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:
|<%!9Z
{]vD@)k 一、实现方法
>1y6DC ?ukw6T 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:
?Ua,ba* Tc2.ciU #pragma data_seg("shareddata")
VYyija: HHOOK hHook =NULL; //钩子句柄
W,q @ww u UINT nHookCount =0; //挂接的程序数目
t=_^$M,yr static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
lQA5HzC\ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
50UdY9E_v} static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
#6sz@X fV static int KeyCount =0;
@Z)|_ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
\l+v,ELX= #pragma data_seg()
$ /VQsb %Bq~b$ 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。
Bx\&7|,x V0ze7tSG[f 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:
r8k (L{W $KHm5*;nd BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
qsj{0 Go cKey,UCHAR cMask)
qTO6I5u {
xm'9n? BOOL bAdded=FALSE;
.Po"qoGy for(int index=0;index<MAX_KEY;index++){
_vQ52H, if(hCallWnd[index]==0){
j;x()iZ< hCallWnd[index]=hWnd;
ez4!5&TzRm HotKey[index]=cKey;
L"_XWno HotKeyMask[index]=cMask;
J0G@]H bAdded=TRUE;
A|A~$v("R KeyCount++;
z^Q'GBoBA break;
bMH~vR }
y@P%t9l }
?vXgHDs^T return bAdded;
5=>1>HYM }
9>}&dQ8 //删除热键
WhPP4 # BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
'H1~Zhv {
`y8pwWo-o BOOL bRemoved=FALSE;
MqmQ52HR for(int index=0;index<MAX_KEY;index++){
Z~'t'.=z if(hCallWnd[index]==hWnd){
t;O) if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
56.!L hCallWnd[index]=NULL;
0.GFg${v` HotKey[index]=0;
z2=bbm: HotKeyMask[index]=0;
V>6klA}o bRemoved=TRUE;
F^ q{[Z KeyCount--;
4vhf!!1 break;
L3&Ys3-h }
)XI[hVUA }
*dBy<dIy }
3bEcKA_z( return bRemoved;
y]9R#\P/ }
\i.]-k dab]>% M ]>3Y~KH( DLL中的钩子函数如下:
w,{h9f 6jE.X LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
&OR(]Wt0 {
;$p !dI\-Q BOOL bProcessed=FALSE;
43=v2P0=Tj if(HC_ACTION==nCode)
!pU$'1D {
0cG'37[ if((lParam&0xc0000000)==0xc0000000){// 有键松开
bWPsfUn# switch(wParam)
z4u.bU {
]HKt7 %, case VK_MENU:
jP@ @<dt MaskBits&=~ALTBIT;
{QG.> lB break;
a`O'ZY case VK_CONTROL:
o|$D|E MaskBits&=~CTRLBIT;
Q3@ zUjq_Q break;
A l[ZU case VK_SHIFT:
wO??"${OH MaskBits&=~SHIFTBIT;
r"H::A break;
Ds1h18 default: //judge the key and send message
*PmZqe break;
{kpad(E }
I{Du/"r# for(int index=0;index<MAX_KEY;index++){
n,I3\l9 if(hCallWnd[index]==NULL)
9>RkFV continue;
$b8[/], if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
emSq{A {
Kda'N$|` SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
mc{z bProcessed=TRUE;
K3&xe( }
x}G:n[B7_V }
Hv6h7- }
osC?2. else if((lParam&0xc000ffff)==1){ //有键按下
.7iRV switch(wParam)
i_qY=*a?y {
v^"\e&XL case VK_MENU:
E@VQxB7+ MaskBits|=ALTBIT;
/t5)& break;
J[/WBVFDf case VK_CONTROL:
OB>Hiy
MaskBits|=CTRLBIT;
z} fpV T break;
AD?zBg Zu case VK_SHIFT:
41
F;X{Br MaskBits|=SHIFTBIT;
N8A)lYT]_u break;
.?}M(mL default: //judge the key and send message
c*KE3: break;
~IhAO}1 }
?v^NimcZ for(int index=0;index<MAX_KEY;index++){
M/ S~"iD if(hCallWnd[index]==NULL)
<q63?Ms' continue;
Vl.,e1)6 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
:Cq73:1\B {
NuZ2,<~9 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Yf0 KG bProcessed=TRUE;
}[+uHR6L }
Gxr\a2Z&r% }
-wU]L5uP }
:EX>Y<`] if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
fWHvVyQ. for(int index=0;index<MAX_KEY;index++){
17hoX4T if(hCallWnd[index]==NULL)
ZTmy} @l continue;
s'HsLe0| if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
ljFq ;!I5 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
d/_D|ivZ= //lParam的意义可看MSDN中WM_KEYDOWN部分
ki1(b]rf }
}*fBHzNN }
'9\cIni0 }
