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:
Fm"$W^H
'Nh^SbD+_| 一、实现方法
@d\F; o< I?QKd@ 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
DZue.or '#PT C,0UJ #pragma data_seg("shareddata")
JFZ p^{ HHOOK hHook =NULL; //钩子句柄
1*fA>v UINT nHookCount =0; //挂接的程序数目
!_@%/I6 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
q<VhP2R static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
9\F^\h{ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
'&d4x c static int KeyCount =0;
\IKr+wlN8 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
#^Y,,GA #pragma data_seg()
scdT/|(U$ cF6|IlhO 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。
.
fIodk C7{w I`~ 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:
uT1x\Rt|e S~T[*Z/m BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
Gsb]e cKey,UCHAR cMask)
' vwBG=9C {
utr_fFu BOOL bAdded=FALSE;
DxlX- for(int index=0;index<MAX_KEY;index++){
{#vo^& B if(hCallWnd[index]==0){
b7-a0zaN hCallWnd[index]=hWnd;
_PIk,!< HotKey[index]=cKey;
v,jU9D\ HotKeyMask[index]=cMask;
Z]tz<YSkG bAdded=TRUE;
.eE5pyw+C KeyCount++;
*4ID$BmO break;
*b&| }
f =Nm2(e }
yZ`\.GgC^& return bAdded;
n3(HA }
`)'YU^s //删除热键
E~B
LY{3: BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
YW*ti|u|w {
KLX>QR@ BOOL bRemoved=FALSE;
4
QWHGh" for(int index=0;index<MAX_KEY;index++){
e*tOXXY1 if(hCallWnd[index]==hWnd){
W+QI
D/ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
hYLu hCallWnd[index]=NULL;
9I,Trk@& HotKey[index]=0;
BEw(SQH HotKeyMask[index]=0;
'>Z
Ou3> bRemoved=TRUE;
aePk^?KbB KeyCount--;
8W{R&Z7aL break;
d/MMPge3 }
F
J)la9 }
7j^,4; }
8qT/1b return bRemoved;
zR%#Q_ }
?n}L+| {J[0UZ6 IMj{n.y4 DLL中的钩子函数如下:
Lr`yl$6 Na4\)({ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
[ACa<U/ {
dI`b AP;\ BOOL bProcessed=FALSE;
L!\I>a5C0G if(HC_ACTION==nCode)
@>:r'Fmu- {
uKK+V6}!kj if((lParam&0xc0000000)==0xc0000000){// 有键松开
D_g+O"];P switch(wParam)
C&\#{m_1B {
zMtx>VI case VK_MENU:
ikUG`F%W MaskBits&=~ALTBIT;
V
V<Zl break;
6:H@=fEv case VK_CONTROL:
>mz<=n
MaskBits&=~CTRLBIT;
{$Qw]?Yv break;
"5=Gu1 case VK_SHIFT:
p~qdkA< MaskBits&=~SHIFTBIT;
n* uT break;
ol-U%J default: //judge the key and send message
s~3"*,3@ break;
:U=*@p4? }
`j9 ;9^ for(int index=0;index<MAX_KEY;index++){
*4]}_ .rG# if(hCallWnd[index]==NULL)
X-=49) continue;
8K'3iw>z if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
"d%o% {
*y0TtEd; SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
N^v"n*M0| bProcessed=TRUE;
UZz/v#y~ }
3VaL%+T$, }
dSkM A }
UyENzK<%u else if((lParam&0xc000ffff)==1){ //有键按下
;0FfP switch(wParam)
\8g'v@$wG {
wNtC5 case VK_MENU:
Y'*oW+K MaskBits|=ALTBIT;
k..AP<hH break;
H}?"2jF case VK_CONTROL:
f?W_/daP MaskBits|=CTRLBIT;
Ir#]p9:x break;
}p5_JXBV case VK_SHIFT:
#x*\dL MaskBits|=SHIFTBIT;
TophV}@B` break;
2{|Z?3FJ^ default: //judge the key and send message
8
kvF~d
; break;
*O_>3Hgl }
>e^bq/' for(int index=0;index<MAX_KEY;index++){
Np7+g`nG if(hCallWnd[index]==NULL)
'hR0JXy continue;
s@zO`uBc if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
z^vfha {
_AzI\8m SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
,oykOda:| bProcessed=TRUE;
1*" 7q9x }
)pSA|Qt N }
R:4@a ':H }
x$;RfK2&p if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
By waD? for(int index=0;index<MAX_KEY;index++){
djH&)&q! if(hCallWnd[index]==NULL)
tk]D)+{u&c continue;
kDol 1v` if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
?Z2`8]-E SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
)(0if0D4 //lParam的意义可看MSDN中WM_KEYDOWN部分
Ge_fU'F }
DQ(0:r }
p#).;\M }
"iTjiH)Q( return CallNextHookEx( hHook, nCode, wParam, lParam );
