXR_)d break;
'
=s*DL`0 case VK_CONTROL:
[UrS%]OSR MaskBits|=CTRLBIT;
\d8=*Zpz7 break;
Q#AHEm{9;s case VK_SHIFT:
M(gWd8?# MaskBits|=SHIFTBIT;
l3
Bc
g break;
iK23`@&%_ default: //judge the key and send message
[\y>&"uk break;
>TVd*S }
B~?Q. <M for(int index=0;index<MAX_KEY;index++){
U0=zuRr n if(hCallWnd[index]==NULL)
C F 0IP continue;
/-9+( if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
"PP0PL^5F {
{}2p1-( SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
k:yu2dQh bProcessed=TRUE;
m|?J^_ }
mAERZ<I }
T[II;[EiE }
~ZIRCTQ" if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
P_Ja?)GT for(int index=0;index<MAX_KEY;index++){
Tm,L?Jh if(hCallWnd[index]==NULL)
FO3*[O continue;
n ]g,)m if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
i2c<q0u SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
$CV'p/^En //lParam的意义可看MSDN中WM_KEYDOWN部分
V&nJT~k }
Uv$u\D+@[ }
Oc3%pb; }
FK('E3PG return CallNextHookEx( hHook, nCode, wParam, lParam );
tUnVdh6L.B }
y.NArN|% tXuxTVhoT 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:
Q(Y,p`> `^Sq>R!; BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Z0@ImhejuB BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
soCHwiE =5#Jsn?U 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:
c.> (/ fXQRsL8
] LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
"C|l3X' {
CzbNG^+ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
+u)$o {
T`G"2|ISS //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
L-T Ve SaveBmp();
}J
lW\# return FALSE;
I=-;*3g6 }
73<yrBxp …… //其它处理及默认处理
a-hGpYJJG }
H( m+rk 0u9h2/ma BGjTa.& 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
|ZzBCL8q -JQg{A 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
+Enff0 =+ Rb*\A7o|; 二、编程步骤
':dHYvP/UX d8I:F9 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
]jrxrUl w#b2iE+Bw 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
}e @-[RJ! `v
er "s; 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
9D21e(7X EF~PM 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
pdu {<n)zLy 5、 添加代码,编译运行程序。
N/=3Bs0y- 1r4/McB 三、程序代码
S!cXc/H-R 1i2O]e! ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
p$<qT^]& #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
a06q-3zw #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
}A^,y #if _MSC_VER > 1000
P
ie!Su` #pragma once
1i2w<VG1 #endif // _MSC_VER > 1000
h!]A(T\J #ifndef __AFXWIN_H__
K@hUif|([ #error include 'stdafx.h' before including this file for PCH
'kK%sE #endif
0&~u0B{ #include "resource.h" // main symbols
>c eU!=> class CHookApp : public CWinApp
-/?<@*n {
'_Op rx public:
bq]a8tSB CHookApp();
'h=2_%l@Y // Overrides
RMXj)~4. // ClassWizard generated virtual function overrides
b5R*] //{{AFX_VIRTUAL(CHookApp)
kMXl
{ public:
s9>!^MzBK virtual BOOL InitInstance();
]^<~[QK_C virtual int ExitInstance();
W@=ilW3RD //}}AFX_VIRTUAL
tT:yvU@a //{{AFX_MSG(CHookApp)
7L"/4w // NOTE - the ClassWizard will add and remove member functions here.
jyr#e // DO NOT EDIT what you see in these blocks of generated code !
sxtGl^,mU: //}}AFX_MSG
1L7,x @w DECLARE_MESSAGE_MAP()
qiN'Tuw9 };
2B;QS\e" LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
t"fD"Xpj BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
1doqznO BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
K(2s% BOOL InitHotkey();
470Pig>I8 BOOL UnInit();
DAi[3`C #endif
IF1}}[Ht k"$V O+}m //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
tAUMSr|? #include "stdafx.h"
nc)`ISI #include "hook.h"
H_^c K #include <windowsx.h>
{VG6m
Hw #ifdef _DEBUG
R2@u[ #define new DEBUG_NEW
t,_[nu(~8% #undef THIS_FILE
r.5F^ static char THIS_FILE[] = __FILE__;
VXS9E383 #endif
).xWjVC #define MAX_KEY 100
3}+
\&[ #define CTRLBIT 0x04
iqeGy&F- #define ALTBIT 0x02
}p~%GA.=98 #define SHIFTBIT 0x01
&@+;]t #pragma data_seg("shareddata")
)3 HHOOK hHook =NULL;
"5K:"m UINT nHookCount =0;
^da-R;o] static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
T*m_rDDt static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
9`AQsZ2 static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
U^D7T|P$V static int KeyCount =0;
b8&9pLl static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
6s;x@g] #pragma data_seg()
|(5=4j] HINSTANCE hins;
z?xd\x void VerifyWindow();
O/Vue BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
"/5b3^a //{{AFX_MSG_MAP(CHookApp)
sTDBK!9I // NOTE - the ClassWizard will add and remove mapping macros here.
