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:
f$o^Xu
+~^S'6yB 一、实现方法
^PZ[;F40 1B~O!']N< 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
Bu{Kjv =_dM@ j #pragma data_seg("shareddata")
KZppQ0 HHOOK hHook =NULL; //钩子句柄
*-T.xo UINT nHookCount =0; //挂接的程序数目
F0:]@0>r static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
d &#_t@% static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
+0pI}a\ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
lMFR_g?r static int KeyCount =0;
cc[(w
#K static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
t?GH
V3V #pragma data_seg()
UM7@c7B? iq; |
i! 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
*)RmX$v3 VE )D4RL 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:
9-42A7g^C X0.H(p#s BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
1sqE/-v1_^ cKey,UCHAR cMask)
;I>nA6A {
WX&IQ@ BOOL bAdded=FALSE;
*g(d}C! for(int index=0;index<MAX_KEY;index++){
OIblBQ! if(hCallWnd[index]==0){
v)5;~.+% hCallWnd[index]=hWnd;
PIri|ZS HotKey[index]=cKey;
S<nF>JRJa HotKeyMask[index]=cMask;
rqamBm 5 bAdded=TRUE;
,h*gd^i KeyCount++;
7V"?o break;
+A3/^C0 }
M)bQvjj }
V! Wy[u return bAdded;
%ih\|jRt }
qOo4T@t3 //删除热键
)CFJXc: BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
W:r[o%B {
u[GZ~L BOOL bRemoved=FALSE;
E|@C:ghG for(int index=0;index<MAX_KEY;index++){
fd)8lK[KJ" if(hCallWnd[index]==hWnd){
{T4_Xn -I if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
OgF[= hCallWnd[index]=NULL;
fbq$:Q44 HotKey[index]=0;
xs"i_se HotKeyMask[index]=0;
'Ea3(OsuXn bRemoved=TRUE;
uMcI'= KeyCount--;
|;gx;qp4cN break;
J
n.7W5v }
>dAl *T }
g257jarkMF }
,P~e)<. return bRemoved;
`cGks }
"hyfo,r #
&v4c 7P{= Pv+ DLL中的钩子函数如下:
fQoAdw iJTG+gx LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
b<u\THy# {
n_QuuUB BOOL bProcessed=FALSE;
('z=/"(l if(HC_ACTION==nCode)
, cxqr3
o {
{Ydhplg{ if((lParam&0xc0000000)==0xc0000000){// 有键松开
~>:JwTy switch(wParam)
ZX_QnSNZ? {
a
,mgM&yD case VK_MENU:
KMhrw s{&B MaskBits&=~ALTBIT;
DI0& _, break;
SgU@`Pb case VK_CONTROL:
: /5+p>Ep} MaskBits&=~CTRLBIT;
?'V78N sA break;
st w@@GQ case VK_SHIFT:
Y9abRrK MaskBits&=~SHIFTBIT;
QytO0K5
break;
r]e{~v/ default: //judge the key and send message
BbB3#/g break;
IjhRSrCv }
2-F7tcya| for(int index=0;index<MAX_KEY;index++){
WyV4p if(hCallWnd[index]==NULL)
*JOK8[Qn continue;
(Q{JI~P if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
oIrc))j,$ {
kHK<~srB SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
#hBqgG:> bProcessed=TRUE;
cC8$ oCR? }
|6AR! }
/IirTmFK }
)QAYjW!Z else if((lParam&0xc000ffff)==1){ //有键按下
k7Nx#%xx switch(wParam)
XU'(^Y8Imz {
>Iij,J5i case VK_MENU:
H;=yR]E MaskBits|=ALTBIT;
8i6iynR break;
}%KQrlbHJl case VK_CONTROL:
Q}&'1J MaskBits|=CTRLBIT;
9^Xndo]y break;
aMqt2{f+ case VK_SHIFT:
!KV!Tkx h MaskBits|=SHIFTBIT;
6F^/k,(k4 break;
Pr>$m{
Z default: //judge the key and send message
%\it4 r3 break;
B~o3Z }
.3EEi3z6z for(int index=0;index<MAX_KEY;index++){
|mhKD#: if(hCallWnd[index]==NULL)
0+0Y$;< continue;
pll5m7[ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
@#wG)TA {
-Ua5anzB SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
]FR#ZvM>x bProcessed=TRUE;
!UzE&CirV }
py$Gy-I~[ }
`y'%dY}$n }
0Y`+L6&UX if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
|TJ gH<I for(int index=0;index<MAX_KEY;index++){
#8d#Jw if(hCallWnd[index]==NULL)
ufR|V-BWx continue;
OBF M70K if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
"4XjABJ4' SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
~&/Nl_# //lParam的意义可看MSDN中WM_KEYDOWN部分
Fmn_fW6 }
