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:
"&`>+Yw
GJU9[ 一、实现方法
Lr
d- >Y\?v-^~; 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:
k}qCkm27 xzFQ)t& #pragma data_seg("shareddata")
u"wWekB HHOOK hHook =NULL; //钩子句柄
n{{"+;oR UINT nHookCount =0; //挂接的程序数目
^qVBg BPb static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
&sYxe:H static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
!I&,!$ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
=\MAz[IDj static int KeyCount =0;
k=d0%}
`M( static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
\hEIQjfi #pragma data_seg()
1U^KN~! _7qa~7?f 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。
k!bJ&} Q(b z;/8R7L& 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:
Bva2f:)K| *5hbD-a: BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
\P"Ol\@ cKey,UCHAR cMask)
;n|%W,b- {
!g)rp`? BOOL bAdded=FALSE;
=}I=s@ for(int index=0;index<MAX_KEY;index++){
9%"\s2T if(hCallWnd[index]==0){
9d( M%F hCallWnd[index]=hWnd;
3^$=XrD HotKey[index]=cKey;
Bga4kjfmk HotKeyMask[index]=cMask;
to1r
88X bAdded=TRUE;
jaavh6h) KeyCount++;
,Jn` qvmi break;
p-w:l*-` }
PY3bn).uR }
AGO"), return bAdded;
\[)SK`cwd }
F!4V!VWA} //删除热键
T5I#7LN# BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
d%nX;w,
{
h^1!8oOYD BOOL bRemoved=FALSE;
EQw7(r|v: for(int index=0;index<MAX_KEY;index++){
f|F=)tJO if(hCallWnd[index]==hWnd){
OA} r*Wz if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
5v`lCu] hCallWnd[index]=NULL;
%3"U|Za+ HotKey[index]=0;
WB<MU:.Vc HotKeyMask[index]=0;
UlNV%34" bRemoved=TRUE;
V\]j^$ KeyCount--;
nG{o$v_| break;
@0C[o9 }
?_p!teb }
8|L@-F }
<r>Sj/w<D return bRemoved;
o1*P|.`
}
y9LO;{( 0M&~;`W} #T{)y DLL中的钩子函数如下:
/(u? k%Q YU)%-V\ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
._<,
Eodv {
=VT\$
5A BOOL bProcessed=FALSE;
iWFtb)3B if(HC_ACTION==nCode)
2Qh)/=8lM {
piuM#+Y\'S if((lParam&0xc0000000)==0xc0000000){// 有键松开
(\r^0>H switch(wParam)
P>_9>k@;Q {
26 1? 8&c case VK_MENU:
E`hR(UL
? MaskBits&=~ALTBIT;
^e;9_( break;
'Nuy/\[{\ case VK_CONTROL:
t.VVE:A^% MaskBits&=~CTRLBIT;
?~.:C' break;
[u^ fy<jdp case VK_SHIFT:
Doq}UWp MaskBits&=~SHIFTBIT;
xO<%lq` break;
mW+5I-~ default: //judge the key and send message
@uN+]e+3 break;
$/5\Hg1 }
W=LJhCpRHj for(int index=0;index<MAX_KEY;index++){
R#8cOmZ if(hCallWnd[index]==NULL)
v}D0t] continue;
Am*lx if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
3/uvw>$ {
/me ]sOkn SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
o:"(\$ bProcessed=TRUE;
-1NR]#P' }
zxD=q5in }
DHuvHK0# }
l{ql'm else if((lParam&0xc000ffff)==1){ //有键按下
55UPd#E' switch(wParam)
`
"-P g5 {
MLM/!N 7 case VK_MENU:
}LQV2 hKTG MaskBits|=ALTBIT;
,Shzew+ break;
:hW(2=% case VK_CONTROL:
W/ WP }QM MaskBits|=CTRLBIT;
7+@-mJMP$D break;
0dS (g&ZR case VK_SHIFT:
R^sgafGl= MaskBits|=SHIFTBIT;
`d4xX@
break;
Q=vo5)t default: //judge the key and send message
.f. tPm break;
8'bZR] }
/-m) for(int index=0;index<MAX_KEY;index++){
*n#
=3D if(hCallWnd[index]==NULL)
jq8TfJ| continue;
NV?XZ[<*< if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
>SziRm>Y7 {
s|c}9/Xe) SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
H.C*IL9 bProcessed=TRUE;
\w1',"l` }
kTT%<
e }
E4Ez)IaKyi }
`,/5skeJ if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
V
EsM for(int index=0;index<MAX_KEY;index++){
Vkd_&z7 if(hCallWnd[index]==NULL)
3fXrwmBT8 continue;
%hZX XpuO if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
@OUBo;/ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
|r?0!;bN0 //lParam的意义可看MSDN中WM_KEYDOWN部分
xN}f? }
O'#;Ge/, }
^-mW k?> }
~&F|g2: return CallNextHookEx( hHook, nCode, wParam, lParam );
T"C.>G'[B }
5M #',(X qp#Euq6 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
@|">j#0 !
