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:
a9NIK/9
m"!Q5[ 一、实现方法
h.q9p! EVP{7}K1 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:
7[I +1 Z"$iB-] #pragma data_seg("shareddata")
zI4d|P HHOOK hHook =NULL; //钩子句柄
n;wViw UINT nHookCount =0; //挂接的程序数目
[}yPy))A static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
`\GRY @cg static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
<<R2
X1 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
#4<=Ira5 static int KeyCount =0;
E;wT4 T= static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
=\G`g# #pragma data_seg()
kPoz&e_@ &4ndi=.#rg 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}=_"IkZ Gn<0Fy2 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:
r+k&W 6|IJwP^Q_ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
-ijzo%&qA cKey,UCHAR cMask)
m^
Epw4eg {
QAAuFZs BOOL bAdded=FALSE;
X ]W)D
S for(int index=0;index<MAX_KEY;index++){
_>ZC;+c? if(hCallWnd[index]==0){
;A4j_8\[ hCallWnd[index]=hWnd;
n.t5:SW HotKey[index]=cKey;
-*Tf.c HotKeyMask[index]=cMask;
(V1;`sI8 bAdded=TRUE;
cQ'x]u_ KeyCount++;
[ r break;
-}PE(c1%?q }
:W6'G@ p }
h?v8b+:0 return bAdded;
<B>hvuCoH }
QUaV;6
4 //删除热键
Pm%5c\ef BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
&*Xrh7K2e {
v(GnG BOOL bRemoved=FALSE;
%|ClYr for(int index=0;index<MAX_KEY;index++){
Ghc
U~ if(hCallWnd[index]==hWnd){
(>E/C^Tc% if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
(EvYrm4 hCallWnd[index]=NULL;
:J_UXtx HotKey[index]=0;
7VG*Wu HotKeyMask[index]=0;
M$Bb,s bRemoved=TRUE;
A+GRTwj KeyCount--;
j}d):3! break;
63J3NwFt }
,A $IFE }
$_;rqTk]g }
~ @*q8lC return bRemoved;
S>r}3,]S }
lNf );!}SM SjpCf8Z( lZ)6d-vK DLL中的钩子函数如下:
,A7:zxnc.V 6P}?+ Gc LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
,9}JPv4Z {
A,t g268 BOOL bProcessed=FALSE;
J%|; if(HC_ACTION==nCode)
U,7 {
7w" !"W# if((lParam&0xc0000000)==0xc0000000){// 有键松开
H ?9Bo! switch(wParam)
5'+g[eNyBV {
8+dsTX`|S case VK_MENU:
YpXd5;' MaskBits&=~ALTBIT;
1Az&BZU[ break;
tmoCy0qWz case VK_CONTROL:
gY[G>D= MaskBits&=~CTRLBIT;
v;5-1 break;
qdwo 2u case VK_SHIFT:
p>\[[Md MaskBits&=~SHIFTBIT;
\p(0H6 break;
wBg?-ji3< default: //judge the key and send message
l3u+fE,;_ break;
4[gbRn' }
H7P}=YW". for(int index=0;index<MAX_KEY;index++){
,1B4FAR& if(hCallWnd[index]==NULL)
[ ^\{>m7 continue;
U&:-Vf~& if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
U';)]vB$ {
@HB=hN SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
B8T5?bl bProcessed=TRUE;
bv(+$YR }
/O$~)2^h }
.pe.K3G& }
t4d/%b~{:U else if((lParam&0xc000ffff)==1){ //有键按下
Ksh[I,+N\ switch(wParam)
"QS(4yw?jg {
;Ccp1a~+ case VK_MENU:
g#l!b%$ MaskBits|=ALTBIT;
YqXN|& break;
<_pLmYI case VK_CONTROL:
muF&t'k MaskBits|=CTRLBIT;
|5FEsts[
break;
c[X6!_ case VK_SHIFT:
yB*aG MaskBits|=SHIFTBIT;
G@~e:v) break;
Z ]ZUK default: //judge the key and send message
Q2]7|C break;
+/n]9l]#h }
rGt]YG#C for(int index=0;index<MAX_KEY;index++){
bT9:9LP if(hCallWnd[index]==NULL)
wRwx((eb continue;
Bqa_l| if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
WTt
/y\'6 {
ujX\^c SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
wod{C ! bProcessed=TRUE;
&.z-itiV }
GpO@1 C/ }
"FGgem%9 }
_h=h43'3 if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
s:,fXg25J for(int index=0;index<MAX_KEY;index++){
GO][`zZJ] if(hCallWnd[index]==NULL)
XM?c*,=fu continue;
p((. (fx if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
P??pWzb6HH SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
?H!&4o //lParam的意义可看MSDN中WM_KEYDOWN部分
n
Zx^ej\ }
T?u*ey~Tv }
/Z#AHfKF }
93w$ck},?G return CallNextHookEx( hHook, nCode, wParam, lParam );
e*Nm[*@UW }
MfLus40;n l{ fL~O 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
SFsT^f< sZqi)lo-s BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
G~*R6x2g BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
YWi Y[ CSm(yB{|pC 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
\4 t;{_ JL:B4f%}B LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
yFFNzw{ {
T%}x%9VO7 if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
+{)V%"{u: {
|?'
