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:
J/=b1{d"n
5q@o,d 一、实现方法
ix,5-j :QB Wy 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:
ig3uY# 1NA>W #pragma data_seg("shareddata")
e>X&[\T HHOOK hHook =NULL; //钩子句柄
y1FS?hSD0 UINT nHookCount =0; //挂接的程序数目
DL<r2h static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
4,UvTw*2z static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
Bz]j&` static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
JoIffI?{(D static int KeyCount =0;
*=)%T(^ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
kC6J@t) #pragma data_seg()
BPtU]Bv- ,}F{V>dhn 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。
enE8T3 /id(atiF^ 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:
L~CwL `G6Nk@9. BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
bv-s}UP0 cKey,UCHAR cMask)
{
+MqXeq {
,,lrF. BOOL bAdded=FALSE;
V(w2k^7)F for(int index=0;index<MAX_KEY;index++){
xLX:>64'o> if(hCallWnd[index]==0){
|-=^5q5 hCallWnd[index]=hWnd;
dKi+~m'w HotKey[index]=cKey;
K%Jy?7
U HotKeyMask[index]=cMask;
L-",.U*; bAdded=TRUE;
^0c:ro KeyCount++;
d%\en&:la break;
d 6j'[ }
NqVe{+1x }
m<hR
Lo return bAdded;
=X]$J@j }
|?i-y3N //删除热键
]t(;bD hT BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
\k;*Ej~. {
rt^<=|Z BOOL bRemoved=FALSE;
[C.Pzo for(int index=0;index<MAX_KEY;index++){
;WWUxrWif if(hCallWnd[index]==hWnd){
vSX71 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
TlQu+w| hCallWnd[index]=NULL;
Si.3Je[q HotKey[index]=0;
Tz:mj HotKeyMask[index]=0;
rq:R6e bRemoved=TRUE;
]|@RWzA KeyCount--;
Xq` '^) break;
mtvfG }
uR"(0_ }
"O!J6 }
H3nx8R$j]( return bRemoved;
zkA"2dh }
E0o= _r^Cu.[7 y?zNxk/p DLL中的钩子函数如下:
:?O+EE 2aNCcZw0 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
37Q9goMov {
Z4b<$t[u BOOL bProcessed=FALSE;
#"jEc*&= if(HC_ACTION==nCode)
ckHHD| {
'x$>h)t] if((lParam&0xc0000000)==0xc0000000){// 有键松开
>T'^&l(: switch(wParam)
CuR.a {
Wz`MEyj case VK_MENU:
Hw-,sze j" MaskBits&=~ALTBIT;
|W[BqQIf break;
3){ /u$iH. case VK_CONTROL:
Xb@lKX5Re MaskBits&=~CTRLBIT;
"u@) break;
82O#Fe q case VK_SHIFT:
_e
E(P1 MaskBits&=~SHIFTBIT;
o4^rE<vJ break;
%3M1zZY default: //judge the key and send message
H.3+5po break;
""|vhgP }
8vjaQ5
for(int index=0;index<MAX_KEY;index++){
ZaIlo5 if(hCallWnd[index]==NULL)
KP(RK4F continue;
c*sK| U7) if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
!vH7vq {
[7]Kvb2t SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
mI_ ?hl?Pv bProcessed=TRUE;
iaPrkMhd }
f|P% }
:OT~xU==H }
h&|q>M3 else if((lParam&0xc000ffff)==1){ //有键按下
@)owj^sA switch(wParam)
8q58H[/c {
Oc8]A=M12 case VK_MENU:
z%Pbs[*C MaskBits|=ALTBIT;
(,z0V+! break;
Dl_y[9 case VK_CONTROL:
Y]!8Ymuww@ MaskBits|=CTRLBIT;
$k5mI1~ break;
ZJlmHlAX case VK_SHIFT:
} Wx#"6 MaskBits|=SHIFTBIT;
yhhW4rz break;
=B-a]?lM default: //judge the key and send message
zGjf7VV2a break;
3\j{*f$J }
B! $a Y for(int index=0;index<MAX_KEY;index++){
f mXU) if(hCallWnd[index]==NULL)
mltG4R
? continue;
KjFNb;mM if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
2mg4*Ys {
w7GF,a SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
;j|T#-. bProcessed=TRUE;
~?T*D* }
#z$FxZT<b }
+0lvQVdp} }
*8ykE if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
X2^`Znq9 for(int index=0;index<MAX_KEY;index++){
nKPvAe( if(hCallWnd[index]==NULL)
/G[; kR" continue;
j5QS/3 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
RRR'azT SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
mVUDPMyZ //lParam的意义可看MSDN中WM_KEYDOWN部分
V bQ9o }
t_%6,?S6 }
MDI[TNYG }
rWzw7T~ return CallNextHookEx( hHook, nCode, wParam, lParam );
