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:<NQd
OI@;ffHSW 一、实现方法
P4h^_*d %jS#DVxBR 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:
S,I|8
YE `E @TPdu #pragma data_seg("shareddata")
Ub>Pl,~' HHOOK hHook =NULL; //钩子句柄
l_?r#Qc7 UINT nHookCount =0; //挂接的程序数目
0!Zp4>l\Z static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
0uw3[,I
static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
pwu8LQ3b{O static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
!YM;5vte+ static int KeyCount =0;
,WvCslZ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
8y9`xRy #pragma data_seg()
Cob<N'. #b^x! lR 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。
e!eUgD d]fo>[%Xr 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:
")gd)_FOS GjHV|)^ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
Qp]-:b cKey,UCHAR cMask)
-W6r.E$mC {
EWU(Al T BOOL bAdded=FALSE;
cx+li4v for(int index=0;index<MAX_KEY;index++){
XIS.0]~ if(hCallWnd[index]==0){
'4T]=s~N hCallWnd[index]=hWnd;
V~9vf*X HotKey[index]=cKey;
@bkZ< Gq HotKeyMask[index]=cMask;
%.NOQ<@W bAdded=TRUE;
ITUwIpAE KeyCount++;
:)djHPP* break;
kdr?I9kwW }
!F^j\ }
|z]O@@j$ return bAdded;
Xp_3EQl }
*>=|"ff //删除热键
R)[ l3 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
yf lt2 R {
bwr}Ge BOOL bRemoved=FALSE;
7Ud for(int index=0;index<MAX_KEY;index++){
Qz[4M` M if(hCallWnd[index]==hWnd){
1vy*u if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
~F{u4p7{N hCallWnd[index]=NULL;
YtQsSU HotKey[index]=0;
QH)uh" HotKeyMask[index]=0;
/4Df 'd bRemoved=TRUE;
ZysZS% KeyCount--;
H@j
D% break;
g^`;B" }
iC$mb~G }
r+#! ]wNPe }
y*f5_ return bRemoved;
Q?1'
JF!G }
]< Ugg Q5!"tF p qGH
s2Og DLL中的钩子函数如下:
,(D:cRN =P,h5J LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
^")SU(` {
bOY<C%;C
BOOL bProcessed=FALSE;
sz7|2OV" if(HC_ACTION==nCode)
T({]fc!c {
2O*(F>>dT if((lParam&0xc0000000)==0xc0000000){// 有键松开
NHL -ll-R switch(wParam)
96 ozt UK {
ME9jN{ le case VK_MENU:
[6$n MaskBits&=~ALTBIT;
t9Sog~:' break;
Z>O2 case VK_CONTROL:
xn=/SIS MaskBits&=~CTRLBIT;
O<H5W|cM break;
<<ze84E case VK_SHIFT:
K~U5jpc MaskBits&=~SHIFTBIT;
xM#+jI break;
GD]yP.. default: //judge the key and send message
C}7c:4c break;
qMHI-h_A }
z. 6-D for(int index=0;index<MAX_KEY;index++){
A.D@21py if(hCallWnd[index]==NULL)
gGtl*9a= continue;
]V `L\ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
2$Fy?08q {
nw)yK%`;M SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
U}=o3u bProcessed=TRUE;
M^e;WY@ D }
P:p@Iep }
&4m\``//9 }
pyf/%9R:d else if((lParam&0xc000ffff)==1){ //有键按下
|z5`h switch(wParam)
O.9r'n4f {
%GY U$aA case VK_MENU:
figCeJ!W4 MaskBits|=ALTBIT;
M?3Nh; break;
IKm_YQ$XOy case VK_CONTROL:
R
_c!
