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:
!.@:t`w
srImk6YD 一、实现方法
eK3d_bF+ 4T)`%Oo<} 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:
+['1~5 n^G[N-\3 #pragma data_seg("shareddata")
+W[{UC4b HHOOK hHook =NULL; //钩子句柄
^eRbp?H*T UINT nHookCount =0; //挂接的程序数目
t?weD{O static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
B=_5gZ4Y static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
e*D,2>o static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
\Z~@/OVc static int KeyCount =0;
Pa|*Jcr static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
>K%+h)%kI #pragma data_seg()
4 l+z iY sQ:3s 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。
Iz#jR2:yn +]H!q
W: 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:
0H'G./8 \)MzUOZn BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
Esj1Vv# cKey,UCHAR cMask)
^q}phj3E {
b|k(:b-G&. BOOL bAdded=FALSE;
a[!:`o1U for(int index=0;index<MAX_KEY;index++){
11A;z[Zk if(hCallWnd[index]==0){
g6SZ4WV hCallWnd[index]=hWnd;
/b4>0DXT5 HotKey[index]=cKey;
-"Nvu HotKeyMask[index]=cMask;
X1u\si%.4S bAdded=TRUE;
\4OU+$m KeyCount++;
h2+"e# _ break;
eVbT<9k }
e5n"(s"G*[ }
+rrA>~ return bAdded;
FB~IO#E8W }
G)3r[C^[k //删除热键
?FZ)
LZM BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
mI^S% HT {
5]3Mj*u\ BOOL bRemoved=FALSE;
uD4W@*PYr for(int index=0;index<MAX_KEY;index++){
+-hfl/$ if(hCallWnd[index]==hWnd){
-7I%^u if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
6LT.ng hCallWnd[index]=NULL;
bSTTr<W HotKey[index]=0;
z=rSb4"W HotKeyMask[index]=0;
>8`;SEnv bRemoved=TRUE;
mLHl]xs4 KeyCount--;
%~Wr/TOt+ break;
!i{5mc\ }
[RDY(}P% }
V)oKsO }
'?mky,:HT return bRemoved;
@_#]7
}
qs
(L2'7/ Nfl5tI$U: 0SZ:C(] DLL中的钩子函数如下:
5S7ATr(* }qhND-9#@ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
OR10IS {
|Yi_|']# BOOL bProcessed=FALSE;
&c=
3BEh if(HC_ACTION==nCode)
"t>H
B6^ {
#Y'ub
5s if((lParam&0xc0000000)==0xc0000000){// 有键松开
d&DQ8Gm ^ switch(wParam)
Hv
=7+O$ {
#J$z0%P case VK_MENU:
|A)a
='Ap MaskBits&=~ALTBIT;
[Z]CBEE break;
~.S/<:`U case VK_CONTROL:
T<0V ^B7 MaskBits&=~CTRLBIT;
kh"APxQ79 break;
-ozcK case VK_SHIFT:
EuD$^# MaskBits&=~SHIFTBIT;
#6 $WuIG break;
\Dx)P[Ur default: //judge the key and send message
v@:m8Y(t break;
J>0RN/38o }
7"])Y for(int index=0;index<MAX_KEY;index++){
G/_8xmsU if(hCallWnd[index]==NULL)
#]wBXzu? continue;
'"V]>) if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
cMAY8$ {
=A/$[POr SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
<ZoMKUuB bProcessed=TRUE;
^%33&<mB} }
qD}O_<_1ym }
P[P]oT.N
}
rWuqlx# else if((lParam&0xc000ffff)==1){ //有键按下
1z8fhE iiE switch(wParam)
l27J {
Lyjp case VK_MENU:
DPlmrN9@= MaskBits|=ALTBIT;
ENZYrWl
break;
&WVRh=R case VK_CONTROL:
>% E=l MaskBits|=CTRLBIT;
;E\ e.R break;
1KI5tf>>p case VK_SHIFT:
"A}2iI MaskBits|=SHIFTBIT;
pxQh;w break;
\.`{nq default: //judge the key and send message
O6\t_. break;
\r\wqz7 }
v-}D>)M^W for(int index=0;index<MAX_KEY;index++){
aw1f;&K4 if(hCallWnd[index]==NULL)
kNUNh[ continue;
SKSI\]Cc if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
'u%SI]*;> {
'&iAPc4= SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
$&0\BvS bProcessed=TRUE;
Z+S1e~~ }
Y:5Gp8Vi }
,k6V?{ZA }
#Gu(h(Z s if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
SMHQh.O?5 for(int index=0;index<MAX_KEY;index++){
{mB &xz:b if(hCallWnd[index]==NULL)
{&)E$M continue;
#D8u#8Dz if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
RV6|sN[x> SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
@?[}\9dW //lParam的意义可看MSDN中WM_KEYDOWN部分
|\h<!xR }
D~f[ R g }
-Rr Qv( }
