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:
Yt{Z+.;9OI
S6C DK: 一、实现方法
PMX'vA` 9b&;4Yq!f 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:
|}:q@]dC# 1}SON4U #pragma data_seg("shareddata")
Snn4RB<( HHOOK hHook =NULL; //钩子句柄
3u 7A( UINT nHookCount =0; //挂接的程序数目
j|qdf3^f static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
U#sv.r/L}3 static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
q4'`qe static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
??|,wIRz static int KeyCount =0;
A[`c+& static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
~(NFjCUY? #pragma data_seg()
1K)9fMr] p%X.$0 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"]" wlh%{l 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:
qlg.\H:W~ DY/%|w*L BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
hOV5WO\ cKey,UCHAR cMask)
&B1!,joH~ {
SOMAs'= BOOL bAdded=FALSE;
,%zE>^~ for(int index=0;index<MAX_KEY;index++){
3h%Nd&_9 if(hCallWnd[index]==0){
#,FXc~ V hCallWnd[index]=hWnd;
#Aj#C> HotKey[index]=cKey;
`K[r5;QFKf HotKeyMask[index]=cMask;
x%T^:R bAdded=TRUE;
>HzTaXCR[ KeyCount++;
3j[<nBsn. break;
/qq*"R }
|%rRALIY }
u*oP:!s return bAdded;
EG_P^<z }
KV'3\`v@LY //删除热键
.m%5Esx BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
hYA1N&yz@ {
c=a;<,Rzb BOOL bRemoved=FALSE;
: Q2=t! for(int index=0;index<MAX_KEY;index++){
/}%C' if(hCallWnd[index]==hWnd){
o/vD]Fs if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
zWhzU|=8 hCallWnd[index]=NULL;
aW;)-0+ HotKey[index]=0;
(y\.uPu! HotKeyMask[index]=0;
P!)F1U]!
bRemoved=TRUE;
a^X% (@Sg KeyCount--;
Nv=% R break;
y1Wb/ d }
kFT*So`' }
(Hmh b}H }
lQt,(@7] return bRemoved;
LW/> % }
j xq89x *13-)yfd
]/%CTD(O DLL中的钩子函数如下:
v0;dk( %RzkP}1>E LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
us<dw@P7{ {
&`-e; Xt BOOL bProcessed=FALSE;
yV6U<AP$3 if(HC_ACTION==nCode)
})q8{Qj! {
/nt%VLms% if((lParam&0xc0000000)==0xc0000000){// 有键松开
BHNJH switch(wParam)
`Cy;/95m {
z~1S/,Ca case VK_MENU:
hsQ*ozv[) MaskBits&=~ALTBIT;
l~@ -oE break;
A9Pq}3U case VK_CONTROL:
K!-iDaVI MaskBits&=~CTRLBIT;
z_y@4B6>} break;
'k<~HQr case VK_SHIFT:
Z%SDN"+'g MaskBits&=~SHIFTBIT;
?fpI,WFu break;
3#F"UG2,_ default: //judge the key and send message
3XUsw1,[ break;
9IacZ }
uw`J5TND for(int index=0;index<MAX_KEY;index++){
1vqc8lC if(hCallWnd[index]==NULL)
w'mn O'% continue;
78]( ZYJV if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
'(3|hh)Tl {
cz$*6P<9J SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
<#T#+uO bProcessed=TRUE;
#,!/Cnqis }
!Pd) }
u1Wixjd| }
H~0B5Hl!F else if((lParam&0xc000ffff)==1){ //有键按下
t-]~^s switch(wParam)
xp\6,Jyh {
h<!!r case VK_MENU:
!\\1#:*_W MaskBits|=ALTBIT;
3Z%jx# break;
WxtB:7J case VK_CONTROL:
K#yCZ2 MaskBits|=CTRLBIT;
zWF[cf>' break;
q~xs4?n1U case VK_SHIFT:
P4s,N|bs` MaskBits|=SHIFTBIT;
<*ME&cgh4 break;
_o>?\ :A default: //judge the key and send message
