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:
C-Mop,w
fu`oDi 一、实现方法
QxK%ZaFZA ReY K5J=O 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:
+$%o#~ 8ViDh #pragma data_seg("shareddata")
ms?h/*E<H HHOOK hHook =NULL; //钩子句柄
J-U}iU| UINT nHookCount =0; //挂接的程序数目
V\
|b#?KL static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
09Fr1PL static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
7-^d4P+|g static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
|Bjb static int KeyCount =0;
gG}<l ': static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
0@
-LV:jU #pragma data_seg()
8WAg{lVs M*x_1h5n 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。
'F@'4[uda *StJ5c_kg2 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:
U@9n7F -kJ`gdS BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
8?PNyO-Wt5 cKey,UCHAR cMask)
gw H6r3=y( {
fE(rDQI BOOL bAdded=FALSE;
,QK>e;:Be for(int index=0;index<MAX_KEY;index++){
4 1Ru@ if(hCallWnd[index]==0){
N-^\e)ln hCallWnd[index]=hWnd;
j,~h:MT HotKey[index]=cKey;
%l>^q`p HotKeyMask[index]=cMask;
^P[-HA| bAdded=TRUE;
p%}oo#%J KeyCount++;
ZY83,:< break;
'p<(6*," }
yPL@uCzA@ }
$zJ.4NA return bAdded;
[u<1DR }
?xy~N?N //删除热键
v8LKv`I's BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
)0NA*<Q+. {
us/x.qPy2 BOOL bRemoved=FALSE;
s)}C&T$Y. for(int index=0;index<MAX_KEY;index++){
$ED<:[3N if(hCallWnd[index]==hWnd){
3N;X|pa if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
MQhL>oQ hCallWnd[index]=NULL;
@6\8&(| HotKey[index]=0;
pBHr{/\5 HotKeyMask[index]=0;
u|+O%s TQ bRemoved=TRUE;
Z
yIn>]{ KeyCount--;
lO:[^l?F break;
/Qbt }
8tsW^y;S }
F77~156 }
LNe-]3wB return bRemoved;
!dZC-U~ }
N/Z<v* i" g4Tc (k# "BK&C6] DLL中的钩子函数如下:
t/HE@xPxI5 vrH/Z.WD LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
:Vv=p*~ {
7dAa~!/( BOOL bProcessed=FALSE;
aaLT% if(HC_ACTION==nCode)
IXg0g<JZ {
@@+\ if((lParam&0xc0000000)==0xc0000000){// 有键松开
pZXva9bE switch(wParam)
qPWYY {
m+CvU?)gJ case VK_MENU:
[N{Rd[{QTL MaskBits&=~ALTBIT;
/']Gnt G. break;
?L'ijzP case VK_CONTROL:
2nk}'HBe MaskBits&=~CTRLBIT;
0nBAO break;
zg[ksny case VK_SHIFT:
euQd MaskBits&=~SHIFTBIT;
J3C"W794} break;
3rs=EMz:w default: //judge the key and send message
>*EcX 3 break;
&Jq?tnNd }
L~~;i'J for(int index=0;index<MAX_KEY;index++){
qL(Qmgd if(hCallWnd[index]==NULL)
8hdd1lVKO8 continue;
Wa
, # if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
:h" Y >1P {
`*N2x\+X SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
lr=*Ty(V bProcessed=TRUE;
ZfS-W&6Z }
iGM-#{5 }
f ~9ADb }
>!?u8^C else if((lParam&0xc000ffff)==1){ //有键按下
rT <=`9^{ switch(wParam)
c/b}39X {
BJ1txdxvS case VK_MENU:
^,@Rd\q MaskBits|=ALTBIT;
AS~O*(po break;
H+ t^eg88 case VK_CONTROL:
"|(+~8[ MaskBits|=CTRLBIT;
I@e{>} break;
5yuR[VU case VK_SHIFT:
njX!Ez MaskBits|=SHIFTBIT;
[26"?};"% break;
LC2t,!RRl& default: //judge the key and send message
YEQ}<\B\& break;
[
q22?kT }
y1B3F5 for(int index=0;index<MAX_KEY;index++){
8nW#Q<s if(hCallWnd[index]==NULL)
1Sr@$+VGO continue;
LsoP >vJG if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
u<:RSg {
\f05(ld SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
o=7 -&F. bProcessed=TRUE;
kF`2%g+ }
gCW.;|2 }
!'[f!vsyM{ }
^dld\t:tV7 if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
Jr|"` f%V for(int index=0;index<MAX_KEY;index++){
vQ$ FMKz7 if(hCallWnd[index]==NULL)
,a_\o&V continue;
z1*8 5?
