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:
#3 }5cC8_
S&;T_^| 一、实现方法
tU-#pB>H %N?W]vbra
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:
'b?#4rq} %Q>~7P #pragma data_seg("shareddata")
Q>06dO~z8 HHOOK hHook =NULL; //钩子句柄
JI{OGr UINT nHookCount =0; //挂接的程序数目
1"~O"m sb static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
Q 37V! static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
ySPlyhGF static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
WOe{mwhhj static int KeyCount =0;
zz+M1n-;o static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
4w?]dDyc% #pragma data_seg()
@ ~0G$ UpE1PLZlB 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。
$;KQY7 ;%3thm7+ 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!Q
$GE?vl wh7i
G8jCz BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
YFC0KU cKey,UCHAR cMask)
]k3GFPw {
>F
LdI BOOL bAdded=FALSE;
5 O{Ip- for(int index=0;index<MAX_KEY;index++){
{ c6DT if(hCallWnd[index]==0){
troy^H hCallWnd[index]=hWnd;
f<$K.i HotKey[index]=cKey;
[1QkcR HotKeyMask[index]=cMask;
TA-(_jm bAdded=TRUE;
p:
Q%Lg_I KeyCount++;
TV[6+i*# break;
&)fhlp5 }
Sl+jduc }
;N> {1 return bAdded;
/S2p ``E+ }
~Q{[fy= //删除热键
!)l%EJngL BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
z_[3IAZ {
nEZ-h7lzl( BOOL bRemoved=FALSE;
q:D0$YY0 for(int index=0;index<MAX_KEY;index++){
o q'J*6r if(hCallWnd[index]==hWnd){
)U/@J+{{ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
fjz2m hCallWnd[index]=NULL;
m`1}O"<&i HotKey[index]=0;
r~Is,.zZ} HotKeyMask[index]=0;
<*~BG)b bRemoved=TRUE;
H*:r>Lm= KeyCount--;
-h^} jP8 break;
=4w^)'/ }
CoKj'jA }
B[U.CAUn }
#4|i@0n}D return bRemoved;
?@,f[ U- }
JE8p5WaR ^|:{,d#Y v2W"+QS}u DLL中的钩子函数如下:
Ej{eq^n %+j]vP LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
s].'@_~s {
,~=z_G`R BOOL bProcessed=FALSE;
9<0$mE^: if(HC_ACTION==nCode)
l#5k8+s {
\I o?ul}za if((lParam&0xc0000000)==0xc0000000){// 有键松开
Sv^'CpQ switch(wParam)
uq#h\p| {
bCac.x#jo case VK_MENU:
vY+_tpuEH MaskBits&=~ALTBIT;
QVZ6;/ break;
5k7(! case VK_CONTROL:
xhVq MaskBits&=~CTRLBIT;
JQvQm|\nc break;
NXG}0`QVT case VK_SHIFT:
Al-%j- j@- MaskBits&=~SHIFTBIT;
^VLUZ break;
hvv>UC/ default: //judge the key and send message
.of:#~ break;
] l qFht }
FO3eg"{N for(int index=0;index<MAX_KEY;index++){
BBuYO$p if(hCallWnd[index]==NULL)
#I{Yf(2Z continue;
tRrY)eElS if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
w
_6Y+ {
1{fwr1b SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
6w`}+3 bProcessed=TRUE;
(Q
p]0 }
;0_J7 }
1wNY}3 }
pl^"1Z=* else if((lParam&0xc000ffff)==1){ //有键按下
uD*s^ switch(wParam)
rsIPI69qJ. {
Le$u$ulS case VK_MENU:
KA*l6`( MaskBits|=ALTBIT;
3~1lVU: break;
'frL/[S case VK_CONTROL:
p/^\(/\]) MaskBits|=CTRLBIT;
'I01F:` break;
:
1f 5;]%N case VK_SHIFT:
V/wc[p
~ MaskBits|=SHIFTBIT;
r7BH{>- break;
$\J9F=<a default: //judge the key and send message
jX8 C2}j break;
,knI26Jh }
a.*j8T for(int index=0;index<MAX_KEY;index++){
$}"Wta if(hCallWnd[index]==NULL)
\oZUG continue;
QT&Ws+@
s{ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
ah$7
Oudj {
1#X=&N SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
:@807OYzy bProcessed=TRUE;
"jN-Yd,z }
`/j|Rb|eow }
`0WA!(W }
u:u 7|\q if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
GbrPtu2{@V for(int index=0;index<MAX_KEY;index++){
~9'4w-Sy if(hCallWnd[index]==NULL)
D"XQ!1B% continue;
?%fZvpn - if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
87 E3pe SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
3usA //lParam的意义可看MSDN中WM_KEYDOWN部分
z&J ow/ }
:W<,iqSCm }
