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:
o>yo9n%t
"QM2YJ55m` 一、实现方法
BXUd
i&'O BqDOo(%1) 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:
a-9sc6@ ]9hhAT44 #pragma data_seg("shareddata")
hu:x,;`9H HHOOK hHook =NULL; //钩子句柄
Enqs|fkbN UINT nHookCount =0; //挂接的程序数目
&Pgk$e%> static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
q(}#{OO static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
x24&mWgU static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
M3H^s_ static int KeyCount =0;
]u"x=S93 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
b
R9iqRbn #pragma data_seg()
@0iXqM#jH 5>rjL; 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
.a}!!\@ >!#or- C DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
5hp)Z7 pY(S]i BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
?# )\SQ cKey,UCHAR cMask)
S5wkBdr{ {
&dJ\}O[r BOOL bAdded=FALSE;
-<^3!C > for(int index=0;index<MAX_KEY;index++){
<Sp>uhet1 if(hCallWnd[index]==0){
Tywrh9[ hCallWnd[index]=hWnd;
-FQS5Zb.! HotKey[index]=cKey;
It5n;,n HotKeyMask[index]=cMask;
{e83 A/{ bAdded=TRUE;
>; k~B KeyCount++;
=v~$&@ break;
.<-~k@ P }
GD#W=O }
M.KXDD#O return bAdded;
)!d_Td\- }
9a{9|p>L //删除热键
>`+lEob BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
gBo~NLrf {
6('xIE(R BOOL bRemoved=FALSE;
wW0m}L for(int index=0;index<MAX_KEY;index++){
&_$xMM,X if(hCallWnd[index]==hWnd){
<"!'>ZUt if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
+!"7=?} hCallWnd[index]=NULL;
wKAxUPzm HotKey[index]=0;
QHe: HotKeyMask[index]=0;
c_syJ< bRemoved=TRUE;
=<z~OE'lV KeyCount--;
!24g_R[3" break;
bs_rw+ }
<u2iXH5w }
c/`Rv{*'o }
GlaZZ, return bRemoved;
*jo1? }
<"x *ZT r }Nq"s< jx8hh}C DLL中的钩子函数如下:
vjYG>YhV t++\&!F LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
l u V_ {
G>W:3y BOOL bProcessed=FALSE;
^uIKwql
if(HC_ACTION==nCode)
]`eJSk. {
X*rB`M7, if((lParam&0xc0000000)==0xc0000000){// 有键松开
"gq_^& switch(wParam)
Vvk\$' {
[`=:uUf3 case VK_MENU:
S-G#+Ue2 MaskBits&=~ALTBIT;
Ui;PmwQc& break;
4mF=A$Q_/ case VK_CONTROL:
`/eh MaskBits&=~CTRLBIT;
JL&ni]m break;
uCGn9] case VK_SHIFT:
+ZeK,Y+Xy MaskBits&=~SHIFTBIT;
T!gq
Z break;
U%_6'5s{^ default: //judge the key and send message
Y'M}lv$sa break;
d,%@*v]S }
]e]hA@4 for(int index=0;index<MAX_KEY;index++){
}}~ t!/x if(hCallWnd[index]==NULL)
Pna2IB+ continue;
C~:!WRCz if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
wfc+E9E {
,v*<yz/ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
B<?fD bProcessed=TRUE;
S[oRq }
6Pu5 k;H }
|Xa|%f }
Q-Rt else if((lParam&0xc000ffff)==1){ //有键按下
%TRH,-@3h switch(wParam)
5}_DyoV {
qGc>+!y case VK_MENU:
8sxH)"S MaskBits|=ALTBIT;
Gzu $ break;
'C|yUsBC case VK_CONTROL:
z3p#` MaskBits|=CTRLBIT;
@ei:/~y3 break;
D1<$]r, case VK_SHIFT:
@X*r5hjc MaskBits|=SHIFTBIT;
Z
)dz break;
~`x<;Ts default: //judge the key and send message
=8)q-{p3 break;
\m;"KyP+ }
WXC}Ie for(int index=0;index<MAX_KEY;index++){
v_Y'o
_
if(hCallWnd[index]==NULL)
'HDbU#vD continue;
)x*pkE**c if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
^YG.eT6iG {
J#'+&DH SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
"Hw%@ bProcessed=TRUE;
{,rVA(I@ }
+A,t9 3:k }
-KG3_k E }
d>qxaX; if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
="*8ja-K for(int index=0;index<MAX_KEY;index++){
/K]<7 if(hCallWnd[index]==NULL)
(j;6}@ continue;
>O&:[CgEF if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
5=--+8[ bV SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
ij=}3;L_! //lParam的意义可看MSDN中WM_KEYDOWN部分
!xxu~j^T }
bqDHLoB\1 }
i@M^9|Gh }
X%._:st return CallNextHookEx( hHook, nCode, wParam, lParam );