gT"# //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
vl%Pg!l SaveBmp();
7#*O|t/' return FALSE;
aM8z_j!!u }
/~<Przw …… //其它处理及默认处理
MD> E0p) }
waV4~BdL }zeKf/?' f'S 0" 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
#]} G{
P L`^v"W() 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
\jkDRR[ F
'HYWH0? 二、编程步骤
6ESS>I"su )OGO
wStz 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
"bO]AG GCcSI;w 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
J/ vcP EJaO"9
( 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
Gn10)Uf8X A#79$[>w 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;
N *n?hN aMJ9U)wnK 5、 添加代码,编译运行程序。
bV@5B#] 2R 2fUz}w ( 三、程序代码
oX/#Mct{s ju"j?2+F ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
\WVY@eB #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
! -gOqo #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
ux7g%Q^" #if _MSC_VER > 1000
sD<8-n #pragma once
}
/Iw]!lK2 #endif // _MSC_VER > 1000
&gm/@_ #ifndef __AFXWIN_H__
o`ODz[04 #error include 'stdafx.h' before including this file for PCH
bqR0./V #endif
y=}a55:qE #include "resource.h" // main symbols
mO\=#Q> class CHookApp : public CWinApp
a>nV!b\n5 {
9>5]y}.{ public:
E|B1h!!\c CHookApp();
'BEM:1) // Overrides
YjG:ECj} // ClassWizard generated virtual function overrides
T=cb:PD{% //{{AFX_VIRTUAL(CHookApp)
nQ'AB~ Do public:
!un_JZD virtual BOOL InitInstance();
pQ+4++7ID virtual int ExitInstance();
j%*<W> O //}}AFX_VIRTUAL
|:`gjl_Nf //{{AFX_MSG(CHookApp)
RAEiIf!3 // NOTE - the ClassWizard will add and remove member functions here.
_P]k6z+ // DO NOT EDIT what you see in these blocks of generated code !
>Gxu8,_; //}}AFX_MSG
@/?$ ZX/e[ DECLARE_MESSAGE_MAP()
opxPK=kJ };
Bk1gE(( LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
%5bN@XD BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
HmEU;UbO- BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
|<7nf7 5c} BOOL InitHotkey();
zhde1JE BOOL UnInit();
r\{; ~V #endif
&nF7CCF C
F< //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
d4-cZw}+ #include "stdafx.h"
.aR$ou,7 #include "hook.h"
<H!;/p/S #include <windowsx.h>
B3Esfk #ifdef _DEBUG
P1QGfp0-J #define new DEBUG_NEW
UBy:W^\g #undef THIS_FILE
8c'E static char THIS_FILE[] = __FILE__;
SbpO<8}8 #endif
Ibl==Irk #define MAX_KEY 100
j6$_U@)%O #define CTRLBIT 0x04
!Lj+&D|z #define ALTBIT 0x02
[k6 5i #define SHIFTBIT 0x01
})r[qsv #pragma data_seg("shareddata")
='r4zz HHOOK hHook =NULL;
utwqP~ UINT nHookCount =0;
9Fxz9_ i static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
NvlG@^&S static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
!.k static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
y3C$%yv0 static int KeyCount =0;
[mk!]r static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
0IjQqI #pragma data_seg()
"Mmvf'N HINSTANCE hins;
/!0{9F< void VerifyWindow();
jCbxI^3A BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
:j,e0#+sA //{{AFX_MSG_MAP(CHookApp)
t%<d}QuHW // NOTE - the ClassWizard will add and remove mapping macros here.
zc-.W2"Hu // DO NOT EDIT what you see in these blocks of generated code!
