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:
=odkz}bU
>O`l8tM 一、实现方法
0Dv JZ|e #} ,x @]p 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:
=J'P. Qu*1g(el!o #pragma data_seg("shareddata")
_cI_# HHOOK hHook =NULL; //钩子句柄
FY0%XW UINT nHookCount =0; //挂接的程序数目
$r.U static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
[2Mbk~ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
1hQN8!: < static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
"l~Ci7& !a static int KeyCount =0;
T`YwJ6N static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
]TpU"JD #pragma data_seg()
0NE{8O0;Fr ~ 9o6 W", 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。
_ *(bmJM oY9FK{ 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:
$Rtgr{ {;" o=+Z.-q BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
{+T/GBF-K= cKey,UCHAR cMask)
EYzg%\HH {
t=wXTK5" BOOL bAdded=FALSE;
D>ef for(int index=0;index<MAX_KEY;index++){
2OBfHO~D if(hCallWnd[index]==0){
m9$:9yRm hCallWnd[index]=hWnd;
D9ufoa&ua HotKey[index]=cKey;
cSD{$B: HotKeyMask[index]=cMask;
93%{scrm bAdded=TRUE;
<-C!;Ce{ KeyCount++;
BNm4k7
]M break;
7ETjn)%bs }
GuQRn }
%uDG75KP{ return bAdded;
Gm8E<iTP }
pK_?}~ //删除热键
9(1rh9`= BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
#*$p-I= {
D@54QJ< BOOL bRemoved=FALSE;
J\co1kO9/ for(int index=0;index<MAX_KEY;index++){
n@>wwp if(hCallWnd[index]==hWnd){
$^% N U if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
0%C^8%(x hCallWnd[index]=NULL;
C0C0GqN, HotKey[index]=0;
H'g?llh1J HotKeyMask[index]=0;
4cgIEw[6 bRemoved=TRUE;
0irr7Y KeyCount--;
ROAI9sW0 break;
v|t{1[C }
?m%h`<wgMc }
%e%7oqR? }
_^!vCa7f return bRemoved;
Opg#*w%- }
[=M% |7F*MP K'b*A$5o DLL中的钩子函数如下:
L4'[XcY L10IF LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
%_)zWlN {
|"7Pv
skT BOOL bProcessed=FALSE;
S3\jcgrS if(HC_ACTION==nCode)
E,"&-`/2v {
JSVeU54T^< if((lParam&0xc0000000)==0xc0000000){// 有键松开
^$?qT60%d| switch(wParam)
APBK9ky {
:h5J r8 case VK_MENU:
pA4 ,@O MaskBits&=~ALTBIT;
Q+[ .Y& break;
&y.dmW case VK_CONTROL:
8e:vWgQpL MaskBits&=~CTRLBIT;
%vqT#+x break;
[1Dm<G
u@ case VK_SHIFT:
MWwJzVL8 MaskBits&=~SHIFTBIT;
3(_!`0#F% break;
)iE"Tl default: //judge the key and send message
BSUPS+@+ break;
T_hV%
}
!C&%T] for(int index=0;index<MAX_KEY;index++){
Z5)eREi= if(hCallWnd[index]==NULL)
]|oJ)5P continue;
.[pUuVq] if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
F'W>
8
{
Hcv u7uD SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
4br6$ bProcessed=TRUE;
U6j/BJT" }
^X1wI9V }
&d^=siL }
%$X\" else if((lParam&0xc000ffff)==1){ //有键按下
Xa,&ef&q switch(wParam)
^X?D#\ {
Ie_I7YJ case VK_MENU:
3:`XG2' MaskBits|=ALTBIT;
*8A6Q9YT break;
/^<en(0=P case VK_CONTROL:
BQrL7y MaskBits|=CTRLBIT;
F@SG((` break;
*@M3p}',M case VK_SHIFT:
%J P!{mqj MaskBits|=SHIFTBIT;
Da,Tav%b break;
"kSwa16O default: //judge the key and send message
d<T%`:s< break;
B@cz
?%] }
2i:zz?
