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:
o}G`t
Bz
L,.~VNy- 一、实现方法
jZ-s6r2= q/zU'7%@ 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:
*]HnFP ms5?^kS2O #pragma data_seg("shareddata")
s&pnB HHOOK hHook =NULL; //钩子句柄
9s_^?q UINT nHookCount =0; //挂接的程序数目
tqpO3 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
@Q,Q"c2 static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
O!nS3%De static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
`XH0S`B static int KeyCount =0;
s!?uLSEdb static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
L(C`<iE&3 #pragma data_seg()
;AJQ2 8Yk*$RR9 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
U!-Nx9 nS3Aadm DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
d/yF}%0QI pD({"A.x9z BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
MhCU;
! cKey,UCHAR cMask)
9MfU{4:;I {
yIn$ApSGY BOOL bAdded=FALSE;
2<B'PR-??y for(int index=0;index<MAX_KEY;index++){
C`t@tgT if(hCallWnd[index]==0){
W9w*=W
)Z hCallWnd[index]=hWnd;
@I-gs( HotKey[index]=cKey;
AvrvBz[ HotKeyMask[index]=cMask;
sw}O g`U bAdded=TRUE;
6Ot~Q KeyCount++;
{aUTTEu break;
S=-$:65 }
Dh8'og)7 }
siI%6Gn; return bAdded;
`WXlq#:K }
>nSt<e //删除热键
+Mijio BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
ou-UR5 {
l90"1I A BOOL bRemoved=FALSE;
2rT^OGw6 for(int index=0;index<MAX_KEY;index++){
v
=y
2 if(hCallWnd[index]==hWnd){
YyxU/UnhG if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
K [DpH& hCallWnd[index]=NULL;
t?G6|3 HotKey[index]=0;
2lsUCQI; HotKeyMask[index]=0;
Sp X;nH-D bRemoved=TRUE;
aA#79LS KeyCount--;
{,sqUq ( break;
AcuF0KWw/ }
3<W%z]k@M }
gm)Uyr$ }
{>1FZsR49t return bRemoved;
M]r?m@) }
@T\n@M] _Z[0:4 z5$Q"Y.D DLL中的钩子函数如下:
A`Dx]y HQm_ K0$ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
?MRY*[$ {
p}JOiiHa BOOL bProcessed=FALSE;
I<940PZ if(HC_ACTION==nCode)
Tp;W4]'a*: {
4{kH;~
z$ if((lParam&0xc0000000)==0xc0000000){// 有键松开
At:8+S<?A switch(wParam)
?'P}ZC8P {
<r:AJ; case VK_MENU:
B%;MGb o MaskBits&=~ALTBIT;
c$V5E t break;
[y@*vQw case VK_CONTROL:
=|P
&G~] MaskBits&=~CTRLBIT;
[o#% Eg; break;
i$E [@ case VK_SHIFT:
T3P9 MaskBits&=~SHIFTBIT;
KCTX2eNN&h break;
%nY\" default: //judge the key and send message
Pt"H_SW~k break;
'M >m$cCMZ }
aq$ hE-{28 for(int index=0;index<MAX_KEY;index++){
=lJ
?yuc if(hCallWnd[index]==NULL)
"wOfs$w%s continue;
4`#Q if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
uem-fTG {
).5X SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
NV4g5)D&L bProcessed=TRUE;
-Ty~lZ)TDT }
!}TsFa }
kh0cJE\_^ }
4uIYX else if((lParam&0xc000ffff)==1){ //有键按下
EpAgKzVpJ switch(wParam)
Z71m(//*} {
e7U\gtZ. case VK_MENU:
{zAI-?#*u MaskBits|=ALTBIT;
u)0I$Tc" break;
_h!.gZB3 case VK_CONTROL:
7l69SQo]? MaskBits|=CTRLBIT;
3{3@>8{w break;
g Y~r{ case VK_SHIFT:
GjhTF| MaskBits|=SHIFTBIT;
|[>@Kk4 break;
<PpvVDy3 default: //judge the key and send message
: ZrJL& break;
T-%=tY+- }
Eu?z! for(int index=0;index<MAX_KEY;index++){
tVn?cS if(hCallWnd[index]==NULL)
R7bG!1SHl continue;
/g<Oh{o8 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
xN-,gT'! {
g5B TZZ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
SQ>i:D; bProcessed=TRUE;
SL4?E<Jb }
qG6s.TcG }
sP(+Z^/ }
5Ml=<^ if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
HK!ecQ^+ for(int index=0;index<MAX_KEY;index++){
Z0Z6aZeb if(hCallWnd[index]==NULL)
Xi&J%N' continue;
W*C~Xba< if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
I$7eiW @ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
+&
r!%j7 //lParam的意义可看MSDN中WM_KEYDOWN部分
OjUPvR2 0 }
{zFME41>g }
p
u(mHB }
