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:
w71YA#cg
-E1-(TS 一、实现方法
.K84"Gdx lrZ]c:%k 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_?U?:!AC S?CT6moXA #pragma data_seg("shareddata")
)!v"(i.5Xo HHOOK hHook =NULL; //钩子句柄
\dJhDR UINT nHookCount =0; //挂接的程序数目
T; tY7;< static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
N& static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
7;|"1H:cmw static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
:pM8Q1:B static int KeyCount =0;
JXL?.{'A static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
HnArj_E #pragma data_seg()
Btxtu"]nJo |kK5:\H 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。
mt+i0PIfj e_e\Ie/pDc 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:
.;g kV-] {ol7*% u BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
Uj;JN}k cKey,UCHAR cMask)
="78#Wfj2 {
$M)SsD~ BOOL bAdded=FALSE;
W:8MqVm34 for(int index=0;index<MAX_KEY;index++){
)T"Aji-hy if(hCallWnd[index]==0){
nQQHm6N hCallWnd[index]=hWnd;
.mfLH N%: HotKey[index]=cKey;
wxqX42v HotKeyMask[index]=cMask;
mDK*LL5]W bAdded=TRUE;
-&D=4,# KeyCount++;
K@*+;6y@ break;
I'*,<BPG }
@Dfg6<0 }
rX)&U4#[m return bAdded;
.O"a: ^i }
W+;=8S //删除热键
(=uT*Cb BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
C*ep8{B {
ewd
eC BOOL bRemoved=FALSE;
mH\zSk for(int index=0;index<MAX_KEY;index++){
i#>t<g`l if(hCallWnd[index]==hWnd){
^85Eveu if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
Soq#cl'll- hCallWnd[index]=NULL;
n4!RGq.} HotKey[index]=0;
]fzXrN_ HotKeyMask[index]=0;
xh:I]('R bRemoved=TRUE;
keLeD1 KeyCount--;
1SztN3'q break;
}?,YE5~ }
#M|lBYdW} }
o3`U;@ &u }
p#jAEY p return bRemoved;
iS,l }
0F-{YQr> l#enbQ`-~ peu9Bgs DLL中的钩子函数如下:
/>mK.FT "'bl)^+?, LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
YA,~qT| {
lND2Kb BOOL bProcessed=FALSE;
OC*28) if(HC_ACTION==nCode)
IrQ.[?C {
.x%w# if((lParam&0xc0000000)==0xc0000000){// 有键松开
h_?`ESI~ switch(wParam)
>I\B_q {
Q&.uL}R case VK_MENU:
0zNbux_ MaskBits&=~ALTBIT;
@\w}p E break;
{)"[_< case VK_CONTROL:
V3ozaVk; MaskBits&=~CTRLBIT;
-B#1+rUW break;
:wS&3:h case VK_SHIFT:
NH|I>vyN MaskBits&=~SHIFTBIT;
_cQ
'3@ break;
is8i_FoD,n default: //judge the key and send message
`{:Nt#7
break;
Ht;Rz*} }
5h/,*p6Nje for(int index=0;index<MAX_KEY;index++){
OU UV8K if(hCallWnd[index]==NULL)
"jyo'r continue;
D<69xT, if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
_l9fNf!@ {
|\Jnr3) SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
,:PMS8pS bProcessed=TRUE;
@
&N }
P6.PjK!Ar }
ldUZ\z(* }
v|(]u3=1_ else if((lParam&0xc000ffff)==1){ //有键按下
nQmHYOF% switch(wParam)
q~
aFV<Q {
nSyLt6zn\ case VK_MENU:
+]cf/_8+s MaskBits|=ALTBIT;
}
doAeTZ break;
3GF67] case VK_CONTROL:
2>9\o]ac4 MaskBits|=CTRLBIT;
$x'jf?zs! break;
pL1ABvBB case VK_SHIFT:
Rb:H3zh MaskBits|=SHIFTBIT;
x3cjyu<K break;
r%f Q$q> default: //judge the key and send message
%]}JWXof break;
?pZU'5le` }
5zBA ]1PY for(int index=0;index<MAX_KEY;index++){
GP c
B( if(hCallWnd[index]==NULL)
Kg';[G\ continue;
l%2VA if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Kj4BVs {
7FoX)54" SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Y:;_R=M bProcessed=TRUE;
9SsVJ<9,R }
`{!A1xKZ }
Hi={(Z5tC4 }
]]:K
l if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
`.J)Z=o for(int index=0;index<MAX_KEY;index++){
,5 ka{Q`K if(hCallWnd[index]==NULL)
((A@VcX continue;
0a89<yX if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
"O>~osj SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
b5)^g+8)w //lParam的意义可看MSDN中WM_KEYDOWN部分
"b`#RohCi }
dh`s^D6Q> }
[T_[QU:A }
aeUgr! return CallNextHookEx( hHook, nCode, wParam, lParam );
