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:
#_L&
.lj! ~_ 一、实现方法
^V,/4u E6-(q!"A 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:
N$a-i ^F0jI5j ). #pragma data_seg("shareddata")
[)6E)E`_e HHOOK hHook =NULL; //钩子句柄
@' :um UINT nHookCount =0; //挂接的程序数目
^^Q32XC, static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
e6xjlaKb static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
~zC fan/ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
Gz5@1CF static int KeyCount =0;
RIqxM static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
G6F['g); #pragma data_seg()
C^:&3, [>9"RzEl 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
!4.^@^L|\ 19{?w6G<k DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
b/}0
&VXo &r%^wfp BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
r9'H7J cKey,UCHAR cMask)
92_H!m/ {
'R5l
=Wf BOOL bAdded=FALSE;
nln[V$ for(int index=0;index<MAX_KEY;index++){
HZ4
^T7G if(hCallWnd[index]==0){
I[IQFka} hCallWnd[index]=hWnd;
OL"5A18;M HotKey[index]=cKey;
<l/Qf[V HotKeyMask[index]=cMask;
s/0FSv
x bAdded=TRUE;
>:nJTr KeyCount++;
R:m=HS_ break;
QD VA*6F }
D)cwttH }
ZGvNEjff return bAdded;
V+5
n|L5 }
{#Cm> @') //删除热键
c0p=/*s( BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
SFNd,(kB*z {
DOU?e9I2 BOOL bRemoved=FALSE;
7+r5?h| for(int index=0;index<MAX_KEY;index++){
4\WkXwoqQO if(hCallWnd[index]==hWnd){
buyz>ICP if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
b:I5poI3 hCallWnd[index]=NULL;
-7VV5W HotKey[index]=0;
1c~#]6[ HotKeyMask[index]=0;
e1 }0f8% bRemoved=TRUE;
iL'
]du<wk KeyCount--;
leJd){ break;
HD|)D5wH| }
4c@F.I }
'E8Qi'g }
w.-i !Ls return bRemoved;
/UyE- "S }
SP1oBR"3 N|L5Ru ,IATJs$E DLL中的钩子函数如下:
hd%F7D5 T5+b{qA LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Ap9wH[H {
hrt-<7U BOOL bProcessed=FALSE;
u#|Jl|aT if(HC_ACTION==nCode)
_Hj,;Z {
Oip..f0 if((lParam&0xc0000000)==0xc0000000){// 有键松开
%=eD)p7l- switch(wParam)
3iL&;D {
<u/({SZ& case VK_MENU:
rWmi 'niu MaskBits&=~ALTBIT;
tJ=zk3BN~ break;
M)Q+_c2* case VK_CONTROL:
Vp4] MaskBits&=~CTRLBIT;
swbD q break;
YHAg4eb8 case VK_SHIFT:
$>m<+nai' MaskBits&=~SHIFTBIT;
?,>y`Qf*| break;
?C\9lLX default: //judge the key and send message
B6&Mtm1 break;
sg\jC# }
t4uxon for(int index=0;index<MAX_KEY;index++){
{u3u%^E;R if(hCallWnd[index]==NULL)
H@2+wr)$} continue;
1D]wW%us if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
n8,/olqwW {
QV1%Zou SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
[} 3Y1t{G bProcessed=TRUE;
.1}(Bywm5 }
?!Gt.