t F^|,9_< }
eJD!dGa Huzw> 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:
Q%:#xG5AmE Sg;c |u BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
H~y 7o_tg BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
s"G;rcS}# ANgfG8> 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:
(o`"s~) ,-,BtfE3 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
?+EN.P[;3 {
eTVI.B@p if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
N4y$$.uv2 {
M8j%bmd(, //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
`uK_}Vy_ SaveBmp();
X$z@ *3= return FALSE;
;/.ZjTRw }
LU
"e9 …… //其它处理及默认处理
9*wS}A&Jh }
pI*/-!I c}(fmJB&( 9;,_Qq 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
V-rzn171Q) V0y Q 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
B]jI^(P >:7W.QLRU 二、编程步骤
--Dd' T 9lk&7W 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
A'(v]w U-+%e:v
2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
uEp
v l n$>E'oG2t 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;
v"x{oD$R zSs5F_ 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
#IH7WaN ;yh}$)^9 5、 添加代码,编译运行程序。
@#sBom+K` |4RuT
.-o 三、程序代码
ai/VbV'| zQsu~8PX ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
Mx&
P^#B3
#if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
GS1Vcav< #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
WPbWG$Li #if _MSC_VER > 1000
nFE0y3GD8 #pragma once
L_$M9G|5n #endif // _MSC_VER > 1000
aBL+i- #ifndef __AFXWIN_H__
\g|u|Y.2[ #error include 'stdafx.h' before including this file for PCH
;-Bi~XD #endif
Gp6|0:2,L~ #include "resource.h" // main symbols
NUB 3L class CHookApp : public CWinApp
6OeRBD& {
6@ `'} public:
>C|/%$kk:f CHookApp();
WHh=hts\ // Overrides
"f'pa&oHi // ClassWizard generated virtual function overrides
bvM\Qzc!<3 //{{AFX_VIRTUAL(CHookApp)
N"d*pi#h public:
6fxf|R\ virtual BOOL InitInstance();
RJMrSz$ virtual int ExitInstance();
?R2`RvQ //}}AFX_VIRTUAL
gm;6v30e //{{AFX_MSG(CHookApp)
ba_T:;';0 // NOTE - the ClassWizard will add and remove member functions here.
Iz;hje4JL // DO NOT EDIT what you see in these blocks of generated code !
)2c[]d/a4 //}}AFX_MSG
WgBV,{C DECLARE_MESSAGE_MAP()
==d@0` };
z;x1p)(xt LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
Vj.5b0/( BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
y~jKytq^@ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
4BSSJ@z BOOL InitHotkey();
nx<q]Juv\ BOOL UnInit();
gB\
a #endif
[[fhfV+H K<`"Sr //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
(C;oot, #include "stdafx.h"
FBfyW-
7 #include "hook.h"
S&BJR!FQ #include <windowsx.h>
]@@3] #ifdef _DEBUG
v 6{qKpU# #define new DEBUG_NEW
UnjUA!v #undef THIS_FILE
I<Vh
Eo, static char THIS_FILE[] = __FILE__;
-QaS/WO_ #endif
y@!kp*0 #define MAX_KEY 100
E3N4(V\* #define CTRLBIT 0x04
HRF4
R o #define ALTBIT 0x02
VU>s{_|{ #define SHIFTBIT 0x01
mtEE,O!+ #pragma data_seg("shareddata")
*.ffyBI*~ HHOOK hHook =NULL;
^FLuhLS\* UINT nHookCount =0;
.F=15A static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
8.vPh static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Y4PU~l static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
5S:&^ A< static int KeyCount =0;
.MO"8}]8Z static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
|0Kj0u8T #pragma data_seg()
Q!DQ!;Br6 HINSTANCE hins;
TI-#\v9 void VerifyWindow();
-B\`O*Q BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
2fc8w3 //{{AFX_MSG_MAP(CHookApp)
wzAp`Zs2Dm // NOTE - the ClassWizard will add and remove mapping macros here.
7S<Z&1( // DO NOT EDIT what you see in these blocks of generated code!
