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:
H0YxPk)
='0f#>0Q 一、实现方法
#D$vH *|RQ
) 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
siHS@S Tej-mr3P #pragma data_seg("shareddata")
eswsxJ/! HHOOK hHook =NULL; //钩子句柄
#w4=kWJ[ UINT nHookCount =0; //挂接的程序数目
u,e(5LU static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
s}d1 k static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
S3=M k~_& static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
.f V-puE static int KeyCount =0;
,xew3c'(W static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
b&;1b<BwD #pragma data_seg()
XK
(y ?Y1 D %`64R 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
D/w4u;E@ ?5qo>W<7 DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
RrkS!E[C ~R]E=/ m| BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
{Tp0#fi cKey,UCHAR cMask)
lGI5 {
6s833Tmb&r BOOL bAdded=FALSE;
7RmL#f` for(int index=0;index<MAX_KEY;index++){
:4"SJ if(hCallWnd[index]==0){
+b.qzgH>r hCallWnd[index]=hWnd;
VJX{2$L HotKey[index]=cKey;
}*~EA=YN; HotKeyMask[index]=cMask;
7 N?x29 bAdded=TRUE;
5O
Ob( KeyCount++;
4-4lh
TE( break;
\]U@=w }
\*H/YByTb }
U
n#7@8, return bAdded;
HM])m>KeT }
mAFqA //删除热键
,uD F#xjl, BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
2roPZj {
x+vNA J BOOL bRemoved=FALSE;
qwu++9BM for(int index=0;index<MAX_KEY;index++){
~ySmN}3~' if(hCallWnd[index]==hWnd){
r3l}I6 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
bh&,*Y6= hCallWnd[index]=NULL;
@^y/V@lDm HotKey[index]=0;
~y}M
GUEC HotKeyMask[index]=0;
z[DUktZl bRemoved=TRUE;
URDb KeyCount--;
5#.uA_Fov break;
2,O-/A;tW* }
TR,,=3n }
J_s?e#s }
J'4{+Q_pa return bRemoved;
}(AUe5aw`G }
t@1e9uR BciwS_Qx ^CTgo,uf6H DLL中的钩子函数如下:
p3:x\P<| U`JzE"ps] LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
+(5 H$O{h {
$V~r*#$. BOOL bProcessed=FALSE;
GA{>=Q_~ if(HC_ACTION==nCode)
&J_|P43 {
z 12[vN if((lParam&0xc0000000)==0xc0000000){// 有键松开
O+1e switch(wParam)
+vkqig {
5nr}5bum case VK_MENU:
hA?j"y0? MaskBits&=~ALTBIT;
sJX/YGHt break;
h:(Jes2 case VK_CONTROL:
-gh',)R MaskBits&=~CTRLBIT;
*eL%[B break;
$"T1W=;j9 case VK_SHIFT:
EA2BN} MaskBits&=~SHIFTBIT;
|H5){ 2V>K break;
S(5.y%"< default: //judge the key and send message
iYA06~d break;
FpE83}@".w }
$nQ; ++ for(int index=0;index<MAX_KEY;index++){
StWDNAf) if(hCallWnd[index]==NULL)
M}}9 continue;
gh}FZs5P if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
A6}M F {
*Xt#04_ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
r_]wa bProcessed=TRUE;
Ly\$?3h }
RMDs~ }
m?xzx^xs/ }
!,Wd$UK else if((lParam&0xc000ffff)==1){ //有键按下
7|T<dfQk switch(wParam)
%96JH
YcX {
{$>*~.Wu case VK_MENU:
OekcU%C MaskBits|=ALTBIT;
Kwfrh? break;
4QK([q case VK_CONTROL:
JiP]FJ; MaskBits|=CTRLBIT;
&6,GX7]Fo break;
*%'4.He7V case VK_SHIFT:
#O^H?3Q3 MaskBits|=SHIFTBIT;
[X)+(-J break;
YWM$% default: //judge the key and send message
zY(*Xk break;
.txgb }
j*Q/vY!T for(int index=0;index<MAX_KEY;index++){
Gp$[u4-6M6 if(hCallWnd[index]==NULL)
nTY`1w.; continue;
@.T' if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
J$&!Y[0 {
]1%H.pF SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
}f^r@3Cb3 bProcessed=TRUE;
eGvHU ;@ }
X.xp'/d }
J @"wJEF }
d7^:z%Eb| if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
zUXqTcj for(int index=0;index<MAX_KEY;index++){
P$.Azrl if(hCallWnd[index]==NULL)
$2Ox;+ continue;
)qD%5} t if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
BkA>':bUr SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
Uk-^n~y //lParam的意义可看MSDN中WM_KEYDOWN部分
jN 5Hku[? }
gnNMuqt }
V8NNIS }
;f[Ki$7 return CallNextHookEx( hHook, nCode, wParam, lParam );
