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:
|$vhu`]Z@^
&@dWd 一、实现方法
DfCo= W1UG\d`2 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
+=y ktf VvO/
#pragma data_seg("shareddata")
MO{6B#(<F HHOOK hHook =NULL; //钩子句柄
U-$ B"w & UINT nHookCount =0; //挂接的程序数目
hupYiI~ static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
dpBG)Xzoyv static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
%`c?cB static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
9xvE?8;M# static int KeyCount =0;
i8`&XGEd static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
~?pF'3q #pragma data_seg()
nx(O]R,Sw (BgO< 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。
z90=,wd mySm:ToT 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:
XB &-k<C NC 0H5 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
9's/~T cKey,UCHAR cMask)
MR90 }wXE {
z/7H/~d BOOL bAdded=FALSE;
$V"~\h8 for(int index=0;index<MAX_KEY;index++){
=sP6 if(hCallWnd[index]==0){
"jVMk hCallWnd[index]=hWnd;
-IR9^) HotKey[index]=cKey;
#![i
{7 HotKeyMask[index]=cMask;
#]ii/Et#x bAdded=TRUE;
'iN8JO> KeyCount++;
:8;8-c break;
/Xi:k }
Dg_/Iu>OAE }
FU0&EO return bAdded;
63QSYn,t }
+:2(xgOP.V //删除热键
~ e[)]b3 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
V#W(c_g {
TA=Ij,z~ BOOL bRemoved=FALSE;
S:] w@$ for(int index=0;index<MAX_KEY;index++){
nMcd(&`N if(hCallWnd[index]==hWnd){
EIl _QV6 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
a%f5dj+ hCallWnd[index]=NULL;
m=2TzLVv HotKey[index]=0;
/^v4[] HotKeyMask[index]=0;
}k}5\%#li5 bRemoved=TRUE;
J4te!, KeyCount--;
Mg95us break;
Q]7Q4U }
_OT kv6;4n }
W K#lE&V3 }
|B4dFI? return bRemoved;
/Mf45U< }
LiJ;A* io:?JnQSA Gq;0j:?CC DLL中的钩子函数如下:
6^['g-\2 KhZ'Ic[vw LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
7,|-%!p[ {
KoQvC=+WI BOOL bProcessed=FALSE;
R+Ke|C if(HC_ACTION==nCode)
l\5qa_{z {
mxjY-Kq if((lParam&0xc0000000)==0xc0000000){// 有键松开
ltHC+8aZ switch(wParam)
udg;jR-^ {
:$[m[y7i case VK_MENU:
?S!lX[#v MaskBits&=~ALTBIT;
F1?@tcr' break;
Vm&fw".J case VK_CONTROL:
@ky5XV MaskBits&=~CTRLBIT;
}mz4 3Sq< break;
xYRL4 case VK_SHIFT:
LL-MZ~ZB MaskBits&=~SHIFTBIT;
<"CG%RGP break;
\u,hS*v0 default: //judge the key and send message
uZ Id.+Rk break;
g}' "&Y }
LP_!g for(int index=0;index<MAX_KEY;index++){
RXgi>Hz if(hCallWnd[index]==NULL)
Q=~e| continue;
Oa7`Y`6 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
L4SFu.J' {
z-(dT SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
blaxUP: bProcessed=TRUE;
k`.-PU }
fYx$3a. }
m+DkO{8F }
2c!?!:s else if((lParam&0xc000ffff)==1){ //有键按下
W32mAz; switch(wParam)
Ik=KEOz {
61T"K case VK_MENU:
Y cOtPS% MaskBits|=ALTBIT;
)y.J2_lI8 break;
|!I# T case VK_CONTROL:
^fS~va MaskBits|=CTRLBIT;
,_YCl09p( break;
LUKdu&M case VK_SHIFT:
\8Fe56 MaskBits|=SHIFTBIT;
*;+lF break;
Dw;L=4F
| default: //judge the key and send message
}RG break;
@?*26}qp }
5Z6$90!k for(int index=0;index<MAX_KEY;index++){
|/ZpZ7 if(hCallWnd[index]==NULL)
l[Ng8[R continue;
3j<]
W if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
&{y-}[~
{
)#Y*] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Uh?SDay bProcessed=TRUE;
T
-C2V$1 }
T\8|Q@ }
5x4JDaG2 }
E+>Qpy if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
z{``v|K for(int index=0;index<MAX_KEY;index++){
6!Ji-'\" if(hCallWnd[index]==NULL)
;2)@NH continue;
t1g)Y|@d if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
A(Ugam~} SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
Jh M.P9 //lParam的意义可看MSDN中WM_KEYDOWN部分
\|DcWH1 }
292e0cE }
-`iZBC50 }
