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:
tvT8UW'
kQVDC,d 一、实现方法
&_d/ciq1f QaWHz
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:
$-Pqs
^g >}b6J7_ #pragma data_seg("shareddata")
IzdTXc
f HHOOK hHook =NULL; //钩子句柄
,|X+/|gm UINT nHookCount =0; //挂接的程序数目
3g[j%`k static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
mO)PJd2ZD static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
t*d >eK`:N static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
K\+}q{ static int KeyCount =0;
.^lbLN^2 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
HI\f>U #pragma data_seg()
*fi;ZUPW3 sD8m< 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
NOr
<,
}{xN`pZ DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
<;cE/W}} R
pI<]1 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
ncattp cKey,UCHAR cMask)
/%YiZ# {
zLQ#GF BOOL bAdded=FALSE;
RO{@RhnV for(int index=0;index<MAX_KEY;index++){
j-YJ." if(hCallWnd[index]==0){
a4(?]ND~6 hCallWnd[index]=hWnd;
]}[Yf HotKey[index]=cKey;
q|o|/ O-{ HotKeyMask[index]=cMask;
Y/,$Y]%g bAdded=TRUE;
wD],{ y KeyCount++;
nS+FX&_ break;
y168K[p }
:X1cA3c! }
t{SMSp return bAdded;
(X(1kj3 }
T5Sg2a1& //删除热键
dHG Io BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
8b:clvh {
6W;?8Z_1 BOOL bRemoved=FALSE;
bug Fl> for(int index=0;index<MAX_KEY;index++){
%,,`N I{ if(hCallWnd[index]==hWnd){
;wXY3|@ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
px|>v8 hCallWnd[index]=NULL;
1Vf78n HotKey[index]=0;
+K;Y+
K&;2 HotKeyMask[index]=0;
X#DL/#z k bRemoved=TRUE;
N
pXgyD KeyCount--;
}B"|z'u break;
_t|G@D{ }
:,NFFN }
e" Eqi- }
z0 2}&^Zzk return bRemoved;
x(9;!4O> }
TTZ['HP
oI 1a&/Zlr t0e{|du DLL中的钩子函数如下:
M_h8#7 {G hB?,7- LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
VJN/#
{
x^)g'16` BOOL bProcessed=FALSE;
^p 2.UW if(HC_ACTION==nCode)
`u#;MUg {
9 $o < if((lParam&0xc0000000)==0xc0000000){// 有键松开
]D LZ&5pv switch(wParam)
U['JFLF {
T2DF'f3A case VK_MENU:
>'aG/( MaskBits&=~ALTBIT;
d$fvg8^ break;
"($Lx case VK_CONTROL:
9jO`gWxV8* MaskBits&=~CTRLBIT;
6[*;M break;
SqXy;S@ case VK_SHIFT:
%'L].+$t MaskBits&=~SHIFTBIT;
|Bx||=z` break;
eQU-&-wt0 default: //judge the key and send message
.!yWF?T8 break;
1mHwYT+ }
]6{(Hjt for(int index=0;index<MAX_KEY;index++){
qGnPnQc if(hCallWnd[index]==NULL)
By?nd) continue;
-RG8<bI, if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
P>*Fj4Z~ {
-ca7x`yo SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
.[T'yc:= bProcessed=TRUE;
%n05Jitl }
@up&q }
}_{y|NW }
5/B#) gm else if((lParam&0xc000ffff)==1){ //有键按下
D:wnO|: switch(wParam)
+`;+RDKY* {
0A#*4ap case VK_MENU:
>vWEUE[ MaskBits|=ALTBIT;
U~uwm/h break;
i`[#W(m case VK_CONTROL:
5vD3K!\u MaskBits|=CTRLBIT;
v:rD3=M- break;
6exI_3A4jh case VK_SHIFT:
YBX)eWslK MaskBits|=SHIFTBIT;
+I|Rk& break;
dqqnCXYuW default: //judge the key and send message
C=N!z break;
^Xs%.`Gv/ }
"^;#f+0 for(int index=0;index<MAX_KEY;index++){
HLjvKE=W if(hCallWnd[index]==NULL)
-xJX _6}A continue;
iv:,fkwG if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
{(rf/:X!p {
JY{X,?s SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
tg~A}1o`0 bProcessed=TRUE;
(y1$MYZQ }
C,o: }
5;W\2yj }
7MY)\aH if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
{7vgHutp for(int index=0;index<MAX_KEY;index++){
P}HC(S1 if(hCallWnd[index]==NULL)
Y!SE;N& continue;
\V]t!mZ-}l if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Y[W6Sc SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
\UQ9MX _ //lParam的意义可看MSDN中WM_KEYDOWN部分
>n]oB~P% }
A -Mj|V }
-i#J[>=w{C }