?r;F'%N= }
Vb 36R_u }
o5],c9R9b return CallNextHookEx( hHook, nCode, wParam, lParam );
dhLd2WSyH }
+46& Zb35 P'$2%P$8:~ 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
#~Kno@ ruhC:rg:/ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
qPu?rU{2 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
`~axOp9N B{#Fm6 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
CS%ut-K<5M ; 180ct4 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
uToi4]w"y {
k8Dk;N if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
} %3;j5 ;6 {
o<|u4r={s //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
8U#14U5rS SaveBmp();
NrcV%-+u% return FALSE;
1%@i4 }
0>Kgz!I …… //其它处理及默认处理
"<oR.f=0 }
w&U28"i> i39_( )X &~"N/o 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
>U:-U"rA? %i&am= 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
y] Q/(O jp-(n z\ 二、编程步骤
.Sm 8t$ x}C$/ 7^ 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";
* R&77 o7 T+V:vuK 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
98}l`J=i MNfc1I_# 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;
m=`V *{fZA;<R 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=PJVw/ 7CT446 5、 添加代码,编译运行程序。
*E@as _=w=!U&W 三、程序代码
c:DV8'fT =+e;BYD#! ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
ZA4sEVHW #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
BQMo*I>I #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
2 $Z4 >! #if _MSC_VER > 1000
,|O|gh$s #pragma once
Swv
=gu #endif // _MSC_VER > 1000
]:6IW: #ifndef __AFXWIN_H__
FOa2VP% #error include 'stdafx.h' before including this file for PCH
]{-ib:f~ #endif
CwF=@:*d #include "resource.h" // main symbols
t-FrF </0 class CHookApp : public CWinApp
l)Cg?9 {
mqQ//$Y
public:
r^d:Po CHookApp();
m]++
! // Overrides
cMUmJH // ClassWizard generated virtual function overrides
Mc|UD*Z //{{AFX_VIRTUAL(CHookApp)
&'5j! public:
5X`m.lhUc virtual BOOL InitInstance();
b<g9L4s virtual int ExitInstance();
;>p{|^X0D //}}AFX_VIRTUAL
Jpe\ //{{AFX_MSG(CHookApp)
{Cw>T-` // NOTE - the ClassWizard will add and remove member functions here.
e=6C0fr // DO NOT EDIT what you see in these blocks of generated code !
:EC[YAK+D //}}AFX_MSG
CIt@xi#I DECLARE_MESSAGE_MAP()
cj3P]2B# };
7baQ4QY?n LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
q-0(
Wx9| BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
yzCamm4~0 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
:jWQev"/ BOOL InitHotkey();
mVyF M -` BOOL UnInit();
!uHVg(} #endif
|P=-m-W *Q3q(rdrp //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
_K>YB>W}7 #include "stdafx.h"
(d5kD#.N #include "hook.h"
fH
5/ #include <windowsx.h>
6c#1Do(W+ #ifdef _DEBUG
~p/1
9/ #define new DEBUG_NEW
!vSj1w #undef THIS_FILE
9&KiG* . static char THIS_FILE[] = __FILE__;
_$qH\>se #endif
&q[`lIV, L #define MAX_KEY 100
G
Y ]bw #define CTRLBIT 0x04
"M:0lUy #define ALTBIT 0x02
(^Hpe5h& #define SHIFTBIT 0x01
r7:4|6E #pragma data_seg("shareddata")
8DJoQl9 HHOOK hHook =NULL;
4}HY= 0Um UINT nHookCount =0;
}W* q static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
/4-6V
d"8 static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
z)y{(gR static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
[Gb8o' static int KeyCount =0;
[[0u|`T/ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
lxD~[e #pragma data_seg()
w'D=K_h HINSTANCE hins;
Zut"P3d=J void VerifyWindow();
~Wj.
4b* BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
\ssqIRk //{{AFX_MSG_MAP(CHookApp)
b\Gw|?Rv // NOTE - the ClassWizard will add and remove mapping macros here.