I5J9,j }
ard<T}|N gnp\z/'> 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:
}6Uw4D61 Z{ A) BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
)} H46 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
0FV?By g qRwN 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:
Ysk,9MR(F R2af>R LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
?][2J {
zU9G:jH if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
nVC:5ie {
Ge>%?\ //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
N}3$1=@Y SaveBmp();
f:h.O# d> return FALSE;
v@0lTl_ }
Uaho.(_GP …… //其它处理及默认处理
8@|rB3J }
{g>k-. ,rp-`E5ap ec4jiE 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
c2z%|\q ~_Tm S9 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
.f V-puE Gw$sL&1m\ 二、编程步骤
o AkF [*j
C 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";
iTt"Ik' tZ]|3wp 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
s9<fPv0w
7)IBIlV 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;
$S Q8,Y, 9K@>{69WQ 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
:4"SJ u":D{+wC| 5、 添加代码,编译运行程序。
XB)e;R oVsj
Q 三、程序代码
&t+ u:pdY'`"# ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
X3DXEeBEL #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
JrTSu`S(' #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
_M+'30 #if _MSC_VER > 1000
sD$
\!7:b #pragma once
<_02)6j #endif // _MSC_VER > 1000
I72UkmK` #ifndef __AFXWIN_H__
6y,M+{ #error include 'stdafx.h' before including this file for PCH
22\Buk}? #endif
C+Wb_ #include "resource.h" // main symbols
}(AUe5aw`G class CHookApp : public CWinApp
2B_6un];W {
aC>r5b#: public:
n37C"qJ/i CHookApp();
e0HG"z4 // Overrides
?#xNz=V // ClassWizard generated virtual function overrides
BBw`8! //{{AFX_VIRTUAL(CHookApp)
hi>Ii2T public:
^Ois]#py virtual BOOL InitInstance();
|EaGKC(
virtual int ExitInstance();
h:(Jes2 //}}AFX_VIRTUAL
PG9won5_ //{{AFX_MSG(CHookApp)
+~=>72/r // NOTE - the ClassWizard will add and remove member functions here.
tnbaU%;|J // DO NOT EDIT what you see in these blocks of generated code !
)1O *~% //}}AFX_MSG
[kzcsJ'/e DECLARE_MESSAGE_MAP()
Qp<?[C}'W };
n<Z;Xh~F LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
sMli! u BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
A6}M F BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
]Ole#Lz}Q BOOL InitHotkey();
f3U#|(%(* BOOL UnInit();
?V#%^ 57p #endif
UuAn`oYhV _%!C;`3Y //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
^LTLyt)/ #include "stdafx.h"
SY["(vP%# #include "hook.h"
iwCnW7: #include <windowsx.h>
ai`fP{WlX #ifdef _DEBUG
JV/K ouL #define new DEBUG_NEW
W&}R7a@:<~ #undef THIS_FILE
qeBfE static char THIS_FILE[] = __FILE__;
z++*,2F #endif
]$4 k+)6 #define MAX_KEY 100
fk5!/>X #define CTRLBIT 0x04
W7WHH \L/O #define ALTBIT 0x02
']ya_ v~e #define SHIFTBIT 0x01
XK`>#*"V #pragma data_seg("shareddata")
mK%!9F
V HHOOK hHook =NULL;
(WVN*OR? UINT nHookCount =0;
=IkQ;L& static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
Kg VLXI6 static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
YKJk)%;+w static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
I')URk[ static int KeyCount =0;
J*-m!0 5 static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
Ih ;6(5z #pragma data_seg()
<?yAIhgN* HINSTANCE hins;
czi$&(N0w$ void VerifyWindow();
glH&v8 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
`4'v)!? //{{AFX_MSG_MAP(CHookApp)
pZ/x,b#. // NOTE - the ClassWizard will add and remove mapping macros here.
05gU~6AF // DO NOT EDIT what you see in these blocks of generated code!
