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:
1n.F`%YG
.H&XPW 一、实现方法
Qdc)S>gp 6]HMhv 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:
ys7Tq+ y^
st
T^ #pragma data_seg("shareddata")
z'gJy HHOOK hHook =NULL; //钩子句柄
w`=XoYQl~* UINT nHookCount =0; //挂接的程序数目
#??[;xjs! static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
T7Ju7_q} static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
~eiD(04^r* static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
5pff}Ru` static int KeyCount =0;
jF#Dc[* static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
N~?#Qh|ZnU #pragma data_seg()
Tg=P*HY6 Tx'anP 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。
4:s,e<Tc4v fP\*5|7%R 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:
VY=YI}E 8@FgvWC BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
/(%!txSNEt cKey,UCHAR cMask)
CRNt5T>qH {
C_h$$G{S( BOOL bAdded=FALSE;
6y{CM/DC for(int index=0;index<MAX_KEY;index++){
TeJ=QpGW2 if(hCallWnd[index]==0){
ArT@BqWd hCallWnd[index]=hWnd;
.rl Lt5b% HotKey[index]=cKey;
"5\6`\/ HotKeyMask[index]=cMask;
}/L#<n`Z bAdded=TRUE;
*A0d0M]cg KeyCount++;
R|*Eg,1g - break;
IfP?+yPa }
G//hZwf0 }
lxR]Bh+ return bAdded;
@)ls+}=Y }
_]0<G8|Rv //删除热键
YlZ&4 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
@qF:v]=_@ {
!bn=b>+ BOOL bRemoved=FALSE;
&}#zG5eu for(int index=0;index<MAX_KEY;index++){
]KUeSg| if(hCallWnd[index]==hWnd){
hij
9r z if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
>`` hCallWnd[index]=NULL;
[[ll4| HotKey[index]=0;
TFXKC l HotKeyMask[index]=0;
$+U6c~^^ bRemoved=TRUE;
<Iil*\SC KeyCount--;
r#J_;P{U break;
a3Xd~Qs }
{?}^HW9{ }
5'|W(yR} }
;[:IC^9fv return bRemoved;
.k,,PuP }
"z*?#&?, 8 9maN !&{"tL@. DLL中的钩子函数如下:
"=2'O qp1 VMu?mqEa LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
m mH
xPd {
+Ur75YPh BOOL bProcessed=FALSE;
X#fjIrn if(HC_ACTION==nCode)
{s:"mkR {
Bf3 QB]9 if((lParam&0xc0000000)==0xc0000000){// 有键松开
@oD2_D2 switch(wParam)
gz Dfx&.0 {
1q|iw case VK_MENU:
!-JvVdM;( MaskBits&=~ALTBIT;
M'pIAm1p break;
j.\0p-, case VK_CONTROL:
{}H/N MaskBits&=~CTRLBIT;
>H,E3Z break;
ofs'xs1C case VK_SHIFT:
ZsP>CELm@ MaskBits&=~SHIFTBIT;
CSBDSz break;
CsjrQ-#9yn default: //judge the key and send message
y&wo"'; break;
q7I(x_y / }
JOwu_% for(int index=0;index<MAX_KEY;index++){
-\25&m!+ if(hCallWnd[index]==NULL)
sDBwD%sb continue;
xO4""/n if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
oE,TA2 {
qXoq<
| SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
" z -tL bProcessed=TRUE;
sg4(@> }
nZEew.T:6 }
m;ju@5X }
R_ )PbFw else if((lParam&0xc000ffff)==1){ //有键按下
m!3D5z]n9 switch(wParam)
bicbCC6kC {
'oUTY * case VK_MENU:
Fx:4d$>; MaskBits|=ALTBIT;
<00=bZzX break;
S Erh"~[ case VK_CONTROL:
2dDhO MaskBits|=CTRLBIT;
WwxV}?Cf+ break;
@c).&7 case VK_SHIFT:
yqP=6 MaskBits|=SHIFTBIT;
*Xh#W7,< break;
!iK{q0 default: //judge the key and send message
CXTtN9N9 break;
6;(b-Dhi }
wU"w for(int index=0;index<MAX_KEY;index++){
%Nx,ZD@ if(hCallWnd[index]==NULL)
7t/Y5Qf continue;
h\+8eeIl if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Y3SV6""y/ {
28 zZ3|Z3 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
#] ;ulDq bProcessed=TRUE;
Af}o/g }
|<uBJ-5 }
g@Rs.Zq }
7JBr{3;eS if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
v<mSd2B* for(int index=0;index<MAX_KEY;index++){
apnpy\in if(hCallWnd[index]==NULL)
#8y"1I=i& continue;
wn\R|'Rdz if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
v4Kf{9q# SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
]2A2<Q_, //lParam的意义可看MSDN中WM_KEYDOWN部分
?6h~P:n. }
n3$u9!|P }
3#eAXIW[ }
-vc
,O77z" return CallNextHookEx( hHook, nCode, wParam, lParam );
+x<OyjY5?] }
L^K,YlNBR alBnN<UM 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
3 Zwhv+CP[ _9?v?mL5; BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
5f2=`C0_ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
\+:`nz3m \ rKUPI\ 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
cg9*+]rc =)a%,H LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
q#\B}'I{ {
+{#Z^y6& if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
9_~9?5PU {
>:BgatyPH //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
RMdU1@ SaveBmp();
j]aIJbi return FALSE;
G3h"Eo?>g }
p(9[*0.}; …… //其它处理及默认处理
XV,ce~ro[ }
IYa(B+nB) e*d lGK3l A+FQmLS 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
X1BqN+=@9 Dn#UcMO>W 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
O9N+<sU=X C'S_M@I= 二、编程步骤
TP)o0U j,z)x[3} 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
dux_v"Xl Mhc5<~? 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
MM( ,D&
Z G&4D0f 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
5xU}}[|~- I.`DBI#-f 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
H}(WL+7 qac:"z'9 5、 添加代码,编译运行程序。
r$ I k*R _qh\
三、程序代码
<N3~X,ch V}Oz!
O ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
KIKIag# #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
^==Tv+T9U #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
'z@]hm# #if _MSC_VER > 1000
-lXQQ#V
- #pragma once
<vu~EY0. #endif // _MSC_VER > 1000
`,4YPjk^ #ifndef __AFXWIN_H__
2EO9IxIf #error include 'stdafx.h' before including this file for PCH
ce719n$
#endif
l_,6<wWp #include "resource.h" // main symbols
Mgu9m8
`J class CHookApp : public CWinApp
;ZkY[5 {
[jEA|rd~} public:
%=V"
}P[ CHookApp();
&3)6WD?:U // Overrides
p0}Yo8? OW // ClassWizard generated virtual function overrides
o,xy' //{{AFX_VIRTUAL(CHookApp)
ZVit]3hd public:
~{N#JOY}Z virtual BOOL InitInstance();
z]=Ks_7 virtual int ExitInstance();
NdRE,HWd?$ //}}AFX_VIRTUAL
JV+Uy$P! //{{AFX_MSG(CHookApp)
JIc9csr:b // NOTE - the ClassWizard will add and remove member functions here.
@]42.oP // DO NOT EDIT what you see in these blocks of generated code !
8:uh0 //}}AFX_MSG
)QmmI[,tq DECLARE_MESSAGE_MAP()
gV*4{d` };
-w'g0/fD LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
::3[H$ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
4#I=n~8a BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
{}=5uU 2Tu BOOL InitHotkey();
?zVcP=p@ BOOL UnInit();
!#E-p?O. #endif
>xH?`I7;f y5VohVa` //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
oeI[x #include "stdafx.h"
^}:0\;|N #include "hook.h"
r]kks_!Z #include <windowsx.h>
.'2"83f #ifdef _DEBUG
S'>KGdF #define new DEBUG_NEW
%O{FZgi%wA #undef THIS_FILE
uVXn/B static char THIS_FILE[] = __FILE__;
vY[u;VU #endif
%f(4jQ0I #define MAX_KEY 100
_ -,[U{ #define CTRLBIT 0x04
e$mVA}>Ybp #define ALTBIT 0x02
MR,A{X #define SHIFTBIT 0x01
W!TTfj #pragma data_seg("shareddata")
`}8)P# HHOOK hHook =NULL;
'%YTMN@ UINT nHookCount =0;
0t*PQ% static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
'8I=Tn static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
7dlMDHp\Y static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
s"8z q;) static int KeyCount =0;
)a+bH </' static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
Qb;]4[3 #pragma data_seg()
"kucFf f HINSTANCE hins;
'z+Pa^)v void VerifyWindow();
v~p?YYOm< BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
9>_VU"T //{{AFX_MSG_MAP(CHookApp)
,3)JZM // NOTE - the ClassWizard will add and remove mapping macros here.
r 2{7h> // DO NOT EDIT what you see in these blocks of generated code!