,y MaskBits|=CTRLBIT;
b/yXE)3
X break;
(B0tgg^jj, case VK_SHIFT:
5y1:oiE/ MaskBits|=SHIFTBIT;
{dbPMx break;
UE-+P default: //judge the key and send message
i8kyYMPP break;
aj$#8l |zu }
nO{m2&r+ for(int index=0;index<MAX_KEY;index++){
wcd1.$ n if(hCallWnd[index]==NULL)
8ph*S&H continue;
<z=d5g{n if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
7FTf8 {
[Ju5O[o SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
5 wT
e? bProcessed=TRUE;
.5'_5>tkv }
2<
"- }
&* Aems{- }
Lwzk<+>w^ if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
+im>| for(int index=0;index<MAX_KEY;index++){
5i$iUDuT>( if(hCallWnd[index]==NULL)
g~A~|di| continue;
^O9_dP: if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
??7c9l5, SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
8vuA`T!~G //lParam的意义可看MSDN中WM_KEYDOWN部分
j~'a %P }
JxV0y }
m7F"kD }
bH7 lUS~ return CallNextHookEx( hHook, nCode, wParam, lParam );
Y
>83G`*}b }
I|SQhbi XEB1%. p 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
';\v:dP #7Pnw.s3zz BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
S
6|#9C& BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
:d!qZFln Vzs_g]V 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
j&c YRKpz B F,8[|%# LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
RAh4#8] {
whoQA}X> if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
@C?.)# {
OX
r%b //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
*?-,=%,z/ SaveBmp();
s_p\
bl. return FALSE;
FVgE^_ }
/3!c
;( …… //其它处理及默认处理
9c}mAg4 }
a9"1a' KcK,%!>B >,&@j,?'] 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
o-f;$]yp> ==?!z<I.d 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。
|BC/ERms bRhc8#kw) 二、编程步骤
He}uE0^ MKr)6PG, 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";
[ 1$p}x GgNqc i, 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
&6#>a"?" FS1>
J%P 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
3rUuRsXn )qL UHE= 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
mk'$ |2O sb3k? q 5、 添加代码,编译运行程序。
y-/,,,r /|HVp 三、程序代码
t
5{Y' a#k=!
W ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
gI/#7Cr #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
_?YP0GpU #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
#3h~Z)+y #if _MSC_VER > 1000
kW!`vQm~ #pragma once
O2n[`9* #endif // _MSC_VER > 1000
z5|m`$gy #ifndef __AFXWIN_H__
ALOS>Bi& #error include 'stdafx.h' before including this file for PCH
icw (y(W #endif
"~|;XoMU #include "resource.h" // main symbols
1>pFUf|cV class CHookApp : public CWinApp
43HZ)3!me {
&l0-0T> public:
FB\lUO)U\c CHookApp();
us0{y7(p // Overrides
6zf3A:]&{ // ClassWizard generated virtual function overrides
l5*sCp*Z //{{AFX_VIRTUAL(CHookApp)
6HK
dBW$/ public:
=rB=! ; virtual BOOL InitInstance();
R'Uw17I virtual int ExitInstance();
eM1=r:jgE //}}AFX_VIRTUAL
&{5v[:$ //{{AFX_MSG(CHookApp)
N"M?kk, // NOTE - the ClassWizard will add and remove member functions here.
O.HaEg/- // DO NOT EDIT what you see in these blocks of generated code !
6bacU#0o //}}AFX_MSG
g:yUZ;U DECLARE_MESSAGE_MAP()
5x}XiMM };
U^@8ebv LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
E;>BcPt5 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
O9_S"\8]@ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
ku&m)' BOOL InitHotkey();
'cpO"d?{ BOOL UnInit();
-<jd/ 5 #endif
Tx|}ke~ jlA?JB //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
yW!+:y_N_ #include "stdafx.h"
?L'4*S] #include "hook.h"
V|njgcn d #include <windowsx.h>
iL ](w3EM #ifdef _DEBUG
#zL0P>P'a #define new DEBUG_NEW
N;6@f*3_i #undef THIS_FILE
/ad]pdF static char THIS_FILE[] = __FILE__;
hHoc>S6^M #endif
+,H6)'#Z #define MAX_KEY 100
OfAh?^R #define CTRLBIT 0x04
d ~`_;.z #define ALTBIT 0x02
]JUb;B;Z #define SHIFTBIT 0x01
D|lm, #pragma data_seg("shareddata")
S7A[HG; HHOOK hHook =NULL;
.bT+#x UINT nHookCount =0;
YM(`E9{h static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
_Cd_i[K[ static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Tam\,j static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
,]\: ]Y&? static int KeyCount =0;
Vjc*D] static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
^-|yF2>` #pragma data_seg()
3!OO_ HINSTANCE hins;
MUeS8:q-N void VerifyWindow();
-l ?J BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
H)Kt!v8 //{{AFX_MSG_MAP(CHookApp)
':[:12y[ // NOTE - the ClassWizard will add and remove mapping macros here.
