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:
uDUSR+E>
T!AQJ:;1 一、实现方法
jKs8i$q C8-q<t#SF 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
L T!X|O. [\y>Gv% #pragma data_seg("shareddata")
e!yt<[ph HHOOK hHook =NULL; //钩子句柄
G{9y`; UINT nHookCount =0; //挂接的程序数目
{0~ p" %* static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
# jyAq$I0 static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
6C=.8eP static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
Xb {y*', static int KeyCount =0;
2oRmro static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
o@-cT`HP #pragma data_seg()
4H)a7<, W\.(~-(So 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。
}#@LZ)]hK ]cK@nq) 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:
4D5)<3N=d' Y-9F*8< BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
[Pl$=[+ cKey,UCHAR cMask)
-rBj-4|" {
c_i;' BOOL bAdded=FALSE;
_`_$UMK; for(int index=0;index<MAX_KEY;index++){
\ U_DTI if(hCallWnd[index]==0){
_{8boDX# hCallWnd[index]=hWnd;
rx<fjA% HotKey[index]=cKey;
G!uxpZ HotKeyMask[index]=cMask;
wS*UXF&f bAdded=TRUE;
bZ=d!)%P-{ KeyCount++;
G9]GK+@&F break;
'?nhpT^ }
?:,j9:m? }
"Y6f.rB return bAdded;
V_:/#G]jeG }
&F)lvtt| //删除热键
pAYuOk9n BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
{chl+au*l {
g~]FI BOOL bRemoved=FALSE;
(,k=mF for(int index=0;index<MAX_KEY;index++){
?V+=uTCq if(hCallWnd[index]==hWnd){
_nF_RpS if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
JL1Whf hCallWnd[index]=NULL;
S;
>_9 HotKey[index]=0;
IcN|e4t^J+ HotKeyMask[index]=0;
N6eY-`4y bRemoved=TRUE;
2gi`^%#k] KeyCount--;
}6\p7n break;
3Dy.mt P
}
5,A/6b }
*l}q,9iQ- }
cK""Xz&m return bRemoved;
ZCa?uzeo] }
><Z2uJZ4x 8AK#bna~- gC?k6)p$N DLL中的钩子函数如下:
@jfd.? RK! /Bc
;)~ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
K=;p^dE {
KQh'5o& BOOL bProcessed=FALSE;
)7f:hg if(HC_ACTION==nCode)
Wh7$')@ {
JA&w"2X*E if((lParam&0xc0000000)==0xc0000000){// 有键松开
%*,'&S switch(wParam)
0I,-1o|s {
%NKf@If) case VK_MENU:
Q~`n%uYg\{ MaskBits&=~ALTBIT;
Oo,<zS=ICk break;
Pp?J5HW case VK_CONTROL:
$WDa}~j~^ MaskBits&=~CTRLBIT;
Pm-@ZZ~ break;
Gg_i:4F case VK_SHIFT:
\ /o`CV{O MaskBits&=~SHIFTBIT;
ie5" break;
(%".=x- default: //judge the key and send message
=2<
>dM#` break;
75a3H` }
&N,c:dNe for(int index=0;index<MAX_KEY;index++){
,+f'%)s_x if(hCallWnd[index]==NULL)
KV Mm<]Z continue;
E0w>c'kH if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
y5>H>NS {
*9G;n!t SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
SJL?(S* bProcessed=TRUE;
9R!.U\sq }
WVKzh }
Pr" 2d\ }
,+0_kndR else if((lParam&0xc000ffff)==1){ //有键按下
dx|j,1e switch(wParam)
kZeb^Q+, {
v~j21` case VK_MENU:
A^G%8 )\ MaskBits|=ALTBIT;
z.FO6y6L break;
Vg0Rc t case VK_CONTROL:
MSu_*&j9T MaskBits|=CTRLBIT;
R{/nlS5 break;
vU::dr case VK_SHIFT:
&R2 5J$ MaskBits|=SHIFTBIT;
XvWUJ6M break;
,?728pfw default: //judge the key and send message
iCx}v[;Ol break;
2\_}81hM }
P)4SrqW_ for(int index=0;index<MAX_KEY;index++){
R'He(x if(hCallWnd[index]==NULL)
GC.