6*kY7 }
Mc~(S$FU$ 6=90 wu3 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:
]s s0~2 ;:cU /{W BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
f`p`c* BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
FM0)/6I'x /`D]m? 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:
u
q:>g ~({aj|Y LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
]0xbvJ8oK {
[xk1}D if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Ws4aCH 1 {
W )q^@6[d //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
rYeFYPS SaveBmp();
QgEG%YqB return FALSE;
bL!NT}y` }
#; E,>0 …… //其它处理及默认处理
jIZQ/xp8_ }
-&M9Yg|Se nmc=RK^cM <'-}6f3 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。
G#)>D$Ck# 4Me*QYD 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
%&4sHDP E0>4Q\n{ 二、编程步骤
@;fdf 3ian TWEmW&Q 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
5ts8o&|
!a~>;+ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
d'kQE_y2. tu6c!o,@ 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
7}%3Aw6]S ^g~Asz5] 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
-}MWA>an8 C:_!zY'z 5、 添加代码,编译运行程序。
4B<D.i ;} K4N~ApLB+ 三、程序代码
45edyQ oA"t`,3 ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
st|$Fu #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
E4HG`_cWb #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
u\ytiGO* #if _MSC_VER > 1000
_|wgw^.LJ] #pragma once
JQ%e' #endif // _MSC_VER > 1000
V(=~p[ #ifndef __AFXWIN_H__
-/B}XNW #error include 'stdafx.h' before including this file for PCH
CP |N2rb #endif
"\vEi
&C #include "resource.h" // main symbols
$[VKM|Zjw class CHookApp : public CWinApp
I(s\ Q[ {
Od^y&$|_%` public:
MH?|>6 CHookApp();
PD$ay^Y // Overrides
:'f#0 ox // ClassWizard generated virtual function overrides
aa.EtKl //{{AFX_VIRTUAL(CHookApp)
l\ts!p4f$ public:
hp%|n:.G virtual BOOL InitInstance();
4M6o+WV virtual int ExitInstance();
=KmjCz: //}}AFX_VIRTUAL
XtNe) Ry //{{AFX_MSG(CHookApp)
bb$1RLyRL // NOTE - the ClassWizard will add and remove member functions here.
oS/<)>\Gv // DO NOT EDIT what you see in these blocks of generated code !
V Z}^1e //}}AFX_MSG
ul?'kuYk DECLARE_MESSAGE_MAP()
8QE0J$d5 };
l-XiQ#-{ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
{uL<$;#i BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
:7e2O!zH_ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
ya5;C" BOOL InitHotkey();
pTST\0? BOOL UnInit();
Um4
} ` #endif
tUGnD<P s59v*
/ //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
*["9;_KD #include "stdafx.h"
YnNB#x8| #include "hook.h"
UVUbxFq: #include <windowsx.h>
!Jh-v #ifdef _DEBUG
G>M#
BuU #define new DEBUG_NEW
E O52 E| #undef THIS_FILE
DFwkd/3" static char THIS_FILE[] = __FILE__;
F8Rd#^9PD #endif
)V!9& #define MAX_KEY 100
Pc nr #define CTRLBIT 0x04
/wljbb/s #define ALTBIT 0x02
?>1AT==wI #define SHIFTBIT 0x01
go|/I& #pragma data_seg("shareddata")
&[3 xpi{v HHOOK hHook =NULL;
y"]?TEd UINT nHookCount =0;
I+!w9o2nZ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
e/6WhFN# static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
@rRBo:0% static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
]sd|u[:k static int KeyCount =0;
d?oupW}uu static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
1C{n!l #pragma data_seg()
y/$WjFj3" HINSTANCE hins;
!qV{OXdrB void VerifyWindow();
"
nq4! BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
m[LIM}Gu //{{AFX_MSG_MAP(CHookApp)
rG:IS= // NOTE - the ClassWizard will add and remove mapping macros here.
*%:p01&+ // DO NOT EDIT what you see in these blocks of generated code!