@#9xSs# //}}AFX_MSG_MAP
tao9icl*` END_MESSAGE_MAP()
kjSzuqB h}S2b@e| CHookApp::CHookApp()
E#kH>q@K`$ {
9mpQusM // TODO: add construction code here,
[yRqSB // Place all significant initialization in InitInstance
37V$Qb_ }
c3\p@} $A(3-n5= CHookApp theApp;
&((04<@e LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
+^$;oG {
HS1{4/ BOOL bProcessed=FALSE;
kC'm |Y@T if(HC_ACTION==nCode)
jank<Q&w {
j\.e6&5%SS if((lParam&0xc0000000)==0xc0000000){// Key up
^Je*k)COn switch(wParam)
D9n+eZ {
9YBlMf`KEf case VK_MENU:
9,}Z1 f\% MaskBits&=~ALTBIT;
#O'g*]j break;
YKx+z[A/p case VK_CONTROL:
\;"S>dg MaskBits&=~CTRLBIT;
F<)f&<5E- break;
@Z96902<t case VK_SHIFT:
6$fwpW MaskBits&=~SHIFTBIT;
gX*
&RsF break;
4@-Wp] default: //judge the key and send message
3V]psZS break;
1+tPd7U }
^SwU]e for(int index=0;index<MAX_KEY;index++){
ikPr> if(hCallWnd[index]==NULL)
J/[PA[Rf continue;
UG<<.1JL if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
WkoYkkuzj {
pU u')y SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
D P:}< bProcessed=TRUE;
%\%&1 }
mn\GLR. }
I*(7(>zgyv }
gER(&L 4[ else if((lParam&0xc000ffff)==1){ //Key down
>rFM8P( switch(wParam)
==bT0-M.~ {
*`tQX$F case VK_MENU:
U.|0y =
MaskBits|=ALTBIT;
^9|&w.:@Q break;
.GW)"`HbU case VK_CONTROL:
eBe5H
=I@ MaskBits|=CTRLBIT;
"fSK7%BP break;
TI7)yxa=` case VK_SHIFT:
W'Qy4bl7C MaskBits|=SHIFTBIT;
|@)jS.Bn break;
{_4zm& default: //judge the key and send message
o7AI break;
`1R[J4e }
+ZRm1q for(int index=0;index<MAX_KEY;index++)
L_>LxF43 {
McvLU+ if(hCallWnd[index]==NULL)
;i 3C continue;
QmsS,Zljo if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
jgw+c3^R_ {
8sL+ik" SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
/IC]}0kkp bProcessed=TRUE;
m9Dg%\B }
0fR?zT? }
D\sh
+}" }
BagV\\#v4 if(!bProcessed){
mpl^LF[ for(int index=0;index<MAX_KEY;index++){
1sfs!b&E if(hCallWnd[index]==NULL)
[wUJ~~2# continue;
mS]soYTQ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
'_xa>T} SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
}i\_`~ }
4Y@q.QP }
r / L }
l{_1`rC' return CallNextHookEx( hHook, nCode, wParam, lParam );
&|Vzo@D(! }
'Ub\8<HfJU E^m2:J]G BOOL InitHotkey()
(DTkK5/% {
IPnx5#eB
if(hHook!=NULL){
Ly6) ,[q~ nHookCount++;
_Tma1~Gq return TRUE;
0O?!fd n }
R"QWap} else
f<@`{oP@ hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
$`/F5R! if(hHook!=NULL)
jt&rOPL7 nHookCount++;
4eS(dPI0 return (hHook!=NULL);
L4Si0 K }
<9?`zo$y BOOL UnInit()
'S;l" {
$60]RCu if(nHookCount>1){
L$f:D2Ei nHookCount--;
cX48?srG return TRUE;
U9q6m3#$ }
Za1VJ5- BOOL unhooked = UnhookWindowsHookEx(hHook);
-O[9{`i] if(unhooked==TRUE){
t$*CyYb{@ nHookCount=0;
y1Yrf,E
m= hHook=NULL;
h/#s\>)T }
X(K5>L> return unhooked;
==~
lc; }
K_BF=C.k Uj~
:|?Wz BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
qg8T}y> {
{+|Em (M BOOL bAdded=FALSE;
`~ R%}ID for(int index=0;index<MAX_KEY;index++){
M{U7yE6*j* if(hCallWnd[index]==0){
&0euNHH;sL hCallWnd[index]=hWnd;
i>@"& HotKey[index]=cKey;
@!Q\|
< HotKeyMask[index]=cMask;
ZN(@M@} bAdded=TRUE;
I~7eu&QZ KeyCount++;
B_|jDH#RyJ break;
irzWk3@: }
o!|TCwt }
,"4 return bAdded;
QgW4jIbx }
q,_ 1?A) 7j\jOklV BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
N>+L?C {
}G[Qm2k BOOL bRemoved=FALSE;
0D48L5kH#' for(int index=0;index<MAX_KEY;index++){
-8, lXrH if(hCallWnd[index]==hWnd){
8E\6RjM if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
2sXX0kq~V hCallWnd[index]=NULL;
`n~bDG> HotKey[index]=0;
ngQ] HotKeyMask[index]=0;
!4!Y~7sI"\ bRemoved=TRUE;
\Y}nehxG@ KeyCount--;
/g]m,Y{OI break;
o_ SR }
qi-!iT(fe }
fk:oCPo }
Q::6|B,G return bRemoved;
}\)O1 }
]!04L}hy|P i.*Utm`1"e void VerifyWindow()
qUF}rlS=r {
iKuSk~ for(int i=0;i<MAX_KEY;i++){
bZ*J]1y(. if(hCallWnd
!=NULL){ X{bqG]j
if(!IsWindow(hCallWnd)){ uE{nnNZy
hCallWnd=NULL; vOYG&)Jm
HotKey=0; B*j
AD2
HotKeyMask=0; 2x&mJ}o#k
KeyCount--; <