'p` for(int index=0;index<MAX_KEY;index++){
h7W}OF_=y if(hCallWnd[index]==NULL)
3E|;r
_;
8 continue;
ejcwg*i if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
rz {
&?<AwtNN SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
_Z#eS/,O@ bProcessed=TRUE;
8&(-8 }
4XG]z_+I }
VXC4% }
)/Y~6A9> if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
X>3^a'2,E for(int index=0;index<MAX_KEY;index++){
iJnh$jo if(hCallWnd[index]==NULL)
h|W%4|]R) continue;
TVkcDS if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
$I8[BYblB SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
&9P<qU^N) //lParam的意义可看MSDN中WM_KEYDOWN部分
a@W7<9fY; }
OlGR<X }
r%-n*_?.s }
TA;,>f* return CallNextHookEx( hHook, nCode, wParam, lParam );
uBeNXOre }
ntH T " i`8l.Lc 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
<94WZ?{p |5ONFde"0 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
FdxsUDL BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
[x_s/"Md; rm|7
[mK 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
%V_eJC""? mw+j|{[ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
h$&rE@N| {
0xP:9rm if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
{hd-w4"115 {
OmNn,PCl8 //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
#"r kuDO SaveBmp();
`ue?Z%p| return FALSE;
,+-h7^{` }
G8P+A1
f/> …… //其它处理及默认处理
SCq3Ds^ }
/djACA 7^wE$7hS cjY@Ot*i$ 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。
4A o{M ND,`QjmZ 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。
_LLshV3 4x]NUt 二、编程步骤
Czh8zB+r Mjw[:70 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";
{PmzkT}LF B\zoJg&7( 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
@_O3&ZK .zwVCW,u 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;
K+> V|zKuk B1,?{Ur 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;
?N_)>&b T{HfP 5、 添加代码,编译运行程序。
|Gc&1*$ 88YC0!Ni 三、程序代码
/j
%_t L9J;8+ge ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
gvr]]}h:O #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
.+uVgSN #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
am(#Fa #if _MSC_VER > 1000
J/[7d?hI/ #pragma once
\E&th p #endif // _MSC_VER > 1000
I+~\
w N #ifndef __AFXWIN_H__
k(9s+0qe #error include 'stdafx.h' before including this file for PCH
kaC+I"4c #endif
B[7A #include "resource.h" // main symbols
FvA|1c class CHookApp : public CWinApp
@7X\tV.Z {
QX+Y(P`vMK public:
'A1E^rl]= CHookApp();
_Q^y_f
// Overrides
W
U0UG$o` // ClassWizard generated virtual function overrides
0#]!#1utg //{{AFX_VIRTUAL(CHookApp)
0STk)>3$- public:
i6A$1(:h virtual BOOL InitInstance();
oVreP virtual int ExitInstance();
e
sGlMq //}}AFX_VIRTUAL
oFn4%S: //{{AFX_MSG(CHookApp)
T7s+9CE // NOTE - the ClassWizard will add and remove member functions here.
%|bN@@ // DO NOT EDIT what you see in these blocks of generated code !
8_Jj+ //}}AFX_MSG
30BR0C DECLARE_MESSAGE_MAP()
2X^iV09 };
w4aiI2KFq LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
Pgx+\;w" BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
13\Sh BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
aYR\ <02 BOOL InitHotkey();
9Mnem* BOOL UnInit();
CP@o,v- #endif
epYj+T ^X$
I= ro //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
T77)Np #include "stdafx.h"
[e1\A&T #include "hook.h"
g\qX7nIH? #include <windowsx.h>
jigbeHRy #ifdef _DEBUG
y]MWd#U #define new DEBUG_NEW
O2$!'!hz #undef THIS_FILE
_3I3AG0e static char THIS_FILE[] = __FILE__;
@X|ok*v` #endif
^`/V i #define MAX_KEY 100
(+@faP
#define CTRLBIT 0x04
Lq%[A*`^ #define ALTBIT 0x02
c.\:peDk #define SHIFTBIT 0x01
svF*@(-P# #pragma data_seg("shareddata")
[KD}U-(Wg HHOOK hHook =NULL;
M Ey1~h/ UINT nHookCount =0;
@H3|u`6V static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
D`8E-Bq static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
;g6 nHek static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
V02309Y static int KeyCount =0;
&8zk3 static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
RlPjki"Mg #pragma data_seg()
l(.7t' HINSTANCE hins;
:S#eg1y.w] void VerifyWindow();
vW9^hbdx BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
{~ ":; //{{AFX_MSG_MAP(CHookApp)
@f-0X1C."N // NOTE - the ClassWizard will add and remove mapping macros here.
y B1W>s8& // DO NOT EDIT what you see in these blocks of generated code!
