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:
XW" 0:}`J
Vm>E F~ r 一、实现方法
~IS8DW$; fyA-*)oHv 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
c$%*p
(zY nGkSS_X #pragma data_seg("shareddata")
=@?[.` HHOOK hHook =NULL; //钩子句柄
%&|
uT UINT nHookCount =0; //挂接的程序数目
%kjG[C static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
!W9:)5^X static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
`+"(GaZ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
y{>f^S< static int KeyCount =0;
?!6Itkg static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
@2)nhW/z6 #pragma data_seg()
%dFJ'[jDL ?(R3%fU 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。
]b!n ;{5 dkZe.pv$j DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
%BP>,E/w k[;)/LfhS BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
<\u3p3"[4 cKey,UCHAR cMask)
~<m^ {
r~j
[Qm"CJ BOOL bAdded=FALSE;
DylO;+ for(int index=0;index<MAX_KEY;index++){
C;N6",s! if(hCallWnd[index]==0){
=abcLrf2G hCallWnd[index]=hWnd;
jk03 Hd HotKey[index]=cKey;
DfD
>hf/ HotKeyMask[index]=cMask;
2!Dz9m3 bAdded=TRUE;
E,}{ iqAb KeyCount++;
4JAz{aw'b break;
. : Wf>: }
j)?M }
uK2HtRY1 return bAdded;
{E:` }
gM\>{ihM' //删除热键
D=TS IJ@ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
SG&,o=I$ {
Og/aTR<;= BOOL bRemoved=FALSE;
$`E?=L`$ for(int index=0;index<MAX_KEY;index++){
q[,p#uJ] if(hCallWnd[index]==hWnd){
&uK(. @ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
6*q1%rs:w hCallWnd[index]=NULL;
^{4BcM7eH HotKey[index]=0;
;7QXs39S HotKeyMask[index]=0;
Mh.1KI[t bRemoved=TRUE;
10Ik_L=' KeyCount--;
25$_tZPAI break;
G?1GkR }
>u&D@7~c }
.d]/:T
-0 }
P 0,]`w return bRemoved;
IR6W'vA }
@MES.g (Xh<F AafS6]y DLL中的钩子函数如下:
o utJ/~9; ?,>3uD# LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
F@i>l{C {
7__[=)(b2X BOOL bProcessed=FALSE;
YsVmU if(HC_ACTION==nCode)
p%I'd^}.! {
i6'=]f'{ if((lParam&0xc0000000)==0xc0000000){// 有键松开
GfE>?mG switch(wParam)
d:(Ex^^ {
|Ns4^2 case VK_MENU:
a)QT#. MaskBits&=~ALTBIT;
.h-mFcjy break;
d m8t~38 case VK_CONTROL:
^l!SIu MaskBits&=~CTRLBIT;
3%kUj break;
"GO!^ZG] case VK_SHIFT:
eU1F7LS MaskBits&=~SHIFTBIT;
mqZH<.mn break;
hCcI]#S& default: //judge the key and send message
/iU<\+ H break;
TTz=*t+D }
>GGM76vB=, for(int index=0;index<MAX_KEY;index++){
!p&<.H_ if(hCallWnd[index]==NULL)
`Nx@MPo continue;
Z7a@$n3h if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
>^s2$@J?p {
_QL|pLf- SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
u}@N
Qeg bProcessed=TRUE;
ba|xf@=& }
K81X32Lm' }
d`^3fr'.4A }
J:@gmo`M;V else if((lParam&0xc000ffff)==1){ //有键按下
)D+BvJ Y" switch(wParam)
$ZM'dIk? {
{N4 'g_ case VK_MENU:
4z0gyCAC A MaskBits|=ALTBIT;
.l1x~( break;
?+t;\ case VK_CONTROL:
ys9:";X;} MaskBits|=CTRLBIT;
>dl5^ break;
4YfM.~
6 case VK_SHIFT:
T+Z[&| MaskBits|=SHIFTBIT;
J4T"O<i$58 break;
>3!~U.AA'x default: //judge the key and send message
o[ZjXLJzV break;
,HZ%q]*:~ }
|?T=4~b
for(int index=0;index<MAX_KEY;index++){
rl|'.~mc if(hCallWnd[index]==NULL)
>v+1v continue;
ip-X r|Bq if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
|a{;<a {
COh#/-`\1 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
q\EYsN</; bProcessed=TRUE;
!mlfG"FE }
jY=y<R_oK }
J&A1]T4d }
Ib..X&N2 if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
ZmsYRk~@- for(int index=0;index<MAX_KEY;index++){
1Wpu if(hCallWnd[index]==NULL)
vB7Gx>BQd continue;
\zBi-GI7 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
ZNBowZI SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
`UsJaoR#f //lParam的意义可看MSDN中WM_KEYDOWN部分
I3Vu/&8f| }
%1i:*~g }
ojM'8z0Hn }
