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:
;h/Y9uYn
8b6:n1<fn 一、实现方法
Pvbw>k; r)U9u 0 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:
pxDZ}4mOh &(Xp_3PO #pragma data_seg("shareddata")
\Cx3^
iX HHOOK hHook =NULL; //钩子句柄
->8n.!F} UINT nHookCount =0; //挂接的程序数目
{a%T <WW static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
&S3szhe static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
@H7dQ,% static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
`I6)e{5t static int KeyCount =0;
2eyvY|:Q> static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
jWP(7}U #pragma data_seg()
G@,qO#5& Lc<Gny^ 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。
mUnnk`v 2Q1* Xq{ 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:
&^&k]JBaV <@;e N& BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
jUBlIVl] cKey,UCHAR cMask)
J
)@x:,o {
~POe0!} BOOL bAdded=FALSE;
w5qhKu!1 for(int index=0;index<MAX_KEY;index++){
v[F_r if(hCallWnd[index]==0){
{(xNC#
hCallWnd[index]=hWnd;
Ai#W.
n HotKey[index]=cKey;
#-e3m/> HotKeyMask[index]=cMask;
8&`s wu& bAdded=TRUE;
xo^_;(; KeyCount++;
(Ca\$p7/ break;
T3M 4r| }
QI`Z[caF }
XUW~8P return bAdded;
n6|}^O7 }
r}*2~;:pW //删除热键
$R7d*\(G BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Z)6bqU<LQE {
$Fd9iJ!k BOOL bRemoved=FALSE;
;h for(int index=0;index<MAX_KEY;index++){
.bL{fBTT~ if(hCallWnd[index]==hWnd){
LR9dQ=fHS if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
T(ponLh hCallWnd[index]=NULL;
wond>m
3 HotKey[index]=0;
ce+\D'q[ HotKeyMask[index]=0;
iW)FjDTP bRemoved=TRUE;
vcV=9q8P1 KeyCount--;
Mc76) break;
xwK<f6H!y }
Y*J`Wf(w }
d/R:-{J)c }
mYa0_P%^ return bRemoved;
We9C9)0 }
mE^6Zu <7^_M*F9 (sr_&7A DLL中的钩子函数如下:
/l:3*u PPE:@!u< LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
,JVD ;u {
}\l5|Ft[! BOOL bProcessed=FALSE;
QD"V=}'? if(HC_ACTION==nCode)
Q@]#fW\Y {
M%9PVePOe if((lParam&0xc0000000)==0xc0000000){// 有键松开
k}jH switch(wParam)
~!)_3o {
: 2?i9F0_ case VK_MENU:
/6L\`\g MaskBits&=~ALTBIT;
;O{AYF?,N break;
.bnoK case VK_CONTROL:
CXA)Zl5# MaskBits&=~CTRLBIT;
fyQAQZT break;
=>ph\ case VK_SHIFT:
-Frx {3 MaskBits&=~SHIFTBIT;
G]q6Ika break;
~>#=$#V default: //judge the key and send message
:Q&8DC#] break;
J0|/g2%0 }
q/%f2U%4: for(int index=0;index<MAX_KEY;index++){
6S`eN\s if(hCallWnd[index]==NULL)
9^Wj< continue;
CE*@CkC0z if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
M^g"U` {
%&z9^}Vd[ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
,ci
tzh bProcessed=TRUE;
JrCm >0g }
Fz>J7(Y.j }
dc%+f }
Is?0q@ else if((lParam&0xc000ffff)==1){ //有键按下
6ng
.
= switch(wParam)
qIO)Z {
ULQ*cW&;? case VK_MENU:
2}509X(* MaskBits|=ALTBIT;
jF-z? break;
5QMu=/ case VK_CONTROL:
dwAju:-H MaskBits|=CTRLBIT;
i:{a-Bd break;
Y.Gr(]tk case VK_SHIFT:
tr/S*0$ MaskBits|=SHIFTBIT;
KY4|C05, break;
atW;S99# default: //judge the key and send message
J. {[> break;
pw&l.t6. }
v*]|1q%/ for(int index=0;index<MAX_KEY;index++){
5=Gq
d4&* if(hCallWnd[index]==NULL)
=@{H7z(p& continue;
W13$-hf9 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
hQl3F6-ud {
ZJ+q<n_4} SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
G%rK{h bProcessed=TRUE;
gpE5ua& }
ot-!_w< }
$IB@|n }
"R):B~8|H{ if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
O!/J2SfuDH for(int index=0;index<MAX_KEY;index++){
bO^%#<7 if(hCallWnd[index]==NULL)
=_L"x~0I- continue;
1Qf5H!5vx if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Mgf80r= SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
&)\0mpLK9 //lParam的意义可看MSDN中WM_KEYDOWN部分
JJ7-$h'0q }
QD /| zi }
Y@#~8\_ }
eMWY[f3 return CallNextHookEx( hHook, nCode, wParam, lParam );
m6'YFpf)V }
"L{;=-e oPre$YT}h 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:
$@Hw DRP p?8>9 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
:
<m0
GG BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
AO/J:` i3#]_ p{ 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:
yUNl)E vxbO>c LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
V-J\!CHX {
B.{0,bW?
