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:
jW_FaPW(p
XnV$}T:?X 一、实现方法
;.b^A (Kaunp5_` 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
rqYx\i? !!UQ,yU #pragma data_seg("shareddata")
x|<89o
L HHOOK hHook =NULL; //钩子句柄
3(>NS ?lX UINT nHookCount =0; //挂接的程序数目
'A9U[| static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
y7Y g$)sL static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
%B-m- =gz static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
f7j9'k static int KeyCount =0;
2?\L#=<F static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
</Ry4x^A #pragma data_seg()
g(F? qP_K >O}J*4A>+# 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。
g+M& _n ,SSq4 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:
/S&8%fb K!_''Fg BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
"\1QJ cKey,UCHAR cMask)
W1p5F\ wt {
-O?&+xIK& BOOL bAdded=FALSE;
J1{ucFa for(int index=0;index<MAX_KEY;index++){
>X-*Hu'U# if(hCallWnd[index]==0){
,{u'7p hCallWnd[index]=hWnd;
-K%~2M< HotKey[index]=cKey;
A0 1D-) HotKeyMask[index]=cMask;
wv_<be[?* bAdded=TRUE;
$+@xwuY'+ KeyCount++;
UJ6zgsD1b? break;
2q*aq% }
};@J)} }
IRl(H_. return bAdded;
?<-ins }
oY0`igH //删除热键
f3HleA&& BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
xEvm>BZi
{
}?XNA.Wz BOOL bRemoved=FALSE;
@mId{w z for(int index=0;index<MAX_KEY;index++){
lT~A~O if(hCallWnd[index]==hWnd){
;OfZEy>7 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
wQ/Z: hCallWnd[index]=NULL;
088"7 s HotKey[index]=0;
u3@v HotKeyMask[index]=0;
e&J_uG bRemoved=TRUE;
qI#ow_lL# KeyCount--;
6b9&V` break;
;gNoiAxW }
52d8EGC }
ZMI
vzQYI }
N"rZK/@} return bRemoved;
dt|f4XWF }
~6-6aYhe h`b[c.% g?d*cwtU DLL中的钩子函数如下:
a#4 'X* SebJ}P1x LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
N_),'2 {
Ig M_l= BOOL bProcessed=FALSE;
F(#~.i if(HC_ACTION==nCode)
AV*eGzz` {
m5rJY/ if((lParam&0xc0000000)==0xc0000000){// 有键松开
!_SIq`5]@ switch(wParam)
#Bgq]6G2 {
_F9O4Q4 case VK_MENU:
*QT|J6ng MaskBits&=~ALTBIT;
nH% 1lD?: break;
y OLqIvN case VK_CONTROL:
BbdJR]N/!h MaskBits&=~CTRLBIT;
&i%1\o break;
"ZLujpZcG case VK_SHIFT:
+1j+%&). MaskBits&=~SHIFTBIT;
njN]0l{p break;
mtn+bV
R% default: //judge the key and send message
%:WM]dc break;
'4}c1F1T_ }
<UMT:`h1MZ for(int index=0;index<MAX_KEY;index++){
37QXML if(hCallWnd[index]==NULL)
]J* y`jn continue;
lTn~VsoRZ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
'{(/C?T {
xMAb=87_
SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
cXo^.u bProcessed=TRUE;
auS.q5
% }
q=40l }
1-bQ
( - }
n%YG)5; else if((lParam&0xc000ffff)==1){ //有键按下
1_z6O!rx switch(wParam)
;c;n.o.)/# {
5pI=K/- case VK_MENU:
ST[+k MaskBits|=ALTBIT;
\<R.F
break;
_cW6H B^j case VK_CONTROL:
~8
w(M MaskBits|=CTRLBIT;
r0 6M.r break;
0{
;[k case VK_SHIFT:
+\ O[)\ MaskBits|=SHIFTBIT;
Udh!%QP%[w break;
bhb*,iWA default: //judge the key and send message
!(wH}ti break;
k;9"L90 }
2og8VI for(int index=0;index<MAX_KEY;index++){
&G"r>,HU if(hCallWnd[index]==NULL)
&RP}w%I1 continue;
\1p5$0z if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
f YuM`O {
^sjL@.'m$N SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
j2/3NF5& bProcessed=TRUE;
sUP!'Av }
@~l?hf }
P_w\d/3 }
4Dd7I if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
S=wJ{?gzAK for(int index=0;index<MAX_KEY;index++){
njy^<7; if(hCallWnd[index]==NULL)
V^U1o[` continue;
i!=28|_ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
^QKL}xiV: SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
&MlBpI //lParam的意义可看MSDN中WM_KEYDOWN部分
<.h\%&'U }
i;Y@>-[e< }
j_r7oARL }
8uO@S*)0 return CallNextHookEx( hHook, nCode, wParam, lParam );