'nTlCYT return CallNextHookEx( hHook, nCode, wParam, lParam );
vi##E0,N'^ }
tWIOy6` hEZvi
抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
*K/K97 5iA>Z!sP[ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
I$;`^z BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
l
U/Xi Y#F.{i 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:
;M~,S^U Y_%:%J LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
05wkUo:9 {
v@\S$qU2 if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
; J W]b] {
Hu|Tj<S //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
vb>F)X?b_ SaveBmp();
AU9C#;JD return FALSE;
JvAXLT }
oMbd1uus …… //其它处理及默认处理
: s
* }
#/YS kLgkUck8] T?1BcY
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。
aO1^>hy =Y2 Rht 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。
4/(#masIL K#OL/2^
5 二、编程步骤
FyEKqYl YiZk|K_ 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";
i@rtt
M [%K6-\S 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
^%f8JoB SJiQg-+<Uf 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;
mF
1f( ?Bu*%+ 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;
B:"D)/\ HYdM1s6vo 5、 添加代码,编译运行程序。
/9_%NR[
38w^="-T 三、程序代码
n-9xfn0U~# B#g~c<4< ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
}TTghE! #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
T,!EL+o4 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
l= {Y[T& #if _MSC_VER > 1000
EDnNS #pragma once
z6`0Uv~ #endif // _MSC_VER > 1000
-E}X`?WhD #ifndef __AFXWIN_H__
/b=C #error include 'stdafx.h' before including this file for PCH
;^N
lq3N #endif
f-M:ap(O #include "resource.h" // main symbols
$OZ= L
class CHookApp : public CWinApp
gAqK/9; {
63E6nW M public:
$#rkvG_w CHookApp();
qm=U<'b^ // Overrides
h3`}{
w // ClassWizard generated virtual function overrides
,>B11Z}PH //{{AFX_VIRTUAL(CHookApp)
Z
)c\B public:
|^1g*fy? virtual BOOL InitInstance();
p$,G`'l virtual int ExitInstance();
{~9z uNi //}}AFX_VIRTUAL
WaB0?jI //{{AFX_MSG(CHookApp)
HO<|EH~lu // NOTE - the ClassWizard will add and remove member functions here.
LuySa2, // DO NOT EDIT what you see in these blocks of generated code !
s)WA9PiC //}}AFX_MSG
uB)q1QQsqp DECLARE_MESSAGE_MAP()
O|t>.<T? };
\ ITd\)F%N LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
Cf(WO-F^ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
I0x)d` BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
AUD)=a> BOOL InitHotkey();
g|Lbe4? BOOL UnInit();
"s|P,*Xf #endif
[)V~U? OJu>#
//////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
~HIj+kN #include "stdafx.h"
9\EW~OgTu #include "hook.h"
tMw65Xei6b #include <windowsx.h>
iZG-ca #ifdef _DEBUG
!L.R"8! #define new DEBUG_NEW
|tAkv #undef THIS_FILE
kTH""h{ static char THIS_FILE[] = __FILE__;
;U3:1hn #endif
vD8pVR+ #define MAX_KEY 100
zg ,=A? #define CTRLBIT 0x04
}W^@mi
#define ALTBIT 0x02
?1L<VL=b #define SHIFTBIT 0x01
rCF=m]1zxT #pragma data_seg("shareddata")
D _dv8 HHOOK hHook =NULL;
fNLO%\G~2 UINT nHookCount =0;
GeJ}myD O static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
ZV--d'YiEm static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
QqQhQ GV static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
>c_fUX={ static int KeyCount =0;
Stwg[K0< static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
x_~_/&X5 #pragma data_seg()
Ug+ K:YUq HINSTANCE hins;
f+9WGNpw void VerifyWindow();
xS UpVK BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
f_)# //{{AFX_MSG_MAP(CHookApp)
EPJ>@A>;D // NOTE - the ClassWizard will add and remove mapping macros here.
Ub\^3f // DO NOT EDIT what you see in these blocks of generated code!
