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:
)V_;]9<wt
7lKatk+7K 一、实现方法
7QoMroR \F""G,AWq{ 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:
U;!J(Us R-wz+j# #pragma data_seg("shareddata")
OEC/'QOae HHOOK hHook =NULL; //钩子句柄
'P[#.9E UINT nHookCount =0; //挂接的程序数目
k*Aee7 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
$2-_j)+ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
S.<4t*, static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
wTG(U3{3K static int KeyCount =0;
O}}rosA static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
qL[SwEc #pragma data_seg()
'G>9 iw \wK4bvUrX 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
VYt<j<ba %}XyzGq{ DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
M* {5> !\ Z/|=@gpw BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
:3b02}b7 cKey,UCHAR cMask)
Q(e {
8.+
yZTg BOOL bAdded=FALSE;
:fq4oHA# for(int index=0;index<MAX_KEY;index++){
Ps[#z@5{x if(hCallWnd[index]==0){
%&q}5Y4! hCallWnd[index]=hWnd;
-~X[j2 HotKey[index]=cKey;
6E9/z HotKeyMask[index]=cMask;
aUA)p}/: bAdded=TRUE;
tCar:p4$ KeyCount++;
#3'M>SaoH break;
kQQDaZ8 }
*v?kp>O }
0'YJczDq:7 return bAdded;
mm.%Dcn }
7?y7fwER //删除热键
~-B+7 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
1MT,A_L {
f*9O39&| BOOL bRemoved=FALSE;
7q5*grm for(int index=0;index<MAX_KEY;index++){
Z&P\}mm if(hCallWnd[index]==hWnd){
mVh;=>8K if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
BBv+*jj hCallWnd[index]=NULL;
"^a"`?J HotKey[index]=0;
~!cxRd5;F HotKeyMask[index]=0;
vAqj4:j bRemoved=TRUE;
bMNr +N KeyCount--;
}&==;7,O break;
\j3dB
tc }
ItZYOt|Hn }
ju.pQ=PSX }
kRBO] return bRemoved;
%H2ios[UO }
o
P;6i &g1\0t a6 0rJ#GD DLL中的钩子函数如下:
F[`dX E0EK88 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
J_m@YkK {
$ ]#WC\Hv BOOL bProcessed=FALSE;
As`=K$^Il. if(HC_ACTION==nCode)
CH;U_b {
^w2 HF if((lParam&0xc0000000)==0xc0000000){// 有键松开
n;Q8Gg2U switch(wParam)
cC NRv$IO\ {
;gD\JA case VK_MENU:
SW'eTG MaskBits&=~ALTBIT;
BenyA:W" break;
XoL DqN! case VK_CONTROL:
I~@8SSO,vH MaskBits&=~CTRLBIT;
Z@f{f:Jc/" break;
gq/Za/!6 case VK_SHIFT:
b78~{ht` MaskBits&=~SHIFTBIT;
G -+!h4p break;
0y?;o*&U\ default: //judge the key and send message
pRL:,q\ break;
gZ7R^]
k }
UxzF5V5 for(int index=0;index<MAX_KEY;index++){
2Q5 @2jT if(hCallWnd[index]==NULL)
Hbd>sS continue;
w`V6vYd@ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
.R'M'a#*!A {
hqmE]hwc SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
79exZ7| bProcessed=TRUE;
.kn2M&P>= }
a#;;0R $ }
|5O>7~Tp }
$~W5! m else if((lParam&0xc000ffff)==1){ //有键按下
&} `a"tYr switch(wParam)
=!xX{o?64 {
q CYu@Ho case VK_MENU:
wWiYxBeN MaskBits|=ALTBIT;
Q}KOb4D break;
g= Vu'p 3u case VK_CONTROL:
UeLO `Ug0; MaskBits|=CTRLBIT;
EG\;l9T break;
6w,"i#E! case VK_SHIFT:
WKlyOK=} MaskBits|=SHIFTBIT;
kP ,8[r break;
[H>u'fy:C default: //judge the key and send message
'wG1un;t break;
wlaPE8Gc }
*Q/^ib9= for(int index=0;index<MAX_KEY;index++){
{7z]+ h if(hCallWnd[index]==NULL)
#S'uqP! continue;
KvPCb%!ZP if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Ez5t)l- {
iaeNY;T SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
fs&$?mHL){ bProcessed=TRUE;
-P/DmSS8V }
kwc
Cf2 }
3mo4;F,h9 }
-bzlp7q* if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
5~@-LXqL for(int index=0;index<MAX_KEY;index++){
aaT3-][ if(hCallWnd[index]==NULL)
cK u[4D{ continue;
k'#3fz\ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
iC=>wrqY> SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
3?]81v/ //lParam的意义可看MSDN中WM_KEYDOWN部分
h%ys::\zF }
Y6VJr+Ap( }
A#T"4'#?< }
3WGE T[3 return CallNextHookEx( hHook, nCode, wParam, lParam );
$S|+U}]C }
&um++
\ ~io. TS|r 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
[Tp?u8$p` Zja3HGL BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
AG=PbY9 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
0P9\; !Y dR1IndZl 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:
*YvtT(Gt ;'8P/a$ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
d\]KG(T {
@ztT1?!e if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
S3Gr}N {
@qp6Y_,E[ //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
`v``}8tm SaveBmp();
+u0of^}= return FALSE;
r+E!V'{C }
|xFA} …… //其它处理及默认处理
~rdS#f&R2 }
ZF[W<Q 1LRP
R@b^ [,AFtg[ 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。
&kmaKc t8EI"| 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。
DX>LB$dy?