F^O83[S return CallNextHookEx( hHook, nCode, wParam, lParam );
~29p|X< }
!&VfOx:PN KG'i#(u[ 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
]Btkoad *HKw;I
BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
>aVgI<
BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
]b4IO4T 7QsD"rL 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
@gI1:-chB fM;,9 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
Rg?6e N {
7N9NeSH if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
/}? 7Eni {
!__0Vk[s //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
[%P#ieD4 SaveBmp();
CZ5\Et6r return FALSE;
#V!a<w4_ }
KrE'M …… //其它处理及默认处理
cl~Yx4 }
n"(!v7YNp P=94 Wgwd?@uK 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
C%XO|sP /v R>.' 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
ZL!u$)(V c$g@3gL 二、编程步骤
n<ZPWlJ &3Zq1o 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
js_`L#t 9@
tp# 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
V%s
g+D2 8+F5n! 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
Kw
-SOFE 4yl{:!la 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
i>F=XE 3P
cVE\GN 5、 添加代码,编译运行程序。
}|P3(*S @UD:zUT)F 三、程序代码
~r --dU W:]FYC ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
UnhVppnex #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
3A#Tn7 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
GShxPH{_j #if _MSC_VER > 1000
-JMn?] #pragma once
-pu5O9
@ #endif // _MSC_VER > 1000
^xZh@e5 #ifndef __AFXWIN_H__
qlO}=b/ #error include 'stdafx.h' before including this file for PCH
.Bm% #endif
[xMa^A>p #include "resource.h" // main symbols
g*Y,. class CHookApp : public CWinApp
y?$DDD {
'0+* public:
0t <nH%N}^ CHookApp();
$83B10OQ&L // Overrides
'/W$9jm // ClassWizard generated virtual function overrides
8|a./%gixs //{{AFX_VIRTUAL(CHookApp)
3A7774n=P public:
C 0w+
j virtual BOOL InitInstance();
lE:g A, virtual int ExitInstance();
#oUNF0L@6 //}}AFX_VIRTUAL
VeoG[Jl //{{AFX_MSG(CHookApp)
zCx4DN` // NOTE - the ClassWizard will add and remove member functions here.
4<efj // DO NOT EDIT what you see in these blocks of generated code !
`Fy-"Uf //}}AFX_MSG
(j:
ptQ2$ DECLARE_MESSAGE_MAP()
V>{< pS };
t[^$F, LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
~3&{`9Y BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
*3GV9'-P BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
(f# (B2j BOOL InitHotkey();
=*mT{q@ BOOL UnInit();
~Z\:Nx #endif
=6%oW2E\ 22\!Z2@T/ //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
EYAaK^ & #include "stdafx.h"
\(o"/* #include "hook.h"
f-b],YE #include <windowsx.h>
,?fJ0n:!% #ifdef _DEBUG
u^80NR #define new DEBUG_NEW
tdy2ZPVtTV #undef THIS_FILE
mDB static char THIS_FILE[] = __FILE__;
^Co-!jM #endif
Zi!Ta"}8 #define MAX_KEY 100
r* *zjv> #define CTRLBIT 0x04
M^FY6TT4O #define ALTBIT 0x02
c`;\sW-_W #define SHIFTBIT 0x01
zzqJeIS #pragma data_seg("shareddata")
Uzu6>yT HHOOK hHook =NULL;
[M?2axOC UINT nHookCount =0;
ahBqYAK9 static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
V$^jlWdR static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
{28|LwmL static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
$XBK_ 5 static int KeyCount =0;
zG!nqSDG static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
dAo;y.3 #pragma data_seg()
Rj8%% G-pt HINSTANCE hins;
P]_d;\
!"v void VerifyWindow();
8%?y)K^
D BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
K1B9t{T //{{AFX_MSG_MAP(CHookApp)
MmuT~d/ // NOTE - the ClassWizard will add and remove mapping macros here.
kB\{1; // DO NOT EDIT what you see in these blocks of generated code!