6/ 5c| //}}AFX_MSG_MAP
?;o0~][! END_MESSAGE_MAP()
07Yak<+~ z00X
?F CHookApp::CHookApp()
yf&_l^! {
SZXSVz0j // TODO: add construction code here,
v@]SddP,? // Place all significant initialization in InitInstance
|Ogh-<|< }
6fw7\u h[u@UGK% CHookApp theApp;
Aa_@&e LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
4AzDWK@/ {
"Bwz
Fh BOOL bProcessed=FALSE;
tf6-DmMH if(HC_ACTION==nCode)
s<LnUF1b {
DTH}=r- if((lParam&0xc0000000)==0xc0000000){// Key up
O[= L#wi switch(wParam)
W0MgY%Qv[ {
lv?`+tU2_ case VK_MENU:
@?e~l:g})g MaskBits&=~ALTBIT;
y0Gblza break;
c$,1j%[) case VK_CONTROL:
A{4,ih"5 MaskBits&=~CTRLBIT;
4
. c1 break;
Q3%] case VK_SHIFT:
OIj.K@Kr MaskBits&=~SHIFTBIT;
@p~scE.#\ break;
:l"BNT[/ default: //judge the key and send message
x-c5iahp' break;
LU;zpXg\ }
qpFxl for(int index=0;index<MAX_KEY;index++){
HI{q# if(hCallWnd[index]==NULL)
;Q,t65+Am continue;
9]Ue%%vM if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
= r/8~~= {
2~\SUGW- SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
LZ_0=Xx% bProcessed=TRUE;
i`e[Vwe2x@ }
baD063P; }
1OExa<Zq }
N$e
mS else if((lParam&0xc000ffff)==1){ //Key down
&xB*Shp,B switch(wParam)
d)V8FX,t {
[uGsF0#e case VK_MENU:
.]h/M,xg MaskBits|=ALTBIT;
#<==7X# break;
O>+=cg case VK_CONTROL:
.xwskzJ3 MaskBits|=CTRLBIT;
riOaqV break;
;8XRs?xyd case VK_SHIFT:
'ux!:b" MaskBits|=SHIFTBIT;
`1P|<VbZ break;
$%cHplQz5 default: //judge the key and send message
i,^3aZwJ' break;
s&pnB }
$adZ|Q\ for(int index=0;index<MAX_KEY;index++)
UL}wGWaoG {
{ rLgyrj$ if(hCallWnd[index]==NULL)
!@ ]IJ"\ continue;
&kzysv-_ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
8Yk*$RR9 {
17?YN< SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
iii|;v]+ bProcessed=TRUE;
3e'6A ^# }
Q;VuoHj! }
2<B'PR-??y }
v.<mrI#? if(!bProcessed){
Ws|`E`6O for(int index=0;index<MAX_KEY;index++){
6Jq[]l"v if(hCallWnd[index]==NULL)
Wgh@X B continue;
_rB,N#{2R= if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
-->0e{y SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
H}kSXKO8!8 }
MuOKauYa }
3%?tUt }
}~+,x# return CallNextHookEx( hHook, nCode, wParam, lParam );
tgG*k$8z }
m=l'9j"D M\4`S& BOOL InitHotkey()
K [DpH& {
t?G6|3 if(hHook!=NULL){
0c`zg7| nHookCount++;
$4xSI"+M% return TRUE;
y&
yf&p }
jG7PT66>; else
Sj ~SG hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
v5'`iO0o if(hHook!=NULL)
G*+^b'7 nHookCount++;
mTI`^e return (hHook!=NULL);
o5a=>|?p> }
7xeqs
q BOOL UnInit()
YS^!'IyG/B {
@T\n@M] if(nHookCount>1){
_Z[0:4 nHookCount--;
V2}\]x'1 return TRUE;
PhC3F4 }
:CE4<
{V BOOL unhooked = UnhookWindowsHookEx(hHook);
=XR6rR8 if(unhooked==TRUE){
\wA:58 -j nHookCount=0;
Cty#|6k hHook=NULL;
` 'Qb?F6 }
-:ucp2 return unhooked;
$!>.h*np }
P!|Z%H .c-a$39 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
&$/
#"lW,V {
d)vP9vXy BOOL bAdded=FALSE;
K#Ck,Y" for(int index=0;index<MAX_KEY;index++){
HCN/|z1Xq if(hCallWnd[index]==0){
*z VN6wG{ hCallWnd[index]=hWnd;
Ll|_Wd.K, HotKey[index]=cKey;
`?Q
p>t HotKeyMask[index]=cMask;
(|^m9v0: bAdded=TRUE;
b&F9<XLqq KeyCount++;
CfU|]< break;
0mSP }
Gf\h7)T\ }
A!bG 2{r return bAdded;
p5#x7*xR6 }
0h@FHw2d *[]E5U BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
X-HE9PT. {
k B>F(^ BOOL bRemoved=FALSE;
AChz}N$C for(int index=0;index<MAX_KEY;index++){
|2q3spd if(hCallWnd[index]==hWnd){
A0)^I:& if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
f zo'9 hCallWnd[index]=NULL;
g.Xk6"kO HotKey[index]=0;
jCJcVO>OZ HotKeyMask[index]=0;
DRQx5fgL bRemoved=TRUE;
J |q(HpB KeyCount--;
#; ?3kuq( break;
xrkl)7; }
B}d&tH2^s }
}'x;J }
GkJcd; return bRemoved;
3^y(@XFt }
z lr! l\s!A&L void VerifyWindow()
pIlEoG=[_ {
a<G&}|6 for(int i=0;i<MAX_KEY;i++){
<