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:
<3B^5p\/
80@\e 一、实现方法
/#Aw7F$Ey ~TRC-H 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
/\/^= j |?^<=% #pragma data_seg("shareddata")
/Pg)7Zn HHOOK hHook =NULL; //钩子句柄
,w#lUgp UINT nHookCount =0; //挂接的程序数目
R}0gIp= static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
R|\eBnfI static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
?CQE6ch static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
_f%s] static int KeyCount =0;
/@ @F
nQ++ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
^~[7])}g6 #pragma data_seg()
v zg^tJ Hloe7+5UD 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
^}-l["u` Qt+D ,X DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
larv6ncV 7_1 Iadb BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
)-3~^Y#r_ cKey,UCHAR cMask)
LBy`N_@ {
Qjj }k) BOOL bAdded=FALSE;
-iDs:J4Iq for(int index=0;index<MAX_KEY;index++){
pKc!sdC if(hCallWnd[index]==0){
_'!?fA hCallWnd[index]=hWnd;
EE 1D>I HotKey[index]=cKey;
A?lLK&* HotKeyMask[index]=cMask;
fg)*TR bAdded=TRUE;
3<r7"/5 KeyCount++;
,IPt4EH$ break;
`Ow]@flLI }
VAL?
Z }
FLMiW]?x return bAdded;
F6q=W#~ }
z[c8W@OJ //删除热键
ta)gOc)r
R BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
{zcG%b WJ {
Ep;uz5 ^8 BOOL bRemoved=FALSE;
`nyz, for(int index=0;index<MAX_KEY;index++){
.4CDQ&B0K if(hCallWnd[index]==hWnd){
m0bxVV^DK! if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
r*`e%`HU hCallWnd[index]=NULL;
9!n:hhJM HotKey[index]=0;
l7VO8p]y[R HotKeyMask[index]=0;
Z?o0Q\}1 bRemoved=TRUE;
.z,-ThTH@\ KeyCount--;
ElW\;C:K* break;
L>14=Pr^( }
-t4:%-wv }
MF"*xr v }
S5hc@^|0Z return bRemoved;
Cb+sE"x] }
XS&Pc Z3TCi7,m ?_gvI DLL中的钩子函数如下:
nnPT08$ \XB,)XDB LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
b;QgL_w {
$l7}e=1 BOOL bProcessed=FALSE;
u<:uL if(HC_ACTION==nCode)
\7LL neq {
eV?%3h. if((lParam&0xc0000000)==0xc0000000){// 有键松开
~RbVcB# switch(wParam)
7I[[S!((s {
aE 07# case VK_MENU:
#-B<u- MaskBits&=~ALTBIT;
nN{DO:_o break;
"Y+VNS case VK_CONTROL:
yT/rH- j;5 MaskBits&=~CTRLBIT;
7-B|B{] break;
0e8 case VK_SHIFT:
epnZGz,A MaskBits&=~SHIFTBIT;
mHMsK}=~ break;
DIGw4g4Kt default: //judge the key and send message
6Mc&=}bV break;
k5\V:P=# }
fh =R for(int index=0;index<MAX_KEY;index++){
M#^q
<K % if(hCallWnd[index]==NULL)
D/=05E%[81 continue;
k$%{w\?Jf if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
#eKKH]J/ {
]#M"|iTR SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
e2=}qE7 bProcessed=TRUE;
F4\:9ws }
']2Vf]dB }
z!6_u@^- }
-4QZ/ * else if((lParam&0xc000ffff)==1){ //有键按下
LkJq Bg switch(wParam)
3/vtx9D {
\/1~5mQ+ case VK_MENU:
2tK~]0x MaskBits|=ALTBIT;
H,KH}25 break;
$CB&>?~ case VK_CONTROL:
-J63'bb7oi MaskBits|=CTRLBIT;
bsu?Q'q
break;
e Fs5l case VK_SHIFT:
|5;,]lbt MaskBits|=SHIFTBIT;
Kc]cJ`P4. break;
mdL T7 default: //judge the key and send message
? /!Fv/ break;
|E K6txRb }
RbUir185Y for(int index=0;index<MAX_KEY;index++){
+DSbr5"VlB if(hCallWnd[index]==NULL)
Qf0P"s` continue;
w31O~Ve if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
aN"YEL>w {
LeN }Q SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Q%aF~ bProcessed=TRUE;
R~oY
R,L; }
A(&\wd }
,'c%S|]U7 }
FiQ&g*=| if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
<tTNtBb for(int index=0;index<MAX_KEY;index++){
>
U3>I^Y if(hCallWnd[index]==NULL)
o
Rk 'I continue;
a'`i#U if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
xqk(id\& SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
]kNxytH\o //lParam的意义可看MSDN中WM_KEYDOWN部分
hRuiuGC }
!m\By%( }
6p;Pf9
f }
;0_T\{H"nR return CallNextHookEx( hHook, nCode, wParam, lParam );
jR1^e$ }
Nkb%4ofKqu >%6j -:S 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:
# d"M(nt 0 F8xS8vK+ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
o7we'1(O BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
im<!JMI C|H`.|Q 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:
gm]q<~eMW ?z)2\D LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
K'8o'S_bF {
R5MN;xG^ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Usht\<{ {
@ ~{TL //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
f4<~_ZGr SaveBmp();
7]u_ return FALSE;
ZD50-w; }
:Dr4?6hdr …… //其它处理及默认处理
,^4"e
( }
b?=r%D->w :fX61S6) ce4rhtkV 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。
q@1A2L\Om T:Q+ Z }v+ 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。
"nJMS6HJ[ uR")@Tc 二、编程步骤
xg%{p`` B7A.~'= 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";
hDJ+Rk@ mq<:^ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
56."&0 b%F'Ou~ 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;
fm^tU0DY n}%_H4t 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;
tvJl-&'N G|?V}pZ 5、 添加代码,编译运行程序。
9[{q5 6UN{Vjr%` 三、程序代码
(q7;/n 9%k4Ic%P ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
!