?3tR(H< //}}AFX_MSG_MAP
MmOGt!}9A END_MESSAGE_MAP()
!Xt=+aKN >c~~i-= CHookApp::CHookApp()
=U3,P% {
%v++AcE // TODO: add construction code here,
yc,Qz.+g // Place all significant initialization in InitInstance
}-{l(8- }
JnX@eBNV \IQP`JR CHookApp theApp;
(tGK~!cAv LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
cTRQI3Oa> {
;D_6u(IC4: BOOL bProcessed=FALSE;
m{gK<T if(HC_ACTION==nCode)
8a{FxCBw {
Kb%j;y if((lParam&0xc0000000)==0xc0000000){// Key up
YW"?Fy switch(wParam)
1 sCF
-r {
o?P(Fuf case VK_MENU:
"42u0rH0J MaskBits&=~ALTBIT;
d>F=|dakL break;
Jrlc%,pZ case VK_CONTROL:
BY:
cSqAW MaskBits&=~CTRLBIT;
(,\`?g break;
uC G^,BQ case VK_SHIFT:
s#sr1[9}G MaskBits&=~SHIFTBIT;
F0Xv84:O break;
.a:Oj3=0 default: //judge the key and send message
B\bIMjXV break;
{:
EQ }
<PkDfMx2 for(int index=0;index<MAX_KEY;index++){
)_EQU8D4ug if(hCallWnd[index]==NULL)
Uc
e#v) continue;
`xbk)oW# if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
EAFKf*K= {
/= P!9d
{ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
<R~(6krJwZ bProcessed=TRUE;
,<zZKR_ }
C<A82u;t%@ }
\@4QG.3& }
zqYfgV else if((lParam&0xc000ffff)==1){ //Key down
Cg
85 switch(wParam)
o
<LA2q`T {
~I/7{B|yX case VK_MENU:
Bd m<<< MaskBits|=ALTBIT;
n[WXIE< break;
J8a4.prqI case VK_CONTROL:
[AR$Sw60 MaskBits|=CTRLBIT;
D8W:mAGEu break;
+u_mT$|T case VK_SHIFT:
y)U8\ MaskBits|=SHIFTBIT;
O3*Vilx break;
`(.ue8T default: //judge the key and send message
=fBJQK2sk break;
@6.1EK0 }
B7t#H? for(int index=0;index<MAX_KEY;index++)
%{/0K<M {
' 7>}I{Lq if(hCallWnd[index]==NULL)
l;Zc[6 continue;
CT4R/wzY7 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
)+w0NhJw {
r3ZY`zf SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
#eE:hiu<v bProcessed=TRUE;
"DWw1{ 5/ }
oB3>0Pm*a. }
Ltcr]T(Ic }
V0JoUyZ if(!bProcessed){
Cgw# c% for(int index=0;index<MAX_KEY;index++){
#f/-i u=L if(hCallWnd[index]==NULL)
%8
cFzyE* continue;
_a*Wk if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
hUGIy( SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
~2A<fL,- }
sut j
G`m }
snj4MA@I] }
iCk34C7 return CallNextHookEx( hHook, nCode, wParam, lParam );
biGaP#"0 }
n2,b~S\e L6$,<}l BOOL InitHotkey()
1Sz5&jz {
v}[KVwse if(hHook!=NULL){
xNxIqq<k nHookCount++;
Q;r 0#" return TRUE;
7F?^gMi }
>1s:F5u" else
nEOhN hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
>tP/"4c if(hHook!=NULL)
#D//oL"u] nHookCount++;
dJNYuTZ' return (hHook!=NULL);
.(9IAAwKn }
e%'9oAz BOOL UnInit()
cx_"{`+e {
drtQEc>qT if(nHookCount>1){
H3OH nHookCount--;
-oF4mi8S return TRUE;
shn`>=0.& }
FG#E?G BOOL unhooked = UnhookWindowsHookEx(hHook);
6t]oSxN if(unhooked==TRUE){
P'ZWAxd nHookCount=0;
:Fj4YP" hHook=NULL;
WlZ[9,:p1 }
^r;}6 return unhooked;
|7%$+g }
Y!&dj95y 7\{<AM?* BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
<#|3z8N2 {
x6Z$lhZ BOOL bAdded=FALSE;
Y]8l]l 1 for(int index=0;index<MAX_KEY;index++){
Iobo5B if(hCallWnd[index]==0){
@gX@mT" hCallWnd[index]=hWnd;
wK#UFOp HotKey[index]=cKey;
uc7np]Z HotKeyMask[index]=cMask;
5W<BEcV\ bAdded=TRUE;
zKV{JUpG KeyCount++;
=t)eT0 break;
5Y9 j/wA }
i-E&Y*\^9H }
)J#@L* return bAdded;
62vz 'b }
JI\u -+BE sMO3eNLn BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
_\o +9X! {
J_P2% b=C BOOL bRemoved=FALSE;
4TR:bQZs for(int index=0;index<MAX_KEY;index++){
6dq U4 if(hCallWnd[index]==hWnd){
)sNtwSl^ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
U?|s/U hCallWnd[index]=NULL;
(Z `Y HotKey[index]=0;
N;[w`d'# HotKeyMask[index]=0;
+}9%Duim bRemoved=TRUE;
=:a3cr~ KeyCount--;
pm )A*][s break;
yDd&*;9%Qg }
8KoPaq }
KQW }
iv;;GW{2 return bRemoved;
$ /wr? }
|Z2_1(
ku Ld`~^<