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:
F{\=PCZ>7
m<3w^mww 一、实现方法
~;8I5Sge x}|+sS,g 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:
FfG%C>E6~ l~D\;F #pragma data_seg("shareddata")
z+
ZG1\ HHOOK hHook =NULL; //钩子句柄
IT18v[-G UINT nHookCount =0; //挂接的程序数目
^&MK42,\ static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
SB/3jH static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
n+rM"Gxz static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
t!:)L+$3 static int KeyCount =0;
o0l74 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
-=a[J;'q #pragma data_seg()
\E77SO,$ (0R2T"/ 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。
Im+7<3Z Yz\
N&0" 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:
X8Fzs!L` BPewc9RxV BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
P$OUi!" cKey,UCHAR cMask)
v%nP*i9 {
$''UlWK BOOL bAdded=FALSE;
1x{kl01m% for(int index=0;index<MAX_KEY;index++){
G|*G9nQ if(hCallWnd[index]==0){
XXm'6xD- hCallWnd[index]=hWnd;
xNIGO/uI~ HotKey[index]=cKey;
#A )Ab%r8" HotKeyMask[index]=cMask;
R5ZIC4p bAdded=TRUE;
-=mwy KeyCount++;
VE$t%QT break;
j8a[
( }
g YUTt }
(v^Z BM_ return bAdded;
"mA1H]r3 }
Zi*%*nX //删除热键
Oyan9~ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
|IN[uQ {
d@ (vg BOOL bRemoved=FALSE;
AG>\aV"b for(int index=0;index<MAX_KEY;index++){
o0mJy' if(hCallWnd[index]==hWnd){
yLqF ,pvO if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
?oKL&I@ hCallWnd[index]=NULL;
R5kH0{zM HotKey[index]=0;
n"Z |e tZ4 HotKeyMask[index]=0;
Y{+3}drJE bRemoved=TRUE;
*)D1!R<\,R KeyCount--;
:j,}{)5= break;
$DE&J4K }
CmHyAw( }
`{o$F ::( }
+?AW>&68y return bRemoved;
``4?a7!! }
4.w"(v9 V V;;#/$oU:4 N}mh} DLL中的钩子函数如下:
~},W8\C> Z0\Iyc G LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
t^U^Tr {
AY88h$a BOOL bProcessed=FALSE;
2y%R:Mu if(HC_ACTION==nCode)
BIj {
Dr+ Ps if((lParam&0xc0000000)==0xc0000000){// 有键松开
12OlrU switch(wParam)
30d#Lq {
oY.\)eJ~> case VK_MENU:
iRt*A6`m+ MaskBits&=~ALTBIT;
vQHpf>o break;
{SdO9Yy?@7 case VK_CONTROL:
FmD +8= MaskBits&=~CTRLBIT;
VB"(9O] break;
iRve) case VK_SHIFT:
ix*muVBj. MaskBits&=~SHIFTBIT;
0OWL break;
Hi8Y6|y$D default: //judge the key and send message
CXAVGO'xw break;
|}Ph"g2D, }
-N# #w= for(int index=0;index<MAX_KEY;index++){
J\A8qh8 if(hCallWnd[index]==NULL)
/b%Q[
Ck_ continue;
A ~&+F>Z if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
X"<|Z]w {
@GeHWv SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Ep ">v>" bProcessed=TRUE;
bV6V02RF }
2Y+:,ud\ }
a+
GJVJ }
doLNz4W else if((lParam&0xc000ffff)==1){ //有键按下
"+h/-2rA switch(wParam)
E9$H nj+m {
y6%<zhs case VK_MENU:
#PFO]j!_b MaskBits|=ALTBIT;
'[0YIn break;
Pa&4)OD case VK_CONTROL:
j^EbO3 MaskBits|=CTRLBIT;
!y*oF{RZ break;
J?D\$u: case VK_SHIFT:
-J?~U2 MaskBits|=SHIFTBIT;
CDCC1B G" break;
GY-M.|% default: //judge the key and send message
RxG^ break;
z<<Tk.65 }
Gru ALx7 for(int index=0;index<MAX_KEY;index++){
hW'
HT if(hCallWnd[index]==NULL)
%\I.DEYH continue;
mx}E$b$<CY if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
6Xa.0(h {
^73=7PZ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
AP w6 bProcessed=TRUE;
e{!vNJ0` }
VMHC/jlX@r }
;J=:IEk }
R|Y~u* D if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
U
~1SF for(int index=0;index<MAX_KEY;index++){
8&.-]{Z if(hCallWnd[index]==NULL)
JXm?2/ continue;
1VLLo~L% if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Z %EQt SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
tlGWl0V?7Q //lParam的意义可看MSDN中WM_KEYDOWN部分
oD0EOT/E }
H[nz]s }
L_?$ayZ; }
a5V=!OoMk return CallNextHookEx( hHook, nCode, wParam, lParam );