if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
L6O*aZ| SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
5fjmr //lParam的意义可看MSDN中WM_KEYDOWN部分
fMy7pXa_ }
9ssTG4Sa }
">j}!n
8J }
C5$1K'X@ return CallNextHookEx( hHook, nCode, wParam, lParam );
i.C+{QH }
ULNU'6 I5
"Z 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:
9m/v^ p$0G EYwM BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
iG!tRNQ{y BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
Dqs{n?@n $_onSYWr 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
%@Bl,!BJ, X3P~z8_ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
1.6yi];6 {
WnyEdYA if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
RQ;pAO {
KC[ql}JP //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
oYG9i=lZ SaveBmp();
KY~p>Jmh return FALSE;
TmxhP
nJ~ }
!uL z%~F …… //其它处理及默认处理
%4*-BCP }
n<+g{QHi [Abq("9p\ w^6rgCl 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
`A_CLVE KmG*`Es 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
W1dpKv ycz6-kEp 二、编程步骤
d="Oge8 Dp3&@M"^yY 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
0z1m!tr ~oWCTj- 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
}6*+>? D2z" Z@ 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
7o_1PwKS6 j^-E,YMC 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
ry)g<OA >4
4A 5、 添加代码,编译运行程序。
N_Q)AXr) DO`
K_B 三、程序代码
^K.
d|z Xn@\p5< ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
hLK5s1#K #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
0}tf*M+a #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
2.)xWCG #if _MSC_VER > 1000
c5C 2xE}T #pragma once
094~ s #endif // _MSC_VER > 1000
WT;4J<O/ #ifndef __AFXWIN_H__
# bc$[%_ #error include 'stdafx.h' before including this file for PCH
W5z<+8R #endif
/
VypN, #include "resource.h" // main symbols
t.Q}V5t{g class CHookApp : public CWinApp
{Rc mjI7 {
o
b;] public:
X67^@~l CHookApp();
RdaAS{>Sk // Overrides
N1/)Fk-z // ClassWizard generated virtual function overrides
#[ZToE4 //{{AFX_VIRTUAL(CHookApp)
&B?TX. public:
3>asl54 virtual BOOL InitInstance();
O=m_P}K virtual int ExitInstance();
{,xI|u2R //}}AFX_VIRTUAL
@D1}). //{{AFX_MSG(CHookApp)
W}jel}: // NOTE - the ClassWizard will add and remove member functions here.
PIOG|E // DO NOT EDIT what you see in these blocks of generated code !
%EV\nwn6 //}}AFX_MSG
\vwsRT 1 DECLARE_MESSAGE_MAP()
eYNu78u };
6bPoC$<Z LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
OD{()E?1B BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
~C M%WvS BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
w(Jf;[o BOOL InitHotkey();
bvn%E
H BOOL UnInit();
X?'Sh XI #endif
rG[iEY m-T@Og //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
>2vUFq`H #include "stdafx.h"
QiO4fS'~W #include "hook.h"
9|BH/&$ #include <windowsx.h>
d ? Uj3G #ifdef _DEBUG
<KY \sb9 #define new DEBUG_NEW
@2(7
ZxI #undef THIS_FILE
[l#
8}dy static char THIS_FILE[] = __FILE__;
[u*-~( #endif
0ndk=V #define MAX_KEY 100
l/*NscYtQ #define CTRLBIT 0x04
OeMI #define ALTBIT 0x02
vX?MB #define SHIFTBIT 0x01
c?(;6$ A #pragma data_seg("shareddata")
#dO8) t HHOOK hHook =NULL;
skaPC#u UINT nHookCount =0;
k|uW~I) static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
y0}3s)lKv static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
fhwJ static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
D@W[Nd5MJ static int KeyCount =0;
k65V5lb static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
_"0, #pragma data_seg()
7 +]+S`p HINSTANCE hins;
~t=73fwB void VerifyWindow();
iEx
sGn]2 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
]F'o //{{AFX_MSG_MAP(CHookApp)
=1ltX+
// NOTE - the ClassWizard will add and remove mapping macros here.