fb }
OPjh"Hv }
3W0:0I else if((lParam&0xc000ffff)==1){ //有键按下
FM];+d0 switch(wParam)
tgnXBWA`! {
n_glYSV! case VK_MENU:
&t4(86Bmq MaskBits|=ALTBIT;
Vd~k4 break;
+N:%`9}2V case VK_CONTROL:
Zv7)+Q MaskBits|=CTRLBIT;
=v9;HPiO break;
SBt:
`, case VK_SHIFT:
inrL'z MaskBits|=SHIFTBIT;
%)V3QnBO break;
HrxEC)V6# default: //judge the key and send message
5~QB.m,> break;
RL9P:]
^ }
U"Oq85vY for(int index=0;index<MAX_KEY;index++){
:wm^04<i if(hCallWnd[index]==NULL)
EZV$1pa continue;
1XRVbQt if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
XzsK^E0R {
dx}!]_mlZ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
THVF@@q bProcessed=TRUE;
V"73^ }
*^ BE1- }
~qH@Kz\% }
^\%%9jY if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
^bGi_YC for(int index=0;index<MAX_KEY;index++){
e#^by(1@} if(hCallWnd[index]==NULL)
>sq9c/}X continue;
;k]pq 4E if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
?9A[;j|a0 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
y5}|Y{5 //lParam的意义可看MSDN中WM_KEYDOWN部分
HDOa N }
In2D32"F }
,zaveQ~l }
B%/Pn
2 return CallNextHookEx( hHook, nCode, wParam, lParam );
\Qn8"I83AV }
P2kZi=0 huIr*)r&p 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
~5b %~: 107SXYdhI BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
EzaOg| BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
uPPe"$ gu!A:Q 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:
arJ[.f9s OoNAW< LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
Lif mYn[ {
\8!HZei if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
xAflcY>Ozs {
'I2)-=ZL6 //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
IcZ 'KV SaveBmp();
NR5A"_' return FALSE;
[(mq8Nb }
$n W>]S\| …… //其它处理及默认处理
A
3l1$t#w }
4w,}1uNEf "yumc5kt !p$V7pFu6 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
gFH_^~7i8p {ig@Iy~DT 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
|j<'[gB\p ]F~5l?4u# 二、编程步骤
#*~Uu.T \Ip<bbB0 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
-h}J%UV {)M4h?.2 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
}`(kX] ][ =|V3cM4' 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
shB(kb{{ 2%I:s6r 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
t9}XO M* f
W ) 5、 添加代码,编译运行程序。
?#'qY6 ^ WBGYk); 三、程序代码
,\M'jV"SK ?g&]*zc^\ ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
{SJLM0=Z #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
c?d#Bj ? #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
TJ<PT #if _MSC_VER > 1000
E$T#o{pai #pragma once
_rM%N+$&d_ #endif // _MSC_VER > 1000
fITml6mbE #ifndef __AFXWIN_H__
Vswi /( #error include 'stdafx.h' before including this file for PCH
_:z~P<%s #endif
7]Egu D4 #include "resource.h" // main symbols
_F,OS<> class CHookApp : public CWinApp
v7-'H/d. {
qrdI" public:
;dnn
2)m CHookApp();
#[8gH>7 // Overrides
$2.DZ // ClassWizard generated virtual function overrides
3Rm$ //{{AFX_VIRTUAL(CHookApp)
AYi$LsLhO public:
$#!~K2$ virtual BOOL InitInstance();
YANEdH`d virtual int ExitInstance();
+38t82%YWo //}}AFX_VIRTUAL
Vl EkT9^: //{{AFX_MSG(CHookApp)
&
2bf // NOTE - the ClassWizard will add and remove member functions here.
R8KL4g-d // DO NOT EDIT what you see in these blocks of generated code !
+%yh@X6 //}}AFX_MSG
[Xrq+O, DECLARE_MESSAGE_MAP()
cE3co(j };
5IepVS(>?v LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
(#:Si~3 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
;9~z_orNQZ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
}yw\+fc BOOL InitHotkey();
{*2A%}S BOOL UnInit();
p#&6Ed*V #endif
'D4NPG`z ^~0r+w61 //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
.cb mCFXL #include "stdafx.h"
G`n-WP #include "hook.h"
zt8ZJlNK #include <windowsx.h>
/\9Kr;@vk #ifdef _DEBUG
Z_;' r|c #define new DEBUG_NEW
[Yv5Sw #undef THIS_FILE
U+ 8[Ia(t static char THIS_FILE[] = __FILE__;
z7CYYU? #endif
#wo_ #define MAX_KEY 100
4eKJ\Q=nX5 #define CTRLBIT 0x04
M]W4S4&Y= #define ALTBIT 0x02
YcI]_[ #define SHIFTBIT 0x01
S.I<Hs #pragma data_seg("shareddata")
<[q)2 5RL HHOOK hHook =NULL;
A-~)7- UINT nHookCount =0;
gp}S 1 static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
oH;Y} h static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
#\jPBLc static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
H0Tt(:.& static int KeyCount =0;
vD(;VeW[ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
lyV]-w #pragma data_seg()
dU\fC{1Z HINSTANCE hins;
T|m+ULp~ void VerifyWindow();
~$@I <=L BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
#: F)A_Y //{{AFX_MSG_MAP(CHookApp)
3lJK[V{'#' // NOTE - the ClassWizard will add and remove mapping macros here.
aV ^2 // DO NOT EDIT what you see in these blocks of generated code!