continue;
-B'<*Y if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
sdrALl;w| {
&W*9'vSm. SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
7aS`SF bProcessed=TRUE;
yqZKn=1: }
^2=11 }
TX$j-TM' }
#Fq6-]y1") if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
{eL XVNR7R for(int index=0;index<MAX_KEY;index++){
Y}QtgZEt if(hCallWnd[index]==NULL)
YjAwt;%-D continue;
re:=fC:t5A if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
y]+q mNw"+ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
YFeF(k!!n //lParam的意义可看MSDN中WM_KEYDOWN部分
}}@xx& }
i.Yz)Bw }
_3.=| @L }
\G:\36l return CallNextHookEx( hHook, nCode, wParam, lParam );
*bsS%qD] }
dL!PpLR$2 u.43b8! 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
C0J/FFBQ ^ p{gJVP#l'Z BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
U*b1yxt BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
"6o}g. U,\3 !D0jt 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
Q#i[Y?$L DHQavHqbZ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
ly9.2<oz}L {
bkTk:-L5: if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
[7oU = {
)cxLpTr //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
K_;'-B SaveBmp();
]y:2OP return FALSE;
+/E`u|%|\] }
llN#4D9s …… //其它处理及默认处理
0e-M 24,C }
7M9Ey29f 'GcN9D 6B'd]Fe 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。
[,JUC< VXX7Y?! 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。
DvhJkdLB> }f45>@uMW 二、编程步骤
1ayL*tr L;6L@D6 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";
G&,F-|` "k&QS@l 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
p,0J $L vr/*z euA 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;
O1[`2kj^HB ;hzm&My 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;
@'P\c /r2*le (H 5、 添加代码,编译运行程序。
$I}7EI `3GYV|LeQ 三、程序代码
e*K1"; l1 Nr5PT ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
;tg9$P<85 #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
2z#gn9Wb #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
o y{
{d #if _MSC_VER > 1000
(@X].oM^y #pragma once
D[#6jJAb #endif // _MSC_VER > 1000
4b5'nu #ifndef __AFXWIN_H__
JlaT
-j #error include 'stdafx.h' before including this file for PCH
?9W2wqN>o #endif
J7a_a>Y #include "resource.h" // main symbols
rW),xfo0 class CHookApp : public CWinApp
LlbRr.wL {
4}&$s public:
D6z*J?3^#& CHookApp();
@~g][O#Fu // Overrides
Ry_"so w4 // ClassWizard generated virtual function overrides
.A%*AlX //{{AFX_VIRTUAL(CHookApp)
V[#eeH)/ public:
/N=;3yWF virtual BOOL InitInstance();
B\*"rSP\ virtual int ExitInstance();
ebv"`0K$ //}}AFX_VIRTUAL
a\_?zi]s&, //{{AFX_MSG(CHookApp)
*UxN~?N| // NOTE - the ClassWizard will add and remove member functions here.
<+3-(& // DO NOT EDIT what you see in these blocks of generated code !
u]`ur#_ //}}AFX_MSG
QTe>EJ12 DECLARE_MESSAGE_MAP()
3IB||oN$T };
!N"Y LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
C[c^zn
BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
8>4@g!9E BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
]&+,`1_q BOOL InitHotkey();
iC(&U YL BOOL UnInit();
;cpQ[+$nKp #endif
)+L.$h 1>)q5D //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
ZlEQzL~ #include "stdafx.h"
_4^#VD#f #include "hook.h"
a I^Z0[P+ #include <windowsx.h>
mssCnr; #ifdef _DEBUG
u"hv
_ml #define new DEBUG_NEW
SyL:=NZ #undef THIS_FILE
qE:/~Q0 static char THIS_FILE[] = __FILE__;
8r{:di* #endif
BU;o$"L #define MAX_KEY 100
VUd=|$'J #define CTRLBIT 0x04
9=o;I;I #define ALTBIT 0x02
?hfyQhR #define SHIFTBIT 0x01
F4:giu ht #pragma data_seg("shareddata")
^s.necg0 HHOOK hHook =NULL;
vXI2u;=y UINT nHookCount =0;
p Xap<T static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
M?[~_0_J static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
FV~ENpncP static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
x%]5Q/|Ur static int KeyCount =0;
N$I@]PL static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
BK*Bw,KQ< #pragma data_seg()
.G/>X%X HINSTANCE hins;
VV'*3/I void VerifyWindow();
vr2cDk{ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
mu$0x) //{{AFX_MSG_MAP(CHookApp)
=]F;{x // NOTE - the ClassWizard will add and remove mapping macros here.