>$7x]f }
Y?TS, ![;={d0 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
^D<CoxG yX4Vv{g BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
T%%
0W J BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
6@TU9AZS` XwUa|"X6 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
Da615d
R\|,GZ!`+ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
.u>[m. {
HdN5zl,q if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
m^!:n$ {
aX`uF<c9 //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
N"}>);r SaveBmp();
WW+xU0 return FALSE;
OKAU*}_ }
]Cj@",/3# …… //其它处理及默认处理
yAfwQ$Ll7 }
P&sWn?q Ol VxBBZsZO~ 0S^&A?$= 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。
arDl2T,igF \?;
`_E`j 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。
&nP0T-T5y ZA+dtEE=f9 二、编程步骤
gYhY1Mym U xBd14-R_ 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";
/kY9z~l S7)qq 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
UxL*I[z5 ao2^3e 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;
uX*2Rs$s K f/[Edn 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
H"FK(N\ gom!dB0J 5、 添加代码,编译运行程序。
\P*_zd@% F%h3?"s 三、程序代码
<%m YsaM q2*A'C ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
m,lZy#02s3 #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
pR$(V4> #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
d.FU))lmD #if _MSC_VER > 1000
c,4~zN8Ou #pragma once
%"0, o$ #endif // _MSC_VER > 1000
moM?aYm #ifndef __AFXWIN_H__
6;Z-Y>\c #error include 'stdafx.h' before including this file for PCH
)O]6dd #endif
SXk.7bMV6 #include "resource.h" // main symbols
eR$@Q class CHookApp : public CWinApp
6nZ]y&$G-k {
:j]1wp+ public:
KLyRb0V CHookApp();
A`n>9|R // Overrides
{Rkd;`Q`! // ClassWizard generated virtual function overrides
17 Ugz? //{{AFX_VIRTUAL(CHookApp)
/W/e%. public:
<0})%V?- virtual BOOL InitInstance();
}|.<EkA virtual int ExitInstance();
&BRk<iwV //}}AFX_VIRTUAL
wtw=RA //{{AFX_MSG(CHookApp)
`,qft[1 // NOTE - the ClassWizard will add and remove member functions here.
,U~A=bsa // DO NOT EDIT what you see in these blocks of generated code !
?{ N,&d //}}AFX_MSG
ye(b 7CX DECLARE_MESSAGE_MAP()
)0VL$A };
dH y9
wU LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
cUY- BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
i g(O$y BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
q&25,zWD BOOL InitHotkey();
YzESVTh BOOL UnInit();
Zw]"p63eMa #endif
|J-X3`^\H j'D%eQI,V //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
vGkemJ^/ #include "stdafx.h"
w"j>^#8 #include "hook.h"
32wtN8kx #include <windowsx.h>
P([!psgu #ifdef _DEBUG
AY /9Io- #define new DEBUG_NEW
;z'&$#pA #undef THIS_FILE
K!6T8^JH static char THIS_FILE[] = __FILE__;
yaR>?[h #endif
0V:H/qu8> #define MAX_KEY 100
M+ +Dk7B #define CTRLBIT 0x04
6u, g #define ALTBIT 0x02
|p:4s"NT #define SHIFTBIT 0x01
,Y:oTo=~ #pragma data_seg("shareddata")
U#z"t&o=L HHOOK hHook =NULL;
7m2iL#5[ UINT nHookCount =0;
,X|Oe@/ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
Z)7{~xq static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
74([~Qs _M static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
~su>RolaX static int KeyCount =0;
ji/`OS-iq static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
xrf|c #pragma data_seg()
A%^?z. HINSTANCE hins;
y!b"Cj void VerifyWindow();
evyjHc Cx BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
7nB4(A2[S4 //{{AFX_MSG_MAP(CHookApp)
MSCH6R"5 // NOTE - the ClassWizard will add and remove mapping macros here.
QRju9x // DO NOT EDIT what you see in these blocks of generated code!