9!XXuMWU< // DO NOT EDIT what you see in these blocks of generated code!
4e`GMtp //}}AFX_MSG_MAP
V8KdY=[ END_MESSAGE_MAP()
xgp 6lO [ etw.l~y CHookApp::CHookApp()
K%jh6c8 {
IN^dJ^1+ // TODO: add construction code here,
OkNBP0e} // Place all significant initialization in InitInstance
78~;j1^6u }
J^w!?nk <ztcCRov CHookApp theApp;
\|@u)n_ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
_s{;9&qX] {
WMi$ATq BOOL bProcessed=FALSE;
>PbB /-> if(HC_ACTION==nCode)
~SzHIVj:6 {
Nh^
lC if((lParam&0xc0000000)==0xc0000000){// Key up
4
*n4P switch(wParam)
I@/s&$H`l {
Sgp1p} case VK_MENU:
hnYL<<AA MaskBits&=~ALTBIT;
fvE:'( #? break;
n=F|bW case VK_CONTROL:
OK] _.v} MaskBits&=~CTRLBIT;
%VH{bpS|i: break;
?zpN09e case VK_SHIFT:
6lAHB*` MaskBits&=~SHIFTBIT;
'G)UIjl break;
QJ4=*tX) default: //judge the key and send message
ztEM>xsk break;
_8 C:Md` }
N\{{:<Cp\ for(int index=0;index<MAX_KEY;index++){
F[@M? if(hCallWnd[index]==NULL)
?y/LMja continue;
L#|6Lnp^ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
^{}$o#iof {
XM#xxf* Y SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
fW3awR{ bProcessed=TRUE;
~bD'QMk }
?mi1PNps# }
t,]E5,1 }
af- else if((lParam&0xc000ffff)==1){ //Key down
1F,>siuh , switch(wParam)
FW@(MIH {
CT0 ~ case VK_MENU:
a%YohfsY?U MaskBits|=ALTBIT;
lKSd]:3Xm break;
S_ER^Pkg case VK_CONTROL:
}K.2 MaskBits|=CTRLBIT;
59MpHkr break;
#?_8 *? case VK_SHIFT:
V44M=c7E MaskBits|=SHIFTBIT;
DG-XX.:z break;
]jRaR~[UN default: //judge the key and send message
B:]%Iu| break;
PZ.q }
&:?2IAe for(int index=0;index<MAX_KEY;index++)
o;"Phc. {
"o}}[hRP if(hCallWnd[index]==NULL)
o6ag{Yp continue;
[/Vi*Z if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
oYmLJzCf {
78UE?) X" SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
%0Mvd;#[ bProcessed=TRUE;
pd\x^F`sk. }
_`~\zzUZ }
ZnNl3MKV }
1m4Xl%KS> if(!bProcessed){
t3 rQ5m for(int index=0;index<MAX_KEY;index++){
GwM(E^AG if(hCallWnd[index]==NULL)
2A(?9
R9&h continue;
YIn
H8Ex if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
vPce6 Cl* SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
kn9e7OO## }
Yc3Rq4I'G }
~YQH] }
ZcE:r+ return CallNextHookEx( hHook, nCode, wParam, lParam );
&cf(} }
+i@{h9"6g I-L:;~. BOOL InitHotkey()
0nsj ihw {
Iw[7;B5v if(hHook!=NULL){
HP(dhsd<c nHookCount++;
oD.[T)G? return TRUE;
~\khwNA
}
O.z\
VI2f else
dxi5p!^^9 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
)aAKxC7w if(hHook!=NULL)
!m:rtPD' nHookCount++;
U+ANSW/ return (hHook!=NULL);
.^!<cFkCE }
TsF>Y""*M BOOL UnInit()
UfSqiu {
=-%10lOI if(nHookCount>1){
PD$'
~2 nHookCount--;
z,K;GZuP return TRUE;
jG{OLF6 ! }
ERy=lP~gV BOOL unhooked = UnhookWindowsHookEx(hHook);
zGNmc7 if(unhooked==TRUE){
K /$-H#;N nHookCount=0;
<$u\PJF7_^ hHook=NULL;
!/e*v>3u& }
@'<=EAXe return unhooked;
uUb`Fy9 }
zpjE_| ~jzjJ&O&
BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
V8Ri2&|3 {
c \;_jg BOOL bAdded=FALSE;
G6dUm_iB for(int index=0;index<MAX_KEY;index++){
U C_$5~8p if(hCallWnd[index]==0){
U;j\FE^+> hCallWnd[index]=hWnd;
msY6zJc` HotKey[index]=cKey;
c:[ZknnCe HotKeyMask[index]=cMask;
( k,?) bAdded=TRUE;
aS``fE;O KeyCount++;
9Dbbk/j| break;
_+.JTk }
L5'?.9] }
Y?3f
Fg return bAdded;
[+_>g4M~% }
4fL`.n1^ .TCDv4? BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
pD('6C; {
!hFhw1 BOOL bRemoved=FALSE;
4xH/a1&p= for(int index=0;index<MAX_KEY;index++){
G\o9mEzQ if(hCallWnd[index]==hWnd){
J;=T"C& if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
_N=f&~T hCallWnd[index]=NULL;
Nv^byWqu HotKey[index]=0;
0U~*uDU HotKeyMask[index]=0;
,Ha <lU2K bRemoved=TRUE;
U(LLIyZv KeyCount--;
+~~2OU L break;
0HUylnXf0 }
yO}5.