9*l!( BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
qTwl\dcncC BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
'W54 T @"/H
er 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
i;]# @n| qxHn+O!h LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
/YJBRU2 {
*&_cp]3-WF if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Bj><0
cNF {
(e!Yu#- //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
(V'w5&f(L SaveBmp();
1{d;Ngx return FALSE;
#DJZ42 }
WJa7
…… //其它处理及默认处理
TqV^\C? }
sMUpkU- eX}aa0 AS~!YR 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
_nxu8g] xt"-Jmox 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
S# baOO =-GxJPL 二、编程步骤
]>k8v6*= q{b-2k 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
V\r{6-%XiW `Je1$)% 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
S<'_{u z ;XjXv' 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;
`Eu,SvkF w QV\af 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;
S'ms>ZENC KQ81Oxu*C 5、 添加代码,编译运行程序。
k2,`W2]^E ]SPuNBsy) 三、程序代码
+_bxza(ma{ }YM\IPsPu ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
5VQ-D`kE+ #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
`"yxmo*0 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
*!*%~h8V #if _MSC_VER > 1000
T{`VUS/ #pragma once
LYd:S #endif // _MSC_VER > 1000
~jHuJ`]DF #ifndef __AFXWIN_H__
~OvbMWu #error include 'stdafx.h' before including this file for PCH
-vY5h%7kf #endif
l Ib
d9F #include "resource.h" // main symbols
7ZyP class CHookApp : public CWinApp
wQd8/&mmk {
}BL7P-km public:
WvfM.D!
CHookApp();
U:3OE97 // Overrides
T{m) = (q // ClassWizard generated virtual function overrides
<-n^h~,4 //{{AFX_VIRTUAL(CHookApp)
fc<y(uX public:
g)TZ/,NQ{ virtual BOOL InitInstance();
[{GN#W|AGP virtual int ExitInstance();
y06**f) //}}AFX_VIRTUAL
zF>;7'\x //{{AFX_MSG(CHookApp)
|K{d5\_ // NOTE - the ClassWizard will add and remove member functions here.
hAc|a9 o // DO NOT EDIT what you see in these blocks of generated code !
(EosLn
h0 //}}AFX_MSG
IpSWg DECLARE_MESSAGE_MAP()
Yo'Y-h# };
xf,A<j(o LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
(jj`}Qe3U BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
i|AWaG) BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
eiyr^Sch. BOOL InitHotkey();
|W=-/~X BOOL UnInit();
w%iwxo #endif
~"J1@< Y_jc *S //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
<rK[ &JlJ #include "stdafx.h"
j3`YaWw #include "hook.h"
s2|.LmC3|B #include <windowsx.h>
p}pd&ut1 #ifdef _DEBUG
6_u!{ #define new DEBUG_NEW
cHT\sJo`l #undef THIS_FILE
0!ZaR6 static char THIS_FILE[] = __FILE__;
3BD&;.<r #endif
8OV=;aM?{ #define MAX_KEY 100
)R'%SLw #define CTRLBIT 0x04
'\op$t/ #define ALTBIT 0x02
4
?PB
Fbd #define SHIFTBIT 0x01
(GpP=lSSeY #pragma data_seg("shareddata")
]cS(2hP7 HHOOK hHook =NULL;
\#) YS UINT nHookCount =0;
$MwBt static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
se2Y:v static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
#5{xWMp/0 static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
]a&riPh" static int KeyCount =0;
G<<;a static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
LiQH!yHW #pragma data_seg()
\ctzv``/n HINSTANCE hins;
W5Pur
lu? void VerifyWindow();
h?OSmzRLd BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
3gVU#T[[ //{{AFX_MSG_MAP(CHookApp)
w42{)S" // NOTE - the ClassWizard will add and remove mapping macros here.
=A'JIssk // DO NOT EDIT what you see in these blocks of generated code!