v9(5HY return CallNextHookEx( hHook, nCode, wParam, lParam );
\Vc[/Qp7Bb }
rr#nBhh8
Pps$=` 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
"i&)+dr- B{Q}^Mcxy BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
<rC%$tr BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
PMjNc_)) U[C>Aoze 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:
5|*{~O| d4o
^+\ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
2A_1 E\ {
MQ,K%_m8 if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Hq.rG-,p {
eV7;#w<] //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
Vr2A7kq SaveBmp();
gP_N|LuF" return FALSE;
: (UK'i }
>u= …… //其它处理及默认处理
"FHJ_$! }
C?qRZB+W# xG!~TQ ^ ` LqNG 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
h<9vm[ . 7FH(C`uKi 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
_k:8ib2TQ }s,NM%oI 二、编程步骤
8}n<3_ 0zW*JJxV 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
-YNpHd/;, FjCGD4x1N 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
rLTBBvV k>&cHCS`* 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
=.`\V] o z*;q] 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
RV~t%Sw^ m6R/, 5、 添加代码,编译运行程序。
?/|Xie E/cV59 三、程序代码
@=kgK[t
9 ky2]%cw ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
~'M<S=W #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
21TR_0g&< #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
u
X,n[u #if _MSC_VER > 1000
4t*%( #pragma once
gC}}8( k #endif // _MSC_VER > 1000
?]><#[?'L #ifndef __AFXWIN_H__
UJO3Yn #error include 'stdafx.h' before including this file for PCH
BX/3{5Y>{ #endif
,Zmjw@w #include "resource.h" // main symbols
luP;P& class CHookApp : public CWinApp
uV:R3#^ {
IiE6i43 public:
T)P)B6q CHookApp();
Gz&} OO // Overrides
tW/k // ClassWizard generated virtual function overrides
EE9w^.3a //{{AFX_VIRTUAL(CHookApp)
V$ZclV2:Ih public:
N.*)-O
virtual BOOL InitInstance();
>XtfT' virtual int ExitInstance();
5 `1 //}}AFX_VIRTUAL
gnJ8tuS //{{AFX_MSG(CHookApp)
a0NiVF-m% // NOTE - the ClassWizard will add and remove member functions here.
jG>W+lq // DO NOT EDIT what you see in these blocks of generated code !
Zn9tG:V //}}AFX_MSG
8-#kY}d. DECLARE_MESSAGE_MAP()
m>=DJ{KQ };
SKC;@? LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
DS?.'"n[u BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Pn!~U] A$% BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
:#:|:q.] BOOL InitHotkey();
MpOU>\ BOOL UnInit();
hs7!S+[.$$ #endif
N
sdpE?V }y6)d. //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
@43psq1 #include "stdafx.h"
<,CrE5Pl #include "hook.h"
N3"Jo uP #include <windowsx.h>
<0d2{RQ; #ifdef _DEBUG
L-+g` #define new DEBUG_NEW
a``|sn9 #undef THIS_FILE
m-t:'B static char THIS_FILE[] = __FILE__;
)Qb,zS6 #endif
SIp)& #define MAX_KEY 100
#*bmwb*i #define CTRLBIT 0x04
VcKB:(:[ #define ALTBIT 0x02
yzN[%/ #define SHIFTBIT 0x01
SfS3}Tn[ #pragma data_seg("shareddata")
|gE1P/%k HHOOK hHook =NULL;
+W4}&S UINT nHookCount =0;
OZ\6qMH3e static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
",,# q static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Mj;V.Y static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
H,} &=SCk static int KeyCount =0;
-,bnj^L static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
uw \@~ ,d #pragma data_seg()
%u!=<yn' HINSTANCE hins;
2 .3_FXSt void VerifyWindow();
[6a-d>e{ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
l!*_[r //{{AFX_MSG_MAP(CHookApp)
l~E~! MR // NOTE - the ClassWizard will add and remove mapping macros here.
Ef] Hpjvp // DO NOT EDIT what you see in these blocks of generated code!