ZC_b`q< //}}AFX_MSG_MAP
YKJk)%;+w END_MESSAGE_MAP()
<dV|N$WV VSx[{yn CHookApp::CHookApp()
2L[/.| {
e=o<yf9>Q // TODO: add construction code here,
k v,'9z // Place all significant initialization in InitInstance
>5%
o9$|z }
`pn]jpW9 ua/A &XQx CHookApp theApp;
7ib~04 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
_SY<(2s]B {
Gx|$A+U BOOL bProcessed=FALSE;
Cl7IP<. if(HC_ACTION==nCode)
1tDd4r?Y {
m>x.4aO1 if((lParam&0xc0000000)==0xc0000000){// Key up
Op" \i switch(wParam)
54_CewL1P] {
h1z[ElEeoP case VK_MENU:
nC$f0r"z MaskBits&=~ALTBIT;
JX7_/P break;
@N7X(@O case VK_CONTROL:
Tsxl4ZK MaskBits&=~CTRLBIT;
'VS!< break;
W#P)v{K case VK_SHIFT:
``nuw7\C: MaskBits&=~SHIFTBIT;
-7fsfcGM$ break;
/+1+6MqRn* default: //judge the key and send message
B[F x2r`0 break;
R(74Px,/ }
M9.jJf for(int index=0;index<MAX_KEY;index++){
H1yl88K if(hCallWnd[index]==NULL)
mQ;b'0& continue;
f$Nz).( if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Pp7}|/ {
|#D3~au
SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Dkayk bProcessed=TRUE;
EA7 8& }
:XxsD D }
BKP XXR }
+7U$qEG else if((lParam&0xc000ffff)==1){ //Key down
Yz us= switch(wParam)
ZN~:^,PO/ {
"^fcXV9Wp case VK_MENU:
p[4KN(PyK MaskBits|=ALTBIT;
\EuMzb"G9p break;
w=
|).qQ] case VK_CONTROL:
6%sX<)n%] MaskBits|=CTRLBIT;
-%E+Yl{v break;
7<*sP%6bD case VK_SHIFT:
0UB)FK,9 MaskBits|=SHIFTBIT;
%"r3{Hs break;
z4!TK ps default: //judge the key and send message
?x7zYE,6 break;
@]uvpI!h }
gXZC%S for(int index=0;index<MAX_KEY;index++)
o9(:m {
'`p#%I@ if(hCallWnd[index]==NULL)
_Jx.?8 continue;
T?4MFx# if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
bX6eNk-L {
2 DJs'"8 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
1Jg&L~Ws" bProcessed=TRUE;
y2;uG2IS_g }
&m&Z^CA }
`wj<d>m }
?){V7<'?y if(!bProcessed){
2a'b}<|[( for(int index=0;index<MAX_KEY;index++){
5Mf bO3 if(hCallWnd[index]==NULL)
bgq/]fI} continue;
{U?/u93~
if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
hm*1w6 = SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
)D\!#<#h }
X31[ }
|=fa`8mG }
_CN5,mLNRk return CallNextHookEx( hHook, nCode, wParam, lParam );
rJH u~/_Dq }
V*5 ~A[r X:+lD58 BOOL InitHotkey()
Tf(-Duxz
{
R".~{6 if(hHook!=NULL){
Yj)H!Cp.xD nHookCount++;
\=Rw/[lR return TRUE;
mlW0ptp }
z2*>5c% else
i}"Eu<
P hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
1O3"W;SR<: if(hHook!=NULL)
_;/onM nHookCount++;
LI1OocY.] return (hHook!=NULL);
}c|)i,bL }
2XI%z4\)! BOOL UnInit()
*WdnP.'Y {
qIIc>By(\" if(nHookCount>1){
FC[8kq>Hk nHookCount--;
`1k0wT( return TRUE;
,7-@eZ }
MWTzJGRT BOOL unhooked = UnhookWindowsHookEx(hHook);
= i9|lU"Va if(unhooked==TRUE){
(Qq;ySZ# nHookCount=0;
P7np
-I* hHook=NULL;
x8
: }
@c,Qj$\1 return unhooked;
fGS5{dti }
p?F%a;V3 5q4sxY9T BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
WX<),u2@ {
+)YU/41W BOOL bAdded=FALSE;
_]zm02| for(int index=0;index<MAX_KEY;index++){
Af y\:&j if(hCallWnd[index]==0){
'b(V8x hCallWnd[index]=hWnd;
4UP#~ HotKey[index]=cKey;
6?\X)qBI HotKeyMask[index]=cMask;
0}v_usP bAdded=TRUE;
?=$=c8xw KeyCount++;
(jhDO7 break;
j0P+< @y }
(#,0\ea{x }
**p|g<wvY* return bAdded;
PCKgdh}, }
%Y!31oC# DvL/xlN BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
mz)Z
=`hy {
9?W!E_ BOOL bRemoved=FALSE;
)~@iM.}S2 for(int index=0;index<MAX_KEY;index++){
LWwWxerZ if(hCallWnd[index]==hWnd){
X|]&K if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
{Aq2}sRl{ hCallWnd[index]=NULL;
))Q3;mI" HotKey[index]=0;
K`%{(^}. HotKeyMask[index]=0;
C.su<B? bRemoved=TRUE;
uRIa
Nwohv KeyCount--;
!<'0
GOl break;
Qn0 1ig
}
(rF XzCI }
`wrN$& }
+2Xq+P return bRemoved;
DVC<P}/ }
8/4i7oOC i_<