6d]4
%Q T }
HSNj ;SU<T^a 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:
?h4[yp=w %cn1d>M+I BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
6"G(Iq'2t3 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
"L]v:lg3 ]Ik~TW& 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:
]7_>l> M}o.= Iqa LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
zNX=V!$ {
#a=]h}&1? if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
*,G<X^ {
[Ix6ArY //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
s U`#hL6; SaveBmp();
.5;
JnJI return FALSE;
8J'5%$3u }
=? !FO'zt" …… //其它处理及默认处理
(E0WZ$f} }
k_}$d{X $V3If <lFHmi$qt{ 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。
esTL3 l{[ t#P7'9Se8 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。
|.Vgk8oTl {2 q"9Ox" 二、编程步骤
[!%5(Ro_ t`Bk2Cc)+ 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";
}Q: CZ wqDf\k}'v 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
VQ('ejv}/ L;:PeYPL 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;
k?7"r4Vc)S Ewz cB\m 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;
3\Xk)a_ }Y7P2W+4? 5、 添加代码,编译运行程序。
_qPKdGoM h!dij^bD 三、程序代码
]mtiIu[ ~s&r.6DW ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
t+A*Ws*o #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
^ulgZ2BQ| #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
$Mg O)bH #if _MSC_VER > 1000
MRz f#o<H #pragma once
I@m(} #endif // _MSC_VER > 1000
Wy-_}wqHg #ifndef __AFXWIN_H__
AAfU]4u0S #error include 'stdafx.h' before including this file for PCH
&w^9#L #endif
^!^M Gzu #include "resource.h" // main symbols
-sv%A7i class CHookApp : public CWinApp
r
jn:E {
Caj H;K\ public:
>uZc#Zt CHookApp();
k
76<CX // Overrides
CP9 Q|'oJ // ClassWizard generated virtual function overrides
u^SInanw //{{AFX_VIRTUAL(CHookApp)
C1f$^N public:
W 3/]
2"0 virtual BOOL InitInstance();
]+,L/P virtual int ExitInstance();
U0-RG //}}AFX_VIRTUAL
. h)VR
5?j //{{AFX_MSG(CHookApp)
mQVlE__ub // NOTE - the ClassWizard will add and remove member functions here.
jjH2!R]^> // DO NOT EDIT what you see in these blocks of generated code !
O+mEE>:w% //}}AFX_MSG
/
:.I&^>P DECLARE_MESSAGE_MAP()
;rL>{UhG };
c86?-u') LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
}f;TG:6 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
/Zs_G=\> BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
p}==aNZK BOOL InitHotkey();
"a;$uW@.6 BOOL UnInit();
O6$,J12l #endif
S^~"# j{FRD8]V
//////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
7)D[ }UXz #include "stdafx.h"
l$!ExXEZO; #include "hook.h"
V"8Go;[ #include <windowsx.h>
fCu;n%
#ifdef _DEBUG
T0fm6
J #define new DEBUG_NEW
Hj`'4 #undef THIS_FILE
~h<T0Zc static char THIS_FILE[] = __FILE__;
p/0dtnXa( #endif
sE]z.Po= #define MAX_KEY 100
:KC]1_zqR #define CTRLBIT 0x04
x Y$x=) #define ALTBIT 0x02
mW)kWuOO #define SHIFTBIT 0x01
3BK
8{/ #pragma data_seg("shareddata")
>P(.yQ8&kL HHOOK hHook =NULL;
/Cwwz UINT nHookCount =0;
jHT^I
as static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
_t]Q*i0p static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
z{BgAI, static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
r-S%gG}~E static int KeyCount =0;
v"
#8^q static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
XjzGtZ#6 #pragma data_seg()
g3'dkS! HINSTANCE hins;
q@S\R
7R void VerifyWindow();
Vq#0MY)2gS BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
a"4X7
D+ //{{AFX_MSG_MAP(CHookApp)
21<Sfsc$ // NOTE - the ClassWizard will add and remove mapping macros here.
C+!=C{@7di // DO NOT EDIT what you see in these blocks of generated code!