h_xzqElZu return CallNextHookEx( hHook, nCode, wParam, lParam );
FmtV[C# }
(L7%V ! +C`zI~8 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:
R"{oj]d;$F 6w$pL( BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
j:J7 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
e\H1IR3 A@
4Oq 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:
x`zE#sD kwpbg Q LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
jsIT{a*] {
SHUn<+/e if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
jRSY`MU}t+ {
JO|xX<#: //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
%`^{Hh` SaveBmp();
h[j(@P return FALSE;
Xwk_QFv3 }
M[5fNK&nD …… //其它处理及默认处理
4mwA o }
uBxs`'C %9`\7h7K "5$2b>_UE 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
Y-:dPc{ v\Xyz
) 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
@"BkLF #w]@yL]|is 二、编程步骤
+Uf+` Te&5IB- 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
~#9(Q *d,Z?S/ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
{~~' iea7*]vW 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
`:;fc vI+X9C? 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
sn:wLc/GAd 4lF?s\W: 5、 添加代码,编译运行程序。
2vX!j!_ &s_)|K 三、程序代码
aX(Y
`g)| T Ue=Yj ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
`>skcvkm #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
Xe:e./@ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
hGlRf_{ #if _MSC_VER > 1000
~mu)Cw #pragma once
h<IPV'1 #endif // _MSC_VER > 1000
)+12r6W #ifndef __AFXWIN_H__
`ouCQ]tKz #error include 'stdafx.h' before including this file for PCH
>`D$Jz, #endif
5TVA1 #include "resource.h" // main symbols
Lsz)\yIPj class CHookApp : public CWinApp
s<fzk1LZ {
n*vhCeL public:
.
I#dR* CHookApp();
dpI! {'"M // Overrides
!ZTBiC5R // ClassWizard generated virtual function overrides
)w&k&TY4H //{{AFX_VIRTUAL(CHookApp)
R{SN.% {; public:
C(lGW,! virtual BOOL InitInstance();
XXZ <r virtual int ExitInstance();
iP+3) //}}AFX_VIRTUAL
V75P@jv5J //{{AFX_MSG(CHookApp)
PvqG5-L~W // NOTE - the ClassWizard will add and remove member functions here.
kJG0X%+w // DO NOT EDIT what you see in these blocks of generated code !
0N4+6k| //}}AFX_MSG
m<| * DECLARE_MESSAGE_MAP()
\ q=Bbfzv };
G7d)X^q!xS LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
b;Uqyc BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
+C){&/=# BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
1JSKK.LuJV BOOL InitHotkey();
8+OcM
;0 BOOL UnInit();
c:sk1I,d~^ #endif
>Yt+LdG!- g~Agy //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
,)7y?*D} #include "stdafx.h"
a) 5;Od #include "hook.h"
P`!31P#]L #include <windowsx.h>
kC4}@{4i #ifdef _DEBUG
Ym/y2B( #define new DEBUG_NEW
0X[uXf #undef THIS_FILE
sj\kp
ni static char THIS_FILE[] = __FILE__;
)-_To&S* #endif
-|nHwSrCZ/ #define MAX_KEY 100
Iji9N!Yx #define CTRLBIT 0x04
=P\Tk)(` #define ALTBIT 0x02
kMY1Xb #define SHIFTBIT 0x01
UfAN)SE" #pragma data_seg("shareddata")
!Xf7RT HHOOK hHook =NULL;
?PST.+l UINT nHookCount =0;
5t-dvYgU static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
-x0VvkHu static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
.0f6b static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
BP`'1Ns static int KeyCount =0;
Fy-N U static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
OVgx2_F #pragma data_seg()
4J6,_8`U HINSTANCE hins;
}E]&,[4&M void VerifyWindow();
j9]H~:g$d BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
P{_Xg,Z //{{AFX_MSG_MAP(CHookApp)
Ed=]RR4R // NOTE - the ClassWizard will add and remove mapping macros here.
E{B=%ZNnm // DO NOT EDIT what you see in these blocks of generated code!