"[%NXan //}}AFX_MSG_MAP
j}|6k6t END_MESSAGE_MAP()
<D=%55 z/TRqD CHookApp::CHookApp()
[7B&<zY/? {
\KEL.}B9E // TODO: add construction code here,
njIvVs`q // Place all significant initialization in InitInstance
lRrOoON }
V6!oe^a7' #qPk ,a CHookApp theApp;
^b%AwzHH} LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
1/gh\9h {
3drgB;:g` BOOL bProcessed=FALSE;
Y5;:jYk#<_ if(HC_ACTION==nCode)
q q`UvU {
8'YL!moG| if((lParam&0xc0000000)==0xc0000000){// Key up
/#X O!%=7 switch(wParam)
X2{3I\'Ft {
Q=dR[t>^ case VK_MENU:
l`1ZS8 [. MaskBits&=~ALTBIT;
\h
yTcFb break;
koUH>J: case VK_CONTROL:
t^YDCcvoQ MaskBits&=~CTRLBIT;
JvG t=v break;
Vf:t!'WD?2 case VK_SHIFT:
6`yq4!&v MaskBits&=~SHIFTBIT;
!=-l760 break;
bNC1[GG[ default: //judge the key and send message
9Hu%Z/[!p break;
0+L5k!1D }
C>;}CH|X for(int index=0;index<MAX_KEY;index++){
iU3co|q7 if(hCallWnd[index]==NULL)
NO<myN+N continue;
DQ~@=%?ni if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
.v;Npm2 {
.-r
1.'.A SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
}vL[N~5\ bProcessed=TRUE;
=?}'\
>G " }
4Qw!YI#40$ }
)&w\9}B: }
B1GSZUd^?0 else if((lParam&0xc000ffff)==1){ //Key down
)~J/,\ switch(wParam)
&K7g8x"x. {
Lt*H|9 case VK_MENU:
*Vc}W MaskBits|=ALTBIT;
j/W#=\xz break;
f(3#5288 case VK_CONTROL:
&38Fj'l MaskBits|=CTRLBIT;
!~RD>N&n break;
bi_R.sfK& case VK_SHIFT:
J/mLB7^R MaskBits|=SHIFTBIT;
OLiYjYd break;
SsaF><{5R default: //judge the key and send message
SVR AkP- break;
;zGGT^Dn }
~v5tx for(int index=0;index<MAX_KEY;index++)
6L4B$'&KQZ {
R &-bA3w$ if(hCallWnd[index]==NULL)
0
xXAhv-)O continue;
j\ )Qn2r if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
-?GYW81Q {
Lrk^<:8; SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Xc@4(Nyp bProcessed=TRUE;
jHFdDw|N` }
"zqt'b0bW }
FY
VcL* }
B
(BWdrG if(!bProcessed){
*"E]^wCn for(int index=0;index<MAX_KEY;index++){
is6JS^Q if(hCallWnd[index]==NULL)
ZJx:?*0a continue;
Q8P;AN_JS if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
2.|Y SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
*z(.D\{% }
3Y=S^*ztd }
Obw uyhjQ }
:&Ul return CallNextHookEx( hHook, nCode, wParam, lParam );
';
qT }
Hv%a\WNS1 f",B;C BOOL InitHotkey()
SI@I {
MF& +4$q if(hHook!=NULL){
M+ H$Jjcs nHookCount++;
$1w8GI\J return TRUE;
Z{e5 OJ }
'SuYNA) else
7`P(LQAr! hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
&)wQ|{P~k if(hHook!=NULL)
v7g-M nHookCount++;
C[[z3tn return (hHook!=NULL);
q-uYfXZ{j }
6#.R'O BOOL UnInit()
l
lQ<x {
jx-W$@ if(nHookCount>1){
mxXQBmW nHookCount--;
pa.W-qyu return TRUE;
wK,tq }