#!4
HSBf break;
cNl$
vP83z }
5&134!hC for(int index=0;index<MAX_KEY;index++){
i| *r/ if(hCallWnd[index]==NULL)
buMST& continue;
5F1P|t# if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
V%FWZn^ {
{9nH#yv SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
aR%E"P-6l bProcessed=TRUE;
=UZQ` { }
h)X"<a++N }
uCf _O~ }
NHaqT@: if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
a0&R! E; for(int index=0;index<MAX_KEY;index++){
)zo:Bo
.< if(hCallWnd[index]==NULL)
}FC(Z-g continue;
A_|X54}w& if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
n%ZOR1u)k# SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
m Wh //lParam的意义可看MSDN中WM_KEYDOWN部分
zj#8@gbh+ }
Yj*!t1qm }
b./MVz }
$HFimU,V=0 return CallNextHookEx( hHook, nCode, wParam, lParam );
0G#s/u# }
oP`Qyk u 9kh@0 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
vC-5_pl :qK^71gz BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
>8w=Vlp BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
[^\HP]*Q{ N7dI}ju 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
PKX
Tj6hj) j>|mpfU LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
q,.@<s W {
t ;bU#THM if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
,h* 'Cs04h {
D+CP?} / //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
lQf38u|| SaveBmp();
}x?2 txuu return FALSE;
8'0I$Qa4 }
ew|e66Tw$ …… //其它处理及默认处理
Bx ru7E" }
G!5~`v "Rr650w[ i-`J+8|d 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。
>vfbXnN *.A{p ;JC( 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。
fzW!- *n2le7 二、编程步骤
*dX
7 B1(T-pr 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";
vALH!Kh Yjh02wo 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
d\j[O9W> EOzw&M];r 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;
pij%u< H{VJS Jc{ 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;
L3'$"L.|u \jHIjFwQ
5、 添加代码,编译运行程序。
\'-E[xNcWI zF#:Uc`C5U 三、程序代码
"aJfW I|vfxf ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
>A ?,[p`< #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
@agxu-Y #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
/=S\v<z #if _MSC_VER > 1000
,HtXD~N #pragma once
Gq0`VHAn #endif // _MSC_VER > 1000
s1%th"e
[ #ifndef __AFXWIN_H__
i{4J$KT #error include 'stdafx.h' before including this file for PCH
) S,f I #endif
@"O|[%7e #include "resource.h" // main symbols
S)=3%toS> class CHookApp : public CWinApp
Ktn:6=, {
tM3Q;8gB! public:
fOt?2Bh CHookApp();
/SD(g@G, // Overrides
9|qzFmE# // ClassWizard generated virtual function overrides
A Y_GD ^ //{{AFX_VIRTUAL(CHookApp)
D2 X~tl5< public:
!YENJJ virtual BOOL InitInstance();
n'qWS/0U= virtual int ExitInstance();
uG=~kO //}}AFX_VIRTUAL
lAJP X //{{AFX_MSG(CHookApp)
e)*-<AGwC // NOTE - the ClassWizard will add and remove member functions here.
v?(z4oOD/> // DO NOT EDIT what you see in these blocks of generated code !
