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:
Q(|PZng
nn @^K6 一、实现方法
1Xy8|OFc[ NoCDY2 $ 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:
.tRr?*V|l R:'Ou:Mh #pragma data_seg("shareddata")
d>%gW* HHOOK hHook =NULL; //钩子句柄
q=6Cc9FN UINT nHookCount =0; //挂接的程序数目
`DLp<_z>
static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
K(nS$x1G static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
,VNi_.W0 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
;rB6u_5"I. static int KeyCount =0;
:}y9$p
static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
#NvQmz?J? #pragma data_seg()
0xJ7M. b?_e+:\UV 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。
\ Md
3 D \N
\BD 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:
qWsylC23 /g_9m BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
EL^8zyg%% cKey,UCHAR cMask)
NO-k- {
U|gpCy BOOL bAdded=FALSE;
CSMeSPOm] for(int index=0;index<MAX_KEY;index++){
CRH{E}> if(hCallWnd[index]==0){
C5P$&s\ hCallWnd[index]=hWnd;
fUC9-?(K HotKey[index]=cKey;
!^m%O0DT HotKeyMask[index]=cMask;
wfgqgPo!v bAdded=TRUE;
~C&*.ZR KeyCount++;
z{S:X:X break;
9\HR60V }
Ju!(gh }
qnB<k,8T return bAdded;
0n
Y6A~ }
w OI^Q~ //删除热键
~h-C&G,v BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
i
AdGgK {
L!t@-5~
BOOL bRemoved=FALSE;
+`@M*kd for(int index=0;index<MAX_KEY;index++){
4({(i if(hCallWnd[index]==hWnd){
_;56^1'T if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
UtnZNdlv hCallWnd[index]=NULL;
ohUdGO[/ HotKey[index]=0;
~#R9i^Y HotKeyMask[index]=0;
x2co>.i bRemoved=TRUE;
~9\$5n)a KeyCount--;
UXT
p break;
S}(8f!9< }
b_TS<, }
G8nrdN-9 }
>nzu],U return bRemoved;
3iRA$C-p }
#] CFA9z F/p,j0S :_5/u|{
DLL中的钩子函数如下:
s,6`RI% %f j+70 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
~e `Bq> {
fmfTSN(Q~` BOOL bProcessed=FALSE;
9i5tVOhE if(HC_ACTION==nCode)
O:'?n8rWL {
:IMdN}(L if((lParam&0xc0000000)==0xc0000000){// 有键松开
OtJ\T/q, switch(wParam)
)[L^Dmd, {
qH>`}/,P case VK_MENU:
ljC(L/I MaskBits&=~ALTBIT;
lhH`dG D break;
>5hhd38 case VK_CONTROL:
'm3t|:nMU MaskBits&=~CTRLBIT;
?YQPlv:<o. break;
`Out(Hn case VK_SHIFT:
=PkO!Mm8 MaskBits&=~SHIFTBIT;
r X'*|] break;
2o3EHZ+]cm default: //judge the key and send message
~j>D=! break;
cc}Key@D }
tz^/J=)" for(int index=0;index<MAX_KEY;index++){
S0d~.ah30 if(hCallWnd[index]==NULL)
+JRF0T continue;
fB1TFtAh if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
(#D*Pl {
Vw tZLP36 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
q%(EYM5Y bProcessed=TRUE;
5| B(\wqG }
JL=U,Mr6 }
rH8@69,B }
2I/xJ+ else if((lParam&0xc000ffff)==1){ //有键按下
7O5`v(<9n> switch(wParam)
A#8q2n270* {
1'.7_EQ4T case VK_MENU:
hR#-u1C MaskBits|=ALTBIT;
hRC break;
QaIjLc~W case VK_CONTROL:
m: n`g1 MaskBits|=CTRLBIT;
E/M_lvQ break;
NLS"eDm case VK_SHIFT:
#LlUxHv # MaskBits|=SHIFTBIT;
?BA]7M(,4 break;
Tm}rH]F& default: //judge the key and send message
4y:]DC" break;
az0<5Bq) }
N;Dp~(1
J1 for(int index=0;index<MAX_KEY;index++){
%nN `|\ if(hCallWnd[index]==NULL)
KWAb-yB continue;
r={c,i if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
@"a6fn {
Od+6 -J SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
K 0gI): bProcessed=TRUE;
dzLQI}89+k }
5oEV-6 }
+#U|skl }
XU!2YO)t;! if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
:NJ_n6E for(int index=0;index<MAX_KEY;index++){
:B3[:MpL} if(hCallWnd[index]==NULL)
Q!-
0xlx continue;
oSiMpQu08 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
{3;AwhN0H SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
:w}{$v}#D; //lParam的意义可看MSDN中WM_KEYDOWN部分
valtev0< }
mxor1P#| }
)u))n# P }