if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
C"hc.A&4 {
gKS^-X{x
//lParam表示是按下还是松开,如果有多个热键,由wParam来区分
tTQ>pg1{qh SaveBmp();
PjRKYa_U return FALSE;
3tOnALv }
QE-t v00 …… //其它处理及默认处理
l2n>Wce9 }
I>ofSaN 8kO|t!?:U b4,yLVi<T 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。
tEf-BV;\y 2R|2yAh 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。
0/-[k R,6?1Z:J 二、编程步骤
EeL~`$f !~>u\h 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";
:Wb+&|dU &=_YL 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
)[%#HT 9)H~I/9Y 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;
: @YZ6?hf i,b>&V/Y$ 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;
#(XP=PUj iCz,|;w% 5、 添加代码,编译运行程序。
=o+t_.)N Lqwc:%Y:_ 三、程序代码
g($ y4~# N2q'$o ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
~-'nEA TE #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
aD%")eP%& #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
X0P<ifIv #if _MSC_VER > 1000
C]eb=rw$ #pragma once
P#76ehR]K #endif // _MSC_VER > 1000
shP,-Vs# #ifndef __AFXWIN_H__
#gi&pR'$ #error include 'stdafx.h' before including this file for PCH
W;Fcp #endif
=]etw #include "resource.h" // main symbols
J#'c+\B<2X class CHookApp : public CWinApp
CUY2eQJ{U {
%Ix^Xb0 public:
2/(gf[elX CHookApp();
tPFV6n
i // Overrides
L(AY)gB // ClassWizard generated virtual function overrides
y{"8VT) //{{AFX_VIRTUAL(CHookApp)
L88oh&M public:
lD 9'^J virtual BOOL InitInstance();
)UN@|IX virtual int ExitInstance();
DQ~+\ //}}AFX_VIRTUAL
UI hB //{{AFX_MSG(CHookApp)
cBc6*%ZD // NOTE - the ClassWizard will add and remove member functions here.
!k%Vw18 // DO NOT EDIT what you see in these blocks of generated code !
hM+nA::w //}}AFX_MSG
s)_sLt8? DECLARE_MESSAGE_MAP()
9SMM%(3, r };
u3ce\ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
><^A4s BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
tXPS@4F BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
i[WTp??Uv BOOL InitHotkey();
U4^dDj BOOL UnInit();
W\FKAvS #endif
WS2TOAya) a Se.]_ //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
vmW4a3 #include "stdafx.h"
d+"KXt5CV #include "hook.h"
hb^e2@i;Oq #include <windowsx.h>
@HaWd3 #ifdef _DEBUG
N[r@Y{ #define new DEBUG_NEW
ygT,I+7\ #undef THIS_FILE
/m9t2,KB static char THIS_FILE[] = __FILE__;
/C3=-Hp #endif
&/Tx@j^.C #define MAX_KEY 100
= `70]% #define CTRLBIT 0x04
.RoO6:T6 #define ALTBIT 0x02
Y@;bA=Du} #define SHIFTBIT 0x01
/kNr5s #pragma data_seg("shareddata")
aD0w82s]J HHOOK hHook =NULL;
Q7`zrCh UINT nHookCount =0;
.8fOc.h8h static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
Gz^g!N[ static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
0^{zq|%Q! static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
M!mTNIj8~ static int KeyCount =0;
A5
8i}G9 static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
z?FZu,h} #pragma data_seg()
`p'L3u5H- HINSTANCE hins;
'p Z~3q void VerifyWindow();
~hP[[? BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
<}.)kg${O //{{AFX_MSG_MAP(CHookApp)
dk;Ed // NOTE - the ClassWizard will add and remove mapping macros here.
AGOK%[[Ws // DO NOT EDIT what you see in these blocks of generated code!