CO5>Q o // DO NOT EDIT what you see in these blocks of generated code!
K+P:g%M //}}AFX_MSG_MAP
%Eq4>o?D END_MESSAGE_MAP()
P&$ m2^K }}s.0Q CHookApp::CHookApp()
oEJYAKN {
&\p=s.y?j // TODO: add construction code here,
7iijATc // Place all significant initialization in InitInstance
EEI!pi }
SSrYFu" 8n2MZ9p] CHookApp theApp;
u#bd*( LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
gR#lRA/ {
%D_pTD\ BOOL bProcessed=FALSE;
}eLnTi{ if(HC_ACTION==nCode)
#)BbW40f6 {
5`tMHgQO if((lParam&0xc0000000)==0xc0000000){// Key up
/\-iV)h1@ switch(wParam)
]
-}Zd\Rs {
.5AyB9a%& case VK_MENU:
J{w[vcf MaskBits&=~ALTBIT;
xtq='s8e break;
P\k5% case VK_CONTROL:
\:/~IZdzF MaskBits&=~CTRLBIT;
c|hT\1XR, break;
) 1PjI9M case VK_SHIFT:
m ,|)$R MaskBits&=~SHIFTBIT;
0x1#^dII break;
jt6q8 default: //judge the key and send message
KEfx2{k b break;
rEfo)jod }
3v?R"2\qS for(int index=0;index<MAX_KEY;index++){
aePLP if(hCallWnd[index]==NULL)
Oye:V continue;
TQ`4dVaf if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
`=QRC.b {
&)Z!A*w] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
K3I|d;Y~X! bProcessed=TRUE;
A8jj]J+ }
}<7S%?TY }
GYJ
lX }
&ZR} Z7E*= else if((lParam&0xc000ffff)==1){ //Key down
4Rv.m*^ B switch(wParam)
drkY~!a {
bw[s<z|LKA case VK_MENU:
ZNN^ MaskBits|=ALTBIT;
sgxD5xj}4 break;
zQ>|`0&8 case VK_CONTROL:
a`t<R MaskBits|=CTRLBIT;
*wu:fb2[(
break;
!ma%Zk case VK_SHIFT:
8~@?cy1j! MaskBits|=SHIFTBIT;
'Z{_ws break;
}#D+}Mo!, default: //judge the key and send message
QKVFH:"3 break;
(fUpj^E)p }
[G#PK5C for(int index=0;index<MAX_KEY;index++)
[gE_\=FSKu {
L5{DWm~@ if(hCallWnd[index]==NULL)
=bgu2#%Z continue;
c8<qn+=%? if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
=_)yV0 {
\LbBK ~l-I SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
VX{9g#y$j bProcessed=TRUE;
1RM@~I$0 }
Smc=-M} }
c7R<5f }
?P>3~3 B if(!bProcessed){
eY'< UO for(int index=0;index<MAX_KEY;index++){
u301xc,N<z if(hCallWnd[index]==NULL)
kS)azV continue;
XcH_Y if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
+ _"AF| SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
]ur_G`B }
MUjfqxTT }
F15Yn }
&4}Uaxt) return CallNextHookEx( hHook, nCode, wParam, lParam );
*kM^l!<g }
8Ts_;uId g*-%.fNA BOOL InitHotkey()
u,&[I^WK`C {
Spm7kw if(hHook!=NULL){
2zN"*Wkn nHookCount++;
ekV|a1) return TRUE;
>\s8S}p }
U9/6F8D1Y1 else
q:a-tdv2 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
@en*JxIM if(hHook!=NULL)
!QXPn}q^0 nHookCount++;
{I^@BW- return (hHook!=NULL);
2M$^|j:[ }
n=1_- ) BOOL UnInit()