WHj4#v( }
C-b% PgA return CallNextHookEx( hHook, nCode, wParam, lParam );
$j2)_(<A%Q }
.AI'L|FQ%c [^BUhm3a 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
N~<}\0 la{:RlW BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
JhXN8Bq33 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
]?^xc[ 6)2M/( 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
)tQ6rd' U.sPFt LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
T9v#Jb6 {
!U~#H_ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
j I@$h_n {
?RAR //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
+
d)~;I$ SaveBmp();
8q[WfD return FALSE;
zZ0V6T} }
Cspm\F …… //其它处理及默认处理
92ww[+RQ@ }
1?$!y 2_~XjwKE Pisr&"A 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。
J9t? ]9.,: Z/UVKJm>: 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。
YhK/pt43C ){|Lh( 二、编程步骤
UNLNY,P/!) 0g uc00IN 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";
v 5ddb) f<:SdtG5 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
w*kFtNBfU W_n.V" hN 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;
{%~Ec4r f]65iE?x 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;
]8nm9qmF< BU{V,|10a 5、 添加代码,编译运行程序。
.wn_e=lT tpzdYokh> 三、程序代码
!PTbR4s s-S"\zX\D ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
M\4;d # #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
BQ)43Rr> #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
4J|t} #if _MSC_VER > 1000
KKJ [ #pragma once
w[[@&T\` #endif // _MSC_VER > 1000
fx"+ZR #ifndef __AFXWIN_H__
#IA(*oM #error include 'stdafx.h' before including this file for PCH
RWcQT` #endif
r>@/XYK&\ #include "resource.h" // main symbols
O*CX@Ne
class CHookApp : public CWinApp
uKzz/Y{ {
\-id[zKb public:
T0)y5 CHookApp();
?
NK}q\$ // Overrides
K1nwv" // ClassWizard generated virtual function overrides
R@aT=\u+ //{{AFX_VIRTUAL(CHookApp)
9+|,aG s public:
yC$7XSr= virtual BOOL InitInstance();
-T6%3>h virtual int ExitInstance();
H
pfI //}}AFX_VIRTUAL
=W^L8!BE' //{{AFX_MSG(CHookApp)
Z6ex<[`I // NOTE - the ClassWizard will add and remove member functions here.
?kefRev<#h // DO NOT EDIT what you see in these blocks of generated code !
R6.#gb8^oS //}}AFX_MSG
Q'M Ez DECLARE_MESSAGE_MAP()
3!UP>,! };
3`q`W9 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
oob0^}^ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
j2n@8sCSO BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
]}c=U@D,9 BOOL InitHotkey();
. M$D BOOL UnInit();
a{.n(M #endif
pD/S\E0@t 9}_f\Bs //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
DYl{{L8@ #include "stdafx.h"
`t2! M\) #include "hook.h"
CU&,Kq@ #include <windowsx.h>
9xp
;$14 #ifdef _DEBUG
Y)RikF > #define new DEBUG_NEW
O:R{4Q*5 #undef THIS_FILE
$QnfpM%+= static char THIS_FILE[] = __FILE__;
^:j:;\; #endif
<p
.[E]a2_ #define MAX_KEY 100
g5\B- 3{ #define CTRLBIT 0x04
\H12~=p`B #define ALTBIT 0x02
)ISTb #define SHIFTBIT 0x01
8R D)yRJ #pragma data_seg("shareddata")
pU/.|Sh HHOOK hHook =NULL;
>GRuS\B UINT nHookCount =0;
%c{)'X static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
5E|2S_)G static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Z:Am\7 I static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
KgSxF# static int KeyCount =0;
!!>G{ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
:]jtV~E\ #pragma data_seg()
g"f^YEQ_ HINSTANCE hins;
o`0H(\en void VerifyWindow();
=Ji:nEl]z BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
$^>vJk< //{{AFX_MSG_MAP(CHookApp)
/HD2F_XA // NOTE - the ClassWizard will add and remove mapping macros here.