6^DsI }
;I+"MY7D b:iZ.I 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:
MK<VjpP0( 9A4h?/ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
s;0eD5b>x BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
g#ZuRL !^|%Z 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:
VnJ-nfA vsM] <t LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
!j3V'XU#Zn {
yT>t[t60/S if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
L#`9# Q {
v0dFP0.;& //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
f~.w2Cna SaveBmp();
/~LXY<-( return FALSE;
ecH-JPm' }
ClH aR …… //其它处理及默认处理
H<SL=mb; }
elgCPX&:W 47iwb #dLp<l) 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。
x\Y%/C[Kc 3PonF4 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。
$J |oVVct Dk'EKT- 二、编程步骤
xmDX1sL** Ohm>^N;
1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
>q&Q4E0 (Jw[}&+ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
ZHshg`I` Te8BFcJG 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
id-VoHdK Hr$oT=x[ 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;
LaZF=<w( k:4?3zJI 5、 添加代码,编译运行程序。
s'^zudx ;!@\|E 三、程序代码
t#y xX'Uq_Jv ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
ndm19M8Y| #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
I_yIVw; #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
r<oI4px #if _MSC_VER > 1000
6bg+U`&g #pragma once
dv0TJ 0% #endif // _MSC_VER > 1000
0;)6ZU #ifndef __AFXWIN_H__
|zu>G9m #error include 'stdafx.h' before including this file for PCH
K)qbd~<\ #endif
sQ^>.yG #include "resource.h" // main symbols
Y\T*8\h_[ class CHookApp : public CWinApp
rI}E2J {
&F}1\6{fL public:
&bJ98Nxl CHookApp();
k~Pm.@,3o // Overrides
!v2,lH // ClassWizard generated virtual function overrides
l\^q7cXG //{{AFX_VIRTUAL(CHookApp)
LeW.uh3. public:
qD\%8l.]Z virtual BOOL InitInstance();
(nrrzOax virtual int ExitInstance();
co3H=#2a //}}AFX_VIRTUAL
4(4JQ(5 //{{AFX_MSG(CHookApp)
=tcPYYD // NOTE - the ClassWizard will add and remove member functions here.
*eXO?6f%s^ // DO NOT EDIT what you see in these blocks of generated code !
^c]Sl //}}AFX_MSG
L\og`L)5\ DECLARE_MESSAGE_MAP()
B>?Y("E };
&Jj> jCg LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
Z-<v5aF BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
.bl0w"c^qq BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
g]xZ^M+ BOOL InitHotkey();
6\,^MI BOOL UnInit();
)
WIlj #endif
FbM5Bqv ^@L[0Z` //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
U8-9^}DBA #include "stdafx.h"
~+>M,LfK #include "hook.h"
wZa;cg.-q #include <windowsx.h>
(r[<g*+3 #ifdef _DEBUG
A2&&iL=j/ #define new DEBUG_NEW
f
5i`B*/ #undef THIS_FILE
T *t$ static char THIS_FILE[] = __FILE__;
-R'p^cMA #endif
7IJb$af:; #define MAX_KEY 100
3r em"M #define CTRLBIT 0x04
29ft!R>[ #define ALTBIT 0x02
YY!(/<VI #define SHIFTBIT 0x01
(&MSP #pragma data_seg("shareddata")
:e@JESlLf HHOOK hHook =NULL;
8VcAtrx_ UINT nHookCount =0;
W? UCo6<m static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
*gz {:}NX static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
SA>;]6)`( static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
.%wEuqW=0 static int KeyCount =0;
)Qxv9:X static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
p>eD{#2 #pragma data_seg()
xYu~}kMu HINSTANCE hins;
@?]-5 ~3; void VerifyWindow();
!v;r3*#Nky BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
UuT[UB=x5 //{{AFX_MSG_MAP(CHookApp)
)N=b<%WD // NOTE - the ClassWizard will add and remove mapping macros here.
/1li^</|p` // DO NOT EDIT what you see in these blocks of generated code!