8{)j"rghah {
V
X"!a if(nHookCount>1){
_i@4R< nHookCount--;
X :wfmb return TRUE;
~[ZRE @ }
E9 6`
aF{] BOOL unhooked = UnhookWindowsHookEx(hHook);
`SM37({c if(unhooked==TRUE){
*w,C5 f nHookCount=0;
=4_Er{AT hHook=NULL;
`~;`q }
0CR~ vQf#r return unhooked;
C>~ms2c }
zNRR('B? HpGI\s BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Zv|TvlyT" {
(Rs052m1 BOOL bAdded=FALSE;
K}a3Bj, for(int index=0;index<MAX_KEY;index++){
(@nEe? if(hCallWnd[index]==0){
J]4pPDm hCallWnd[index]=hWnd;
<%ba
3<sg HotKey[index]=cKey;
Z#znA4;) HotKeyMask[index]=cMask;
T6^H%;G bAdded=TRUE;
"fN=Y$G KeyCount++;
qS?uMms7w break;
`E:&a]ul }
/kH
7I }
e?yrx6 return bAdded;
/c|X:F!;X# }
RTQtXv6mD -F~"W@9r BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
4uy:sCmu {
45aFH}w: BOOL bRemoved=FALSE;
ApSzkPv* for(int index=0;index<MAX_KEY;index++){
^jB17z[ if(hCallWnd[index]==hWnd){
+.pri if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
j[Z<|Da hCallWnd[index]=NULL;
[$e\?c HotKey[index]=0;
<;P40jDL HotKeyMask[index]=0;
PHU$<> bRemoved=TRUE;
0qp Pz|h KeyCount--;
^+k~{F,) break;
e754g(|>b }
O]VHX![Y$ }
.u3Z*+ }
peD7X:K\s return bRemoved;
H_vGa!_ }
/Dj-@7.C/ -J]j= void VerifyWindow()
G;he:Bf {
_2~+%{/m, for(int i=0;i<MAX_KEY;i++){
5lrjM^E| if(hCallWnd
!=NULL){ H63?Erh>a
if(!IsWindow(hCallWnd)){ F1GFn|OA
hCallWnd=NULL; p:?h)'bA<
HotKey=0; \PL0-.t,
HotKeyMask=0; 'aqlNBG*
KeyCount--; q#_<J1)z
} q~6a$8+t
} U%V4@iz~\m
} o>75s#=
b=
} M.u1SB0
b-?d(-
BOOL CHookApp::InitInstance() ~jD~_JGp
{ GWW#\0*Bn
AFX_MANAGE_STATE(AfxGetStaticModuleState()); _ZHDr[
hins=AfxGetInstanceHandle(); GAU7w"sE
InitHotkey(); :zp9L/eh
return CWinApp::InitInstance(); ,"U|gJn|^
} k<A|+![
]47!Zo,
int CHookApp::ExitInstance() )'i n}M
{ pv"QgH
VerifyWindow(); zXaA5rZO
UnInit(); 2ut)m\)/)
return CWinApp::ExitInstance(); r<OqI*7
} Nz;f| 2h
L2>
)HG
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file .kc{)d*0K
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) 5b$QXO
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ Y.KJP ?
#if _MSC_VER > 1000 h pKrP
#pragma once <V1y^EW0
#endif // _MSC_VER > 1000 l&{+3 aC:
@B9O*x+n:
class CCaptureDlg : public CDialog 4Hq6nT/
{ bPA1>p7
// Construction BT|n+Y[
public: OMm'm\+/
BOOL bTray; &Pe[kCO]
BOOL bRegistered; R/P9 =yvg0
BOOL RegisterHotkey(); auHP^O>4L
UCHAR cKey; 0w!:YB ,}
UCHAR cMask; B4t,@,\O
void DeleteIcon(); }iRRf_
void AddIcon(); ge|Cvv
UINT nCount; 3U4h>T@s|
void SaveBmp(); U[G5<&Z^
CCaptureDlg(CWnd* pParent = NULL); // standard constructor &UIS