@-0Fe9 n= return CallNextHookEx( hHook, nCode, wParam, lParam );
9Ei5z6Vk/+ }
N99[.mErU oP/>ju 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
:<L5sp /@VsqD BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
6\NvG,8 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
-*?p F_*w swttp` 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
]k[x9,IU\y H#OYw#L"u LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
%/5 1o6a {
F8;mYuA if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
+A@m9 {
<mL%P`Jj
//lParam表示是按下还是松开,如果有多个热键,由wParam来区分
{$;2HbM( SaveBmp();
@B?FE\ return FALSE;
5J
ySFG3 }
j(j#0dXLh …… //其它处理及默认处理
[w!C*_V 9 }
# Mu<8`T- ^w.]Hd2 4Rx~s7l 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。
TN5>" ??" oz LH ]* 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。
+jUgx;u, ]D O&x+Rb 二、编程步骤
lr,q{; Z:!IX^q;}n 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";
C,fY.CeI Pb#P`L7OB 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
vm8$:W2 } !v0"$V5+i 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;
`xCOR /jM_mrpz 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;
!NTH.U:g 2HD:JdL 5、 添加代码,编译运行程序。
q]CeD XIKvH-0& 三、程序代码
5$kdgFq( \^jjK,OK ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
C0QM#"[ #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
k)cP! %z #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
Q^L)
Vp" #if _MSC_VER > 1000
3f"C!l]Xu #pragma once
O5zE {# #endif // _MSC_VER > 1000
H(b)aw^(% #ifndef __AFXWIN_H__
{?Od{d9 #error include 'stdafx.h' before including this file for PCH
b]T@gJ4H= #endif
YScvyh?E #include "resource.h" // main symbols
eeM?]J- class CHookApp : public CWinApp
8] `Ru5nd {
\Wr,<Y public:
}9^@5!qX CHookApp();
wjrG7*_Y4v // Overrides
M%I@<~wl // ClassWizard generated virtual function overrides
Xwt`(h[u //{{AFX_VIRTUAL(CHookApp)
yI&9\fn public:
>{wuEPA virtual BOOL InitInstance();
z8E1 m" virtual int ExitInstance();
];1R&:t //}}AFX_VIRTUAL
&kzj?xK=(j //{{AFX_MSG(CHookApp)
@ &pqt6/t // NOTE - the ClassWizard will add and remove member functions here.
-\4zwIH // DO NOT EDIT what you see in these blocks of generated code !
Br!9x{q* //}}AFX_MSG
#Y2i*:< DECLARE_MESSAGE_MAP()
S( };
Or8kp/d LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
E$A3|rjnoN BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
~Wei|,w'< BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
lj4o#^lC BOOL InitHotkey();
.1#kDM BOOL UnInit();
l(!/Q|Q| #endif
E"6X|I n :Wc_Utt //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
wksl0:BL #include "stdafx.h"
:QPf~\w? #include "hook.h"
19W:-Om #include <windowsx.h>
lq>AGw #ifdef _DEBUG
H; Ku
w #define new DEBUG_NEW
t0Mx!p'T #undef THIS_FILE
^AL2H' static char THIS_FILE[] = __FILE__;
X:|8vS+0gU #endif
}gv8au< #define MAX_KEY 100
j/KO|iNL2 #define CTRLBIT 0x04
po7>IQS] #define ALTBIT 0x02
* ?]~
# #define SHIFTBIT 0x01
PX2c[CDE^ #pragma data_seg("shareddata")
iX "C/L|JN HHOOK hHook =NULL;
s2REt$.q UINT nHookCount =0;
6KRO{QK static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
Yf}xwpuLk static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
*z8|P#@ static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
pDl3!m static int KeyCount =0;
D=+NxR[ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
,eRQu. #pragma data_seg()
TB!((' HINSTANCE hins;
T^:fn-S}= void VerifyWindow();
QI_4* BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
) #+^
sAO //{{AFX_MSG_MAP(CHookApp)
l63hLz // NOTE - the ClassWizard will add and remove mapping macros here.
