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:
YHRI U Yd
vo(?[[ 一、实现方法
F#<PFT4i 1)PR]s:-m@ 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:
ntkinbbD bA^a@ lv a #pragma data_seg("shareddata")
z
vYDE] HHOOK hHook =NULL; //钩子句柄
n `Xz<Q! UINT nHookCount =0; //挂接的程序数目
Ti/iD2g static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
(7wR*vO^ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
|(H|2]b4= static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
S2s-TpjB< static int KeyCount =0;
<|`@K|N static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
RYhdf #pragma data_seg()
Em]T.'y N7jRdT2k% 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。
CM#EA"9 0$_imjZ DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
d!LV@</ <V8i>LBlz BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
}mGD`5[` cKey,UCHAR cMask)
aw4+1.xy {
T8(wzs BOOL bAdded=FALSE;
^+wzm2i for(int index=0;index<MAX_KEY;index++){
t/D
Q<B_ if(hCallWnd[index]==0){
1*jL2P]D hCallWnd[index]=hWnd;
:hr@>Y~r HotKey[index]=cKey;
7cy~qg HotKeyMask[index]=cMask;
xXYens} bAdded=TRUE;
B*AMo5 KeyCount++;
R`?^%1^N break;
6;b 'j\jG }
Uy1xNb/d }
[O)Zof return bAdded;
C/vLEpP{(/ }
jlP7'xt1% //删除热键
,qHG1#^ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
xq)/ QR {
_NZHrN BOOL bRemoved=FALSE;
A-u5 for(int index=0;index<MAX_KEY;index++){
=iQm_g if(hCallWnd[index]==hWnd){
W.R'2R# if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
Rp|&1nS hCallWnd[index]=NULL;
U; xWW9 HotKey[index]=0;
&; skB. HotKeyMask[index]=0;
^0
lPv!2 bRemoved=TRUE;
k$ M4NF~$ KeyCount--;
@~XlI1g$i break;
(KMobIP^ }
&}$D[ 4N }
/
IS WC }
&aQ)x return bRemoved;
=arsoCa }
DnFl*T> q{ 1U Pb;`'<*U DLL中的钩子函数如下:
F)5Aq H/p n6Zx0ad? LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
o5@ jMU; {
y
m{/0&7 BOOL bProcessed=FALSE;
~b[4'm@ if(HC_ACTION==nCode)
@(?4g-*E {
M!l5,ycF if((lParam&0xc0000000)==0xc0000000){// 有键松开
D ` X6'PP switch(wParam)
e;'T?&t {
T!A}ipqb case VK_MENU:
v`w?QIB] MaskBits&=~ALTBIT;
L
_y|l5 break;
Lp WEu^j case VK_CONTROL:
L#
1vf MaskBits&=~CTRLBIT;
S:uEK break;
SkA'+( case VK_SHIFT:
x=#5\t9 MaskBits&=~SHIFTBIT;
.8!0b iS break;
{wXN kq default: //judge the key and send message
$:N
"* break;
|P7f^0idk }
` W>B8 for(int index=0;index<MAX_KEY;index++){
E|;5Z* if(hCallWnd[index]==NULL)
vUs7#* continue;
O*{H;7Pv if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
!q\w"p0X {
tuUXW5!/ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
;T+U&U0d| bProcessed=TRUE;
BZc- }
<'_GQM`G }
Lp)8SmN }
{kH^OZ^(e else if((lParam&0xc000ffff)==1){ //有键按下
JW[\"`x! switch(wParam)
\=V[ba:q {
cgeS)C7 case VK_MENU:
mRY6[*u MaskBits|=ALTBIT;
:*'?Ac
? break;
"BfmX0&? case VK_CONTROL:
I=yj MaskBits|=CTRLBIT;
&:#8ol(n5b break;
E}vO*ZZEw case VK_SHIFT:
}n%Rl\p MaskBits|=SHIFTBIT;
m
Ap|?n/K break;
n{r#K_ default: //judge the key and send message
5l/l] break;
<^_Vl8% }
HHTsHb{7 for(int index=0;index<MAX_KEY;index++){
>m1V9A if(hCallWnd[index]==NULL)
^!F5Cz 48 continue;
Su$ 1 t if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
G?d,$NMo| {
dd7nO
:] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
F'$S!K58 bProcessed=TRUE;
$jh>zf }
O)JUY*&I5 }
EJ ~kZ3 }
,wi=!KzX if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
9PqgBq for(int index=0;index<MAX_KEY;index++){
U"Hquo if(hCallWnd[index]==NULL)
\u-e\w continue;
PbHh?iH if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
M .` SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
WTYFtZD[yH //lParam的意义可看MSDN中WM_KEYDOWN部分
|kNGpwpI }
ls7A5 < }
LA`VqJ }
[ky6E*dV` return CallNextHookEx( hHook, nCode, wParam, lParam );
![]I%'s }
)c >B23D /+t[, 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
&:I
+]G/W LZC?383' BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
=&VXn{e BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
5 t`ap H..ZvGu 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
,Zf!KQw d74g|`/ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
!GGGh0Bj {
niHL/\7u if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
jJ"EGFa8 {
s
P4,S(+e //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
71" JL", SaveBmp();
zMYd|2bc return FALSE;
8{<[fZyC }
[&qbc#L …… //其它处理及默认处理
a950M7 }
iQ{&&>V% *Z]WaDw /4
LR0`A' 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
W_,;eyo ,ANK3n\ 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
}t51U0b% XCIa2Syo 二、编程步骤
+Sd,l>8\ ?
