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:
I/njyV)H
+ kMj|()>\ 一、实现方法
"M5 6
^3RfF^W 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:
o`c+eMwr( ~Tt@v`} #pragma data_seg("shareddata")
C^"zU>W_ HHOOK hHook =NULL; //钩子句柄
eY :"\c3
UINT nHookCount =0; //挂接的程序数目
=T9h7c R static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
j<~Wp$\i7> static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
3FR(gr$X static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
SQ,-45@W static int KeyCount =0;
-kk7y static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
G~1;_' #pragma data_seg()
!-OZ/^l|O` lq:q0>vyI 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。
^Q`5+ aPelt` 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:
gw"cXny Cy?]o?_? BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
1]:,Xa+|S cKey,UCHAR cMask)
{KHI(*r; {
M3-lL;!n BOOL bAdded=FALSE;
2%WeB/)9 for(int index=0;index<MAX_KEY;index++){
&"%Ws{Qn] if(hCallWnd[index]==0){
7=Muq]j2 hCallWnd[index]=hWnd;
our
^J8 HotKey[index]=cKey;
yDqwz[v b HotKeyMask[index]=cMask;
iKaX8c,zI bAdded=TRUE;
8s6[-F5 KeyCount++;
u"qu!EY2 break;
"j_iq"J }
"a[;{s{{. }
qI uo8o} return bAdded;
,<L4tp+y0 }
r[!~~yu/o //删除热键
)58O9b BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
yb',nGl~ {
h7+"*fN BOOL bRemoved=FALSE;
Vx<{cHQQ for(int index=0;index<MAX_KEY;index++){
;9j ]P56 if(hCallWnd[index]==hWnd){
90}vFoy if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
9$$ Ijf hCallWnd[index]=NULL;
73X*|g[O HotKey[index]=0;
^}~Q(ji7 HotKeyMask[index]=0;
@HbRfD/! bRemoved=TRUE;
xK6`|/e KeyCount--;
clU ?bF~e1 break;
E'\gd7t ; }
t[q2W"#.
}
y7UU'k` }
tlQ6>v' return bRemoved;
W]eILCo }
l!:bNMd #k9&OS? [ojL9.6 DLL中的钩子函数如下:
c(=>5 =7+%31 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
KuwhA-IL {
:-d#kU BOOL bProcessed=FALSE;
*}C%z( if(HC_ACTION==nCode)
@2"3RmYLo {
5Yv*f: if((lParam&0xc0000000)==0xc0000000){// 有键松开
YWn""8p;P switch(wParam)
68?&`/t {
R_G2C@y* case VK_MENU:
AHs%?5YTY; MaskBits&=~ALTBIT;
,mm97I break;
!LH;K case VK_CONTROL:
lx2#C9L_ MaskBits&=~CTRLBIT;
/4Wf\
Zu break;
g
sm%4>sc case VK_SHIFT:
R8[VD iM6E MaskBits&=~SHIFTBIT;
/UunWZ u% break;
&C
MBTY#u default: //judge the key and send message
E?+~S M1~ break;
P WS8Dpb }
N>3{!K>/Y: for(int index=0;index<MAX_KEY;index++){
R7rM$|n=o if(hCallWnd[index]==NULL)
d"n>Q Tn\ continue;
PV,Z@qm@^ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
0E#??gN {
dE8f?L' SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
75H!i$(*+ bProcessed=TRUE;
<y?+xZM]#| }
**m8 HD }
2j4202 }
&PPnI(s^K else if((lParam&0xc000ffff)==1){ //有键按下
EC$F|T0f switch(wParam)
{Yxvb** {
QswPga(- case VK_MENU:
e*'bY;8lo MaskBits|=ALTBIT;
b&!}SZ break;
(+v':KH3_ case VK_CONTROL:
7a9">:~ MaskBits|=CTRLBIT;
D>jtz2y=D break;
Ch?yk^cY case VK_SHIFT:
iyCH)MA MaskBits|=SHIFTBIT;
xytWE:= break;
H9jlp.F default: //judge the key and send message
L$c 1<7LU break;
5(#z)T }
8-+# !] for(int index=0;index<MAX_KEY;index++){
4wKCzPy if(hCallWnd[index]==NULL)
Fb<'L5}i continue;
O=U,x-Wl if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
kVsX/~$ {
LiHJm- SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Mm8_EjMp bProcessed=TRUE;
qDGx(d }
_lI(!tj( }
8Q/cJ+& }
Tg
O]q4 if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
H8"RdKwg? for(int index=0;index<MAX_KEY;index++){
,+BFpN' if(hCallWnd[index]==NULL)
Ke^/aGi}O continue;
'2l[~T$* if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
@}UOm-M SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
O(evlci //lParam的意义可看MSDN中WM_KEYDOWN部分
N@0/=B[n }
c%G~HOE=B }
rY Puo }