5 ah]E return CallNextHookEx( hHook, nCode, wParam, lParam );
o*I=6`j }
2HkP$;lED e}kEh+4 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:
cl1h;w9s /S\P=lcb BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
^#lPXC Bg BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
n/S1Hae` hUB_[#8# 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:
@\z2FJ79w d1``}naNw LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
/V2^/`&;a {
PRWS[2[yk if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
5R/k -h^` {
C:l
/% //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
HeNg<5v%Y SaveBmp();
B Lw ssr. return FALSE;
4mQ:i7~ }
Kt;h'? …… //其它处理及默认处理
DE^{8YX, }
x<~ pqq8] 80&JEtRh HKb8z@;%@ 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。
~*- eL. e%U0^! 8 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。
}O<=!^Y;A sD_Z`1 二、编程步骤
@i$9c)D 75jq+O_: 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
r|{h7' 1<\@i{;xsU 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
w(eAmN:zR `QnKal ) 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
(XX6M[M8 [C,<Q 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
B ;9^ ltO:./6v 5、 添加代码,编译运行程序。
c'vxT<8fWW *rXESw]BR 三、程序代码
kBS;SDl) =%%\b_\L ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
|Z0? #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
qb]n{b2 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
'u@
)F` #if _MSC_VER > 1000
dpDVEEs84 #pragma once
Q&opnvN #endif // _MSC_VER > 1000
+%OINMo.A #ifndef __AFXWIN_H__
E5~HH($b #error include 'stdafx.h' before including this file for PCH
r1\c{5Wt #endif
TUw^KSa #include "resource.h" // main symbols
ryB^$Kh,, class CHookApp : public CWinApp
jr|(K*; {
w4Qqo( public:
h3Nwxj~E CHookApp();
.{1G"(z // Overrides
1XSA3;ZEc // ClassWizard generated virtual function overrides
#g#vDR! //{{AFX_VIRTUAL(CHookApp)
z\Rs?v" public:
AON";&dLq- virtual BOOL InitInstance();
=Mzg={)v virtual int ExitInstance();
y>Zvos e //}}AFX_VIRTUAL
r Lg(J|^ //{{AFX_MSG(CHookApp)
ng0IRJ:3 // NOTE - the ClassWizard will add and remove member functions here.
jL(=<R(~y // DO NOT EDIT what you see in these blocks of generated code !
<H<5E'm //}}AFX_MSG
&tB|l_p_-p DECLARE_MESSAGE_MAP()
b'Pq[ ) };
]( V+ qj LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
7F5t& BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
bE#=\kf| BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
X,:pT\G BOOL InitHotkey();
VUC BOOL UnInit();
x%23oPM #endif
\(Dq=UzQI 1sl^+)z8 //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
?VrZM #include "stdafx.h"
jb~a z #include "hook.h"
&I
Iw>,, #include <windowsx.h>
kT@RA} #ifdef _DEBUG
!sQ$a#Ea #define new DEBUG_NEW
I<e[/#5P\` #undef THIS_FILE
r=Z#"68$ static char THIS_FILE[] = __FILE__;
4!p~Mr[E #endif
mr6/d1af_ #define MAX_KEY 100
.j:.?v #define CTRLBIT 0x04
|:$D[= #define ALTBIT 0x02
8>S"aHt 7 #define SHIFTBIT 0x01
vCyvy^s-I #pragma data_seg("shareddata")
] as_7 HHOOK hHook =NULL;
_I8L#4\(= UINT nHookCount =0;
dya]^L}fL static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
s\i=-` static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
xoF]r$sC8 static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
k@JDG]R<{ static int KeyCount =0;
DnvJx!#R static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
Rn~FCj,- #pragma data_seg()
@P#uH5U HINSTANCE hins;
^29w@* void VerifyWindow();
=]&?(Gq BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
^'.=&@i- //{{AFX_MSG_MAP(CHookApp)
_+g5;S5 // NOTE - the ClassWizard will add and remove mapping macros here.