FceT' // DO NOT EDIT what you see in these blocks of generated code!
`Ec+i //}}AFX_MSG_MAP
wlJ1,)n^2 END_MESSAGE_MAP()
#A!0KN;GC2 yyc&'J CHookApp::CHookApp()
KMV!Hqkk {
O9Aooe4W= // TODO: add construction code here,
9}N*(PI // Place all significant initialization in InitInstance
G`jhzG }
i{2KMa{K P;34Rd CHookApp theApp;
9EEHLx" LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
K4"as9oFP {
}O/Nn0, BOOL bProcessed=FALSE;
{8Ll\j@ " if(HC_ACTION==nCode)
V|=
1<v {
.;'xm_Gw< if((lParam&0xc0000000)==0xc0000000){// Key up
AO6;aT switch(wParam)
jo;n~>3P {
<S
qbj; case VK_MENU:
b~}}{fm&f MaskBits&=~ALTBIT;
s6I]H break;
<OUApp H case VK_CONTROL:
c1i7Rc{q MaskBits&=~CTRLBIT;
(c"!0v break;
IF=rD-x case VK_SHIFT:
N@g+51ye MaskBits&=~SHIFTBIT;
l-&f81W break;
-nW-I\d% default: //judge the key and send message
i!NGX break;
:.<&Y=^ }
L@wnzt for(int index=0;index<MAX_KEY;index++){
ag6S"IXh if(hCallWnd[index]==NULL)
'py
k continue;
#!2gxm;g if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
(w*$~p {
kQ + SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
1na[=Q2 bProcessed=TRUE;
a
<3oyY' }
^P[*yf }
_R]h]<TQ }
bWqGypq4 else if((lParam&0xc000ffff)==1){ //Key down
<YC{q>EMc switch(wParam)
]@xc9tlG {
+=R:n^r^, case VK_MENU:
gI]Vyg<{d MaskBits|=ALTBIT;
~'ovJ46tx break;
XP'KgTF case VK_CONTROL:
Xe5J MaskBits|=CTRLBIT;
HN:{rAIfc break;
z"<PveVo case VK_SHIFT:
|^ qW
MaskBits|=SHIFTBIT;
t5&$ y` break;
1g;3MSn~ default: //judge the key and send message
n}l Z break;
HBt?cA ' }
t/3veDh@ for(int index=0;index<MAX_KEY;index++)
"783F:mPh {
C oaqi`v4T if(hCallWnd[index]==NULL)
]C!u~A\jq continue;
1yhx)m;f if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
!MbRI {
$z<CkMP!U7 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
_?{2{^v bProcessed=TRUE;
&rn,[w_F[ }
_2|,j\f;L }
\1tce`+ }
nP}/#Wy if(!bProcessed){
IflpM ] for(int index=0;index<MAX_KEY;index++){
/fX]Yu if(hCallWnd[index]==NULL)
$1axZ~8sS continue;
HwDb &pP" if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
,yB-jk? SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
D!:Qy@Zw }
bc+'n }
f~]5A%=cZ }
LcF0: h' return CallNextHookEx( hHook, nCode, wParam, lParam );
G^+0</Q }
b^ v.FK46G ;>PV]0bOm> BOOL InitHotkey()
zIQ\_> {
, 7}Ri if(hHook!=NULL){
4F'@yi^Gt nHookCount++;
@gZ%>qe return TRUE;
Y$(G)Fs }
j#-74{Y$
J else
7|{QAv hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
NWKD:{ if(hHook!=NULL)
1r;Q5[@ nHookCount++;
46mu,v return (hHook!=NULL);
Fr3Q"( }
qWWy}5SOm BOOL UnInit()
#oHHKl=M {
UOa{J|k>h if(nHookCount>1){
;N)qNiJY nHookCount--;
cM55
vVd return TRUE;
[\I\). }
P|G:h& BOOL unhooked = UnhookWindowsHookEx(hHook);
(j2]:BVu if(unhooked==TRUE){
z8gp<5= nHookCount=0;
n.XT-X^ hHook=NULL;
?f a/}|T }
towQoqv return unhooked;
Z!*Wn`d-k }
/ZAEvdO*P " I:j a7 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
'06[@Cw {
b6#V0bDXHD BOOL bAdded=FALSE;
C<{k[!N%zm for(int index=0;index<MAX_KEY;index++){
k&9
b&-=fk if(hCallWnd[index]==0){
](^xA` hCallWnd[index]=hWnd;
]E, HotKey[index]=cKey;
xNT[(( HotKeyMask[index]=cMask;
:
G<