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:
FUI/ A>
ruhC:rg:/ 一、实现方法
qPu?rU{2 ; <- 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:
.9DhD=8aIO 89[/UxM) #pragma data_seg("shareddata")
8f,",NCgc HHOOK hHook =NULL; //钩子句柄
yJx,4be UINT nHookCount =0; //挂接的程序数目
k8Dk;N static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
QKk7"2t| static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
,9OER!$y static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
w_@6!zm static int KeyCount =0;
:4:U\k;QwA static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
6hcs)X7m #pragma data_seg()
*"|f!t Z'AjeZyyE 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
"<oR.f=0 wKW.sZ!S1 DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
P EzT|uY UXa%$gwFw BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
B_!S\?}$ cKey,UCHAR cMask)
Xk^<}Ep)c {
y=GDuU% BOOL bAdded=FALSE;
BAqwYWdS for(int index=0;index<MAX_KEY;index++){
R]Fa?uQW
if(hCallWnd[index]==0){
0Dd8c\J hCallWnd[index]=hWnd;
s$^ 2Cuhv HotKey[index]=cKey;
GWx?RIKF HotKeyMask[index]=cMask;
<{V{2V# bAdded=TRUE;
_)CCD33$ KeyCount++;
45+kwo0 break;
p3%cb?G%w }
V(G{_>> }
[CnoMN return bAdded;
&Ai+t2 }
6_EfOD9 //删除热键
jJ>I*'w BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
%AMF6l[ {
_=w=!U&W BOOL bRemoved=FALSE;
d.sn D)X for(int index=0;index<MAX_KEY;index++){
a/d8_(0 if(hCallWnd[index]==hWnd){
nQw, /Lk if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
(!ud"A|ab4 hCallWnd[index]=NULL;
&WbHM)_n HotKey[index]=0;
B(@uJ^N HotKeyMask[index]=0;
q!d7Ms{q bRemoved=TRUE;
]VVx2ERs KeyCount--;
iA2TvP# break;
17rg!'+ }
5Shc$Awc! }
(i)O@Jve }
5N>L|J2 return bRemoved;
5t-(MY }
c*8k _o, ?f6Fj P+p:Ed80 DLL中的钩子函数如下:
G!GGT?J B3u:D"t LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
~\R+p~> {
cMUmJH BOOL bProcessed=FALSE;
P; =,Q$e8 if(HC_ACTION==nCode)
V=GP_^F {
)=h+5Z>E1 if((lParam&0xc0000000)==0xc0000000){// 有键松开
g*U[?I"sC switch(wParam)
7*&q"
{
_t7aOH case VK_MENU:
-A8CW9|mk MaskBits&=~ALTBIT;
ECOzquvM break;
4!+IsT case VK_CONTROL:
v~O2y>8Z MaskBits&=~CTRLBIT;
oFJx8XU break;
!"^//2N+, case VK_SHIFT:
+_fxV|}P MaskBits&=~SHIFTBIT;
kEdAt5/U{ break;
y#{> tC default: //judge the key and send message
LZpqv~av break;
u_)'} }
0o!Egq_ for(int index=0;index<MAX_KEY;index++){
$T'lWD * if(hCallWnd[index]==NULL)
[{-;cpM\ continue;
ue6&)7:~ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
*Q3q(rdrp {
^paM{'J\\) SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
pu+jw<7 bProcessed=TRUE;
vB/G#\Zqz }
9<!Ie^o? }
XCZNvLG }
_$qH\>se else if((lParam&0xc000ffff)==1){ //有键按下
LT '2446 switch(wParam)
?F%,d{^ {
#.W<[KZf case VK_MENU:
8<g9 ~L MaskBits|=ALTBIT;
G
C3G=DTt break;
k'{Bhi4 case VK_CONTROL:
=qTmFszT MaskBits|=CTRLBIT;
dxeLu break;
>uDE<MUC case VK_SHIFT:
Bt-2S,c,o MaskBits|=SHIFTBIT;
TzY[-YlvF break;
!.5,RIf default: //judge the key and send message
4T:@W C break;
e/!xyd }
eN]9=Y~-K for(int index=0;index<MAX_KEY;index++){
w'D=K_h if(hCallWnd[index]==NULL)
dX~$#-Ad86 continue;
p# (5
; if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
nJo6;_MI! {
6<C|O- SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
_QOZ`st bProcessed=TRUE;
t2q{;d~. }
nx'D&,VX }
-]~vEfq+T }
f+W %X if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
=ET |h}I for(int index=0;index<MAX_KEY;index++){
PzDekyl if(hCallWnd[index]==NULL)
!@kwHJkv continue;
wtnC^d$ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Bgj^n{9x SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
<MBpV^Y} //lParam的意义可看MSDN中WM_KEYDOWN部分
-eoXaP{[ }