j#P4& //}}AFX_MSG_MAP
|ZifrkD= END_MESSAGE_MAP()
c U(z5th .B2e$`s$ CHookApp::CHookApp()
Pp69|lxV=k {
,P`G IGvkA // TODO: add construction code here,
y_q1Y70i2r // Place all significant initialization in InitInstance
Ax~
i` }
Et-|[ eL mrG?5.7W CHookApp theApp;
nFG X2|d LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Q{uO/6 {
N2[j By8M BOOL bProcessed=FALSE;
u #}1
M if(HC_ACTION==nCode)
# .(f7~ {
L?0IUGY if((lParam&0xc0000000)==0xc0000000){// Key up
E)jd>" switch(wParam)
S[/udA {
'sa)_?Hy case VK_MENU:
tS3&&t MaskBits&=~ALTBIT;
5MCgmF*Y2 break;
<6+B;brh case VK_CONTROL:
/`aPV"$M MaskBits&=~CTRLBIT;
@zi0:3`#0\ break;
/@&o%I3h case VK_SHIFT:
!XI9evJw MaskBits&=~SHIFTBIT;
(]I=';\ break;
r]D>p&4 default: //judge the key and send message
+cmi?~KS* break;
X_D-K F }
4Jc~I for(int index=0;index<MAX_KEY;index++){
mA,{E-T if(hCallWnd[index]==NULL)
Bv3B|D&+ continue;
>>C
S8 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
G}NqVbZ9] {
knV*,
SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
T9r6,yY bProcessed=TRUE;
#X$s5H }
$;=?[Cn }
Da6l=M }
DyZ6&*s$ else if((lParam&0xc000ffff)==1){ //Key down
]qq2VO<b switch(wParam)
NhF"% {
D[6sy`5l case VK_MENU:
if\`M'3Xx MaskBits|=ALTBIT;
})uyq_nz break;
3?_%|;ga case VK_CONTROL:
LXrk5>9 MaskBits|=CTRLBIT;
W[Z[o+7pK break;
OuWRLcJ! case VK_SHIFT:
lm&^`Bn) MaskBits|=SHIFTBIT;
/FPO'} 6i break;
4JO16 default: //judge the key and send message
tr/.pw6 break;
+tg${3ti_ }
ta x:9j|~ for(int index=0;index<MAX_KEY;index++)
).e}.Z6[i` {
~Ij/vyB_ if(hCallWnd[index]==NULL)
,v=pp; continue;
j*f\Z!EeZ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
i 2uSPV!Tf {
#NL'r99D/o SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
>X"\+7bw bProcessed=TRUE;
0blbf@XA }
CMv8n@ry }
sP%b?6 }
t pxk8Ys if(!bProcessed){
o^owv( for(int index=0;index<MAX_KEY;index++){
-GB,g=Dk if(hCallWnd[index]==NULL)
ty%,T.@e continue;
mC(YO y if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
,TB$D]u8 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
Pl`Nniy }
Y!Io @{f }
I};*O6D` }
,zK E$ return CallNextHookEx( hHook, nCode, wParam, lParam );
jPx}-_jM }
8=0I4\ V(io!8, BOOL InitHotkey()
@+y,E-YTdV {
pNmWBp|ER if(hHook!=NULL){
A
McZm0c` nHookCount++;
<viC~=k; return TRUE;
in K;n }
6'<[QoW]; else
YGc:84S hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
<Kl$ek8 if(hHook!=NULL)
C[#C/@ nHookCount++;
pe3;pRh' return (hHook!=NULL);
puMbB9) }
_.BT%4 BOOL UnInit()
n:k4t {
?gjx7TQ? if(nHookCount>1){
tp&|*M3 nHookCount--;
=]"I0G-s! return TRUE;
k{UeY[,jb }
?`O^;f BOOL unhooked = UnhookWindowsHookEx(hHook);
G\V*j$}! if(unhooked==TRUE){
Xw7'I nHookCount=0;
ev_' .t' hHook=NULL;
j4]3}t0q }
h@(+(fVHrp return unhooked;
m&'!^{av }
_jgtZ '!,(G3 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
DGS,iRLnA {
Vry_X2 BOOL bAdded=FALSE;
C4|OsC7J for(int index=0;index<MAX_KEY;index++){
!H9^j6| if(hCallWnd[index]==0){
QgQ$> hCallWnd[index]=hWnd;
4udj"-V HotKey[index]=cKey;
Q {BA`Q@V HotKeyMask[index]=cMask;
{s*2d P) bAdded=TRUE;
{ w sT KeyCount++;
v=cQ`nou break;
',LC!^:~Nw }
ZrZDyXL }
4i^WE;|s return bAdded;
j:/Z_v' }
)58~2vR \[^!
ys BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
pIYXYQ=Z {
$60`Hh 4/ BOOL bRemoved=FALSE;
N0vECk for(int index=0;index<MAX_KEY;index++){
+{I" e,Nk if(hCallWnd[index]==hWnd){
H6|eUU[& if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
j0a=v}j3 hCallWnd[index]=NULL;
+8itP> HotKey[index]=0;
(K84J*; HotKeyMask[index]=0;
$gD8[NAIx= bRemoved=TRUE;
; D/6e6 KeyCount--;
CS(2bj^6D break;
c%gL3kOT }
i.`n^R;N }
}*xjO/Ey }
~ A=Gra return bRemoved;
U"+W)rUd }
()O&O+R|) fFr9] void VerifyWindow()
f86Z #% {
`&