vH+g*A0S< //}}AFX_MSG_MAP
tA#Pc6zBuC END_MESSAGE_MAP()
:|;@FkQ [v~,|N>w CHookApp::CHookApp()
coAXYn {
5{'hsC // TODO: add construction code here,
lp}S'^ y // Place all significant initialization in InitInstance
#,tT`{u1q }
N,TV?Q5l7 R!dC20IMvH CHookApp theApp;
,4'gj0 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
H*0Y_H= {
9rEBq& BOOL bProcessed=FALSE;
3y)\dln if(HC_ACTION==nCode)
2j+w5KvU {
~xd?y*gk; if((lParam&0xc0000000)==0xc0000000){// Key up
9[/0 switch(wParam)
k|-\[Yl . {
s70Z&3A case VK_MENU:
wsmgkg MaskBits&=~ALTBIT;
+Kk1[fh-
break;
8n3]AOc'~- case VK_CONTROL:
poBeEpbs MaskBits&=~CTRLBIT;
T >8P1p@A, break;
iTHwH{! case VK_SHIFT:
-,")GA+[7 MaskBits&=~SHIFTBIT;
! VR&HEru break;
D1rVgM default: //judge the key and send message
`/sNX<mp break;
&D3]O9a0; }
cUq]PC$| for(int index=0;index<MAX_KEY;index++){
P3"R2- if(hCallWnd[index]==NULL)
*
BM|luYL continue;
Qxz[ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
h
/ {
_r-LX" SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
w*`:v$ bProcessed=TRUE;
z_>~=Mm }
g`pq*D }
mn@1c4y }
ZxvH1qx8 else if((lParam&0xc000ffff)==1){ //Key down
es7;eH*O9 switch(wParam)
8$NVVw]2, {
9d"*Z%!j case VK_MENU:
5e7Y M@ng MaskBits|=ALTBIT;
ox&5}&\ break;
3%*igpj\) case VK_CONTROL:
z 3aGK MaskBits|=CTRLBIT;
%"`p&aE: break;
jt}Re, case VK_SHIFT:
7.29' MaskBits|=SHIFTBIT;
FQ>$Ps*a[ break;
]ogifnwv default: //judge the key and send message
t/[lA=0 )2 break;
yv-R<c!' }
ebze_: for(int index=0;index<MAX_KEY;index++)
J2qsZ {
( 1z"=NCp if(hCallWnd[index]==NULL)
O1v)*&NAI continue;
ExG(*[l if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
hJM&rM7 {
L62'Amml SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
IRbyW?/Xv bProcessed=TRUE;
GDLi?3q }
Gj?Zbl < }
=n,;S W }
llZU: bs if(!bProcessed){
{($bzT7c for(int index=0;index<MAX_KEY;index++){
{L;sF=d if(hCallWnd[index]==NULL)
%*
0GEfl/ continue;
-H%v6E%yh if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Kxr{Nx SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
w Q[|D2; }
g!^N#o }
~IZ-:?+S^ }
I<2`wL= return CallNextHookEx( hHook, nCode, wParam, lParam );
?J2{6,}O*. }
Xy(QK2| Onx6Fy]L BOOL InitHotkey()
3#t9pI4 {
IRg2\Hq if(hHook!=NULL){
/!ElAL
nHookCount++;
>7BP}5`.; return TRUE;
~) ;4O8~. }
"]"0d[d else
C@Wzg hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
I7vP*YE 7F if(hHook!=NULL)
N[
=I nHookCount++;
JA4Zg*7I return (hHook!=NULL);
i$y=tJehi }
bkJ bnW= BOOL UnInit()
=OK#5r[UV {
k5< n:dS if(nHookCount>1){
_YX% M|# nHookCount--;
04U|Frc return TRUE;
QjLU@?& }
Z0&^(Fb BOOL unhooked = UnhookWindowsHookEx(hHook);
Vs5 &X+k if(unhooked==TRUE){
[6TI_U~ nHookCount=0;
3X(^`lAf) hHook=NULL;
ZSNbf|ldiE }
Vu(NP\Wm return unhooked;
3.YH7rN
}
| +;ZC y $+PioSq BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Xt O..{qU {
SGl|{+(A BOOL bAdded=FALSE;
U)kyq for(int index=0;index<MAX_KEY;index++){
mH,s!6j?Vp if(hCallWnd[index]==0){
])?dqgwa hCallWnd[index]=hWnd;
B<s+I# HotKey[index]=cKey;
Hs)] HotKeyMask[index]=cMask;
cPtDIc, bAdded=TRUE;
F,_cci`p KeyCount++;
),{3LIr break;
*wJ$U }
(~G*'/) }
@zS/J,:v} return bAdded;
W\[E }
q tOuA OyDoktz$) BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
=-!jm? st* {
q5g_5^csM{ BOOL bRemoved=FALSE;
HZ<#H3_ix for(int index=0;index<MAX_KEY;index++){
il>+jVr if(hCallWnd[index]==hWnd){
:(enaHn#~ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
.U(6])%;@ hCallWnd[index]=NULL;
iY>xx~V HotKey[index]=0;
#4|RaI|. HotKeyMask[index]=0;
9y\nO)\Tv bRemoved=TRUE;
w8D8\`i!" KeyCount--;
_LF'0s* break;
pXNhU88 }
V.3#O^S }
ybJa: }
}|h-=T ' return bRemoved;
I&|8
qx# }
fp||<B RPa]VL1W void VerifyWindow()
M}jl\{ {
_$*-?*V& for(int i=0;i<MAX_KEY;i++){
'tTlBf7# if(hCallWnd
!=NULL){ Db2#QQ
if(!IsWindow(hCallWnd)){ ?Ho$fGz
hCallWnd=NULL; fXevr `
HotKey=0; h`fZ8|yw
HotKeyMask=0; "Io-%Su+
KeyCount--; 3Dc^lfn
} ~@@t-QY
} F@/syX;bb5
} TJ>YJD
} kk126?V]_
e77s?WxbK
BOOL CHookApp::InitInstance() W9cvxsox
{ Nj6Np^@sH
AFX_MANAGE_STATE(AfxGetStaticModuleState()); p,WBF
hins=AfxGetInstanceHandle(); L,_U co
InitHotkey(); -C^qN7Bz
return CWinApp::InitInstance(); .~'q
yD2V
} Ge$&