J;BG/VI1 //}}AFX_MSG_MAP
+hS}msu' END_MESSAGE_MAP()
:ITz\m <)(STo CHookApp::CHookApp()
xlaBOK a% {
wXsA-H/` // TODO: add construction code here,
QFf lx // Place all significant initialization in InitInstance
dPRGL
hWF }
e[8p /hId "^ cn9AG{ CHookApp theApp;
j^~WAWbFh LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
%@jv\J
{
Iih~rWJ BOOL bProcessed=FALSE;
~8EG0F;t if(HC_ACTION==nCode)
Lw.N3!e[ {
'4qi^$|\ if((lParam&0xc0000000)==0xc0000000){// Key up
~?{@0,$ switch(wParam)
dKyX70Zy9 {
e]{X62] case VK_MENU:
aKC3T- MaskBits&=~ALTBIT;
hzc2 c.gcF break;
S\jN:o#b case VK_CONTROL:
scUWI" MaskBits&=~CTRLBIT;
=X2EF break;
"U& case VK_SHIFT:
UvOB`Vj MaskBits&=~SHIFTBIT;
x_\e&"x break;
@cF
aYI default: //judge the key and send message
'?k*wEu break;
B9^@] }
Jj'~\j for(int index=0;index<MAX_KEY;index++){
/Et:',D if(hCallWnd[index]==NULL)
#3u;Ox continue;
o^},L? if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
X Jy]d/ {
_A\c 6# SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
}T+pd#> bProcessed=TRUE;
7@Qz }
S-:l
60. }
z6R<*$4 }
|S:St HZm else if((lParam&0xc000ffff)==1){ //Key down
h^bbU. switch(wParam)
kf$0}T` {
*, o)` case VK_MENU:
J%_
:A" MaskBits|=ALTBIT;
'on, YEp break;
@&d/}Mx"t case VK_CONTROL:
Jh[fFg] MaskBits|=CTRLBIT;
yHhBUpIo break;
|k+Y >I& case VK_SHIFT:
y4Plm. MaskBits|=SHIFTBIT;
-q\1Tlc]3 break;
BaTE59W default: //judge the key and send message
NQ%lwE~ break;
e ?H`p"l }
w.Ft-RXA W for(int index=0;index<MAX_KEY;index++)
aC$hg+U$G {
.t0Q>:}&b if(hCallWnd[index]==NULL)
ueYZM<], continue;
KaHjL&! if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Uw][ U {
Ohnd:8E SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
T.aY{Y bProcessed=TRUE;
h 5ST`jZ }
aBT|Q@Y. }
\=4[v-3H }
p}}o#a~V), if(!bProcessed){
icHc!m? for(int index=0;index<MAX_KEY;index++){
4RNB\D if(hCallWnd[index]==NULL)
Hc4]2pf continue;
cyG3le& +G if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
{v56k8uZ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
<`a!%_LC
[ }
Bi)1* }
Fmk,
"qs }
hIC$4lR~ return CallNextHookEx( hHook, nCode, wParam, lParam );
X5527`?e }
*^Wx=#w$V 2RidI&?c< BOOL InitHotkey()
-}{c;pT {
>ZuWsA0q if(hHook!=NULL){
e&E""ye nHookCount++;
n_hV; return TRUE;
u-At k-2M }
X61]N^y else
%X
O97 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
.T/\5_Bx if(hHook!=NULL)
vVmoV0kGt nHookCount++;
=zt@*o{F return (hHook!=NULL);
)avli@W-3j }
InMF$pw BOOL UnInit()
+hRAU@RA {
*obBo6!zM if(nHookCount>1){
TP[<u-@G nHookCount--;
!iA0u return TRUE;
Q\Fgc ;.U }
\;}F6g BOOL unhooked = UnhookWindowsHookEx(hHook);
)&<BQIv9/ if(unhooked==TRUE){
me#VCkr# nHookCount=0;
KZ
pqbI Z hHook=NULL;
Uoh!1_oV }
kb]PWOz return unhooked;
`[w:l[i }
A$Mmnu% 2}[)y\`t3 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
l_y:IY$" {
(qnzz!s BOOL bAdded=FALSE;
t0d1??G for(int index=0;index<MAX_KEY;index++){
lW1Al>dW< if(hCallWnd[index]==0){
Mk7,:S hCallWnd[index]=hWnd;
|[;9$Vn HotKey[index]=cKey;
+HQX]t:Y
HotKeyMask[index]=cMask;
lO9ML-8C1 bAdded=TRUE;
5\V>Sj(
KeyCount++;
f+j\,LJ break;
Dx/BxqG6}_ }
(\>3FwFHW| }
(V)nHF*<> return bAdded;
/\hybx' }
r*fZS$e Q}2aBU.f BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
%Iw6oG {
<<W{nSm# BOOL bRemoved=FALSE;
D$d8u=S for(int index=0;index<MAX_KEY;index++){
+6-c<m| if(hCallWnd[index]==hWnd){
Fx*iAH\e if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
d:.S]OI0 hCallWnd[index]=NULL;
x}$SB%9/ HotKey[index]=0;
Ly0^ L-~| HotKeyMask[index]=0;
) RS*MEgA bRemoved=TRUE;
'z8?_{$ KeyCount--;
w
xKlBx7 break;
Jw)Uk<