R#W&ery // DO NOT EDIT what you see in these blocks of generated code!
~b)74M/ //}}AFX_MSG_MAP
Zsx3/} END_MESSAGE_MAP()
$n!K6fkX% =a}b+(R CHookApp::CHookApp()
G8J*Wnwu[K {
[0y$! f4 // TODO: add construction code here,
{<=#*qx[Y! // Place all significant initialization in InitInstance
/>44]A< }
,|h)bg7. "@/62b CHookApp theApp;
F(,UA+$A LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Iz@)!3h {
Fmr}o(q1 BOOL bProcessed=FALSE;
yN6>VD{F if(HC_ACTION==nCode)
Vzl^Ka' {
VIJ<``9[ if((lParam&0xc0000000)==0xc0000000){// Key up
8gy_Yj&{P switch(wParam)
gckI.[!b {
@~ETj26U' case VK_MENU:
y[?-@7i MaskBits&=~ALTBIT;
qfoD break;
{d<;BLA case VK_CONTROL:
yuhnYR\`m MaskBits&=~CTRLBIT;
~*W!mlg break;
SF*n1V3hx case VK_SHIFT:
eq4C+&O& MaskBits&=~SHIFTBIT;
Wwujh2g"0| break;
>znRyQ~bM default: //judge the key and send message
$O)3q
$| break;
?OlV"zK }
]#2Y e7+ for(int index=0;index<MAX_KEY;index++){
alq%H}FF if(hCallWnd[index]==NULL)
VQ#3#Hj continue;
tmUFT if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
kwpK1R4zs {
OEx^3z^ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
hC <O`|lF bProcessed=TRUE;
cLVe T }
:'iYxhM.V }
OTDg5:> }
H1n1-!%d else if((lParam&0xc000ffff)==1){ //Key down
W ~f(:: switch(wParam)
JM- t<. {
\>QF(J [8 case VK_MENU:
GL{57 MaskBits|=ALTBIT;
/3 B
$( break;
uocHa5J case VK_CONTROL:
}a
AH MaskBits|=CTRLBIT;
UMl#D>:C< break;
NKb1LbnZ*y case VK_SHIFT:
$37
g]ZD MaskBits|=SHIFTBIT;
xg_Df, break;
6GPp>X default: //judge the key and send message
Q6'x\ break;
<Z}SKR"U% }
6(d }W2GP for(int index=0;index<MAX_KEY;index++)
' Z0r>. {
jw<pK4?y if(hCallWnd[index]==NULL)
=L;] ;i continue;
I`KQ|h0% if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
_BdE<
!r {
kHw_ S- SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
r$Co0!. bProcessed=TRUE;
+5VLw }
QTX8
L }
^sN ( }
U8qtwA9t if(!bProcessed){
^V$Ajt for(int index=0;index<MAX_KEY;index++){
D%6;^^WyUx if(hCallWnd[index]==NULL)
om?-WJI continue;
|sRipWh if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Mi'8
~J SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
26T "XW'_ }
8#!i[UFdj }
5%sE]Y# }
2MZCw^s> return CallNextHookEx( hHook, nCode, wParam, lParam );
Vq;dJ%sY }
4vBL6!z:Z ~.;<
Bj BOOL InitHotkey()
;JZS^Wa {
yE[#ze if(hHook!=NULL){
J+d1&Tw& nHookCount++;
ok|qyN+ return TRUE;
V,rq0xW }
3gd&i else
oy<WsbnS hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
8JmFi if(hHook!=NULL)
rV08ad nHookCount++;
M%jPH return (hHook!=NULL);
}!IL]0q }
]Oq[gBL"A BOOL UnInit()
.9Y)AtJTS {
~3uP6\F if(nHookCount>1){
V< k8N^ nHookCount--;
C8z{XSo return TRUE;
da)NK! }
-B86U6^s BOOL unhooked = UnhookWindowsHookEx(hHook);
^%O]P`$ if(unhooked==TRUE){
V5*OA??k< nHookCount=0;
\=_{na_ hHook=NULL;
Y ')x/H }
0}_[DAd6 return unhooked;
giz7{Ai }
qucq,Yw x c{hC4^V BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