}
QIg'js$W }
C T\@>!'f return bRemoved;
7WwE] ^M }
b;%t*?t lh[?`+A void VerifyWindow()
Z #T {
Z/dhp0k for(int i=0;i<MAX_KEY;i++){
4Us_Z{. if(hCallWnd
!=NULL){ ]x{.qTtw
if(!IsWindow(hCallWnd)){ r?IBmatK/
hCallWnd=NULL; @mmnr?_w
HotKey=0; $rlrR'[H
HotKeyMask=0; y/5GY,z%aL
KeyCount--; R8_I ASs
} 'y=N_/+s
} GGf<9!:
} uovv">Uw
} [h8s0
%~y>9K
BOOL CHookApp::InitInstance() Sg4{IU
{ |-)8=QDz)r
AFX_MANAGE_STATE(AfxGetStaticModuleState()); hf^<lJh~=
hins=AfxGetInstanceHandle(); :m(DRD
InitHotkey(); '_^T]fr}
return CWinApp::InitInstance(); #n}~u@,o_
} 6i2%EC9
L7d1)mV
int CHookApp::ExitInstance() 0{g*\W*+~
{ X6",Xr!{
VerifyWindow(); '&'m#H*:
UnInit(); 9}u,`&
return CWinApp::ExitInstance(); hHGuD2%
} DY9]$h*y
OZ+v ~'oD
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file yu)^s!UY;
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) AYgXqmH~+
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ u*TC8!n
#if _MSC_VER > 1000 B\v+C!/f|
#pragma once Pc_aEBq
#endif // _MSC_VER > 1000 76wNZv)9
}f]Y^>-Ux
class CCaptureDlg : public CDialog _'LZf=V0
{ -(t7>s
// Construction pF4Z4?W
public: u8]FJQ*\6+
BOOL bTray; h693TS_N
BOOL bRegistered; <^'{=A>
BOOL RegisterHotkey(); #{vC =m73
UCHAR cKey; t*=[RS*
UCHAR cMask; r!+{In+Z
void DeleteIcon(); W*t]
d
void AddIcon(); xH xTL>,?
UINT nCount; ~Ix2O
void SaveBmp(); 'gvR?[!t
CCaptureDlg(CWnd* pParent = NULL); // standard constructor X!p`|i
// Dialog Data %VH, (}i
//{{AFX_DATA(CCaptureDlg) nuXL{tg6
enum { IDD = IDD_CAPTURE_DIALOG }; =o~GLbsER
CComboBox m_Key; sVK?sBs]
BOOL m_bControl; p,goYF??
BOOL m_bAlt; lQ-<T<g
BOOL m_bShift; Jsysk $R
CString m_Path; L23}{P
CString m_Number; w?8SQI,~X
//}}AFX_DATA ;~EQS.Qp
// ClassWizard generated virtual function overrides 5$:
toL
//{{AFX_VIRTUAL(CCaptureDlg) Aj)Q#Fd[
public: xwf-kwF8^
virtual BOOL PreTranslateMessage(MSG* pMsg); nUOi~cs
protected: L%T(H<