SJD@&m%?[ return CallNextHookEx( hHook, nCode, wParam, lParam );
kEwaT$ }
5T sU Qc BA\/YW @ 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:
@SCI"H%[ %ZHP2j
%~ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
(c0A.L)
BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
}Zl&]e 2,ECYie^ 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:
YK|bXSA[ %%(R@kh9 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
wFG3KzEq ~ {
U(~+o if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
{vAE:W.s {
UK9@oCIB //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
2WUT/{:X SaveBmp();
*#TUGfwy return FALSE;
Y*mbjyt[?X }
(sVi\R …… //其它处理及默认处理
l5L.5$N }
ySI~{YVM J2uZmEt N !TW! 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
bn
|zl!Pq C8F 7bG8c 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
V5}B:SUB OY?y ^45y 二、编程步骤
qzb<J=FAU &89oO@5 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
/x3/Ubmz~x q^6 +!&" 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
+F
dB ' ZvcJK4hi 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
;WldHaZ9r McPNB`.H 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
a#c6[! CbN!1E6). 5、 添加代码,编译运行程序。
M DF%\Sx #r3l[bKK 三、程序代码
z0/}
! ZyEHzM{$ ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
.7n\d55a #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
O]qU[y+ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
N/GQt\tV< #if _MSC_VER > 1000
xLx]_R() #pragma once
$8a(veXd #endif // _MSC_VER > 1000
k__$Q9qj( #ifndef __AFXWIN_H__
M,ir`"s #error include 'stdafx.h' before including this file for PCH
!+:ov'F #endif
8uA,iYD
#include "resource.h" // main symbols
umdG(osR class CHookApp : public CWinApp
5O`dO9g}$ {
%$TGzK 1 public:
%TsPyiYl CHookApp();
Oh4AsOj@ // Overrides
hHDOWHWE // ClassWizard generated virtual function overrides
X6^},C'E.: //{{AFX_VIRTUAL(CHookApp)
[V}S<Xp public:
z)uuxNv[R virtual BOOL InitInstance();
GIAc?;zY virtual int ExitInstance();
)Z %T27r,^ //}}AFX_VIRTUAL
nVJPR //{{AFX_MSG(CHookApp)
d[;.r // NOTE - the ClassWizard will add and remove member functions here.
+&["HoKg}& // DO NOT EDIT what you see in these blocks of generated code !
5/O'R9A4 //}}AFX_MSG
77Bgl4P DECLARE_MESSAGE_MAP()
G}9=) };
`8FUX= Sh LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
cm[c ze+* BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
y9KB< yh/ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
F-*2LMe BOOL InitHotkey();
ek
N'k BOOL UnInit();
|`;54_f #endif
+Y+Y6Ac[} ;}'D16`j //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
}@r{?8Ru #include "stdafx.h"
\Vl`YYjZ #include "hook.h"
_@R0x#p5M #include <windowsx.h>
c,*9K/: #ifdef _DEBUG
lvp8z)G #define new DEBUG_NEW
YX*Qd$chZ #undef THIS_FILE
<G*nDFWf static char THIS_FILE[] = __FILE__;
@UdfAyL #endif
kQ #define MAX_KEY 100
6eokCc"o #define CTRLBIT 0x04
}=!,o #define ALTBIT 0x02
#h@J=Ki #define SHIFTBIT 0x01
Q#EP| #pragma data_seg("shareddata")
i9=&;_z HHOOK hHook =NULL;
kD}Y|*]5-5 UINT nHookCount =0;
F!.E5<&7= static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
q5L51KP2 static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Lq>&d,F06) static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
lKgKtQpi static int KeyCount =0;
f$'2}'.!$ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
tBct #pragma data_seg()
>YUoh-]` HINSTANCE hins;
> 0<)= void VerifyWindow();
*~/OOH$" BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
RDtU43 //{{AFX_MSG_MAP(CHookApp)
0dh=fcb // NOTE - the ClassWizard will add and remove mapping macros here.
sm$(Y.N // DO NOT EDIT what you see in these blocks of generated code!