).1F0T }
P>i[X0UnL }
3rw<#t;v return CallNextHookEx( hHook, nCode, wParam, lParam );
:HQQ8uQfb }
x.~A vJ %Y// } 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:
1|Z!8:&pj Z |CL:)h BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
-mK;f$X BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
EG[Rda i"o
%Gc 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
&ywU^hBh =5m~rJ<{ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
uMe]].04 {
i_6 Y6 if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
o&"nF+, {
aoVfvz2Y //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
?#P@N4Uw}y SaveBmp();
g/6>>p`J return FALSE;
=Hwlo! }
`z{sDe; …… //其它处理及默认处理
'&hk? }
3=~0m i@p0Jnh| ev;R; 0< 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
wXnluE -3On^Wj] 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
Q9h;`G
7t E2~&GkU.UN 二、编程步骤
(W4H?u@X0 m]#oZVngy 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
Q,m1mIf 9(
"<NB0y 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
(TJ )Y7E zo~5(O@ 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
Y(3X5v?[ )tW0iFY 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
=9AX\2w*H; soXIPf 5、 添加代码,编译运行程序。
gkw/Rd1oG hYS}PE 三、程序代码
nkn4VA?" .P^&sl*J ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
&nyJ :? #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
AeN$AqQd/ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
\=NS@_t, #if _MSC_VER > 1000
*kE<7 #pragma once
51&K #endif // _MSC_VER > 1000
L|H:&|F #ifndef __AFXWIN_H__
lqoJ2JMy #error include 'stdafx.h' before including this file for PCH
--chU5 #endif
qzt.k^'-^
#include "resource.h" // main symbols
K r DG class CHookApp : public CWinApp
Mo~zq. {
+#V.6i public:
r?j2%M\ CHookApp();
&<RK=e'*x // Overrides
gJC~$/2 // ClassWizard generated virtual function overrides
-L&%,% //{{AFX_VIRTUAL(CHookApp)
m#.N public:
iu+r=sp virtual BOOL InitInstance();
r#X6jU virtual int ExitInstance();
MGU%"7i'} //}}AFX_VIRTUAL
AkE(I16Uy~ //{{AFX_MSG(CHookApp)
bs9X4n5 // NOTE - the ClassWizard will add and remove member functions here.
+9!=pRq // DO NOT EDIT what you see in these blocks of generated code !
Cl>{vSN //}}AFX_MSG
j}fu|- DECLARE_MESSAGE_MAP()
9H#;i]t & };
ZGZ1Q/WH LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
o/~Rf1 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
-b`O"Ck* BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
d,d ohi BOOL InitHotkey();
zD,K_HicI BOOL UnInit();
8%EauwAx #endif
]u<8jr )~[rb<:)b //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
x>TIQU=\ #include "stdafx.h"
cWS 0B $$ #include "hook.h"
DP5}q"l #include <windowsx.h>
la}Xo0nq0+ #ifdef _DEBUG
BDiN*.w5 #define new DEBUG_NEW
DO{Lj#@ #undef THIS_FILE
>Xv
Fg static char THIS_FILE[] = __FILE__;
>#Ue`)d`aY #endif
u]uZc~T #define MAX_KEY 100
0 F-db #define CTRLBIT 0x04
&6q67 #define ALTBIT 0x02
o@47WD'm #define SHIFTBIT 0x01
J[ 7Sf^r #pragma data_seg("shareddata")
#m;|QWW HHOOK hHook =NULL;
|\3X7)^8D UINT nHookCount =0;
AREpZ2GiU static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
o<8SiVC2 static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
%("WoBPH` static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
}u?DK,R static int KeyCount =0;
6O0CF}B* static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
iwx*mC{|A #pragma data_seg()
YM.Q?p4g HINSTANCE hins;
>%1mx\y^ void VerifyWindow();
Oz-;2 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
GMW,+ //{{AFX_MSG_MAP(CHookApp)
/|#" ;QsPN // NOTE - the ClassWizard will add and remove mapping macros here.