E~'mxx~i //}}AFX_MSG_MAP
x(_[D08/TT END_MESSAGE_MAP()
*b~6 B M$ p?@ %/!S CHookApp::CHookApp()
@mp`C}x"0& {
je4l3Hl // TODO: add construction code here,
bDI%}k9# // Place all significant initialization in InitInstance
6@S6E(^ }
:2 ;Jo^6Se KyvZ?R CHookApp theApp;
Tb/TP3N LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
oeSN9O {
FLal}80.o: BOOL bProcessed=FALSE;
+i ?S if(HC_ACTION==nCode)
+=Jir1SLV {
,&PE6hn if((lParam&0xc0000000)==0xc0000000){// Key up
VLsxdwHgb switch(wParam)
C,V%B {
1sE?YJP- case VK_MENU:
8*SDiZ MaskBits&=~ALTBIT;
_8fr6tO+ break;
A61^[Y,dX_ case VK_CONTROL:
Mj-vgn&/ MaskBits&=~CTRLBIT;
,H}_%}10 break;
5IOFSy` case VK_SHIFT:
~0$NJrUy MaskBits&=~SHIFTBIT;
-\ZcOXpMx= break;
5*PYT=p} default: //judge the key and send message
`0H g y= break;
c$S{^IQ }
cEW0;\$ for(int index=0;index<MAX_KEY;index++){
2M<R(W!& if(hCallWnd[index]==NULL)
8,D 2^Gg continue;
(@X~VACT if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Wc3kO'J {
fy@avo9 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Dih6mTP{ bProcessed=TRUE;
r?m+.fJB }
j.~!dh$mg }
(Q[fS:U }
76tdJ!4Z else if((lParam&0xc000ffff)==1){ //Key down
\y6OUM2y switch(wParam)
/[:dp< {
ZN"j%E{d case VK_MENU:
LZPuDf~/ MaskBits|=ALTBIT;
f-6vLX\Vu break;
waX>0e case VK_CONTROL:
AL/?,%F MaskBits|=CTRLBIT;
.iCDXc{# break;
GWsE; case VK_SHIFT:
rqv))Zo` MaskBits|=SHIFTBIT;
)m6M9eC break;
@uo ~nF j, default: //judge the key and send message
Yw5' 6NU
break;
-yxOBq }
~pa!w?/bQ for(int index=0;index<MAX_KEY;index++)
IJTtqo {
Qjx?ri// if(hCallWnd[index]==NULL)
s?8<50s continue;
9[!,c`pw if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
u&G.4QQF {
Vc^HVyAx@n SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
$VAx:Y| bProcessed=TRUE;
jR=s#Xz }
>56>*BHD }
x@mL $ }
f)]%.> if(!bProcessed){
AV 8n( for(int index=0;index<MAX_KEY;index++){
"G>3QL+O| if(hCallWnd[index]==NULL)
>+.
(r] continue;
[{4MR%-- if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
T0)4v-EO SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
js1!9%BV }
y"]n:M:( }
y(R?