|$aTJ9 Iq: //}}AFX_MSG_MAP
F1UTj"<e END_MESSAGE_MAP()
#>@~3kGg &['cZ/bM CHookApp::CHookApp()
@Ap~Wok {
[
bB
// TODO: add construction code here,
l/F'W} // Place all significant initialization in InitInstance
B2DWSp-8* }
( :ObxJ* @#= ail CHookApp theApp;
UOAL7 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
pz]#/Ry? {
BmGY#D, BOOL bProcessed=FALSE;
P]b *hC if(HC_ACTION==nCode)
Y] "_} {
>qhoGg if((lParam&0xc0000000)==0xc0000000){// Key up
^wm>\o;
switch(wParam)
&]mZp& {
:^oF0,-qZ case VK_MENU:
KoL3CA"N MaskBits&=~ALTBIT;
p{BBqKv break;
FqT2+VO~ case VK_CONTROL:
b9gezXAcd MaskBits&=~CTRLBIT;
g(Dr/D break;
DEcsFC/SK case VK_SHIFT:
vsL)E:0 MaskBits&=~SHIFTBIT;
:`w'}h7m break;
lyYi2& % default: //judge the key and send message
eH9Ofhsry break;
/<WK2G }
="*:H) for(int index=0;index<MAX_KEY;index++){
i1E~ F if(hCallWnd[index]==NULL)
JTn\NSa
continue;
x."/+/ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
h<8.0 {
?rG>SA>o SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
mqFo`Ee bProcessed=TRUE;
c
Oi:bC@ }
E=9xiS }
,J63?EQ3 }
+^\TG>le else if((lParam&0xc000ffff)==1){ //Key down
G$)f5_]7{ switch(wParam)
2y0J~P! I {
,m)k;co^ case VK_MENU:
!QTfQ69Y0 MaskBits|=ALTBIT;
;@R=CQ6 break;
=T0;F0@#4 case VK_CONTROL:
]s))O6^f MaskBits|=CTRLBIT;
wxx3']: break;
[~[)C]-= case VK_SHIFT:
RZg8y+jM MaskBits|=SHIFTBIT;
3w-0IP]< break;
8UahoNrSt default: //judge the key and send message
r%^l~PN break;
Gec? }
^[]@dk9 for(int index=0;index<MAX_KEY;index++)
9h$08l {
jLZ^EM- if(hCallWnd[index]==NULL)
?Dr K2;q continue;
--}5%6 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
i:coNK)4 {
E1&9( L5 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
4%s6 d,6" bProcessed=TRUE;
}+{?
Ms }
} qf=5v }
C=6.~&( }
X*^^W_LH. if(!bProcessed){
$k|:V&6SV for(int index=0;index<MAX_KEY;index++){
PS=N]e7k' if(hCallWnd[index]==NULL)
4|#@41\ B continue;
WX9ABh& 5 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
-xXz}2S4 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
m@Vz42g~+ }
oY K(=j }
_,?<r&>v6 }
KT>eE return CallNextHookEx( hHook, nCode, wParam, lParam );
^z%ShmM&LZ }
b,tf]Z- Ww[Xqmg BOOL InitHotkey()
P,}cH;w6Ck {
A./VO if(hHook!=NULL){
Q,f~7IVX nHookCount++;
b-+~D9U< return TRUE;
0S%xm'|N }
z3bRV{{YqN else
'[z529HN hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
Q/[g|" if(hHook!=NULL)
R'udC} nHookCount++;
?m(]@6qa return (hHook!=NULL);
PXRkK63 }
a
At<36{? BOOL UnInit()
5C|Y-G {
T.}wcQf&* if(nHookCount>1){
6Bop8B nHookCount--;
`u't return TRUE;
s
IE2a0+ }
!*tV[0i2 BOOL unhooked = UnhookWindowsHookEx(hHook);
V8Fp1?E9S if(unhooked==TRUE){
{#_CzI.0f nHookCount=0;
OABMIgX hHook=NULL;
?DwI>< W }
p";5J+?( return unhooked;
'BiR ,M$mY }
=Lc!L
!(,b r+D ?_Lk BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
OtVRhR3> {
b:M1P&R BOOL bAdded=FALSE;
/Z ?$!u4I for(int index=0;index<MAX_KEY;index++){
Bo#,)%80 if(hCallWnd[index]==0){
zJ=lNb?q hCallWnd[index]=hWnd;
1z6$>{FUR HotKey[index]=cKey;
wOLDHg_ HotKeyMask[index]=cMask;
VbG#)>"F bAdded=TRUE;
S <RbC KeyCount++;
n?[JPG2X break;
9Ev<t\B }
5Qh$>R4!" }
VK]cZ%) return bAdded;
[B,w\PLub }
l+vD`aJ 3 wqnHaWd* BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
^c-8~r|y, {
<l.l6okp BOOL bRemoved=FALSE;
I""zg^Rq for(int index=0;index<MAX_KEY;index++){
,l47;@kr if(hCallWnd[index]==hWnd){
6/5Xy69:h if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
=<;C5kSD hCallWnd[index]=NULL;
cEK<CV HotKey[index]=0;
#B!HPlrv HotKeyMask[index]=0;
%A$5mi^ bRemoved=TRUE;
zJ
$&`= KeyCount--;
HVHd@#pDZ break;
V'q?+p]
a }
_u{z$; }
{O=PVW2S }
#aua6V!" return bRemoved;
z8@[]6cW }
K7-z.WTUR B4Fuvi void VerifyWindow()
J85S'cwZZ {
0Xw$l3@N^ for(int i=0;i<MAX_KEY;i++){
!0Mx Bem if(hCallWnd
!=NULL){ -\9K'8 C
if(!IsWindow(hCallWnd)){ EEn8]qJC
hCallWnd=NULL; @"G+kLv0
HotKey=0; dHsI<