$d +n},[C{ // DO NOT EDIT what you see in these blocks of generated code!
,O;+fhUJ( //}}AFX_MSG_MAP
^UJ#YRzi END_MESSAGE_MAP()
`"#0\Wh zq?Iwyo CHookApp::CHookApp()
w{HDCPuS {
NETji:d // TODO: add construction code here,
(K}Md~ // Place all significant initialization in InitInstance
qOi3`6LCV }
4wa8Vw` bktw?{h CHookApp theApp;
tK$x=9M LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
DKzP)!B " {
#G/
_FRo` BOOL bProcessed=FALSE;
k\~A\UIYo if(HC_ACTION==nCode)
3o>.Z; {
,fQs+*j if((lParam&0xc0000000)==0xc0000000){// Key up
_1?
PN8 switch(wParam)
@NY$.K#] {
@uWPo2 case VK_MENU:
JuD$CHg;# MaskBits&=~ALTBIT;
[)ybPIv]
break;
&7gE=E(M case VK_CONTROL:
:2\H>^uV MaskBits&=~CTRLBIT;
u\]aUP
e break;
)t/[z3rn case VK_SHIFT:
<>&!+|# MaskBits&=~SHIFTBIT;
YnCWmlC break;
DW,fh8 w
default: //judge the key and send message
pKM5<1J break;
w,CZ*/^ }
CLU[')H0 for(int index=0;index<MAX_KEY;index++){
luEP5l2& if(hCallWnd[index]==NULL)
jgb>:]: continue;
;h
}^f- if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
dF-d {
wW1E
'Vy{ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
z+J4XpX0, bProcessed=TRUE;
7r_Y. }
ke(LjRS }
j(8I+|| }
g[W`4 else if((lParam&0xc000ffff)==1){ //Key down
0k];%HV| switch(wParam)
W9$mgs=S`E {
wkp|V{k case VK_MENU:
fR4O^6c: MaskBits|=ALTBIT;
<^Hh5kfS' break;
>#MGGCGL case VK_CONTROL:
-/s2' MaskBits|=CTRLBIT;
L'>t:^QTh break;
p4|Zz:f case VK_SHIFT:
'$cU\DTN6 MaskBits|=SHIFTBIT;
/y\KLa break;
Ff\U]g default: //judge the key and send message
3j2% '$>E^ break;
mxpncM=q }
ZA;wv+hF= for(int index=0;index<MAX_KEY;index++)
f"0{e9O]2 {
o~Im5j],* if(hCallWnd[index]==NULL)
mh4NZ @; continue;
T]5JsrT if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
W .c:Pulg {
/FZ@Z]Q0G SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
z]NN ^pIa bProcessed=TRUE;
FL5tIfV+ }
Ve4!MM@ti }
U 9?!|h;7 }
\mt0mv;c if(!bProcessed){
}b#KV?xgW for(int index=0;index<MAX_KEY;index++){
FuYV}C if(hCallWnd[index]==NULL)
R ks3L continue;
XZaei\rUn) if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
C?FUc cI SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
#eqy!QdePf }
8bB'[gJ]{ }
J%
B(4` }
!2('Cq_^ return CallNextHookEx( hHook, nCode, wParam, lParam );
~D4%7U"dv }
0!n6tz lT >^@/Ba$h BOOL InitHotkey()
XK)qDg {
<tEN1i if(hHook!=NULL){
Ou
_bM n nHookCount++;
CbJ ]}Z return TRUE;
ACg5" }
T[iwP~l else
|zV-a2K%J hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
\h%/Cp+p if(hHook!=NULL)
x)hp3&L nHookCount++;
C^po*(W6 return (hHook!=NULL);
?PIOuN= }