G0s:Dum //}}AFX_MSG_MAP
A}y1v;FB END_MESSAGE_MAP()
c0G/irK f!$J_dz CHookApp::CHookApp()
>qF KXzI {
sf*SxdoZU // TODO: add construction code here,
[!R%yD; // Place all significant initialization in InitInstance
bOz\-=au }
LVEVCpp@ <$yer)_J!k CHookApp theApp;
,IJ Nuu\ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Ee|+uQ981> {
_SP
u`=~K BOOL bProcessed=FALSE;
3sZK[Y|ax if(HC_ACTION==nCode)
f[}SS]d:E {
@$+[IiP if((lParam&0xc0000000)==0xc0000000){// Key up
?ha}# switch(wParam)
:
m5u=:t {
aq5<Ks `r case VK_MENU:
E7eVg*Cvi MaskBits&=~ALTBIT;
ygfqP break;
&HXSO,@ case VK_CONTROL:
FY|x<-f MaskBits&=~CTRLBIT;
hE6tu' break;
ewY[vbF case VK_SHIFT:
>Ed^dsb& MaskBits&=~SHIFTBIT;
|%V.Lae break;
fBLd5 default: //judge the key and send message
qBNiuV;* break;
`X^e}EGWu }
YqJIp. Z for(int index=0;index<MAX_KEY;index++){
^w12k2a if(hCallWnd[index]==NULL)
fcZOsTj continue;
`p ?E{k.N if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
(&*F`\ {
'9/kDkt! SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
blN1Q%m6 bProcessed=TRUE;
Qx,G3m[} }
.4Ny4CMHZ }
o7T|w~F~R }
1I+5 else if((lParam&0xc000ffff)==1){ //Key down
:> q?s switch(wParam)
Y>#c2@^i< {
j d81E case VK_MENU:
W_
6Jl5] MaskBits|=ALTBIT;
7}x-({bqy break;
)ED[cYGx case VK_CONTROL:
PjP%,-@1 MaskBits|=CTRLBIT;
>Qx#2x+ break;
2>!ykUw^O case VK_SHIFT:
m5p~>]}fYF MaskBits|=SHIFTBIT;
" /'=gE break;
L,D>E default: //judge the key and send message
/r%+hS break;
$F-XXBp }
".0W8= for(int index=0;index<MAX_KEY;index++)
H\k5B_3OU {
>eTlew<5 if(hCallWnd[index]==NULL)
CbHNb~ continue;
<M7*N. if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
j%}Jl {
xK r,XZu SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
`SwnKg bProcessed=TRUE;
0&\Aw'21 }
(>K$gAQH }
2$o[ }
0/ Ht;( if(!bProcessed){
'oHR4O* for(int index=0;index<MAX_KEY;index++){
_Nn!SE if(hCallWnd[index]==NULL)
.;:xx~G_Q continue;
:}JZKj!}M if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
JB(;[# '~ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
R,\
r{@yrz }
0c5_L6_z }
V3o AZ34) }
1 ~7_! return CallNextHookEx( hHook, nCode, wParam, lParam );
C#~MR+; }
oSl>%} ZYsFd_ BOOL InitHotkey()
/(V=Um^0 {
8[C6LG if(hHook!=NULL){
6\3k0z
nHookCount++;
[KH?5C return TRUE;
DOerSh_0W }
zFtGc else
OVyy}1Hx hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
88>Uu!M=f if(hHook!=NULL)
Z ~(XyaN nHookCount++;
RNdnlD#P return (hHook!=NULL);
y2R=%EFh6 }
re!8nuBsA BOOL UnInit()
]CZLaID~
{
vVYduvw if(nHookCount>1){
+_eb*Z`5o nHookCount--;
pNlisS return TRUE;
^JtHTLHL= }
Y*k<NeDyn BOOL unhooked = UnhookWindowsHookEx(hHook);
lAk1ncx if(unhooked==TRUE){
i'wF>EBz nHookCount=0;
?X'*
p<` hHook=NULL;
?i~/gjp
}
}BJ1#< return unhooked;
5Mr;6
]I< }
{_Qxe1^g / D ]B BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
2]9<%-=S {
U_- K6:tr BOOL bAdded=FALSE;
kkBU<L2 for(int index=0;index<MAX_KEY;index++){
2NknC>9(\ if(hCallWnd[index]==0){
@'*#]YU8 hCallWnd[index]=hWnd;
CLfb`rF HotKey[index]=cKey;
!)3s <{k# HotKeyMask[index]=cMask;
cf'}*$[S bAdded=TRUE;
-mJ&N KeyCount++;
UWp8I)p!\O break;
l _O~v? }
DH9?2)aR }
~Ls I<z return bAdded;
-^H5z+"^ }
~{YgM/c|dt xD#I&. BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
o'7ju~0L {
;CMC`h9, BOOL bRemoved=FALSE;
23$hwr&G\ for(int index=0;index<MAX_KEY;index++){
kA<r:/ if(hCallWnd[index]==hWnd){
#>jH[Q if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
8MeXVhM hCallWnd[index]=NULL;
gVU\^KN] HotKey[index]=0;
pMp9O/u% HotKeyMask[index]=0;
3Z:!o$ bRemoved=TRUE;
htYrv5q=M KeyCount--;
-Y=c g; break;
d:pm|C|F }
%`T5a< }
M3@fc,Ch }
6Y)^)dOi return bRemoved;
!*Z)[[ }
!7`=rT&