}$X/HK // DO NOT EDIT what you see in these blocks of generated code!
&X&msEM //}}AFX_MSG_MAP
;U<}2M!g END_MESSAGE_MAP()
cl1>S 3 TKs l.| CHookApp::CHookApp()
bJ5 VlK67R {
GX0S9s // TODO: add construction code here,
u #Y#,:{ // Place all significant initialization in InitInstance
dk>qTY+j5 }
`),ACkU>U _oAWj]~rO CHookApp theApp;
&Fy})/F3v LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
E@[ZwTnJ {
h"ZR`?h BOOL bProcessed=FALSE;
L)yc_ d5 if(HC_ACTION==nCode)
!}I+)@~\w {
={[9kR i if((lParam&0xc0000000)==0xc0000000){// Key up
Ce`#J6lT switch(wParam)
!5* {
V<ExR@|}.% case VK_MENU:
;%B:1Z MaskBits&=~ALTBIT;
y)uxj-G break;
hA:RVeS{ case VK_CONTROL:
D7|qFx;]g MaskBits&=~CTRLBIT;
2qpUUo f break;
=" ;G&)H- case VK_SHIFT:
2`P=ekF] MaskBits&=~SHIFTBIT;
`PS^o# break;
Q nmv?YXS default: //judge the key and send message
`RHhc{ break;
C7Ny-rj}IA }
/Xf_b.ZM& for(int index=0;index<MAX_KEY;index++){
#fT<]j( if(hCallWnd[index]==NULL)
zTS P8Q7 continue;
/v8yE9N_ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
oxZXY]$y {
kG>m(n SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
W'" p:Uhq bProcessed=TRUE;
T0v{qQ }
k@}g?X`8 }
Ju"K" }
'
o(7@ else if((lParam&0xc000ffff)==1){ //Key down
Gy6PS{yY6t switch(wParam)
sg%Ptp {
;Z!x\{-L case VK_MENU:
'LMMo4o3 MaskBits|=ALTBIT;
Xv2Q8-}w break;
8fWk C<f} case VK_CONTROL:
"Ta"5XW MaskBits|=CTRLBIT;
1w} DfI break;
Lhmb=
@ case VK_SHIFT:
@FaK/lKK MaskBits|=SHIFTBIT;
RxO!h8 break;
#u/5
nm default: //judge the key and send message
U0@Qc}y break;
(-%1z_@Y }
d7P'c!@+ for(int index=0;index<MAX_KEY;index++)
S+7u,%n/ {
+j(7.6ia if(hCallWnd[index]==NULL)
:CGh$d] + continue;
Wxa</n8S[n if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
71G\b|5 {
yn|U<Hxl~H SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
,;)_$%bHc bProcessed=TRUE;
.f-s+J&ED }
X?++I4\ }
E~
+g6YlT }
k]=lo'bF4 if(!bProcessed){
8;$zD]{D1 for(int index=0;index<MAX_KEY;index++){
l?O%yf`s if(hCallWnd[index]==NULL)
MnTqWC90 continue;
!0X/^Xv@= if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
#b>D^=NV>) SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
p-kug]qX }
B3Da w/G }
(y5]]l }
@cB6,iUr return CallNextHookEx( hHook, nCode, wParam, lParam );
S7(tGD }
>)bn #5 Xq%ijo BOOL InitHotkey()
"@UyUL {
Dd'J"|jF38 if(hHook!=NULL){
^\g?uH6k U nHookCount++;
|* B9{/;4 return TRUE;
&0RKNpwg }
.f9&.H# else
j5!pS xOC hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
=y0h\<[ if(hHook!=NULL)
M.``o1b nHookCount++;
$fAZ^ return (hHook!=NULL);
Bk@&k}0 }
Np@RK1} BOOL UnInit()
{r?+PQQ# {
L0>7v if(nHookCount>1){
WZN0`Od nHookCount--;
<lP5}F87 return TRUE;
>!PCEw<i }
p%-;hL! BOOL unhooked = UnhookWindowsHookEx(hHook);
wUKt$_]`` if(unhooked==TRUE){
;8g[y"I nHookCount=0;
2#X>^LH hHook=NULL;
D2'J( }
U*\1d return unhooked;
Zp+orc7 }