h5Z%|J>;0 BOOL unhooked = UnhookWindowsHookEx(hHook);
Yc9 M6=E^ if(unhooked==TRUE){
te:@F]A nHookCount=0;
y<5s)OehG hHook=NULL;
]o_ Ps| }
]A_)&`"Cb return unhooked;
z`/v}'d[X }
."MBKyg6 ]qrO"X= BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
u|Db%)[ {
;Yi ;2ttW BOOL bAdded=FALSE;
VD1*br^, for(int index=0;index<MAX_KEY;index++){
KC if(hCallWnd[index]==0){
M T{^=F ] hCallWnd[index]=hWnd;
($ae n HotKey[index]=cKey;
VNPuO U= HotKeyMask[index]=cMask;
d/|@"z^? bAdded=TRUE;
]
Li(E: KeyCount++;
Um*{~=;u break;
}B"kJNxV }
O-G4^V8 }
g6nBu return bAdded;
mvYr"6f8 }
}J:~}?^%n .lqo>Ta
y BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
rJR"[TTJ {
}mX;0qO BOOL bRemoved=FALSE;
q7X/"Dfx for(int index=0;index<MAX_KEY;index++){
V-t! if(hCallWnd[index]==hWnd){
1z*] MYU if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
YKj7~yK? hCallWnd[index]=NULL;
4,uH 4[7 HotKey[index]=0;
{Rbc HotKeyMask[index]=0;
_sw,Y!x%dF bRemoved=TRUE;
\<V{6#Q= KeyCount--;
uTOL break;
.\i9}ye }
y|c]r!A }
_e/vw: }
U+nwLxe' return bRemoved;
.(3B}}gB> }
W4T>@b. (3 B;
V void VerifyWindow()
'|Cs!Zl {
0gxbo for(int i=0;i<MAX_KEY;i++){
?e yo2:-$ if(hCallWnd
!=NULL){ ij%\ld9kd
if(!IsWindow(hCallWnd)){ MB:E/
hCallWnd=NULL; M]eH
JZ~v
HotKey=0; *p +%&z_<
HotKeyMask=0; skr^m%W
KeyCount--; 670g|&v.
} Pgb<;c:4
} 1P&c:n
} O'o`
} QIGMP=!j
z]~B@9l
BOOL CHookApp::InitInstance() YpXUYNy
{ w0VJt<e*
AFX_MANAGE_STATE(AfxGetStaticModuleState()); Gv3a<Knn4
hins=AfxGetInstanceHandle(); ~[l2"@
InitHotkey(); lshO'I+)*
return CWinApp::InitInstance(); BpRQG]L
} 389T6sP]
&yWl8O
int CHookApp::ExitInstance() X+Xjf(
{ pX|\J>u)
VerifyWindow(); @yqy$I
UnInit(); 6Kg
lp\2
return CWinApp::ExitInstance(); '^n2]<
} ^uC1\!Q1
ZA+$ZU^
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file J?u",a]|H"
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) <#LHL
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ ^[lg1uMW
#if _MSC_VER > 1000 _qM'm^z5
#pragma once ;?bRRW
#endif // _MSC_VER > 1000 *p p1U>,
eQJLyeR+
class CCaptureDlg : public CDialog R7( + ^%
{ lB.P
// Construction V_(lZDjh*
public: U3az\E)HV
BOOL bTray; 8Q?)L4.]
BOOL bRegistered; p%_r0
BOOL RegisterHotkey(); DBbmM*r
UCHAR cKey; j=M_>
UCHAR cMask; 0g~WM
void DeleteIcon(); ^=}~
void AddIcon(); T&6{|IfM_
UINT nCount; :>;-uve8'
void SaveBmp(); /w`{]Ntgu
CCaptureDlg(CWnd* pParent = NULL); // standard constructor ,r+=>vre
// Dialog Data kjJ\7x6M
//{{AFX_DATA(CCaptureDlg) rN8 ZQiJC
enum { IDD = IDD_CAPTURE_DIALOG }; '9]%#^[Q
CComboBox m_Key; wlmi&kq
BOOL m_bControl; 4f'WF5S/}8
BOOL m_bAlt; \^w=T*
BOOL m_bShift; Ds$FO}KD{
CString m_Path; }|&