,wa=] }
YV=QF
J' return CallNextHookEx( hHook, nCode, wParam, lParam );
2|\A7. }
ld$i+6| d0'JC* BOOL InitHotkey()
"5cM54Z0 {
+q6ydb, if(hHook!=NULL){
imQURC nHookCount++;
}QZQ3@ return TRUE;
G!4(BGx& }
zf3v5Hk else
yH][(o=2 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
AM=z`0so if(hHook!=NULL)
kq\)MQ"/X nHookCount++;
.CP&bJP% return (hHook!=NULL);
s
{^yj }
+_-bJo2a BOOL UnInit()
:akT 'q# {
S"9zc
,] if(nHookCount>1){
"#mBcQ;QLV nHookCount--;
S9HwIH\m return TRUE;
}68i[v9Njk }
Nn>'^KZNG BOOL unhooked = UnhookWindowsHookEx(hHook);
=PGs{?+&O if(unhooked==TRUE){
f#ri'&}c
: nHookCount=0;
$ d?.2Kg hHook=NULL;
;?C#IU }
9@Cv5L?p\ return unhooked;
bINvqv0v }
d1[ZHio2c? +r3IN){jz BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
8[6o ( {
ZiLj=bh BOOL bAdded=FALSE;
o1nURJ! for(int index=0;index<MAX_KEY;index++){
(8_\^jJ if(hCallWnd[index]==0){
h6dPO" hCallWnd[index]=hWnd;
Y^<bl2"y8 HotKey[index]=cKey;
+{sqcr1G HotKeyMask[index]=cMask;
s/089jlc bAdded=TRUE;
{Ay"bjZh KeyCount++;
P2Vg 4 break;
s+tGFjq }
q -8t'7 }
3Hf0MAt return bAdded;
.s$z/Jv }
D7_*k%;@ VK@!lJu! BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Q1@A2+ c {
9mZ BOOL bRemoved=FALSE;
k4 F"'N for(int index=0;index<MAX_KEY;index++){
Cu6%h>@K$ if(hCallWnd[index]==hWnd){
)8g(:`w if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
A$6$,h hCallWnd[index]=NULL;
\d::l{VB HotKey[index]=0;
@JdZ5Q HotKeyMask[index]=0;
}1IpON
bRemoved=TRUE;
`({T]@]V KeyCount--;
LR"9D break;
YuB+k^ }
S*yjee<@ }
BT}&Y6 }
eYx Kp!f return bRemoved;
tBpC: SG }
v+99
-. F2X0%te void VerifyWindow()
P;4w*((} ~ {
w3$ for(int i=0;i<MAX_KEY;i++){
6AocmR0D' if(hCallWnd
!=NULL){ 4`,j =3
if(!IsWindow(hCallWnd)){ Dc)dE2
hCallWnd=NULL; s.8{5jVG
HotKey=0; qP<Lr)nUH
HotKeyMask=0; v0L\0&+
KeyCount--; m# =z7.XrX
} $ `7^+8vHV
} _YRE (YZ/
} 43=,yz2Ef
} ,a#EW+" Z
JchSMc.9
BOOL CHookApp::InitInstance() 0wS+++n$5
{ Y".RPiTL
AFX_MANAGE_STATE(AfxGetStaticModuleState()); * RtgC/
hins=AfxGetInstanceHandle(); *?MGMhE
InitHotkey(); kZ"BBJ6w
return CWinApp::InitInstance(); R
LD`O9#j
} Z(Jt~a3o
n?V+dC=F}
int CHookApp::ExitInstance() -lv)tHs<
{ l#n,Fg3
VerifyWindow(); R4-~j gzx
UnInit(); tsk)zP,<
return CWinApp::ExitInstance(); !F?XLekTi
} }\C-}
Q
&\_iOw8
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file 4!KoFoZt*
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) j)q\9#sI/(
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ &4_qF^9J
#if _MSC_VER > 1000 i&n'N8D@
#pragma once jmeRrnC}
#endif // _MSC_VER > 1000 cv`~y'?D
c%qv9
class CCaptureDlg : public CDialog C`q@X(_
{ ?Q&yEGm(
// Construction _Zr.ba
public: b".L_Ma1*
BOOL bTray; }1r m
BOOL bRegistered; Ps<d('=
BOOL RegisterHotkey(); N?.%?0l
UCHAR cKey; 9+pmS#>_
UCHAR cMask; A=
w9V
void DeleteIcon(); aFLO{t r`
void AddIcon(); HJY2#lSha6
UINT nCount; AoyX\iqQ
void SaveBmp(); $.bBFWk
CCaptureDlg(CWnd* pParent = NULL); // standard constructor 9H%X2#:fH
// Dialog Data h;0S%ZC
//{{AFX_DATA(CCaptureDlg) +U@<\kIF
enum { IDD = IDD_CAPTURE_DIALOG }; ZzX~&95G
CComboBox m_Key; n?c]M
BOOL m_bControl; &