x?&$ ci {
,}K<*t[I BOOL bAdded=FALSE;
[jmd for(int index=0;index<MAX_KEY;index++){
!.d@L6 if(hCallWnd[index]==0){
9k{PBAP hCallWnd[index]=hWnd;
:9k Ty: HotKey[index]=cKey;
fW?o@vlO HotKeyMask[index]=cMask;
N<~ku<nAU bAdded=TRUE;
uu`G 2[t KeyCount++;
S~|T4q( break;
@')[FEdW }
9-MUX^?u }
7hsGu a return bAdded;
5LOo8xN }
,cNLkoN KZ/=IP= BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
ght$9>'n {
T?X_c"{8M BOOL bRemoved=FALSE;
<>Hj
;q5p for(int index=0;index<MAX_KEY;index++){
(DI>5.x" if(hCallWnd[index]==hWnd){
6'Fd GS if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
qT+%;( hCallWnd[index]=NULL;
vh$%9ed HotKey[index]=0;
%f]:I HotKeyMask[index]=0;
<_7*67{ bRemoved=TRUE;
P'_H/r/# KeyCount--;
rW=Z>1 break;
AJ=qn a }
?"g! }
@ta7"6p-i@ }
!jTcsN% return bRemoved;
Y=Kc'x[,Zj }
"men &G-!qxe void VerifyWindow()
.X;3,D[w {
/{&tY:;m for(int i=0;i<MAX_KEY;i++){
MjU6/pO}L if(hCallWnd
!=NULL){ _ jsK}- \
if(!IsWindow(hCallWnd)){ .hifsB~
hCallWnd=NULL; Om5Y|v"*
HotKey=0; cI4K+
HotKeyMask=0; w 47tgPPk
KeyCount--; n^g|Ja
} (=om,g}
} _WRFsDZ'
} B\XKw'
} x U4 +|d
z*!%g[3I
BOOL CHookApp::InitInstance() X<I+&Zi
{ /#)/;
AFX_MANAGE_STATE(AfxGetStaticModuleState()); xsD($_
hins=AfxGetInstanceHandle(); j-lfMEa$o
InitHotkey(); s6@DGSJ
return CWinApp::InitInstance(); ATK_DEAu
} 6}FP
Jt}Bpg!J
int CHookApp::ExitInstance() 32`{7a3!=
{ z62;cv
VerifyWindow(); j3{D^|0bP
UnInit(); yjF1}SQ
return CWinApp::ExitInstance(); N u<_}
} $adbCY\
6V7B;tB
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file %yv<y+yP~
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) ]d!
UJ&<?
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ qm"rY\:
#if _MSC_VER > 1000 ~=uWD&5B4
#pragma once ,Vt/(x-
#endif // _MSC_VER > 1000 1ng!G 7g
?j"KV_
class CCaptureDlg : public CDialog vzim<;i
{ E2Q[ZoVS
// Construction !1$])VQWI
public: 4b98KsYg
BOOL bTray; )p<ExMIxd
BOOL bRegistered; ~?K ~L~f5
BOOL RegisterHotkey(); 0.8 2kl
UCHAR cKey; )-a'{W/t
UCHAR cMask; &E.^jR~*
void DeleteIcon(); ewctkI$,5
void AddIcon(); tFp Ygff<
UINT nCount; s~5[![1
K
void SaveBmp(); x-^`~p
CCaptureDlg(CWnd* pParent = NULL); // standard constructor z=q3Zo
// Dialog Data YS/Yd[ e
//{{AFX_DATA(CCaptureDlg) hoK>~:;
enum { IDD = IDD_CAPTURE_DIALOG }; .y!<t}
CComboBox m_Key; 9_Be0xgJ3^
BOOL m_bControl; RO 4Z?tz
BOOL m_bAlt; e4?>-
BOOL m_bShift; RBs-_o+ %
CString m_Path; Vf]
"L.G
CString m_Number; A#EDkU,
//}}AFX_DATA t/VD31
// ClassWizard generated virtual function overrides onz?_SAW
//{{AFX_VIRTUAL(CCaptureDlg) wl#@lOv-P
public: (|klSz_4LM
virtual BOOL PreTranslateMessage(MSG* pMsg); n\*!CXc
protected: '>-gi}z7
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support m
qMHL2~
virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam); A%KDiIA
//}}AFX_VIRTUAL Z2qW\E^_r
// Implementation /5(Yy}
protected: Azl&m