TT8|Os 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
yb4tJu$ IiK(^:~% 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
#>:(#^Uu yLz,V} 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;
)Bn>/- \;*}zX 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;
^~6] 0$yJ pP0Vg'V 5、 添加代码,编译运行程序。
uB<F.!3 M=AvD(+ha 三、程序代码
U7"BlT!V\ H
:
T N ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
.K@x4
/1 #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
q#(/*AoU #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
HD:%Yv #if _MSC_VER > 1000
|N$?_<H #pragma once
<P^hYj-swh #endif // _MSC_VER > 1000
?YO=J #ifndef __AFXWIN_H__
%]<RRH.w #error include 'stdafx.h' before including this file for PCH
Sq-3-w,R~ #endif
3IK(f. #include "resource.h" // main symbols
%7]XW 2u class CHookApp : public CWinApp
U$A7EFK' {
Q-`{PJ(p public:
YXzZ-28,< CHookApp();
m@Ip^]9ry // Overrides
i2:+h}o$e // ClassWizard generated virtual function overrides
XW?ybH6 //{{AFX_VIRTUAL(CHookApp)
9fuJJ3L[ public:
iTLW<wG virtual BOOL InitInstance();
pYfV~Q^3 virtual int ExitInstance();
MKe^_uF //}}AFX_VIRTUAL
R#/?AD& //{{AFX_MSG(CHookApp)
e$Bf[F#;- // NOTE - the ClassWizard will add and remove member functions here.
7V=MRf&xQ // DO NOT EDIT what you see in these blocks of generated code !
%K^gUd>,R //}}AFX_MSG
)8$:DW; DECLARE_MESSAGE_MAP()
{x[;5TM };
X7H'Uk9: LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
`8Jq~u6_Z BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
kG$E
tE# BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
'(*&Ax BOOL InitHotkey();
jJUGZVM6) BOOL UnInit();
&]VQR2J}: #endif
1 Itil~ Q=(@K4 //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
rv}mD #include "stdafx.h"
6QII&Fg #include "hook.h"
U=kx`j> #include <windowsx.h>
x7.QL?qR. #ifdef _DEBUG
5pM&h~M #define new DEBUG_NEW
(LRM~5KVg #undef THIS_FILE
Vd%v_Ek static char THIS_FILE[] = __FILE__;
_r\$NgJIM #endif
PUP"ky^q" #define MAX_KEY 100
e"fN~`NhY #define CTRLBIT 0x04
;}/U+`=D? #define ALTBIT 0x02
tyEPU^PM #define SHIFTBIT 0x01
I/On3"U% #pragma data_seg("shareddata")
#v4LoNm HHOOK hHook =NULL;
sTtX$&Qu UINT nHookCount =0;
+}^|dkc static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
W|25t)cJ8h static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
z.3<{-n}0i static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
;8ET!&k*>E static int KeyCount =0;
skIiJ'db static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
bo@,4xw #pragma data_seg()
~+N76BX HINSTANCE hins;
s.y q}Q void VerifyWindow();
(*6m^ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
FxCZRo& //{{AFX_MSG_MAP(CHookApp)
7v_i>_m] // NOTE - the ClassWizard will add and remove mapping macros here.
fB~O
|g // DO NOT EDIT what you see in these blocks of generated code!