,]Fx #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
Qmd2C&Xw #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
'#K~hep #if _MSC_VER > 1000
ZnbpIJ8cV #pragma once
JKYtBXOl #endif // _MSC_VER > 1000
M9Z9s11{H #ifndef __AFXWIN_H__
K:4G(?w #error include 'stdafx.h' before including this file for PCH
S-6i5H"B& #endif
P'5Lu #include "resource.h" // main symbols
C>l (4*S class CHookApp : public CWinApp
]w)uo4<^J {
/$8& r public:
UQ e1rf CHookApp();
f:t5`c. // Overrides
,+Ya'4x // ClassWizard generated virtual function overrides
;rh=63g //{{AFX_VIRTUAL(CHookApp)
K/(Z\lL public:
kad$Fp39 virtual BOOL InitInstance();
^y&2N virtual int ExitInstance();
kYS\TMt,C //}}AFX_VIRTUAL
u 8~5e //{{AFX_MSG(CHookApp)
UBwYwm0 // NOTE - the ClassWizard will add and remove member functions here.
BhyLcUBuB // DO NOT EDIT what you see in these blocks of generated code !
T2T?)_f /
//}}AFX_MSG
W.7u6F` DECLARE_MESSAGE_MAP()
zS\m8[+] };
u7wZPIC{_ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
}
F*=+n BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
5',b~Pp BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
R;/LB^X] BOOL InitHotkey();
up3mum BOOL UnInit();
D1fUEHB}A8 #endif
)A;jBfr fK4O
N'[R: //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
Xp|$z ~ #include "stdafx.h"
DqH]F S?] #include "hook.h"
z_&T>ME #include <windowsx.h>
C5^N)-]" #ifdef _DEBUG
Mm^6*L] #define new DEBUG_NEW
k"`^vV[{F #undef THIS_FILE
(yeN> x}_ static char THIS_FILE[] = __FILE__;
j~ qm5} #endif
G#^6H]`[J: #define MAX_KEY 100
G|$n,X1O( #define CTRLBIT 0x04
dfeN_0`- #define ALTBIT 0x02
B<!wh #define SHIFTBIT 0x01
1N8YD .3 #pragma data_seg("shareddata")
#
WL5p. HHOOK hHook =NULL;
xiQd[[(sM UINT nHookCount =0;
Zvz}Z8jW static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
JZNvuP D static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
=?B[oq static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
BI6`@}%7> static int KeyCount =0;
na/,1iI< static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
oA
]F`N= #pragma data_seg()
# f{L; HINSTANCE hins;
jAFJ?L( void VerifyWindow();
?7*J4. BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
-uK@2}NZ
//{{AFX_MSG_MAP(CHookApp)
ubi6= // NOTE - the ClassWizard will add and remove mapping macros here.
CYk"
// DO NOT EDIT what you see in these blocks of generated code!