Cx$9#3\ //}}AFX_MSG_MAP
BzN/6VEw END_MESSAGE_MAP()
h=:*7>} ;U8dm" CHookApp::CHookApp()
YHJ' {
7eTA`@v5A // TODO: add construction code here,
;.L!%$0i# // Place all significant initialization in InitInstance
T..-)kL+p }
69N1 mP )0'Y et} CHookApp theApp;
>h|UC J1
` LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
HE9.
k.sS {
"MW55OWYU BOOL bProcessed=FALSE;
1LV|t+Sex if(HC_ACTION==nCode)
>>/nuWdpO {
"sC$%D<oc if((lParam&0xc0000000)==0xc0000000){// Key up
\?J=mE@;1 switch(wParam)
_CHKh*KHML {
6ch@Be5* case VK_MENU:
VOD1xWrb MaskBits&=~ALTBIT;
qdKh6{ break;
7'c8]/qh case VK_CONTROL:
Ty)gPh6O MaskBits&=~CTRLBIT;
]eY Qio! break;
5L/Yi case VK_SHIFT:
Q,ZkeWQ7% MaskBits&=~SHIFTBIT;
v\J!yz break;
=#7s+ d- default: //judge the key and send message
D-;J;m
\ break;
AviT+^7E }
Kv(Y } for(int index=0;index<MAX_KEY;index++){
M|5^':Y if(hCallWnd[index]==NULL)
^w.k^U=B continue;
VG? yL2y if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
ER0TY, {
}Ox2olUX SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Z`e$~n(Bh bProcessed=TRUE;
':5U& }
tW'qO:y+ }
ZKVp[A }
[I#Q else if((lParam&0xc000ffff)==1){ //Key down
b=6ZdN1 switch(wParam)
= .fc"R|<K {
8f5%xY$ case VK_MENU:
5;r({J MaskBits|=ALTBIT;
`PXoJl break;
!.x=r case VK_CONTROL:
Y;~EcM MaskBits|=CTRLBIT;
rCV$N&rK break;
LX&=uv%-^ case VK_SHIFT:
Ly@U\%. MaskBits|=SHIFTBIT;
MZgmv break;
&Z#Vw.7U default: //judge the key and send message
Yqq$kln break;
zW|$x<M^ }
pP=_@3 D for(int index=0;index<MAX_KEY;index++)
M)bC%(xJ {
Zb5T90s% if(hCallWnd[index]==NULL)
p]atH<^;K continue;
1aXIhk4 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
DR#3njjEC {
M}_M_ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
0nF>zOmc bProcessed=TRUE;
)AZ`R8-A }
Ip1QVND }
2}W6{T' }
^/4{\3 if(!bProcessed){
?,A8 fR for(int index=0;index<MAX_KEY;index++){
n=<q3}1Jej if(hCallWnd[index]==NULL)
J-HabHv continue;
G5C#i7cpm if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
oW` *FD SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
#CBo }
#RsIxpc }
PDa06(t7 }
^^W`Lh%9 return CallNextHookEx( hHook, nCode, wParam, lParam );
dW] Ej"W }
"' LOaf$X qX}dbuDE"P BOOL InitHotkey()
`0/gs {
k;9#4^4( if(hHook!=NULL){
O;.d4pO(tC nHookCount++;
I+-Rs2wb return TRUE;
4.$hHFqS^5 }
|G5=>W else
?L.p9o-S0 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
#oS if(hHook!=NULL)
-F~9f> nHookCount++;
Xqq?S return (hHook!=NULL);
2n\i0?RD }
J@&$U7t BOOL UnInit()
**
"s~ {
s`dkEaS if(nHookCount>1){
w^vK7Z
1$ nHookCount--;
*8(t y%5F0 return TRUE;
TO8\4p*tE }
P7^TRrMF BOOL unhooked = UnhookWindowsHookEx(hHook);
}pU!1GsO if(unhooked==TRUE){
`^@g2c+d nHookCount=0;
6 I>xd hHook=NULL;
h_}BmJ h_ }
?7uStqa return unhooked;
KH CdO }
M 2U@gC|{ IT{.^rP BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Z2Y583D {
w Lg:YM" BOOL bAdded=FALSE;
V%Z[,C
u+ for(int index=0;index<MAX_KEY;index++){
h3vm<R; if(hCallWnd[index]==0){
0L
4]z'5 hCallWnd[index]=hWnd;
cUX]tiC0 HotKey[index]=cKey;
=&