S
W%>8 二、编程步骤
bXF8V c-XO}\? 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
>j hcSvM6 mnK<5KLg1 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
JR.)CzC xOj#%; 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
v.Bwg7R3 A&t8C8, 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
-^CW}IM{ I 18rV Acj 5、 添加代码,编译运行程序。
Y:TfD{Xgc sT2`y$' 三、程序代码
=f!A o:Uc RxYENG]/6 ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
}'eef"DJ9 #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
a~0 ~Y y #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
FXJ0
G>F #if _MSC_VER > 1000
%u66H2 #pragma once
uD=Kar #endif // _MSC_VER > 1000
yC\UT
~j/ #ifndef __AFXWIN_H__
z.-yL,Rc`- #error include 'stdafx.h' before including this file for PCH
Eb4NPWo #endif
";rXCH. #include "resource.h" // main symbols
|> STb\ class CHookApp : public CWinApp
94#,dA,M {
~F'6k&A^q public:
m_/Ut CHookApp();
,FzkGB# // Overrides
JT0j2_*Rr // ClassWizard generated virtual function overrides
N)g _LL>^ //{{AFX_VIRTUAL(CHookApp)
$J4\jIipL public:
~O\A 0e virtual BOOL InitInstance();
VtLRl0/ virtual int ExitInstance();
@rbd`7$% //}}AFX_VIRTUAL
azv173XZ //{{AFX_MSG(CHookApp)
_D{A`z // NOTE - the ClassWizard will add and remove member functions here.
Gkuqe3 // DO NOT EDIT what you see in these blocks of generated code !
e7;7TrB. //}}AFX_MSG
:KO&j"[ DECLARE_MESSAGE_MAP()
Hvk~BP'
m
};
!VWA4 e!+ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
I~n4}}9M BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
}[JB% BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
9
fB|e| BOOL InitHotkey();
'9f0UtT|[ BOOL UnInit();
>va_,Y} #endif
=fRS UtX aJ(/r.1G //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
Y`j$7!j #include "stdafx.h"
L'{W|Xb+ #include "hook.h"
c<|y/n #include <windowsx.h>
crb^TuN #ifdef _DEBUG
s oY\6mHio #define new DEBUG_NEW
'/8/M{`s #undef THIS_FILE
<WIIurp static char THIS_FILE[] = __FILE__;
b:F;6X0~Hl #endif
PEvY3F}_rh #define MAX_KEY 100
[oU\l+t #define CTRLBIT 0x04
f5 bq)Pm& #define ALTBIT 0x02
vmAnBY #define SHIFTBIT 0x01
n5d8^c! 2 #pragma data_seg("shareddata")
`YqtI/-w HHOOK hHook =NULL;
6o#/[Tz UINT nHookCount =0;
c46-8z$ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
Qa=Y?=Za static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
PSq?8. static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
Vt}QPNt static int KeyCount =0;
@h|qL-:!vG static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
ASbIc"S6 #pragma data_seg()
DW7E ]o
HINSTANCE hins;
doL-G?8B void VerifyWindow();
5wV J.B~s BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
sF!#*Y //{{AFX_MSG_MAP(CHookApp)
pL{oVk#, // NOTE - the ClassWizard will add and remove mapping macros here.
Vhv'Z\ // DO NOT EDIT what you see in these blocks of generated code!