n. N0Nhd return CallNextHookEx( hHook, nCode, wParam, lParam );
sifjmNP }
&56\@t^ fR;[??NH 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:
:Hitx xs6!NY BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
-d!84_d9 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
6@0?~ SgQmR#5 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:
oSYJXs ]p(es,[ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
CA|W4f} {
/!&eP3^ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
?a+J4Zr3 {
[EPRBK`= //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
3J4OkwqD SaveBmp();
M| }?5NS
return FALSE;
( q*/=u }
.gNJY7`b …… //其它处理及默认处理
qu1! KS }
%A
`9[icy P<1&kUZL 4Vj]bm 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。
[Ketg C.=%8|Zy 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。
}rVLWt J|V*g]#kP 二、编程步骤
:ldI1*@i< 3KD:JKn^ 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";
sFfargl =`}|hI 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
<vg|8-,#m NSRY(#3 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;
MkZoHzg}c Xa}y.qH 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;
h _c11# }+NlYD:qF 5、 添加代码,编译运行程序。
29@m:=-}7 s*CBYzOm 三、程序代码
$\oe}`#o &xj,.; ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
AA|G&&1y
#if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
9Z2aFW9 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
=;8q` #if _MSC_VER > 1000
4tiCxf) #pragma once
xjDaA U, #endif // _MSC_VER > 1000
q/7T-"q/G #ifndef __AFXWIN_H__
L{f0r!d| #error include 'stdafx.h' before including this file for PCH
yF
XPY=EQ #endif
t]t(/x# #include "resource.h" // main symbols
'Um\m class CHookApp : public CWinApp
<ihJp^kgQ {
BW`Tw^j public:
coXm*X>z CHookApp();
A8nf"mRD: // Overrides
k~Y_%#_
// ClassWizard generated virtual function overrides
mk-L3H1@J3 //{{AFX_VIRTUAL(CHookApp)
tpV61L
public:
@!\lt$ virtual BOOL InitInstance();
ewYk> virtual int ExitInstance();
KmF+3g~#s //}}AFX_VIRTUAL
k
V'0rb //{{AFX_MSG(CHookApp)
vO;:~ // NOTE - the ClassWizard will add and remove member functions here.
"8[Vb#=*e // DO NOT EDIT what you see in these blocks of generated code !
Ip,0C8T`Q //}}AFX_MSG
K]U8y$^ DECLARE_MESSAGE_MAP()
f,+ONV]5Tt };
I}
]s( LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
oM}P Wf- BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
/ vzwokH BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
rYyEs
I#qo BOOL InitHotkey();
Zg;Ht BOOL UnInit();
bu\D*- #endif
Wf
*b"# ?P2d
9b //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
`t#Ie* #include "stdafx.h"
sgeME^ v #include "hook.h"
@aoHz8K #include <windowsx.h>
D7N` %A8 #ifdef _DEBUG
{<^PYN>` #define new DEBUG_NEW
yc$8X sns #undef THIS_FILE
;fY)7
' static char THIS_FILE[] = __FILE__;
'$CJZ`nt #endif
{uO2m*JrI #define MAX_KEY 100
:B_ itl0{e #define CTRLBIT 0x04
'l'[U #define ALTBIT 0x02
aQfrDM<*XS #define SHIFTBIT 0x01
""F'Nzy #pragma data_seg("shareddata")
h,Tsb:Q"M HHOOK hHook =NULL;
1QDAfRx UINT nHookCount =0;
( /_Z^m9 static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
X?] 1/6rV static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
/aMeKM[L` static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
^p7Er! static int KeyCount =0;
A!5)$>!o static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
y$pT5X G #pragma data_seg()
[hXU$Y>"0 HINSTANCE hins;
D\GP+Ota void VerifyWindow();
uw&'=G6v BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
\Mod4tQ //{{AFX_MSG_MAP(CHookApp)
I'RhA\` // NOTE - the ClassWizard will add and remove mapping macros here.
,ffH:3F // DO NOT EDIT what you see in these blocks of generated code!