Y[b08{/ //}}AFX_MSG_MAP
xv>8rW(Np5 END_MESSAGE_MAP()
9`qw,X&AK_ WllQM,h CHookApp::CHookApp()
p:tp|/ {
9:%')M&Q // TODO: add construction code here,
i\
7JQZ // Place all significant initialization in InitInstance
cfBlHeYE }
%t* 9sh JI-.SR CHookApp theApp;
AWFq5YMSI LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
I^LU*A= {
|R91|-H BOOL bProcessed=FALSE;
vfT
@;` if(HC_ACTION==nCode)
iX2exJto {
KX\=wFbP) if((lParam&0xc0000000)==0xc0000000){// Key up
E rA*a3 switch(wParam)
m_ wvi {
OP(om$xm case VK_MENU:
OJydt; a MaskBits&=~ALTBIT;
o6x8jz break;
&!:mL], case VK_CONTROL:
u9q#L.Ij MaskBits&=~CTRLBIT;
U7zd7O break;
(@BB@G case VK_SHIFT:
4Af7x6a; MaskBits&=~SHIFTBIT;
DcRoW break;
b~ig$!N] default: //judge the key and send message
6L~5qbQ break;
S{XO3 }
|'}r-} for(int index=0;index<MAX_KEY;index++){
T|$tQgY^ if(hCallWnd[index]==NULL)
l9%ckC*q continue;
b
H5lLcdf if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
B|^=2 >8s {
P"Q6 wdm SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Wl&6T1A`" bProcessed=TRUE;
+sZY0(|K8 }
FD~uUZTM }
ze8 MFz'm }
'g<FL`iP else if((lParam&0xc000ffff)==1){ //Key down
@Z""|H"0 switch(wParam)
g("[wqgG {
b,ZBol|X case VK_MENU:
jX$U)O MaskBits|=ALTBIT;
lUnC+w#[ break;
yJ; ;& case VK_CONTROL:
#K-O<:s=y MaskBits|=CTRLBIT;
{v d+cE break;
h|z59h&X8G case VK_SHIFT:
2xy{g&G MaskBits|=SHIFTBIT;
G!F_Q7|- break;
K.? S,qg default: //judge the key and send message
%gqu7}' break;
A$zC$9{0I }
?5 6;<%0 for(int index=0;index<MAX_KEY;index++)
PEtr8J$uB {
5}9rpN{y if(hCallWnd[index]==NULL)
<pT1p4T< continue;
Y!u">M#@ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Cw.DLg {
}p9#Bzc SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
ZD?LsD 3 bProcessed=TRUE;
n#P?JyGm1g }
TuwSJS7 }
ZQ\O|
n8 }
5Yk| if(!bProcessed){
GXTjK! for(int index=0;index<MAX_KEY;index++){
@-1VN;N if(hCallWnd[index]==NULL)
#zn`)n continue;
nl-tJ.MU" if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
L6=5]?B= SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
<HW2W"Go\ }
8fWIZ }
uF*tlaV6 }
%yVP@M return CallNextHookEx( hHook, nCode, wParam, lParam );
VRv.H8^{ }
t<p4H^ |' kC9H[> BOOL InitHotkey()
DT]3q4__Q {
,{RWs^W2 if(hHook!=NULL){
%LL?' && nHookCount++;
I'R|B\ return TRUE;
:WSszak }
$4CsiZ6 else
*U,W4>(B hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
cbx(
L8 if(hHook!=NULL)
1[?xf4EMG nHookCount++;
bFIv}c+; return (hHook!=NULL);
<5c^DA }
M1Th~W9l BOOL UnInit()
{`% q0Nr {
u&Xn#fh if(nHookCount>1){
^12}#I nHookCount--;
+\B.3%\- return TRUE;
+227SPLd }
!?{%9 BOOL unhooked = UnhookWindowsHookEx(hHook);
AT^MQvn
if(unhooked==TRUE){
kqS_2[=] nHookCount=0;
TGG-rA6@Lx hHook=NULL;
ueJ_F#y }
N!af1zj return unhooked;
iS8yJRy }
u,S}4p&l 2C&l\16 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
o2riy'~ {
3q (]Dg;v BOOL bAdded=FALSE;
z
2Ao6*% for(int index=0;index<MAX_KEY;index++){
/5R?(- if(hCallWnd[index]==0){
c~Z\|Y`#B hCallWnd[index]=hWnd;
IqjH HotKey[index]=cKey;
G]>P!] HotKeyMask[index]=cMask;
Jy#21 bAdded=TRUE;
NK(; -~{P KeyCount++;
X&