ebN(05ZV //}}AFX_MSG_MAP
oZvA~]x9\ END_MESSAGE_MAP()
V@D]bV@4 {~bIA!kAFI CHookApp::CHookApp()
4^DVW*OiI {
?;|@T ty% // TODO: add construction code here,
b!0DH[XKV // Place all significant initialization in InitInstance
BXg!zW%+ }
p$Kj<:qiP yiVG ]s CHookApp theApp;
(j' {~FB LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
#:J:YMv {
*@_u4T7|{ BOOL bProcessed=FALSE;
{p`mfEE( if(HC_ACTION==nCode)
Y?yo\(Cdx {
e>l,(ql if((lParam&0xc0000000)==0xc0000000){// Key up
i:o}!RZ> switch(wParam)
E *F*nd]K {
9>by~4An? case VK_MENU:
&{%MjKJ._ MaskBits&=~ALTBIT;
Ia629gi5s break;
:qKF58W case VK_CONTROL:
}q% jO MaskBits&=~CTRLBIT;
&]P"48NT break;
nPcS3!7B# case VK_SHIFT:
i"vawxm MaskBits&=~SHIFTBIT;
'LVn^TB_f& break;
\dRzS@l default: //judge the key and send message
6M ^IwE break;
Ji;SY{~kv }
@}<"N for(int index=0;index<MAX_KEY;index++){
Q%ruQ# if(hCallWnd[index]==NULL)
8|O=/m ^] continue;
N&T:Lt_N if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
yN*:.al {
+TC1nkX SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
CqqXVF3 bProcessed=TRUE;
LA-_3UJx }
B?LXI3sQZ }
q-3]jHChh }
ddsUz1%l else if((lParam&0xc000ffff)==1){ //Key down
0$6*o}N% switch(wParam)
b'i'GJBQ+$ {
.~3kGf": case VK_MENU:
`Da+75 f6v MaskBits|=ALTBIT;
'\`6ot8 break;
![ZmV case VK_CONTROL:
mjb{~ MaskBits|=CTRLBIT;
_%Bz,C8 break;
No)
m/17y case VK_SHIFT:
gv#4#] MaskBits|=SHIFTBIT;
4q hWm"&CM break;
5[C ~wvO default: //judge the key and send message
n` q2s'Pc break;
@mf({Q> }
aD9rp
V for(int index=0;index<MAX_KEY;index++)
79ckLd9 {
Sk:2+inU if(hCallWnd[index]==NULL)
AoYaVlKG8 continue;
IdPn%)>6 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
bd!U)b(}OV {
J$F nm\ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
c<wavvfUo bProcessed=TRUE;
P;vxT}1 }
-Ep!- a }
Z%}4bJ }
yGTziv! if(!bProcessed){
$r\"6e for(int index=0;index<MAX_KEY;index++){
<} ,1Ncl if(hCallWnd[index]==NULL)
brh=NAzt continue;
u$%A#L[ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
kneuV8+(5 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
$X\va?( }
["y6b*;x }
fkjeR
B }
nnwJYEi return CallNextHookEx( hHook, nCode, wParam, lParam );
W|MWXs5'1* }
[4*1}}gW%5 BOvF)4` BOOL InitHotkey()
n9%]-s\Hn {
5t\HJ`C1Z if(hHook!=NULL){
u%u&F^y nHookCount++;
1<.5ub*i4 return TRUE;
RRADg^}l|" }
TBCp
L]QT else
^~$\ g] hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
^T6S()G if(hHook!=NULL)
03=5Nof1 nHookCount++;
?]#OM_,8 return (hHook!=NULL);
A`[@8 }
W@.Ji B BOOL UnInit()
j8++R&1f] {
f'X9HU{Cz if(nHookCount>1){
.oqIZ\iik nHookCount--;
hmpr%(c ` return TRUE;
wpXgPVZT }
,:)`+v< BOOL unhooked = UnhookWindowsHookEx(hHook);
1!1!PA9u if(unhooked==TRUE){
{E A1vo" nHookCount=0;
1@>$ Gcc hHook=NULL;
|mhKI is U }
eQUe
>* return unhooked;
+5!&E7bcd }
\OQkZ.cU; Apj; BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
$TG=w {
?>$l BOOL bAdded=FALSE;
N\NyXh$ for(int index=0;index<MAX_KEY;index++){
-fy9< if(hCallWnd[index]==0){
B4h5[fPX hCallWnd[index]=hWnd;
>|g?wC}V; HotKey[index]=cKey;
:z&7W< HotKeyMask[index]=cMask;
8|@9{ bAdded=TRUE;
e(?]SU| KeyCount++;
f>2MI4nMG break;
wM~H(=s`D }
wi_'iv }
SmhGZ return bAdded;
I9?Ec6a_ }
aUc|V{Jp pTJX""C BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
MHU74//fe {
E5</h"1 BOOL bRemoved=FALSE;
M5g\s;y; for(int index=0;index<MAX_KEY;index++){
$,3J7l3 if(hCallWnd[index]==hWnd){
u JY)4T if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
-C-yQ.>\T# hCallWnd[index]=NULL;
jQS 6J+F] HotKey[index]=0;
c9wfsapJ HotKeyMask[index]=0;
UAn&\ 8g_ bRemoved=TRUE;
6gH{R$7L= KeyCount--;
cl@g break;
k^\pU\J }
k&