?rwHkPJ{* //}}AFX_MSG_MAP
H!g9~a END_MESSAGE_MAP()
zL:k(7E %t-}dC& CHookApp::CHookApp()
H`U>ZJ. {
6FI`0j=~ // TODO: add construction code here,
/%^^hr // Place all significant initialization in InitInstance
3DrW[\ }
yH@2nAn EO.}{1m=hx CHookApp theApp;
x8h=3e$ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
FiN B$A {
Q"{Q]IT BOOL bProcessed=FALSE;
V_Y2 @4 if(HC_ACTION==nCode)
MW.,}f {
cNuBWLG if((lParam&0xc0000000)==0xc0000000){// Key up
'~Gk{'Nx" switch(wParam)
{B\lk:"X {
`l}r&z(8 case VK_MENU:
K}Pi"Le@W MaskBits&=~ALTBIT;
0bMbM^xV6 break;
T+<OlXpL case VK_CONTROL:
o,y{fv:ki MaskBits&=~CTRLBIT;
/\uW[mt break;
BO=j*.YKy case VK_SHIFT:
:sb+jk MaskBits&=~SHIFTBIT;
u!VY6y7p break;
FkIT/H default: //judge the key and send message
X=b]Whuv break;
h`p9H2}0 }
GI*2*m!u for(int index=0;index<MAX_KEY;index++){
h]okY49hY if(hCallWnd[index]==NULL)
*}`D2_uP continue;
vJ!<7 l& if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
lF1ieg"i M {
&l1CE19< SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
IDv|i.q3 bProcessed=TRUE;
`BZX\LPHm }
w4p<q68 }
+LAj h)m }
Q" an6ht| else if((lParam&0xc000ffff)==1){ //Key down
3P2L phW switch(wParam)
Jx1JtnyP@ {
&8wluOs/5 case VK_MENU:
o.H(&ex| MaskBits|=ALTBIT;
N,NEg4 q[ break;
o8lwwM* case VK_CONTROL:
vErlh:~e MaskBits|=CTRLBIT;
-J=N break;
%]i("21 case VK_SHIFT:
,t_Fo-i7vI MaskBits|=SHIFTBIT;
|F#L{=B break;
J~vK`+Zs default: //judge the key and send message
?rgk break;
+'!vm6 }
bfjtNF*^ for(int index=0;index<MAX_KEY;index++)
?rn#S8nNx< {
D#,P-0+% if(hCallWnd[index]==NULL)
!EQMTF=( continue;
oUwu:&<Orm if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
.AgD`wba {
$w$4RQk3n SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
77ID
82 bProcessed=TRUE;
lE?F Wt }
"Q ~-C|x }
x
p#+{} }
M _z-~G if(!bProcessed){
yr
/p3ys for(int index=0;index<MAX_KEY;index++){
Ag`:!* if(hCallWnd[index]==NULL)
G6b\4}E continue;
<v)Ai;l, if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
!mX 2 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
_ADK8a6%) }
:A{ US9D }
~\z\f}w }
jci'q=Vpu return CallNextHookEx( hHook, nCode, wParam, lParam );
JUlV$b.)J }
S?5z YbrsXp" BOOL InitHotkey()
Px)/`'D {
xv{iWJcs if(hHook!=NULL){
3Yd)Fm nHookCount++;
H+>l][ return TRUE;
?N|B, F }
i}5
#n else
Uv06f+P( hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
@edi6b1W if(hHook!=NULL)
:h&*<!O2B` nHookCount++;
[yF4_UoF return (hHook!=NULL);
ega< {t }
:hp=>^$Y BOOL UnInit()
/L1qdkG {
WBA0!
g98 if(nHookCount>1){
F:CqB| nHookCount--;
N(]>(S
o return TRUE;
UEJX0= }
}>w;(R BOOL unhooked = UnhookWindowsHookEx(hHook);
'lU9*e9 if(unhooked==TRUE){
@,-xaZ[ nHookCount=0;
$e! i4pM hHook=NULL;
l\yFx }
U&6!2s- return unhooked;
B=/*8,u }
8yH) 8:w .s_wP BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
~T')s-,l,: {
`bGAc&,& BOOL bAdded=FALSE;
sYt8NsQ for(int index=0;index<MAX_KEY;index++){
3H%oTgWk if(hCallWnd[index]==0){
K@6tI~un hCallWnd[index]=hWnd;
C`D5``4 HotKey[index]=cKey;
uE>2*u\ HotKeyMask[index]=cMask;
xOjCF&W bAdded=TRUE;
=J,aB p KeyCount++;
Ywf.,V break;
|/g\N,] }
Zjt3U;Y }
j+n1k^jC return bAdded;
7:1c5F~M }
EY(@R2~#J 9z,?DBMvc BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
<dzE5]%\ {
C,w$)x5kls BOOL bRemoved=FALSE;
\)ac,i@fy for(int index=0;index<MAX_KEY;index++){
?Ee HeN_ if(hCallWnd[index]==hWnd){
n2R{$^JxO if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
}Y5Sf"~M hCallWnd[index]=NULL;
UKx91a}g HotKey[index]=0;
YXH9Q@Gn HotKeyMask[index]=0;
oSt-w{! bRemoved=TRUE;
P'Jw: )k( KeyCount--;
.3,s4\.kT break;
f;6a4<bz }
J%3%l5/ }
Z^AACKME }
?0+D1w return bRemoved;
v"L<{HN }
1dOVH7 4ow)vS( void VerifyWindow()
"qb3\0O {
_.Y?BAQ for(int i=0;i<MAX_KEY;i++){
Xb42R1 if(hCallWnd
!=NULL){ abtAkf
if(!IsWindow(hCallWnd)){ @R?S-*o
hCallWnd=NULL; OFCOMM
HotKey=0; X LPO_tD
HotKeyMask=0; "!gd)^<e
KeyCount--; L&