7b[vZNi_ //}}AFX_MSG_MAP
4#@zn 2l END_MESSAGE_MAP()
K1Wiiw (}n,Ou[ CHookApp::CHookApp()
oBTRO0.s+ {
E%C02sI // TODO: add construction code here,
hAp<$7 // Place all significant initialization in InitInstance
i;B)@op.# }
H23-%+*J wrW768WR CHookApp theApp;
GKKf#r74 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Z:}d\~`x$% {
vSy#[9} BOOL bProcessed=FALSE;
6<<ihm+ if(HC_ACTION==nCode)
JB= L\E} {
A#j'JA>_ if((lParam&0xc0000000)==0xc0000000){// Key up
p1L8g[\ switch(wParam)
Gvw:h9v {
{wx!~K case VK_MENU:
Y/_b~Ahn MaskBits&=~ALTBIT;
`!\`yI$!%w break;
BI-xo}KI case VK_CONTROL:
@{!c [{x,T MaskBits&=~CTRLBIT;
'Nv*ePz break;
J@c)SK%2h case VK_SHIFT:
k:0HsN!F9 MaskBits&=~SHIFTBIT;
\{[Gdj` break;
<M|kOi default: //judge the key and send message
ca1A9fvo break;
@t6B\ ?4'T }
RE(R5n28, for(int index=0;index<MAX_KEY;index++){
O=PyXOf if(hCallWnd[index]==NULL)
PN n{Rt continue;
BK8)'9/ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
LHb(T`.= {
^H1B62_ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
QvH=<$ bProcessed=TRUE;
Zg/ra1n }
'J&$L c }
P'6eK? }
?_9A`LC*
else if((lParam&0xc000ffff)==1){ //Key down
kN*,3)T;} switch(wParam)
J!,<NlP0K {
wQX,a;Br case VK_MENU:
Rb~NX
MaskBits|=ALTBIT;
Vn-y<*np break;
b*xw=G3% case VK_CONTROL:
/}\EMP MaskBits|=CTRLBIT;
/8i3 I5* break;
7 Ld5 case VK_SHIFT:
9a5x~Z:' MaskBits|=SHIFTBIT;
tTB,eR$ break;
x_vaYUl) default: //judge the key and send message
Z!P7mH\c} break;
c1?_L( }
_Jc[`2Uv_c for(int index=0;index<MAX_KEY;index++)
Re{vO&. {
{]/}3t if(hCallWnd[index]==NULL)
%(,Kj
~0 continue;
?6F\cl0. if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
7Rf${Wv0 {
W4Ey]y" SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
wtCz%!OYB bProcessed=TRUE;
P"LbWZ6Nj }
%># VhK }
%(IkUD }
oZkjg3 if(!bProcessed){
YzqUOMAt"V for(int index=0;index<MAX_KEY;index++){
:O}= $[ if(hCallWnd[index]==NULL)
]E\o<"#t/ continue;
HrH-e=j if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
}j^asuf~c SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
?CgqHmf\\( }
'`#sOH }
x78`dX }
*UVo>; return CallNextHookEx( hHook, nCode, wParam, lParam );
[=[>1<L> }
EIqe|a+ ]Z?y\L*M- BOOL InitHotkey()
E)l0`83~^ {
Nr?Z[6O| if(hHook!=NULL){
wJs#rkW nHookCount++;
7{%_6b" return TRUE;
);o2eV }
!e5!8z else
PT7-_r hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
B8){ if(hHook!=NULL)
}&+b\RE nHookCount++;
uOzol~TU) return (hHook!=NULL);
tA2Py }
'O%itCy) BOOL UnInit()
&DQyJJ`k {
[ZC{eg+D if(nHookCount>1){
v803@9@ nHookCount--;
WZ\bm$
return TRUE;
),ur!v }
LO8`qq*rq BOOL unhooked = UnhookWindowsHookEx(hHook);
m5c?A+@fZ if(unhooked==TRUE){
%~eIx=s nHookCount=0;
tI42]:z hHook=NULL;
-?_#Yttu }
AI{Tw>hZ return unhooked;
Ah5`Cnv }
-][~_Hd{ I!FIV^}Z( BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
3K2B7loD)~ {
cZB?_[Cp BOOL bAdded=FALSE;
tk'1o\@p9b for(int index=0;index<MAX_KEY;index++){
rucgav if(hCallWnd[index]==0){
N8hiv'3 hCallWnd[index]=hWnd;
I$.HG] HotKey[index]=cKey;
w$Zi'+&* HotKeyMask[index]=cMask;
vGe]; bAdded=TRUE;
c2Q KI~\x KeyCount++;
q~esxp break;
Ass : }
2a=3->D& }
usj:I`> return bAdded;
RLy(Wz3% }
-|0nZ BbU%p BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
b`a4SfbQS {
@|AHTf! BOOL bRemoved=FALSE;
- BQoNEh for(int index=0;index<MAX_KEY;index++){
BC: d@
if(hCallWnd[index]==hWnd){
7s8-Uwl< if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
{)V!wSi hCallWnd[index]=NULL;
8DAHaS; HotKey[index]=0;
<v&L90+s\; HotKeyMask[index]=0;
oeV.K. bRemoved=TRUE;
63'Rw'g^|2 KeyCount--;
dY=]ES}` break;
o#GZ|9IL }
Qt-7jmZw1 }
5&59IA%S }
Z^tTR]u\$ return bRemoved;
*Ubsa9'fS }
Y~E
8z WC&V9Yk void VerifyWindow()
<{ZDD]UGs0 {
ltQo_k for(int i=0;i<MAX_KEY;i++){
i}u,_
} if(hCallWnd
!=NULL){ bwrM%BL
if(!IsWindow(hCallWnd)){ #)}K,FDd
hCallWnd=NULL; (G1KMy
HotKey=0; W&g