-lEh}r // DO NOT EDIT what you see in these blocks of generated code!
r"{1H //}}AFX_MSG_MAP
5E=Odep` END_MESSAGE_MAP()
@]4 s&;
J n/=v\K@ CHookApp::CHookApp()
nVD
YAg' {
WRM}gWv* // TODO: add construction code here,
A/aQpEb% // Place all significant initialization in InitInstance
gQwmYe }
UkKpSL}Q2 qo|iw+0Y CHookApp theApp;
v_h{_b8 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
?sE21m?b- {
gV BV@v!W BOOL bProcessed=FALSE;
$!w%= if(HC_ACTION==nCode)
;wZ.p"T9^ {
AR^Di`n! if((lParam&0xc0000000)==0xc0000000){// Key up
v2R:=d
')> switch(wParam)
6 [E" {
rK wkj) case VK_MENU:
PN=yf@<V3F MaskBits&=~ALTBIT;
:f:C*mYvu break;
HS9U.G> case VK_CONTROL:
9m4|1) MaskBits&=~CTRLBIT;
#u^d3
$Nj break;
39#>C~BOl case VK_SHIFT:
_L>n!"E/ MaskBits&=~SHIFTBIT;
X.qKG0i break;
M`'2
a default: //judge the key and send message
<KX#;v!I
break;
GYO"1PM }
9:s!#FYFM for(int index=0;index<MAX_KEY;index++){
?=&*6H_v if(hCallWnd[index]==NULL)
AaVlNjB continue;
M-hnBt if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
r9[J3t*({~ {
g;T`~
SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
pz+#1=b] bProcessed=TRUE;
k$c!J'qL& }
5B6:pH6e }
(B5G?cB9 }
L\I/2aiE else if((lParam&0xc000ffff)==1){ //Key down
~MF. M8 switch(wParam)
1)y}.y5S {
(X/JXu{ case VK_MENU:
"^`AS"z' MaskBits|=ALTBIT;
qS>el3G break;
A\>qoR!Y case VK_CONTROL:
&/p9+gd MaskBits|=CTRLBIT;
X*@Sj;|m break;
; V8 =B8w case VK_SHIFT:
t)h3G M MaskBits|=SHIFTBIT;
>b0}X)Z+U break;
RWYA` default: //judge the key and send message
="4 )! break;
L 'y+^L|X }
%o>1$f] for(int index=0;index<MAX_KEY;index++)
q_bB/ {
7JbrIdDl| if(hCallWnd[index]==NULL)
=zdRoXBY[b continue;
A7se#"w if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
kmwFw># {
~Q5HM SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Wp $\> bProcessed=TRUE;
n7vi@^lf( }
V!p;ME }
p6p_B }
hI$an%Y( if(!bProcessed){
A]1](VQ)4 for(int index=0;index<MAX_KEY;index++){
o'G")o if(hCallWnd[index]==NULL)
<pCZ+Yv E" continue;
3f0RMk$pH if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
~9=g" v SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
TD'1L:mv }
oT
OMqR{" }
?]S*=6 }
'tekne return CallNextHookEx( hHook, nCode, wParam, lParam );
8I%1
`V }
>
ewcD{bt ? T9-FGW BOOL InitHotkey()
p)`JVq,H/B {
tP3Upw"U if(hHook!=NULL){
<?+\\Z!7 nHookCount++;
Ad(j&P return TRUE;
idHBz*3~ps }
%VgR * else
r?{tBju^ hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