*$A`+D9 //}}AFX_MSG_MAP
Ic'D#m END_MESSAGE_MAP()
;P S4@, bW`nLiw}% CHookApp::CHookApp()
mnA_$W3~I {
EID-ROMO // TODO: add construction code here,
WSozDNF!'f // Place all significant initialization in InitInstance
EB3/o7)L }
Zf$mwRS[_ [A~?V.G CHookApp theApp;
Ce+:9} [ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Mi.#x_ {
dk7x<$h-h0 BOOL bProcessed=FALSE;
e#oK%
{A if(HC_ACTION==nCode)
o(tJc}Mh+( {
LH54J;7Y if((lParam&0xc0000000)==0xc0000000){// Key up
"~VKUvDu switch(wParam)
Ry+?#P+ {
:
;8L1' case VK_MENU:
eBa#Z1Z MaskBits&=~ALTBIT;
qlM<X? break;
?GX@&_ case VK_CONTROL:
,~3rY,y- MaskBits&=~CTRLBIT;
"`;-5d g break;
u.A}&'H case VK_SHIFT:
]EK(k7nH MaskBits&=~SHIFTBIT;
iY>P7Uvvz break;
g{Av
=66Z default: //judge the key and send message
)"?'~ 5A break;
Fug4u?-n }
Gd|kAC
g for(int index=0;index<MAX_KEY;index++){
`a52{Wa if(hCallWnd[index]==NULL)
Ab[o~X" continue;
{_!,T%>+1 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
"$N$:B @U {
COsy.$|4 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
0to`=;JI bProcessed=TRUE;
0xZ^ f}@L }
JFI*Pt;X9 }
" O
r1 fC }
Ep(xlHTv else if((lParam&0xc000ffff)==1){ //Key down
kMW9UUw switch(wParam)
P84YriLo {
5`3x(=b case VK_MENU:
~rb]u
Ny- MaskBits|=ALTBIT;
/*;a6S8q break;
4"|3pMr case VK_CONTROL:
uhj]le! MaskBits|=CTRLBIT;
?#a&eW break;
\s[L=^! case VK_SHIFT:
Syseiw MaskBits|=SHIFTBIT;
l1kHFeq break;
'+Jy//5? default: //judge the key and send message
sCJ|U6Q- break;
9_==C"F }
!\| for(int index=0;index<MAX_KEY;index++)
^O<v'\!z- {
hlreeXv if(hCallWnd[index]==NULL)
W\-`}{B_/ continue;
.h4NG4FIF if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
3{.]! {
dSKvs" SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
/pkN=OBR bProcessed=TRUE;
VMF?qT3Nd }
FO>!T@0G }
&u^]YE{ }
RSj8T< if(!bProcessed){
J|hVD for(int index=0;index<MAX_KEY;index++){
I*j~5fsS' if(hCallWnd[index]==NULL)
fJ\?+, continue;
=\u,4 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
q|%+?j( SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
l?IeZisX }
O13]H"O_ }
u(yN81 }
H!0m8LCnb return CallNextHookEx( hHook, nCode, wParam, lParam );
"5dke^yk0 }
}|/A &c !"<rlB,J BOOL InitHotkey()
F,)+9/S& {
QKEtV if(hHook!=NULL){
D^h!
].3
T nHookCount++;
3n)Kzexh return TRUE;
9;I%Dv }
*tT}N@<% else
i,"Xw[H*s hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
huA?*fat if(hHook!=NULL)
#b&tNZ4!_ nHookCount++;
DazoY&AWE return (hHook!=NULL);
ts(u7CJd }
GK-P6d BOOL UnInit()
m;4ti9 {
\"RCJadK if(nHookCount>1){
d0}(d Gl nHookCount--;
b{-"GqMO return TRUE;
BI%~0Gj8 }
Q|+ a BOOL unhooked = UnhookWindowsHookEx(hHook);
#wT6IU1 if(unhooked==TRUE){
&`s{-<t<L nHookCount=0;
2 <OU)rVE4 hHook=NULL;
3rFku"zT$ }
+1yi{!j1 return unhooked;
!%}n9vr!}\ }
:4 z\Q] V,VL?J\ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
(y?F8]TfM {
451.VI}MR BOOL bAdded=FALSE;
!pRu?5 for(int index=0;index<MAX_KEY;index++){
ox<&T| if(hCallWnd[index]==0){
WY>$.e hCallWnd[index]=hWnd;
h*y+qk-!\g HotKey[index]=cKey;
f^hJA Z HotKeyMask[index]=cMask;
@8`I!fZ bAdded=TRUE;
ed5oN^V.< KeyCount++;
2DsP "q79k break;
WvF{`N }
f{L;, }
ipMSMk7gx return bAdded;
M0C)SU5" }
hR0a5 l,Y5VGiH# BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
#6#n4`%ER {
6RxI9{ry BOOL bRemoved=FALSE;
w[l#0ZZ for(int index=0;index<MAX_KEY;index++){
j3%Wrt if(hCallWnd[index]==hWnd){
j+-`P5 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
3t.!5L hCallWnd[index]=NULL;
|[5;dt_U/ HotKey[index]=0;
6J JA"] ` HotKeyMask[index]=0;
44~ReN}` bRemoved=TRUE;
D9P,[:" KeyCount--;
DFZ@q=ZT break;
0e#PN@ }
>*O5Ry:4 }
bG"FN/vg }
OSUiS`k return bRemoved;
bp?TO]LH }
G8w @C &