Qz|T0\=V //}}AFX_MSG_MAP
~7ZZb*].( END_MESSAGE_MAP()
zG_n x3 cQt&%SVT]E CHookApp::CHookApp()
~NK $rHwi% {
rlKR
<4H // TODO: add construction code here,
Y
]()v // Place all significant initialization in InitInstance
[M[#f&=Z }
5T#v& 9DA|;| CHookApp theApp;
P'8RaO&d LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
A^z{n/DiL {
Py
v> BOOL bProcessed=FALSE;
v>`Fo[c if(HC_ACTION==nCode)
4O-LLH {
[Kc ?<3W if((lParam&0xc0000000)==0xc0000000){// Key up
5oG~ Fc switch(wParam)
nUj`#% {
f1aZnl case VK_MENU:
htbE
Q NW MaskBits&=~ALTBIT;
I;'{X_9$a break;
Nt$4; case VK_CONTROL:
]YI9 MaskBits&=~CTRLBIT;
eX#.Zt] break;
&qg6^& case VK_SHIFT:
yx|iZhK0:} MaskBits&=~SHIFTBIT;
y-E'Y=j break;
.@)vJtH) default: //judge the key and send message
L/rf5||@ break;
P{A})t7 }
:L@;.s for(int index=0;index<MAX_KEY;index++){
~o_JZ: if(hCallWnd[index]==NULL)
L-`V^{R] continue;
lW|=rq-| if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
x,mt}> {
-6DRX SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
`$> Y bProcessed=TRUE;
cS%dTrfo }
<?B3^z$ }
hdw.S`~}% }
#l}Fk)dj else if((lParam&0xc000ffff)==1){ //Key down
ljK?2z> switch(wParam)
`]W9Fj<1j {
:-jbIpj' case VK_MENU:
H14Q-2U1xa MaskBits|=ALTBIT;
a9e0lW:=c break;
>G|RVB case VK_CONTROL:
B$rhsK% MaskBits|=CTRLBIT;
x"q]~u<rB break;
D@&xj_#\} case VK_SHIFT:
lkT :e)w MaskBits|=SHIFTBIT;
{*+J`H_G2a break;
zn-=mk;W default: //judge the key and send message
=%~- M break;
ftRFG }
+TqrvI. for(int index=0;index<MAX_KEY;index++)
nV8'QDQ:Al {
K/*R}X if(hCallWnd[index]==NULL)
>niv>+!N continue;
t >"`rcg if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
8/>.g.] {
EY"of[p SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
zp8x/,gwF bProcessed=TRUE;
P+f}r^4} }
Kfb(wW }
[j/|)cj }
7_ oUuNw if(!bProcessed){
wuXQa
wo for(int index=0;index<MAX_KEY;index++){
H8w[{'Mei
if(hCallWnd[index]==NULL)
@H`jDaB9 continue;
ZX&e,X~V if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
pZS]i
" SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
^|Z'}p|& }
a&JY x }
dUa>XkPa\2 }
goiI*"6M return CallNextHookEx( hHook, nCode, wParam, lParam );
IoOOS5a }
|v7Je?yh Pi"?l[T0 BOOL InitHotkey()
8lx}0U {
6V$ )ym*F if(hHook!=NULL){
UY9*)pEE nHookCount++;
1,=:an return TRUE;
)zO|m7 }
8F>9CO:&N else
a%c <3' hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
T`@brL if(hHook!=NULL)
#+D][LH4 nHookCount++;
M <JX return (hHook!=NULL);
/#T {0GBXe }
kHr-UJ! BOOL UnInit()
r4P%.YO+X {
(.=Y_g. if(nHookCount>1){
>8{w0hh; nHookCount--;
~"%'(j_4 return TRUE;
Ry}4MEq] }
2fkyz BOOL unhooked = UnhookWindowsHookEx(hHook);
4RDY_HgF6 if(unhooked==TRUE){
*-=/"m nHookCount=0;
&Y1h=,KR9 hHook=NULL;
f4pIF"U9> }
?J2A.x5`a return unhooked;
\LJ!X3TZ }
@#hQ0F8 %' WC7s BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Vf:.C|Z {
1p~ORQ BOOL bAdded=FALSE;
^@/wXj: for(int index=0;index<MAX_KEY;index++){
k'%yvlv if(hCallWnd[index]==0){
873 bg|^hs hCallWnd[index]=hWnd;
OP+*%$wR HotKey[index]=cKey;
@$kO7k0{g HotKeyMask[index]=cMask;
`#iL'ND[ bAdded=TRUE;
uq[5 om" KeyCount++;
lS Y " break;
0#Gm# =F }
9j^rFG!n }
CC^]Y.9 return bAdded;
<EqS
,cO^ }
Dn<3#V )6%*=- BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
e=h-}XRC {
5D<Zbn.>q BOOL bRemoved=FALSE;
y(<{e~ for(int index=0;index<MAX_KEY;index++){
AVLY|79# if(hCallWnd[index]==hWnd){
>|RoLV if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
"Ai\NC hCallWnd[index]=NULL;
&V
7J5~_ HotKey[index]=0;
:j~4mb?$ HotKeyMask[index]=0;
;g8v7>p bRemoved=TRUE;
:4[>]&:u3 KeyCount--;
{.oz^~zs]g break;
u= dj3q }
&b