o5 WW{)Q }
/^4"Qv\@/ VQ<5%+ 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:
VGZ6 qd(hQsfqYU BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Ub)M*Cq0(o BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
yekRwo| ]>8)|]O6n 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:
4bI*jEc\[
~6d5zI4\ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
3cThu43c {
[Vp\$;\nT if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Le&;g4% {
, N
344y //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
J"&y|;G SaveBmp();
q"nGy#UWR return FALSE;
zs8I }
v<&v]!nF …… //其它处理及默认处理
";dU-\3M }
e/94y6*> K7RKF$Z\ oAz<G 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。
x'i0KF }n[Bq# 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+ ? U~/ID 二、编程步骤
kl<g;3 )
,Npv3( 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";
2.qpt'p[ 0N5bPb 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
!Uy>eji} e1^l.>2d6 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;
uV77E*+7\ c&e0OV\m 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;
^Y 7U1I CQ1 8%w6 5、 添加代码,编译运行程序。
cL7C2wB` gjZx8oIoP 三、程序代码
SQ <f KN, 4@4 ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
jY+Do:#/wO #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
}]GbUC!Zb #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
J6auUm` ` #if _MSC_VER > 1000
4J}3,+ #pragma once
!.eAOuq #endif // _MSC_VER > 1000
"TFwHe3C4 #ifndef __AFXWIN_H__
F*\4l;NJ #error include 'stdafx.h' before including this file for PCH
[*HiI= #endif
j@t{@Ke #include "resource.h" // main symbols
|j#
^@R class CHookApp : public CWinApp
"dq>)JF\ {
[q"NU&SX public:
gh61H:t kR CHookApp();
<<<NXsH // Overrides
(&c,twa~ // ClassWizard generated virtual function overrides
T#r=<YH[C //{{AFX_VIRTUAL(CHookApp)
7LdzZS0OM public:
XtzOFx/ virtual BOOL InitInstance();
{u4i*udG`) virtual int ExitInstance();
-TZ^ ~s //}}AFX_VIRTUAL
"XB4yExy //{{AFX_MSG(CHookApp)
w%2ziwgh // NOTE - the ClassWizard will add and remove member functions here.
UR,?! rJ^B // DO NOT EDIT what you see in these blocks of generated code !
^U{P3%uZ //}}AFX_MSG
;@4sd%L8V DECLARE_MESSAGE_MAP()
UN(3i(d };
)Ga8`t" LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
PW)8aLU BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
6sy,A~e BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
.hne)K%={y BOOL InitHotkey();
hgwn> p:S# BOOL UnInit();
TrQm]9 @ #endif
^'YHJEK rkIMM, //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
|0]YA #include "stdafx.h"
1tyNRoET #include "hook.h"
rXDJ:NP #include <windowsx.h>
@ExLh9 #ifdef _DEBUG
`u=oeM: #define new DEBUG_NEW
5"uNj<.V #undef THIS_FILE
y($EK(cb static char THIS_FILE[] = __FILE__;
3P`WPph #endif
f}blB?e #define MAX_KEY 100
wt\m+!u` #define CTRLBIT 0x04
y9ip[Xn-$: #define ALTBIT 0x02
=h7[E./U1 #define SHIFTBIT 0x01
ogp{rY #pragma data_seg("shareddata")
xD^wTtT HHOOK hHook =NULL;
pJ6Jx( UINT nHookCount =0;
E4Zxv* static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
?sE@]]z static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
{83C,C- static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
O$U}d-Xnx static int KeyCount =0;
UQnBqkE static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
C$_G'XI #pragma data_seg()
8=pv/o HINSTANCE hins;
A$ J9U3+O void VerifyWindow();
R.O BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
?-S8yqe //{{AFX_MSG_MAP(CHookApp)
wA1Ey:q // NOTE - the ClassWizard will add and remove mapping macros here.
XD
5n]AL // DO NOT EDIT what you see in these blocks of generated code!