:VPZGzK4 BOOL UnInit()
<B;l).[6 {
r )cGee if(nHookCount>1){
-Kj^ l3w nHookCount--;
[Ng#/QXk{ return TRUE;
^G,]("di` }
Y9TaU]7] BOOL unhooked = UnhookWindowsHookEx(hHook);
[T;0vv8 if(unhooked==TRUE){
e+z_Rj%Y;I nHookCount=0;
G<C[A
hHook=NULL;
4Lx#5}P }
mis
cmD return unhooked;
/\-qz$ }
k,xY\r$ _u^ S[ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
)g9&fGYf {
i;1aobG BOOL bAdded=FALSE;
BzqM$F(
L, for(int index=0;index<MAX_KEY;index++){
,%+i}H,3 if(hCallWnd[index]==0){
d/8I&{. hCallWnd[index]=hWnd;
pJ6Z/3] HotKey[index]=cKey;
a;Q6S HotKeyMask[index]=cMask;
-<gGNj.x- bAdded=TRUE;
|0?h6 KeyCount++;
Y~T;{&wi break;
K .cMuh }
H|4O`I;~( }
DiyviH return bAdded;
+$:bzo_u }
CT@JNG$<" *5k" v"NM( BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
ZM/*cA!" {
n|vIo) BOOL bRemoved=FALSE;
NhyVX%qt: for(int index=0;index<MAX_KEY;index++){
<im
BFw if(hCallWnd[index]==hWnd){
yz}Agc4.I if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
F:.rb
Ei hCallWnd[index]=NULL;
(gQ^jmZPG HotKey[index]=0;
DFKU?#R HotKeyMask[index]=0;
c|[:vin bRemoved=TRUE;
qALlMj--m KeyCount--;
/s3AZ j9 break;
m$xL#omD }
-MV </ }
nz:I\yA }
`<Xq@\H return bRemoved;
#`5{?2gS9 }
lzz rzx^ `1F[.DdF void VerifyWindow()
>&mlwxqv {
cB
U,! for(int i=0;i<MAX_KEY;i++){
iN0gvjZ if(hCallWnd
!=NULL){ ] Cpd`}'
if(!IsWindow(hCallWnd)){ MP\$_;&xB
hCallWnd=NULL; F#KO!\iA+
HotKey=0; <N11$t&_
HotKeyMask=0; "q(#,,_
KeyCount--; klduJT
>
} SF2A?L?}+
} q1sK:)Hu+
} .%7#o
} .
KJEA#
r3oAP[+n
BOOL CHookApp::InitInstance() Qi',[Xmf
{ 3A%/H`
AFX_MANAGE_STATE(AfxGetStaticModuleState()); `#&pB0.y
hins=AfxGetInstanceHandle(); &B\tcF
InitHotkey(); F gM<2$h
return CWinApp::InitInstance(); _D:#M
} Z-`j)3Y
JnCp'`
int CHookApp::ExitInstance() >cEc##:5
{ "$KU+?
VerifyWindow(); 8;YeEW5
UnInit(); )&}\2NK6L
return CWinApp::ExitInstance(); {yQeLION
} %"~\Pu*>
N!>Gg|@~
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file YB/A0 J
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) T_bk%
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ kVk^?F
#if _MSC_VER > 1000 5K13
#pragma once 8Czy<}S<G
#endif // _MSC_VER > 1000 gNJ,Bj Pd
#/zPAcV:
class CCaptureDlg : public CDialog &o$E1;og
{ euO!+9p
// Construction Hzs]\%"
public: |><hdBQXX<
BOOL bTray; = R|?LOEK+
BOOL bRegistered; )=TD}Xb
BOOL RegisterHotkey(); /NCEZ@2BN,
UCHAR cKey; j?D=Ij"o
UCHAR cMask; [$)C(1zY
void DeleteIcon(); [@Y<:6
void AddIcon(); deSrs:.
UINT nCount; m`!C|?hu
void SaveBmp(); bj4cW\b(
CCaptureDlg(CWnd* pParent = NULL); // standard constructor _y&m4V