W=\45BJ //}}AFX_MSG
T$*#q('1"} DECLARE_MESSAGE_MAP()
0t2n7Y?N };
^50\c$ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
AS/z1M_U BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
g<g$c<sm BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
PM`iqn)@ BOOL InitHotkey();
;C,t`( BOOL UnInit();
JiFB<Q\ #endif
&.[I}KH|B <7_s'UAL! //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
R^&.:;Wi> #include "stdafx.h"
2"IDz01ne #include "hook.h"
\Sv8c}8 #include <windowsx.h>
@Io@1[k j #ifdef _DEBUG
'9@AhiNV #define new DEBUG_NEW
#T++5G #undef THIS_FILE
K8RV=3MBLD static char THIS_FILE[] = __FILE__;
l-$5CO #endif
P71] Z #define MAX_KEY 100
_f"KB=A_x #define CTRLBIT 0x04
rVZl v3 #define ALTBIT 0x02
tP4z#0r2 #define SHIFTBIT 0x01
z>z9xG' #pragma data_seg("shareddata")
:pvB}RYD HHOOK hHook =NULL;
=d#(n M* UINT nHookCount =0;
[,sm]/Xlc static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
jr/IU=u*v static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
ti!kJ"q static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
2B b,ZC* static int KeyCount =0;
Hq#q4Y static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
]DjnzClx #pragma data_seg()
Scfe6+\EW HINSTANCE hins;
</!GU* void VerifyWindow();
E?S BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
^j7>Ul, //{{AFX_MSG_MAP(CHookApp)
*JF7 B // NOTE - the ClassWizard will add and remove mapping macros here.
`Gh J)WA< // DO NOT EDIT what you see in these blocks of generated code!
~(\.j=x //}}AFX_MSG_MAP
B["jndyr END_MESSAGE_MAP()
ca<OG;R^ DdqE6qE CHookApp::CHookApp()
xM=?ES {
Jk;dtLL}4 // TODO: add construction code here,
QXEz[R // Place all significant initialization in InitInstance
Y 2[ik< }
HT7I~]W -f["1-A CHookApp theApp;
)zkr[;j~` LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
r-o+NV {
@cc}[Uw4B BOOL bProcessed=FALSE;
9Y+7o%6e if(HC_ACTION==nCode)
q\xsXM {
;$3epP if((lParam&0xc0000000)==0xc0000000){// Key up
T_[ switch(wParam)
NZz^* Ela {
hWi2S!*Y case VK_MENU:
m-]F]c=)w< MaskBits&=~ALTBIT;
d)GR]^=r break;
5E^P2Mlc case VK_CONTROL:
(dwb{+HW MaskBits&=~CTRLBIT;
RQU-]qQ8BM break;
!uP8powO case VK_SHIFT:
pZKK7
MaskBits&=~SHIFTBIT;
!m8T< LtMl break;
2=,d.1E3d default: //judge the key and send message
;gLOd5*0 break;
Cz6bD$5 }
.>1vN+ for(int index=0;index<MAX_KEY;index++){
?(M$r\\ if(hCallWnd[index]==NULL)
baGV]=j continue;
;@qQ^!g2 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
IZuP{7p$ {
Vi#[kn' SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
wb ^>/ bProcessed=TRUE;
6Ev+!!znu }
Tnas$=J }
V`@/"Dj j }
Z%JAX>v&B else if((lParam&0xc000ffff)==1){ //Key down
x>+sqFd\ switch(wParam)
2M)E1q|a {
`yh][gqVE~ case VK_MENU:
q8MyEoc:n MaskBits|=ALTBIT;
\+Y5b} break;
^UBzX;|p case VK_CONTROL:
~:*V'/2k
MaskBits|=CTRLBIT;
#vc!SI break;
MzF,is case VK_SHIFT:
F~/~_9RJ MaskBits|=SHIFTBIT;
rpc;*t+z break;
F^&@[k7WW default: //judge the key and send message
DABV}@ K" break;
BwAmNW&i }
{vk%&{D0) for(int index=0;index<MAX_KEY;index++)
N'0nt]&a {
\H
5t-w= if(hCallWnd[index]==NULL)