)M^;6S //}}AFX_MSG_MAP
b]CJf8'u END_MESSAGE_MAP()
M`iJ6L &[JI L=m5 CHookApp::CHookApp()
P),%S9jP; {
NL2n\%n // TODO: add construction code here,
Zw"6-h4 // Place all significant initialization in InitInstance
M,y='*\M }
]FQ4v.7 E2%7 v CHookApp theApp;
H$\?D+xlf LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
hoSk {
s7T=/SC54 BOOL bProcessed=FALSE;
2yeq2v if(HC_ACTION==nCode)
!YAkHrF`[0 {
H${Ym BG if((lParam&0xc0000000)==0xc0000000){// Key up
O(WFjmHx switch(wParam)
_BcB@a {
OJkPlDym case VK_MENU:
f~W.i] MaskBits&=~ALTBIT;
(}]74Lc break;
"ZT=[&2 case VK_CONTROL:
v-OGY[|97 MaskBits&=~CTRLBIT;
$0cMrf@ break;
_%<7!|" case VK_SHIFT:
b*.)m MaskBits&=~SHIFTBIT;
PS \QbA
break;
TSE(Kt default: //judge the key and send message
>+1^X eeS break;
c WK@O> }
\U~ggg0h for(int index=0;index<MAX_KEY;index++){
VO++(G) if(hCallWnd[index]==NULL)
zA-?x1th& continue;
}qbz &%R if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
s?OGB} {
zA( 2+e 7 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
APK@Oq bProcessed=TRUE;
r+$ 0u~^ }
SHz& o[u }
eb.`Q+Gb }
{SK8Mdn else if((lParam&0xc000ffff)==1){ //Key down
kl2]#G( switch(wParam)
]l+2Ca:-[j {
/Tv<
l case VK_MENU:
oHeo]<Fbv MaskBits|=ALTBIT;
'fK_J}+P break;
hRc\&+#/ case VK_CONTROL:
kv `x MaskBits|=CTRLBIT;
r!Mr\ break;
Q9W*)gBvn case VK_SHIFT:
UP, 0`fh(y MaskBits|=SHIFTBIT;
T_YN^za(q break;
azOp53zR default: //judge the key and send message
Q5 ohaxjF break;
S5bk<8aPP }
KHF5Nt for(int index=0;index<MAX_KEY;index++)
<<n8 P5pXt {
F!a YK2 if(hCallWnd[index]==NULL)
9(u2jbA continue;
TD\QX2m if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Lg9ktRKK {
hkW"D<ii- SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
T
0^U
]C bProcessed=TRUE;
U0)(k}Q) }
Qy4AuMU2 }
Z/Mp=273 }
Za=<euc7 if(!bProcessed){
:Z1_;`>CT for(int index=0;index<MAX_KEY;index++){
yd>kJk^~/ if(hCallWnd[index]==NULL)
rZ0@GA continue;
XUMCz7&j if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Or6'5e?N SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
9';0vrFeM }
ts9N$?0:V }
*?\2Ohp }
_#N~$ return CallNextHookEx( hHook, nCode, wParam, lParam );
GI6 EZ}.MZ }
B_}=v$ bM;tQ38* BOOL InitHotkey()
~(hmiNa; {
})&0e:6 if(hHook!=NULL){
ixfkMM,W nHookCount++;
5|H?L@_9 return TRUE;
vz@QGgQ9~2 }
~Bu~?ZJmd else
X>*zA?: hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
G. <9K9K if(hHook!=NULL)
C'zMOR6c nHookCount++;
tx5@r; return (hHook!=NULL);
-U;s,>\) }
KZD&Ih(vC BOOL UnInit()
,[cWG)- {
E}"&?oY if(nHookCount>1){
%M'"%Yn@(y nHookCount--;
X}p4yR7' return TRUE;
BAzqdG }
lkw[Z}\ BOOL unhooked = UnhookWindowsHookEx(hHook);
L i< c if(unhooked==TRUE){
k$I[F<f nHookCount=0;
Dw.>4bA. hHook=NULL;
7a@V2cr@ }
,ew<T{PL return unhooked;
",~3&wx }
'# (lq 5
c ?$r+#'asd( BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
3&2,[G04 {
U][.ioc BOOL bAdded=FALSE;
V(w[`^I>~ for(int index=0;index<MAX_KEY;index++){
^P{'l^CVX if(hCallWnd[index]==0){
hXMC!~Th hCallWnd[index]=hWnd;
EaP#~x HotKey[index]=cKey;
+S3'ms HotKeyMask[index]=cMask;
%81tVhg bAdded=TRUE;
`_<AZ{&& KeyCount++;
qTffh{q V break;
dB_\,%vAd }
]FFU,me2 }
/Ee0S8!Z!1 return bAdded;
2<