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:
*1`q
x+1
k!)Pl,nJ 一、实现方法
bTep TWv
O3~7 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:
PDNbhUAV =GJ)4os #pragma data_seg("shareddata")
E@[ZwTnJ HHOOK hHook =NULL; //钩子句柄
u%b.#! UINT nHookCount =0; //挂接的程序数目
y1Op Z static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
1.IEs:(; static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
)y"8Bx=x4 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
:TkR]bhm static int KeyCount =0;
fb|%)A= static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
hywy(b3 #pragma data_seg()
2`P=ekF] S2<evs1d 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。
zr@HYl Gph:'3
*X 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:
J>N^ FR9 &3CC | BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
6BH
P#B2j cKey,UCHAR cMask)
@5tGI U;1 {
%Fp1c K BOOL bAdded=FALSE;
, .]1N:
for(int index=0;index<MAX_KEY;index++){
JDP /vNq if(hCallWnd[index]==0){
(,^jgv|I hCallWnd[index]=hWnd;
`BzjDI:a HotKey[index]=cKey;
_;'<}a HotKeyMask[index]=cMask;
hF`Qs bAdded=TRUE;
K'U8ft*_ KeyCount++;
2}0S%R( break;
/vNHb_- }
'
o(7@ }
2#)z%K6T return bAdded;
ioJ|-@!#o }
JyDg=%-$2 //删除热键
V)jF]u~g BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
E'+?7ZGWj {
Zonr/sA ~ BOOL bRemoved=FALSE;
d*R('0z{ for(int index=0;index<MAX_KEY;index++){
@XQItc< if(hCallWnd[index]==hWnd){
8>AST, if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
V(wANvH hCallWnd[index]=NULL;
'dJ(x HotKey[index]=0;
0 HPqoen$ HotKeyMask[index]=0;
bwyj[:6l bRemoved=TRUE;
N}CeQ'l[R KeyCount--;
uy rS6e0 break;
w^E$R }
HyC826~-rI }
@&9 ,0x }
RfQ*`^D return bRemoved;
wu~ ?P ` }
3A!Qu$r9 TrR=3_;.7 cm17hPe`}n DLL中的钩子函数如下:
e N^6gub K9QC$b9( LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
WPDi)UX {
Z3 O_K BOOL bProcessed=FALSE;
Lq]t6o] if(HC_ACTION==nCode)
LO@o`JF {
bzyy;`;6Q~ if((lParam&0xc0000000)==0xc0000000){// 有键松开
Nq"J[l*+g switch(wParam)
w=kW~gg {
5bo')^xa case VK_MENU:
]/[$3rPwZ MaskBits&=~ALTBIT;
P2fiK break;
kzmw1*J case VK_CONTROL:
,b9!\OWDF MaskBits&=~CTRLBIT;
EI8KK o * break;
:=?od
0]W case VK_SHIFT:
9s&dN MaskBits&=~SHIFTBIT;
MeDlsO break;
{y`n_ default: //judge the key and send message
SYA0Hiw7P break;
1T0s
UIY }
q);@iiJ- for(int index=0;index<MAX_KEY;index++){
cCv@fks if(hCallWnd[index]==NULL)
F*p@hl continue;
S7(tGD if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
)St`}qu; {
f0 "_ {\ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
O"9Or3w bProcessed=TRUE;
`M!'PMX }
N)
'|l0x0 }
@Px_\w }
A7R [~ else if((lParam&0xc000ffff)==1){ //有键按下
A`nzqe#(1 switch(wParam)
=3|5=ZU034 {
h3j`X' case VK_MENU:
09J,!NN MaskBits|=ALTBIT;
jIjW +D` break;
OZ4% 6/ case VK_CONTROL:
l*b0uF MaskBits|=CTRLBIT;
U*\1d break;
]23+ d/ case VK_SHIFT:
ZVDi;
MaskBits|=SHIFTBIT;
9`cj9zz7 break;
C:p` default: //judge the key and send message
6ag0c&k break;
wRu\9H} }
rO]2we/B,4 for(int index=0;index<MAX_KEY;index++){
juB /?'$~ if(hCallWnd[index]==NULL)
tN0? continue;
:'Tq5kE if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
<~
?LU^ {
ld7B{ ?] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
ZM_-g4[H bProcessed=TRUE;
P\&n0C~ }
Ygc.0VKMR }
;aDYw [ }
JfzfxfM if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
2#@-t{\3-p for(int index=0;index<MAX_KEY;index++){
V(M7d>N5G if(hCallWnd[index]==NULL)
&IP`j~b continue;
3bagL)'iz if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
qRCUkw} fs SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
:?:R5_Nd= //lParam的意义可看MSDN中WM_KEYDOWN部分
vu3zZMl }
emG1Wyl }
o$Z]qhq }
O