8 %p+:6kP5 continue;
JsEnhE}] if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
WR_B:%W. {
4#W*f3d[@: SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
L s+zJ1 bProcessed=TRUE;
yq!peFu }
Y=,9 M }
Gn4XVzB`O }
b>]UNf"- if(!bProcessed){
tMXNi\Bj for(int index=0;index<MAX_KEY;index++){
4{G>T if(hCallWnd[index]==NULL)
GC|V>| tz# continue;
iFZ.a.NDc if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Ym6v 4k!@O SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
jI~$iDdOfs }
qDgy7kkQ }
>1HXC2 Y }
&'Xgf!x return CallNextHookEx( hHook, nCode, wParam, lParam );
*VUJ);7k }
UG4I@@=
IFW7MF9V BOOL InitHotkey()
'<'5BeU {
b5?k gY if(hHook!=NULL){
V9cj nHookCount++;
/N,\ st return TRUE;
g ;XK3R }
?)Je%H else
7>F [7_ hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
.3#Xjhebvu if(hHook!=NULL)
`aA)n;{/2u nHookCount++;
"~KTLf return (hHook!=NULL);
>_$_fB }
[zSt+K; BOOL UnInit()
PEaZ3{- {
:ciD!Ly if(nHookCount>1){
-Ir>pY\! nHookCount--;
uo;m return TRUE;
,W;|K 5 }
Bn.5ivF3 BOOL unhooked = UnhookWindowsHookEx(hHook);
6PC?*^v if(unhooked==TRUE){
y1[@4TY] nHookCount=0;
S,Q(,e^& hHook=NULL;
`fl$ o6S/ }
3Bcv"O,B!{ return unhooked;
X$?0C{@.} }
d(9-T@J i 1Kq(7 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
\GKR(~f {
1H-~+lf BOOL bAdded=FALSE;
N#@v`S for(int index=0;index<MAX_KEY;index++){
/2MZH if(hCallWnd[index]==0){
8~T=p:z' hCallWnd[index]=hWnd;
tY:,9eh7B HotKey[index]=cKey;
_xBhMu2f HotKeyMask[index]=cMask;
;= 1[D
bAdded=TRUE;
4UK>Vzn KeyCount++;
:Ys
;)W+R break;
X":2o|R }
d=
?lPEzSA }
oFT1d return bAdded;
DyA1zwp} }
=#A/d`2
b L\!Oj5 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
4,?beA {
b *3h}n; BOOL bRemoved=FALSE;
\HQ.Pwr 6 for(int index=0;index<MAX_KEY;index++){
Ocn@JOg if(hCallWnd[index]==hWnd){
qEVpkvEq if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
P+C5
s hCallWnd[index]=NULL;
Z v*uUe HotKey[index]=0;
AYfe_Dj HotKeyMask[index]=0;
s,l*=< bRemoved=TRUE;
BuUM~k&SY KeyCount--;
T0.sL9 break;
ooP{Q r }
}*O8]lG }
3,#v0 # }
InRcIQT return bRemoved;
L3 KJ~LI }
;0NJX)GL c#>:U,j void VerifyWindow()
C5jt(!pi {
4W<[& )7 for(int i=0;i<MAX_KEY;i++){
7#X`D if(hCallWnd
!=NULL){ [Z&<# -
if(!IsWindow(hCallWnd)){ EMdU4YnE"
hCallWnd=NULL; qT&zg@m
HotKey=0; oel?w e6
HotKeyMask=0; wDW/?lT&
KeyCount--; M(uJ'Ud/!
} 73_-7'^mQ
} de[NIDA;`
} 0-57_";%Q
} zQUNvPYM
P"Z1K5>2L
BOOL CHookApp::InitInstance() g@pK9R%wH<
{ 1]vDM&9
AFX_MANAGE_STATE(AfxGetStaticModuleState()); ?_v_*+b_
hins=AfxGetInstanceHandle(); ;7QG]JX
InitHotkey(); 51*[Ibx
return CWinApp::InitInstance(); |34w<0Pc,
} z46Sh&+
} :gi<#-:G
int CHookApp::ExitInstance() [HQ/MkP-Z
{ }_H\75Iv
VerifyWindow(); %?F$3YN,
UnInit(); ^+gD;a|t
return CWinApp::ExitInstance(); : #so"O
} `-K[$V
NL2D,
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file Q]/{6:C
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) %:Y(x$Qy
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ B|{E[]iK
#if _MSC_VER > 1000 VW;E14
#pragma once M a3}w-=;
#endif // _MSC_VER > 1000 H6Gs&y