*(YtO // DO NOT EDIT what you see in these blocks of generated code!
0-p LCf //}}AFX_MSG_MAP
[RCUP. END_MESSAGE_MAP()
jLX{$, ,oX48Wg_+ CHookApp::CHookApp()
LuY`mi {
jK/2n}q&] // TODO: add construction code here,
wNL!T6"G // Place all significant initialization in InitInstance
0Ge*\Q }
:bI4HXT3 e`k6YO CHookApp theApp;
r7Bv?M^! LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
9)0AwLlv {
A!Zjcp| BOOL bProcessed=FALSE;
_=E))Kp{z if(HC_ACTION==nCode)
In^MZ)? {
@*q WV*$h if((lParam&0xc0000000)==0xc0000000){// Key up
;8/w'oe*j switch(wParam)
95Bw;U3E {
7Ipt~K} case VK_MENU:
E]w1!Ah M MaskBits&=~ALTBIT;
tagkklJ~ break;
Mf7Q+_! case VK_CONTROL:
LSb3w/3M MaskBits&=~CTRLBIT;
WRU/^g3O@' break;
eO;i1 > case VK_SHIFT:
txQyHQ)@ MaskBits&=~SHIFTBIT;
7IW:,=Zk8+ break;
EJ{Z0R{{ default: //judge the key and send message
j*f%<`2`j break;
&[,g`S0 }
I2kqA5>)j for(int index=0;index<MAX_KEY;index++){
q"ba~@<BEl if(hCallWnd[index]==NULL)
0i\ol9,bf continue;
L>+g;GJ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
rt$zM {
pq_DYG] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
~K% ]9
bProcessed=TRUE;
$l-|abLELz }
mE)65@3% }
%Q5D#d"p` }
uXq?Z@af|f else if((lParam&0xc000ffff)==1){ //Key down
{`QF(WL switch(wParam)
^Dh j<_ {
o^dt#
& case VK_MENU:
S+H#^WSt MaskBits|=ALTBIT;
c\FyX\i break;
W!q'wrIx( case VK_CONTROL:
;e;lPM{+ MaskBits|=CTRLBIT;
*-$u\?$ break;
hj64ES#x case VK_SHIFT:
k|0Fa}Z[ MaskBits|=SHIFTBIT;
ya5a7 break;
#3u3WTk+ default: //judge the key and send message
& tQHxiDX break;
y?O{J!U }
2+"=i/8 for(int index=0;index<MAX_KEY;index++)
EquNg@25W {
W=M&U if(hCallWnd[index]==NULL)
/{ YUM~ continue;
^y'xcq if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
wpu]{~Y {
o_/C9[: SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
vW]Frb bProcessed=TRUE;
*LcLYxWo }
(Tp+43v }
:Q2\3 }
Dntcv|%u if(!bProcessed){
ASY
uZ for(int index=0;index<MAX_KEY;index++){
/k<*!H]KSg if(hCallWnd[index]==NULL)
eHK}U+"\ continue;
&<@{ d if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
,]Yjo>`tW SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
;hF >iw }
/'
L20aN2 }
J9ovy>G }
S;NChu?8
return CallNextHookEx( hHook, nCode, wParam, lParam );
&=|W95 }
7}Z.g9< \sHM[nF0 BOOL InitHotkey()
$>'}6?C. {
%r6LU<;1@ if(hHook!=NULL){
:eS7"EG{3 nHookCount++;
\F,?ptu return TRUE;
5{#9b^ }
iJ42` 51 else
xp/u, q hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
mDipP if(hHook!=NULL)
@SPmb o nHookCount++;
#:T5_9p return (hHook!=NULL);
vtR<(tOu@ }
<y*#[:i BOOL UnInit()
!f)'+_d {
8v1asFxs. if(nHookCount>1){
( NjX?^ nHookCount--;
_kH#{4`Hw return TRUE;
~FZLA} }
St|sUtj<r BOOL unhooked = UnhookWindowsHookEx(hHook);
[lS'GszA if(unhooked==TRUE){
|:!#kA nHookCount=0;
-iBu:WyY$ hHook=NULL;
mwbkXy;8 }
.^@+$} return unhooked;
WSDNTfpI }
_<