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:
ant2];0p
Zqb*-1Qw"* 一、实现方法
'lOQb) K>n@8<7 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:
&kT!GU^n $9u:Ox
2 #pragma data_seg("shareddata")
^mN`!+ HHOOK hHook =NULL; //钩子句柄
lwIxn1n UINT nHookCount =0; //挂接的程序数目
b*4aUpW static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
Bm<tCN-4 static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
q_[`PYT static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
s+E4AG1r static int KeyCount =0;
{Z178sik static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
uuL(BUGt- #pragma data_seg()
a %?v/Ku XJk~bgO* 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
_,igN> Xe(]4Ux DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
q Ll4t/p N2lz{ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
We'= /! cKey,UCHAR cMask)
?a'EkZ.dB {
TP)o0U BOOL bAdded=FALSE;
j,z)x[3} for(int index=0;index<MAX_KEY;index++){
dux_v"Xl if(hCallWnd[index]==0){
Mhc5<~? hCallWnd[index]=hWnd;
MM( ,D&
Z HotKey[index]=cKey;
Nnoj6+b HotKeyMask[index]=cMask;
-OnKvpeI bAdded=TRUE;
`'gcF}); KeyCount++;
'2rSX[$tf break;
uA cvUN-@ }
9E|QPT }
wB+F/]]|N return bAdded;
3}C-Hg+gt }
;ULw-&]P //删除热键
%Z8pPH~T BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
v?n# C {
T7l,}G BOOL bRemoved=FALSE;
J|HV8 for(int index=0;index<MAX_KEY;index++){
IoV"t, if(hCallWnd[index]==hWnd){
zvfdfQ-i if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
E,ooD3$h hCallWnd[index]=NULL;
i+lq:St HotKey[index]=0;
;ZkY[5 HotKeyMask[index]=0;
[jEA|rd~} bRemoved=TRUE;
%=V"
}P[ KeyCount--;
&3)6WD?:U break;
k?/! ` }
RN;#H_
q }
z80*Ylx }
/q/^B>] return bRemoved;
Oi{J}2U }
K7/&~;ZwT `m$,8f%j6_ $U(D*0+o/ DLL中的钩子函数如下:
-O?A" <TSps!(# LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
!>&G+R+k {
lLK||2d BOOL bProcessed=FALSE;
Bgai|l if(HC_ACTION==nCode)
V9%9nR!' {
L:Faq1MG if((lParam&0xc0000000)==0xc0000000){// 有键松开
P$3!4D[ switch(wParam)
c;=St1eoz {
0
t/mLw& case VK_MENU:
D%=&euB MaskBits&=~ALTBIT;
;6?,Yhk$h break;
>4HB~9dKU case VK_CONTROL:
cBHUa}: MaskBits&=~CTRLBIT;
j
J54<.D break;
)0Vj\> case VK_SHIFT:
c)q=il7ef MaskBits&=~SHIFTBIT;
H)y_[:[ break;
Z+4Mo*# default: //judge the key and send message
%O{FZgi%wA break;
uVXn/B }
u{dkUG1ia for(int index=0;index<MAX_KEY;index++){
u/N_62sk5 if(hCallWnd[index]==NULL)
W&m3"~BJ continue;
kHQn'r6 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
{3!A\OR {
&?']EcU5h9 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
cvx"XxE, bProcessed=TRUE;
ZT,auSX }
Cn.dv- }
Upm#:i|" }
#;m^DX QZn else if((lParam&0xc000ffff)==1){ //有键按下
$lJ!f switch(wParam)
KCqz] {
7JY9#+?p> case VK_MENU:
Oe^9pH,1t MaskBits|=ALTBIT;
-vt6n1A&b break;
a(h@4 x case VK_CONTROL:
':utU1dL MaskBits|=CTRLBIT;
UA#=K+2 break;
`eGp.[ffT case VK_SHIFT:
d Z+7S`{ MaskBits|=SHIFTBIT;
NVDIuh break;
"k),;1 default: //judge the key and send message
:MH=6 break;
a&`^M }
-7 EwZRS@9 for(int index=0;index<MAX_KEY;index++){
64:p 4N if(hCallWnd[index]==NULL)
sr~VvciIy continue;
`2xt%kC if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
C3 m_sv#e {
Gr3 q SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
!=+;9Ry$z bProcessed=TRUE;
ADMeOdgca }
Q0Gfwl }
~\%H0.P6 }
IY?o \vC if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
nYj7r*e[ for(int index=0;index<MAX_KEY;index++){
q"-Vh,8h if(hCallWnd[index]==NULL)
~fO#En
continue;
~0vNs2D,S if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
&3*r-9BZ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
R!rMrWX //lParam的意义可看MSDN中WM_KEYDOWN部分
TdoH((nY }
XW{cC`&
}