OOfyGvs //}}AFX_MSG_MAP
ZIe + END_MESSAGE_MAP()
<OIUyZS }1,'rmT CHookApp::CHookApp()
FvAbh]/4 {
s!aO*\[<h // TODO: add construction code here,
3l$E8?[Zwi // Place all significant initialization in InitInstance
y,V6h*x2 }
9u?Eb~#$ VZTmzIk.Y CHookApp theApp;
X'xUwT|_+ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
n_1jHJo {
@wMQC\Z BOOL bProcessed=FALSE;
@Jm.HST#S8 if(HC_ACTION==nCode)
%fBP:5%K {
4?v$<=#21* if((lParam&0xc0000000)==0xc0000000){// Key up
r:73uRk switch(wParam)
G LoiH#R {
{wHvE4F2 case VK_MENU:
*h:D|4oJ( MaskBits&=~ALTBIT;
^glX1 ) break;
OgQntj:%lN case VK_CONTROL:
{hM"TO7\ MaskBits&=~CTRLBIT;
;*nh=w break;
8-A:k E case VK_SHIFT:
.(JE-upJ" MaskBits&=~SHIFTBIT;
O%52V|m}{ break;
:Jm!=U%'Z default: //judge the key and send message
^] i"
H|(x break;
?P%|P }
%n4@[fG%K for(int index=0;index<MAX_KEY;index++){
&{BBxv)y if(hCallWnd[index]==NULL)
?THa5%8f continue;
J}:&eS if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
ed=n``P~} {
#jOOsfH|k SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
dV)Y,Yx0${ bProcessed=TRUE;
X=JFWzC }
WFRsSp2 }
~m!#FTc* }
n%n'1AUP: else if((lParam&0xc000ffff)==1){ //Key down
R9Ldl97' switch(wParam)
#t){ 4J {
k]t,q$Vd case VK_MENU:
xna7kA MaskBits|=ALTBIT;
'y< t/qo break;
b By'v/ case VK_CONTROL:
Ywmyr[Uh' MaskBits|=CTRLBIT;
akMJ4EF/ break;
ccRlql( case VK_SHIFT:
)4@M`8 MaskBits|=SHIFTBIT;
J`4Z<b53 break;
Y$>+U default: //judge the key and send message
s%5Uj} break;
j,\tejl1 }
cT\Ov
P*_ for(int index=0;index<MAX_KEY;index++)
K!9y+%01 {
NWw<B3aL if(hCallWnd[index]==NULL)
3'.!
+# continue;
HJc<Gwm if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
fn3*2 {
K*TnUQ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
L^6"'# bProcessed=TRUE;
p@vpd }
" 98/HzR }
u$ap H{ }
%B[YtWqm`/ if(!bProcessed){
Tc9&mKVE%( for(int index=0;index<MAX_KEY;index++){
,?Ok[G!cm if(hCallWnd[index]==NULL)
TFNUv<>X continue;
d:A\<F if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
+d.u##$ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
_L8Mpx*E }
hJecCOA)' }
>9 q]>fJ }
wj}=@HS,3! return CallNextHookEx( hHook, nCode, wParam, lParam );
)t*S'R }
lB=(8. 0Wjd-rzc, BOOL InitHotkey()
m"5{D*| {
~u};XhZ if(hHook!=NULL){
\)FeuLGL9 nHookCount++;
7F,07\c return TRUE;
f KFnCng }
ixIh
T else
rH[5~U hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
O'"YJ, if(hHook!=NULL)
Ii|uGxEc nHookCount++;
pTc$+Z73 return (hHook!=NULL);
S4;wa6 }
+G<}JJ'V BOOL UnInit()
&,^mM'
C {
u
wH)$Pl if(nHookCount>1){
c'"#q) nHookCount--;
,jAx%]@,I return TRUE;
!>CE(;E>z }
V+Y|4Y& BOOL unhooked = UnhookWindowsHookEx(hHook);
s.f`.o if(unhooked==TRUE){
d&/^34gn nHookCount=0;
>_rzT9gX& hHook=NULL;
` 52%XI }
j kSc& return unhooked;
kTr6{9L }
E%-Pyg* 7bctx_W&6 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
!y.ei1diw {
KK@
&q BOOL bAdded=FALSE;
K4iI: for(int index=0;index<MAX_KEY;index++){
eKL]E! if(hCallWnd[index]==0){
!x`;>0 hCallWnd[index]=hWnd;
='7er.~\ HotKey[index]=cKey;
K#_~
!C4L HotKeyMask[index]=cMask;
:&xz5c`"04 bAdded=TRUE;
83mlZ1jQz KeyCount++;
NYWG#4D break;
f 1sy9nQs }
}@3Ud'
Y }
w%>aR_G return bAdded;
b7?U8/#' }
MDMtOfe| }v_p gatC BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
59&T