n!h952" d,E2l~s BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
#D^(dz* {
h@ @q:I= BOOL bAdded=FALSE;
rO]2we/B,4 for(int index=0;index<MAX_KEY;index++){
#&snl if(hCallWnd[index]==0){
l4AXjq2 hCallWnd[index]=hWnd;
z_%}F': HotKey[index]=cKey;
/mwsF]Y HotKeyMask[index]=cMask;
J<MuWgx& bAdded=TRUE;
KJW^pAj$B KeyCount++;
jdd3[ break;
$|VD+[jSV }
'5\?l:z }
eA-$TSWh return bAdded;
o,!W,sx_ }
En ]"^* j`QXl BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Sr+ & {
%Mf3OtPiJW BOOL bRemoved=FALSE;
&W%fsy< for(int index=0;index<MAX_KEY;index++){
y$+_9VzYB if(hCallWnd[index]==hWnd){
q3ebps9^ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
wDKA1i%G hCallWnd[index]=NULL;
h3V;
J HotKey[index]=0;
>S@><[C HotKeyMask[index]=0;
Q&vU|y bRemoved=TRUE;
emG1Wyl KeyCount--;
o$Z]qhq break;
O
+Xu?W] }
|`O210B@ }
EO\- J-nM }
& sgzSX return bRemoved;
H={5>;8G }
0}-MWbG RY]jY | E void VerifyWindow()
qU^`fIa {
' pfkbmJ for(int i=0;i<MAX_KEY;i++){
Q#pgl if(hCallWnd
!=NULL){ rQ)I
if(!IsWindow(hCallWnd)){ /gP"X1.
hCallWnd=NULL; UVD*GsBk
HotKey=0; yH(%*-S
HotKeyMask=0; e/zz.cd){
KeyCount--; 4R&pb1eF
} <
;fI*km
} +@MG$*}Oz
} i([|@Y=
} sPRs;to-
QLb!e"C
BOOL CHookApp::InitInstance() 95*=&d
{ }*VRj;ff
AFX_MANAGE_STATE(AfxGetStaticModuleState()); |M|>/U 8
hins=AfxGetInstanceHandle(); bf/z
T0
InitHotkey(); Xbc:Vr
return CWinApp::InitInstance(); ;M5]XCPk
} Oe&gTXo
K%YR; )5A
int CHookApp::ExitInstance() C:RA(
{ \iAs
VerifyWindow(); C,,S<=L:
UnInit(); B1va]=([)W
return CWinApp::ExitInstance(); 07>Iq8<mu
} H'jo3d~+
F+9(*|x%
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file ^\w!D{Y7Q
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) ye`-U?7.
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ 4#ZZwa]y
#if _MSC_VER > 1000 {
P @mAw
#pragma once 8:k-]+#o
#endif // _MSC_VER > 1000 V BjA$.
4B@Ir)^(*
class CCaptureDlg : public CDialog >uwd3XW5
{ 4)d"}j
// Construction 3u4P
[
public: bEb+oRI
BOOL bTray; IhXP~C6
BOOL bRegistered; )odz/\9n3c
BOOL RegisterHotkey(); |\N))K-2D
UCHAR cKey; ;&
zBNj
UCHAR cMask; ?;DzWCL~9
void DeleteIcon(); hz rS_v
void AddIcon(); l:j>d^V*&x
UINT nCount; B1 xlWdm
void SaveBmp(); ?'^yw C`
CCaptureDlg(CWnd* pParent = NULL); // standard constructor U\6Ee-1#_
// Dialog Data )pw53,7>aN
//{{AFX_DATA(CCaptureDlg) uwu`ms7z 2
enum { IDD = IDD_CAPTURE_DIALOG }; `}#n#C)
CComboBox m_Key; }h=3[pe}
BOOL m_bControl; h 2C9p2.
BOOL m_bAlt; >Slu?{l'
BOOL m_bShift; m,r>E%;Cj
CString m_Path; S~V?Qe@&Z
CString m_Number; RIq\IQ_|
//}}AFX_DATA g4GU28 l
// ClassWizard generated virtual function overrides N.-*ig.YR7
//{{AFX_VIRTUAL(CCaptureDlg) Zi.w+V
public: c@{M),C~E
virtual BOOL PreTranslateMessage(MSG* pMsg); IaGF{O3.
protected: 59k-,lyU,
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support TJs ~}&L
virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam); {#&j