}E)t,T> }
s2nZW pIy return CallNextHookEx( hHook, nCode, wParam, lParam );
eE{
2{C }
YT@H^= rPHM_fW(O@ 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:
-3XnUGK V0gu0+u~R BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
W5&KmA BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
(c[DQS j rhN"#? 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:
/]nrxT :[Ie0[H/M LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
#;"lBqxY` {
mUiJ@ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
(k%r_O 6 {
pU u')y //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
D P:}< SaveBmp();
g
G|4+' t return FALSE;
4&~*;an7 }
YIYuqtnSJ …… //其它处理及默认处理
>EgMtZ88.< }
u5,vchZ d-]!aFj|U =e6!U5
f 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。
A}1:fw\Fn3 #|Je%t}~ 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。
[bN_0T.YI <H1e+l{8$ 二、编程步骤
V("T9g K%/g!t) 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";
Ge76/T%{Q fqol-{F.V 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
Ft>, BU^E68?G 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;
ulk yP o* QZf*M 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;
u 0 K1n_ QW%xwV?8 5、 添加代码,编译运行程序。
<XnxAA QwI HEmdM 三、程序代码
1_LGlu~& C,{ Ekbg ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
r;fcBepO #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
8sL+ik" #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
j*_#{niy: #if _MSC_VER > 1000
"%=K_WJ? #pragma once
4o@^._-R #endif // _MSC_VER > 1000
p vu% p8 #ifndef __AFXWIN_H__
1qwJPM #error include 'stdafx.h' before including this file for PCH
Z0Qh7xWve #endif
q4u-mM7#7 #include "resource.h" // main symbols
c* )PS`]t class CHookApp : public CWinApp
&Fch{%S> {
=Flr05}m public:
YMn=9EUp CHookApp();
]T>YYz
// Overrides
x}N1Wl=8g // ClassWizard generated virtual function overrides
&)EL%o5 //{{AFX_VIRTUAL(CHookApp)
S,C/l1s public:
OEHw% virtual BOOL InitInstance();
V}4u1oG virtual int ExitInstance();
cHwN=mg]S //}}AFX_VIRTUAL
Zor Q2> //{{AFX_MSG(CHookApp)
!(N,tZ // NOTE - the ClassWizard will add and remove member functions here.
!]!9 $6n // DO NOT EDIT what you see in these blocks of generated code !
jL~. =QD //}}AFX_MSG
8;Df/% DECLARE_MESSAGE_MAP()
hx@E, };
W-vEh LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
X""}]@B9z BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
jt&rOPL7 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
4eS(dPI0 BOOL InitHotkey();
L4Si0 K BOOL UnInit();
<9?`zo$y #endif
'S;l" vslN([@JR //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
iIg99c7/&9 #include "stdafx.h"
XN'<H(G #include "hook.h"
Fi#b0S #include <windowsx.h>
U9q6m3#$ #ifdef _DEBUG
q.p.y0 #define new DEBUG_NEW
>zv}59M #undef THIS_FILE
UC"_#!3 static char THIS_FILE[] = __FILE__;
[b@9V_ #endif
F#7A6| #define MAX_KEY 100
IQ9Rvnna #define CTRLBIT 0x04
~ponYc.Y #define ALTBIT 0x02
.BZ3>]F3< #define SHIFTBIT 0x01
Uj~
:|?Wz #pragma data_seg("shareddata")
1?T^jcny:M HHOOK hHook =NULL;
6XGqZ!2 UINT nHookCount =0;
T@DT|lTI static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
ww~gmz static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
}Ym~[S*x static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
u-~?ylh static int KeyCount =0;
X1lL@ `r.5 static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
xXZ{ #pragma data_seg()
/w(t=Y HINSTANCE hins;
7vK}aOs0 void VerifyWindow();
x^6sjfAW BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
\jByJCN //{{AFX_MSG_MAP(CHookApp)
dn=g!= // NOTE - the ClassWizard will add and remove mapping macros here.