?,x3*'-( // DO NOT EDIT what you see in these blocks of generated code!
nx'D&,VX //}}AFX_MSG_MAP
t=(CCq_N, END_MESSAGE_MAP()
0)-yLfTn Sy`7 })[ CHookApp::CHookApp()
3 At%TA: {
niJtgK:H^ // TODO: add construction code here,
<-m[0zgq // Place all significant initialization in InitInstance
UgZuEfEGve }
;V\l,
u jAb R[QR1% CHookApp theApp;
q*4=sf,> LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
pbePxOG {
3]g|Cwu BOOL bProcessed=FALSE;
0T7""^'& if(HC_ACTION==nCode)
x\R
8W8M {
T4x%dg if((lParam&0xc0000000)==0xc0000000){// Key up
$Q< >MB7 switch(wParam)
Ves
x$!F# {
0_faJjTbP; case VK_MENU:
V0!$k.Wk MaskBits&=~ALTBIT;
uMe]].04 break;
u'+;/8 case VK_CONTROL:
f&
>[$zh MaskBits&=~CTRLBIT;
a$ FO5%o break;
Gg=Y}S7: case VK_SHIFT:
&;Jg2f%. MaskBits&=~SHIFTBIT;
0'0GAh2 break;
U0X? ~ 1 default: //judge the key and send message
[GqQ6\ break;
ijR,% qg }
(^).$g5Hg for(int index=0;index<MAX_KEY;index++){
a8laPN if(hCallWnd[index]==NULL)
-3On^Wj] continue;
V*w~Sr% if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
zBTyRL
l {
$,9A?' SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
.8EaFEd bProcessed=TRUE;
SV0h'd(b }
U^.kp#x# }
2Ub!wee }
Xe7/ else if((lParam&0xc000ffff)==1){ //Key down
Gm2q`ki switch(wParam)
TcM;6h` {
%DR8M\d1~H case VK_MENU:
ic(`E v MaskBits|=ALTBIT;
hYS}PE break;
8\{1y:| case VK_CONTROL:
yO`HL'SMo MaskBits|=CTRLBIT;
{WoS&eL break;
6wY6*R case VK_SHIFT:
-\V!f6Q MaskBits|=SHIFTBIT;
51&K break;
tlJ@@v&= default: //judge the key and send message
VHihC]ks, break;
=AIeYUh }
\hr2#! for(int index=0;index<MAX_KEY;index++)
qPG>0
O {
A,;V|jv9 if(hCallWnd[index]==NULL)
/pS Y ~* continue;
Uop`) if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Ods/1 KW {
VW/ICX~"d SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
$]t3pAI[H0 bProcessed=TRUE;
vlS+UFH0 }
m#.N }
g`9`/ }
|s$w
i>7l if(!bProcessed){
82*nC!P3E for(int index=0;index<MAX_KEY;index++){
]5Mq^@mD' if(hCallWnd[index]==NULL)
X&14;lu%p continue;
JRYCM}C] if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
{\62c;. SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
g/f^|: }
p]E \!/ }
l1I\khS }
_(%;O:i return CallNextHookEx( hHook, nCode, wParam, lParam );
{GP#/5$= }
'`nf7b( x^]J^L45 BOOL InitHotkey()
ly~tB LH} {
;xxu , if(hHook!=NULL){
!/RL.`!> nHookCount++;
J,Rp&tavt: return TRUE;
~,O&A B }
Lsb` ,: else
(29BS(|! hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
thK4@C|X4 if(hHook!=NULL)
uoi~JF nHookCount++;
{&,MkWgG return (hHook!=NULL);
RoYwZX~ }
5|_El/G BOOL UnInit()
3EO:Uk5< {
&X&msEM if(nHookCount>1){
P?/Mrz nHookCount--;
%s*F~E return TRUE;
O3~7 }
4RyQ^vL BOOL unhooked = UnhookWindowsHookEx(hHook);
/k^!hI"4c if(unhooked==TRUE){
?w5>Z/V nHookCount=0;
y1Op Z hHook=NULL;
Q.i_?a }
]gjB%R[.m return unhooked;
AXT(D@sI= }
b;jr;I n}L
Jt BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
i)=dp!Bx^ {
zr@HYl BOOL bAdded=FALSE;
0f9*=c for(int index=0;index<MAX_KEY;index++){
g(QT"O!dY if(hCallWnd[index]==0){
dh K<5E hCallWnd[index]=hWnd;
P={8qln,X HotKey[index]=cKey;
/ei(Q'pc[ HotKeyMask[index]=cMask;
UiQF4Uc" bAdded=TRUE;
qW
2'?B3< KeyCount++;
n7VQi+i' break;
xua
E\*m }
'y%*W:O }
V)jF]u~g return bAdded;
w42=tN+B }
EZJ[+ -Q; =O??W8u BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
vM?jm!nd {
T
)!kJ;vc BOOL bRemoved=FALSE;
w^E$R for(int index=0;index<MAX_KEY;index++){
@&9 ,0x if(hCallWnd[index]==hWnd){
)QAS 7w#k if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
RN"Ur'+ hCallWnd[index]=NULL;
d^qTY?k. HotKey[index]=0;
Ef\&