`f'K@ //}}AFX_MSG_MAP
1[]&(Pa END_MESSAGE_MAP()
mYU9
trHV A?G^\I~v CHookApp::CHookApp()
a[2vjFf#C {
A 8 vbQ // TODO: add construction code here,
@X3{x\i'I // Place all significant initialization in InitInstance
)yo
a }
xTGxvGv8 xW[ -n CHookApp theApp;
yAN=2fZm LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
C.kxQ< {
e${>#> BOOL bProcessed=FALSE;
mR;qMX)0h if(HC_ACTION==nCode)
FE o269Ur {
7$rjlVe if((lParam&0xc0000000)==0xc0000000){// Key up
>><.3 switch(wParam)
=tU{7i*+ {
a
{ab*tM case VK_MENU:
c"n ?'e MaskBits&=~ALTBIT;
n$[f94d= break;
&P,^.' case VK_CONTROL:
r_YIpnJ MaskBits&=~CTRLBIT;
Jdy=_88MD
break;
x3rlJs`$; case VK_SHIFT:
6{qIU}! MaskBits&=~SHIFTBIT;
$v8l0JA * break;
2Dd|~{% default: //judge the key and send message
StI1){Wf break;
pN\Vr8tJ }
VxFOYC>p for(int index=0;index<MAX_KEY;index++){
s`Cy
a` if(hCallWnd[index]==NULL)
?m
c%.Bt continue;
d^(1TNS if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
kw`WH)+F {
8_K60eXz SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
i!~'M;S bProcessed=TRUE;
r ]>\~&?^F }
na^sBq?\ }
3gQPKBpc }
A?Wk
wf else if((lParam&0xc000ffff)==1){ //Key down
a iCn"j switch(wParam)
HMY@F_qY`u {
!6}O.Nu case VK_MENU:
KS*oxZ MaskBits|=ALTBIT;
6bBdIqGb} break;
U1_&gy @y case VK_CONTROL:
0Aa`p3.) MaskBits|=CTRLBIT;
XR0O;JN break;
#%@MGrsK case VK_SHIFT:
IaFr& MaskBits|=SHIFTBIT;
wve=.n break;
~Ki`Ze"x default: //judge the key and send message
zX{ .^| break;
0|D&"/.R#! }
D@X+{ for(int index=0;index<MAX_KEY;index++)
^/Sh=4=G {
]IJv-( if(hCallWnd[index]==NULL)
xv7"WFb continue;
2=ztKfsBhE if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
s~26 {
ji+{ :D SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
2>em0{e bProcessed=TRUE;
bl/,*Wx:4. }
)gR=<oa }
o ojiJ~ }
8Z85D if(!bProcessed){
j;K#] for(int index=0;index<MAX_KEY;index++){
<@bA?FY if(hCallWnd[index]==NULL)
AY_Q""v continue;
*Dr5O 9Y if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
;+pOP |P= SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
wHsB,2H }
> 8]j
}
(foBp }
UBO^EVJ return CallNextHookEx( hHook, nCode, wParam, lParam );
0'$p$K }
+?`b=6e(` GIHpSy`z BOOL InitHotkey()
PI5j"u UO {
n"aCt%v if(hHook!=NULL){
J7-^F)lu- nHookCount++;
-pTI? return TRUE;
Sav`%0q?7a }
"PpjoM
~ else
C>|@& o1 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
2pyt&'NJua if(hHook!=NULL)
0o&}mKe nHookCount++;
L*]E`Xxd9 return (hHook!=NULL);
:,*eX' fH }
`hB1b["( BOOL UnInit()
L~FTr {
E1>/R if(nHookCount>1){
:_d3//| nHookCount--;
J me% return TRUE;
0|)19LR }
?p8k{N(1 BOOL unhooked = UnhookWindowsHookEx(hHook);
Gm=>!.p if(unhooked==TRUE){
5)lW nHookCount=0;
E;-qP)yU hHook=NULL;
T'rjh"C&| }
`n-vjjG%# return unhooked;
~-Oa8ww }
Qd8b-hg + Oobb-v BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
RLKj
u;u {
q=Xg*PM, BOOL bAdded=FALSE;
U|fTb0fB for(int index=0;index<MAX_KEY;index++){
E5x]zXy4 if(hCallWnd[index]==0){
Q(\ wx hCallWnd[index]=hWnd;
A_r<QYq0| HotKey[index]=cKey;
l`rC0kJ] HotKeyMask[index]=cMask;
M4<+%EV} bAdded=TRUE;
M9V-$ _) KeyCount++;
$N.`)S< break;
8Uj: }
^LO]Z }
?6:cNdN return bAdded;
29O]S8 }
r>3^kL5UI ul}'{|4 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
1KJZWZy {
Dt {') BOOL bRemoved=FALSE;
<3#<I)# for(int index=0;index<MAX_KEY;index++){
6D*chvNA; if(hCallWnd[index]==hWnd){
L[]^{ O if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
-lp"#^ ; hCallWnd[index]=NULL;
(@?eLJlT HotKey[index]=0;
Es:6 HotKeyMask[index]=0;
i/:5jI| bRemoved=TRUE;
8?Wgawx KeyCount--;
F^sw0 .b break;
o4'v> b }
|F~88j{VN }
"z/V%ZK~f }
,|x\MHd?t_ return bRemoved;
<[8@5 ?&& }
j1F w
U pU DO7Q] void VerifyWindow()
o>K &D$J;O {
FAd``9kRT for(int i=0;i<MAX_KEY;i++){
8}K"IW if(hCallWnd
!=NULL){ %L cH>sV
if(!IsWindow(hCallWnd)){ Xv*}1PZH
hCallWnd=NULL; SauHFl8?
HotKey=0; ;r@!a!NLB
HotKeyMask=0; W2n*bNI
KeyCount--; 7%tR&F -u
} e7's)C>/'
} >@:667i,`
} n\*JaY
} () <`t}FQ
pDmK
BOOL CHookApp::InitInstance() kyK'
{ v<+4BjV!J}
AFX_MANAGE_STATE(AfxGetStaticModuleState()); W1<