+Xu?W] return CallNextHookEx( hHook, nCode, wParam, lParam );
;-VXp80J }
4okZ v*^'|QyM7 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
bdj')%@n v,c;dlg_ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
@Uqcym. BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
scyv]5Hm! 1 Ay.^f 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
KNSMx<GP 4R&pb1eF LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
B:fulgh2ni {
+@MG$*}Oz if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
6JD~G\$ {
+K48c,gt? //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
BP=<TRp. SaveBmp();
.2SD)<}(9 return FALSE;
aPHNX) }
sM@1Qyv&0 …… //其它处理及默认处理
?zK\!r{ }
K}tC8D b"eG8 }T"&4Rvs2R 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。
0>yuB gh i .''\ 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。
F+9(*|x% I]Vkaf I>( 二、编程步骤
a>#]d _^p\
u 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";
"T.Qb/97@ @UW*o&pGqL 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
4d%QJ7y U?j[
8z 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;
c
Sktm&SP 5
&s<&h 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;
*_eY +\j qTV.DCP 5、 添加代码,编译运行程序。
)b-KF}]d afye$$X 三、程序代码
x*wr8$@J -fD W>]_ ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
_aw49ag; #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
oI x!?,1 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
]>,Lw=_[_ #if _MSC_VER > 1000
\8]("l}ms8 #pragma once
trlZ #endif // _MSC_VER > 1000
Cg]S`R- #ifndef __AFXWIN_H__
v(^;% #error include 'stdafx.h' before including this file for PCH
&W
N
R{ #endif
iM~qSRb#mJ #include "resource.h" // main symbols
`Lr|KuFN class CHookApp : public CWinApp
@O
HsM?nW {
Gy!bPVe public:
Im@Yx^gc CHookApp();
$Fv|w9 // Overrides
#X*=oG // ClassWizard generated virtual function overrides
8\m[Nuq5 //{{AFX_VIRTUAL(CHookApp)
vzZ"TSP public:
**F-#", virtual BOOL InitInstance();
+uMK_ds~ virtual int ExitInstance();
m>+e;5 //}}AFX_VIRTUAL
_q`f5*Z[ //{{AFX_MSG(CHookApp)
JjQ9AJ?-V // NOTE - the ClassWizard will add and remove member functions here.
F*=}}H/ // DO NOT EDIT what you see in these blocks of generated code !
)gNVJ //}}AFX_MSG
r_3=+ DECLARE_MESSAGE_MAP()
Y{2L[5_1 };
qnnP*15` LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
P*kC>lvSv BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
eKL3Y_5p@ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
)`}4rD^b BOOL InitHotkey();
}c'T]h\S BOOL UnInit();
zX&wfE8T #endif
iH)-8Q 1p(9hVA //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
n@9R|biO #include "stdafx.h"
d2*uY., #include "hook.h"
HQV#8G#B #include <windowsx.h>
n(jrK9] #ifdef _DEBUG
nh>lDfJV< #define new DEBUG_NEW
pGsu#`t #undef THIS_FILE
=5#sB* static char THIS_FILE[] = __FILE__;
94L>%{59 #endif
mxl"Y&l2< #define MAX_KEY 100
2,G9~<t #define CTRLBIT 0x04
en29<#8TO #define ALTBIT 0x02
?$%2\"wX~7 #define SHIFTBIT 0x01
~s>Ud<l%r #pragma data_seg("shareddata")
_+.
)8
HHOOK hHook =NULL;
z&Lcl{<MA UINT nHookCount =0;
"K#zY~>L static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
=B"^#n ; static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
^zR*s |1Q static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
{@>6E8)H5 static int KeyCount =0;
z:JJ>mxV static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
F^X:5g~K
#pragma data_seg()
dU#}Tk HINSTANCE hins;
zE]h]$oi void VerifyWindow();
8Xz \,}$O BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
$ cYKVhf //{{AFX_MSG_MAP(CHookApp)
'~[JV>5 // NOTE - the ClassWizard will add and remove mapping macros here.