QgW4jIbx // DO NOT EDIT what you see in these blocks of generated code!
iYzm<3n? //}}AFX_MSG_MAP
^2!l/(? END_MESSAGE_MAP()
N>+L?C \-)augq([ CHookApp::CHookApp()
[+4--#&{ {
0D48L5kH#' // TODO: add construction code here,
-8, lXrH // Place all significant initialization in InitInstance
8E\6RjM }
P 4jg]g 4 O~zkg CHookApp theApp;
]_P!+5]< LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
8w4cqr4m {
,W~a%8* BOOL bProcessed=FALSE;
8{J{)gF if(HC_ACTION==nCode)
G+f@m, {
_#6ekl|% if((lParam&0xc0000000)==0xc0000000){// Key up
Y,C3E>}Dq switch(wParam)
s4Z5t$0| {
-<WQ>mrB& case VK_MENU:
L\H,cimN MaskBits&=~ALTBIT;
[|\BuUT' break;
<Q?X'. case VK_CONTROL:
<YBA
7i MaskBits&=~CTRLBIT;
*ZA.O break;
>2?O-WXe case VK_SHIFT:
0=Z_5.T> MaskBits&=~SHIFTBIT;
uE{nnNZy break;
vOYG&)Jm default: //judge the key and send message
A!j6JY.w break;
I^fKZ^]8P }
tV,Y38e for(int index=0;index<MAX_KEY;index++){
`O|PP3S if(hCallWnd[index]==NULL)
(E(kw=" continue;
&B5@\Hd; if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
)6:nJ"j# {
o w<.Dh SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
]
6rr;S bProcessed=TRUE;
y9L:2f\ }
r(QjVLjj`k }
!|gln)|A }
:svRn9_8H else if((lParam&0xc000ffff)==1){ //Key down
uyITUvPg[ switch(wParam)
m;d#*}n\p {
Jd>"g9 case VK_MENU:
/`V:; MaskBits|=ALTBIT;
s'|^ 6/ break;
AHre#$`97 case VK_CONTROL:
@.Pe.\Z MaskBits|=CTRLBIT;
-Am~CM break;
]MXeWS( case VK_SHIFT:
Z6I^HG{: MaskBits|=SHIFTBIT;
bl;C=n break;
ngoAFb default: //judge the key and send message
e$+?l~ break;
O0i[GCtP5 }
%XieKL for(int index=0;index<MAX_KEY;index++)
71ctjU`U2 {
l|P(S(ikh if(hCallWnd[index]==NULL)
vg5;F[e continue;
U^$o<2 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
*@2?_b}A
^ {
k6vY/)-S SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
v&GBu bProcessed=TRUE;
r!vSYgee }
,!?&LdPt> }
k )T;WCia }
h)qapC5z, if(!bProcessed){
sKT GZA for(int index=0;index<MAX_KEY;index++){
g&30@D" if(hCallWnd[index]==NULL)
mw1|>*X&R continue;
kU5chltGF if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
wv8WqYV SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
si nnHQ }
*VFUC: }
|-c)OS3#D }
/~Q2SrYH return CallNextHookEx( hHook, nCode, wParam, lParam );
Q!<b"8V] }
qUY QN2wG KXP^F6@l BOOL InitHotkey()
+)4_1i4"x {
( &U8NeWZ if(hHook!=NULL){
E}V8+f54S nHookCount++;
d?)C} 2 return TRUE;
mG!Rh }
(bk~,n_ else
TrHz(no hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
H *gF>1 if(hHook!=NULL)
#lM :BO nHookCount++;
>d&_e[j return (hHook!=NULL);
0N~AQu }
gZ*8F|sg BOOL UnInit()
Jm|eZDp {
Ub8|x]ix if(nHookCount>1){
DV(^h$1_ nHookCount--;
Gmi w(T return TRUE;
-$#' }
9:!<=rk BOOL unhooked = UnhookWindowsHookEx(hHook);
P7;=rSW if(unhooked==TRUE){
(dxkDS-G nHookCount=0;
AK/_^?zA s hHook=NULL;
xA-O?s"CY }
RSLMO8 return unhooked;
*t'qn }
TM8WaH S"iz
fQ@ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
UGNFWZ c {
{]aB3 BOOL bAdded=FALSE;
'G!w0yF for(int index=0;index<MAX_KEY;index++){
\h DH81L if(hCallWnd[index]==0){
LB|FVNW/S hCallWnd[index]=hWnd;
p-H q\DP HotKey[index]=cKey;
h[SuuW HotKeyMask[index]=cMask;
XAV|xlfm bAdded=TRUE;
k{3:$,
b KeyCount++;
QQ4
&,d break;
]e?cKC\"e }
8kz7*AO
}
Q]7Rqslz return bAdded;
opK=Z }
Ldnw1xy H[ DrG6GA BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
T.vkGB=QZ% {
1'dL8Y BOOL bRemoved=FALSE;
*7'}"@@ for(int index=0;index<MAX_KEY;index++){
`k} if(hCallWnd[index]==hWnd){
85P7I=`*d if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
G'/36M@ hCallWnd[index]=NULL;
HF9d~7R HotKey[index]=0;
;Zb+WGyj HotKeyMask[index]=0;
IiG~l+V~ bRemoved=TRUE;
^Tbw#x]2 KeyCount--;
)E<<