4rO07)~l //}}AFX_MSG_MAP
WB'&W= END_MESSAGE_MAP()
@N7X(@O yH;=Y1([ CHookApp::CHookApp()
>to NGGU=~ {
S)iv k x // TODO: add construction code here,
~k/'_1)c // Place all significant initialization in InitInstance
&$lz@Z }
i~@e}= r,(rWptf4 CHookApp theApp;
`J|bGf# LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
j5Vyo> {
EA7 8& BOOL bProcessed=FALSE;
q{ItTvL if(HC_ACTION==nCode)
(@B
gsY {
1#qyD3K if((lParam&0xc0000000)==0xc0000000){// Key up
"a6[FqTs switch(wParam)
\EuMzb"G9p {
/csj(8^w case VK_MENU:
G#t!{Q}8 MaskBits&=~ALTBIT;
<.HX_z3l break;
Z
`sM(?m case VK_CONTROL:
7;:R\d6iL MaskBits&=~CTRLBIT;
=H%c/Jty break;
sWX iY case VK_SHIFT:
_Jx.?8 MaskBits&=~SHIFTBIT;
Y #E/"x%+ break;
)cJ9YKKy default: //judge the key and send message
(2RZc].M~ break;
X`/8fag }
]dHU for(int index=0;index<MAX_KEY;index++){
K'kWL[Ut! if(hCallWnd[index]==NULL)
qPDe;$J) continue;
m/Ou$ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
H:Y?(" k {
1v)ur\>R SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
vnwS&;-k~ bProcessed=TRUE;
Au<NUc
2 }
ShbW[*5 }
Tf(-Duxz
}
89e<,f`h else if((lParam&0xc000ffff)==1){ //Key down
fQ33J> switch(wParam)
w/BaaF.0 {
Y>
ElE- case VK_MENU:
1O3"W;SR<: MaskBits|=ALTBIT;
ZFpi'u.& break;
>Vc;s!R case VK_CONTROL:
P>n}\"z4 MaskBits|=CTRLBIT;
M:K5r7Q!yv break;
`1k0wT( case VK_SHIFT:
~iI4v#0 MaskBits|=SHIFTBIT;
1(t{)Z< break;
vncLB&@7 default: //judge the key and send message
HjCcfOej break;
-7{ qTe{ }
uvC ![j^~ for(int index=0;index<MAX_KEY;index++)
:j feY {
$fZVh% if(hCallWnd[index]==NULL)
'b(V8x continue;
4+46z| if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
U0>Uqk", {
1 ? be SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
$bSnbU< bProcessed=TRUE;
x[L/d"Wf }
r0jhIE# }
DvL/xlN }
=, kH(rp2 if(!bProcessed){
S 2vjjS for(int index=0;index<MAX_KEY;index++){
J;@g#h? if(hCallWnd[index]==NULL)
JR>v continue;
e+416
~X
v if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
mtfEK3?2* SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
a(cZ]`s]* }
U4PnQ
K, }
`wrN$& }
~t0\Q; @($ return CallNextHookEx( hHook, nCode, wParam, lParam );
BuwJR
Ql. }
4l)Q ";vP77|m7R BOOL InitHotkey()
xn1=@0
a {
XNZW J if(hHook!=NULL){
\M(#FS nHookCount++;
lxSCN6 return TRUE;
?-.Qv1hs6p }
~#
~XDcc else
(c3%rM m] hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
#21t8 if(hHook!=NULL)
(zv)cw% nHookCount++;
bIs@CDB return (hHook!=NULL);
0{0A,;b }
0xZX%2E BOOL UnInit()
#}y(D{z c {
`-,yJ if(nHookCount>1){
83~9Xb=!\ nHookCount--;
f3bZ*G%f return TRUE;
iRwlK5(& }
P%%[_6<%M BOOL unhooked = UnhookWindowsHookEx(hHook);
Wa {()Cz if(unhooked==TRUE){
cx_.+ R nHookCount=0;
J|Af`HJ hHook=NULL;
g#Doed.30= }
k uEB return unhooked;
:f9O3QA }
8r|5l~`8 cbHb!Lbg BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
(K"8kQLY {
/d/Quro BOOL bAdded=FALSE;
u=mJI* for(int index=0;index<MAX_KEY;index++){
{\87]xJ if(hCallWnd[index]==0){
F~qiNV hCallWnd[index]=hWnd;
"@h 5
SF HotKey[index]=cKey;
c"<bq}L7S HotKeyMask[index]=cMask;
JE[+ bAdded=TRUE;
kJy
bA KeyCount++;
,pc\
)HR break;
@qGg=)T }
y%9Q]7&= }
x?|C-v return bAdded;
bM%c*_$F7 }
^KK9T5H 1zz.`.R2U BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
T -'B-g {
.W9/*cZV0 BOOL bRemoved=FALSE;
p]7Gj&a for(int index=0;index<MAX_KEY;index++){
XI rNT:h4 if(hCallWnd[index]==hWnd){
WecJ^{g>r{ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
>Za66<: hCallWnd[index]=NULL;
e 1k\:]6 HotKey[index]=0;
fK$N|r HotKeyMask[index]=0;
Xc^7 bRemoved=TRUE;
uy,ySBY KeyCount--;
N,><,7!q$, break;
H$
sNp\[{ }
<_|H]^o }
v7l4g&