9oxn-)6JC // DO NOT EDIT what you see in these blocks of generated code!
IeGVLC //}}AFX_MSG_MAP
:PQvt/-'(D END_MESSAGE_MAP()
l6< bV#_qe tQcn%CK CHookApp::CHookApp()
3/4r\%1b+ {
4!DXj0^ // TODO: add construction code here,
6_O3/ // Place all significant initialization in InitInstance
*."50o=T }
!Q5NV4gd+ n^%",*8gD* CHookApp theApp;
_:VIlg
U LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
}vt>}%% {
7kh(WtUz BOOL bProcessed=FALSE;
'klYGp if(HC_ACTION==nCode)
br4 %(w(d {
yIma7H@=L if((lParam&0xc0000000)==0xc0000000){// Key up
GaLQ/V2R switch(wParam)
R9O1#s^ {
,2lH*=m; case VK_MENU:
zfm#yDf MaskBits&=~ALTBIT;
i
E)Fo.H break;
Q a3+ 9 case VK_CONTROL:
D@o8Gerq~ MaskBits&=~CTRLBIT;
'*n2<y break;
)jed@? case VK_SHIFT:
3Jw}MFFV MaskBits&=~SHIFTBIT;
mI-9=6T_ break;
n@y*~sG] default: //judge the key and send message
x4;ndck%U break;
YQ7tZl;:t }
>m8~Fs0 for(int index=0;index<MAX_KEY;index++){
-*~~00w if(hCallWnd[index]==NULL)
QZamf
lk continue;
e\'=#Hw if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
z;6,, {
L<_zQ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
7r wNjY# bProcessed=TRUE;
Z'o'd_g>I+ }
: 5<u!-}
}
E*{_=pX }
}g_\?z3gt else if((lParam&0xc000ffff)==1){ //Key down
C^nTLw;K switch(wParam)
HR$;QHl~F {
@V qI+5TA case VK_MENU:
W,ik ;P\ MaskBits|=ALTBIT;
pX]"^f1?O break;
>0.a#-u^ case VK_CONTROL:
?$ 0t @E MaskBits|=CTRLBIT;
8 ;o*c6+ break;
l[M?"<Ot; case VK_SHIFT:
y(*#0fJrTV MaskBits|=SHIFTBIT;
hO0g3^ break;
G~KYFNHr default: //judge the key and send message
tW}At break;
nv_9Llh=z }
]c\d][R N for(int index=0;index<MAX_KEY;index++)
W;!)Sj4<T! {
0=V
-{ if(hCallWnd[index]==NULL)
KIYs[0*k continue;
{q|Om?@ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
^>m"j6`h, {
QV9z81[ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
jRNDi_u?Wb bProcessed=TRUE;
)jHH-=JM }
eD?f|bif }
&AhkP=Yw }
zHk7!|%Y if(!bProcessed){
TI}Y U for(int index=0;index<MAX_KEY;index++){
q@Oe} if(hCallWnd[index]==NULL)
B):hm continue;
vw[i.af if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
; )rXQm SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
~(K{D
D7[N }
g0>Q* x }
C}Ucyzfr,p }
\TnRn(Kw return CallNextHookEx( hHook, nCode, wParam, lParam );
R;`C;Rbf }
wi@Qf6(mn h#(J6ht BOOL InitHotkey()
l-<EG9m@ {
6"<q{K if(hHook!=NULL){
tl+ 9SBl nHookCount++;
f&NXWo/ return TRUE;
B`wrr8"Rz }
0=Mu|G|Z else
_FtsO<p)" hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
QI*<MF,1 if(hHook!=NULL)
`e^sQ>rDI nHookCount++;
}b=Cv?Zg$m return (hHook!=NULL);
h"t\x}8qq }
{ {@* BOOL UnInit()
olca
Z {
y{Vh?Z<E if(nHookCount>1){
5`p>BJ+n nHookCount--;
vXT>Dc2\! return TRUE;
+~f=L- > }
g[$4a4X BOOL unhooked = UnhookWindowsHookEx(hHook);
]'5 G/H5?; if(unhooked==TRUE){
s"B+),Jod nHookCount=0;
<BjrW]pM hHook=NULL;
M<