6B=J*8
Hs if(hHook!=NULL)
zrcSPh nHookCount++;
9"[#\TW9Vb return (hHook!=NULL);
hq|/XBd|| }
/n_N`VJ7H BOOL UnInit()
HjrCX>v {
lq74Fz&( if(nHookCount>1){
K=V)"v5o3 nHookCount--;
)9s[-W,e return TRUE;
CAk.2C/ }
IIzdCa{l BOOL unhooked = UnhookWindowsHookEx(hHook);
n=`UhC if(unhooked==TRUE){
EG,RlmcPp nHookCount=0;
+]G;_/[2 hHook=NULL;
?(Nls.c }
Xh5
z8 return unhooked;
&W1c#]q@r }
72aj4k]^ r!+)U#8 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
u?!p[y6 {
cYK3>p
A BOOL bAdded=FALSE;
TWMD f for(int index=0;index<MAX_KEY;index++){
x@yF|8 if(hCallWnd[index]==0){
Zi^&x6y^ hCallWnd[index]=hWnd;
gqE{ HotKey[index]=cKey;
@l 1 piz8 HotKeyMask[index]=cMask;
K:mb$YJ& bAdded=TRUE;
\%UA6uj KeyCount++;
JHcC}+H[ break;
vb# d%1b5 }
UhNeY{6 }
P:=3;d{v return bAdded;
mAz':R[ }
fU,sn5zZ KdUmetx1 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
bx1' {
Pt E>08 BOOL bRemoved=FALSE;
R ~#\gMs for(int index=0;index<MAX_KEY;index++){
f5AK@]4G if(hCallWnd[index]==hWnd){
{$b]K-B if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
e(sQgtM6 hCallWnd[index]=NULL;
oE}1D?3Sp HotKey[index]=0;
E}UlQq HotKeyMask[index]=0;
:WE(1!P@ bRemoved=TRUE;
QHOem=B KeyCount--;
C;_10Rb2ut break;
jlItPdCv }
_rOKif?5 }
!9B)/Xi }
`zF=h#i return bRemoved;
k \|Hd"T }
~)ls.NXI Pn0V{SJOJ% void VerifyWindow()
B+ +:7! {
.Gw;]s3 for(int i=0;i<MAX_KEY;i++){
't]=ps if(hCallWnd
!=NULL){ ,JX/`7y
if(!IsWindow(hCallWnd)){ ygh*oVHO
hCallWnd=NULL; SBs_rhe
HotKey=0; 9 u{#S}c`
HotKeyMask=0; ~!\n
KeyCount--; |nIm$ p'
} r/SV.`
k
} |oa9 g2
} IWX%6*Zz
} !ce5pA
ZdfIe~Oni
BOOL CHookApp::InitInstance() lIz"mk
{ pno]Bld'z
AFX_MANAGE_STATE(AfxGetStaticModuleState()); jU/0a=h9
hins=AfxGetInstanceHandle(); p \1-.
InitHotkey(); <rNCb;
return CWinApp::InitInstance(); |\J8:b>}
} w`q):yXX
wjDLsf,
int CHookApp::ExitInstance() f3h^R20qmO
{ 5#~u U
VerifyWindow(); vzG(u_,9[
UnInit(); 6Dwj^e0
return CWinApp::ExitInstance(); _Uc le
} Srg`Tt]
v[\'
M
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file wS9EC}s:Q
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) b$[O^p9x
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ BNL Q]
#if _MSC_VER > 1000 {fmSmD
#pragma once q,A; d^g
#endif // _MSC_VER > 1000 blEs!/A`
{dTtYL$'"
class CCaptureDlg : public CDialog @|sDb?J
{ [kaj8
// Construction r$<[`L+6
public: 1 :<f[l
BOOL bTray; 8SR ~{
BOOL bRegistered; r&U