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:
fI2y(p{?
'r ^.Ao5 一、实现方法
w{lj'3z I :-lq Yd5^ 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:
DU)q]'[u tQYV4h\Qj #pragma data_seg("shareddata")
eK5~gnv, HHOOK hHook =NULL; //钩子句柄
2{Dnfl'k UINT nHookCount =0; //挂接的程序数目
zUDXkG*Lv static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
Qds:*]vGS static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
+?ZP3vgGA static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
B0Ay static int KeyCount =0;
HmkxE static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
x7G)^ #pragma data_seg()
V6_5v+n );yZyWDV 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。
,3iD/8_ ]Hq,Pr_+ 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:
akPd#mf W`c$2KS?DO BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
6rWq
hIaI cKey,UCHAR cMask)
R,["w98a {
)V+/@ 4 BOOL bAdded=FALSE;
I<,~>'cq. for(int index=0;index<MAX_KEY;index++){
{T,}]oX if(hCallWnd[index]==0){
K7.ayM 0 hCallWnd[index]=hWnd;
3-6MGL9 HotKey[index]=cKey;
"L`BuAB HotKeyMask[index]=cMask;
{O).! bAdded=TRUE;
!fd>wvJ,: KeyCount++;
0VNpd~G$ break;
r..f$FF)\ }
c`hENPhW }
zHg=K / return bAdded;
7HY8 F5Brx }
tS5J{j>T //删除热键
F(Zf=$cx BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
~%
t'}JDZ {
V2AsZc0U( BOOL bRemoved=FALSE;
M;'GnGFf for(int index=0;index<MAX_KEY;index++){
{QmK4(k?|c if(hCallWnd[index]==hWnd){
EE | c@M^ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
;$1x_
Cb hCallWnd[index]=NULL;
EAm31v C HotKey[index]=0;
&OE-+z HotKeyMask[index]=0;
@$L| bRemoved=TRUE;
ePl+ M KeyCount--;
[\ Sd*- break;
^c9_ F9N }
6[RTL2&W }
#`U?,>2q }
\CE+P5 return bRemoved;
R.l!KIq }
2M\7j n@h$V\&\iM `F1Yfm
jZT DLL中的钩子函数如下:
yS:w>xU @< |+JO]J#bc LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
)c1Pj#| {
R/fE@d2~In BOOL bProcessed=FALSE;
}.U(Gxu$ if(HC_ACTION==nCode)
OC-d5P
{
c+7I if((lParam&0xc0000000)==0xc0000000){// 有键松开
|
2<zYY switch(wParam)
d8R|0RZ {
#*lDKn[vO case VK_MENU:
-^t.eZ*| MaskBits&=~ALTBIT;
C`3XOth break;
$s]&92 case VK_CONTROL:
'@WBq!p MaskBits&=~CTRLBIT;
\L$]2"/v- break;
8tf>G(I{ case VK_SHIFT:
N+5f.c+S- MaskBits&=~SHIFTBIT;
VKu_l break;
<0hVDk~ default: //judge the key and send message
ubsv\[:C break;
g`C"t3~%S }
=B'Yx for(int index=0;index<MAX_KEY;index++){
i$}G[v<4 if(hCallWnd[index]==NULL)
@MFEBc} continue;
EbVC4uY if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
nGK=Nf.5 {
QhAYCw2 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
7@y}J5, bProcessed=TRUE;
[AFGh
L+t3 }
zL50|U0H }
r8N)]HsZH }
D'{o3Q,%K else if((lParam&0xc000ffff)==1){ //有键按下
'Z,7{U1P switch(wParam)
*%_M?^ {
Au/'|%2#( case VK_MENU:
W>?aZv MaskBits|=ALTBIT;
mr_NArF break;
;}KJ[5i-V case VK_CONTROL:
4AvIU!0w MaskBits|=CTRLBIT;
TV_a(#S break;
ygm6(+ case VK_SHIFT:
|a /cw" MaskBits|=SHIFTBIT;
0$Zh4Y break;
*Sbc
8Y default: //judge the key and send message
k%sA+= break;
A,4}
$-7 }
4\ )WMP for(int index=0;index<MAX_KEY;index++){
5^l-3s?M if(hCallWnd[index]==NULL)
"]'W^Fg continue;
_U*1D*kLI[ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
6 !fq658 {
N>P" $ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
f4dHOH bProcessed=TRUE;
prIJjy-F }
2JeEmG9 }
[!} uj`e }
Kuk@x.~0m if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
yTe25l{QaF for(int index=0;index<MAX_KEY;index++){
LS#_K- if(hCallWnd[index]==NULL)
#L*MMC" continue;
ww%4MHPp8 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
QZO<'q`L SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
+:c}LCI9< //lParam的意义可看MSDN中WM_KEYDOWN部分
4IM_6
}
+, rm }
v] Xy^7? }
ogdAJw6 9 return CallNextHookEx( hHook, nCode, wParam, lParam );
3z#fFP@E }
-wNhbV2 o@} qPvt0 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:
HC>k/Gk" 4`r-*Lx BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
la]Zk BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
G"vEtNoV \tS|
N40 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:
NB( GE '$ G%HUn LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
,S, R6#3G {
V|nJ%G\ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
q^@*k,HG {
{w99~? //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
Pb@$RAU63 SaveBmp();
;D[I/U return FALSE;
vDc&m }
[{ A5BE - …… //其它处理及默认处理
q'biTn]2 }
1gYvp9Ma N$Tzxs ]tbl1=| 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。
}k8&T\V! _.,"`U; H 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。
~%: TE}
Zzr 二、编程步骤
4%TmW/yd [ID#PUle 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";
;b,
bHL 'w\Gd7E 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
4'`*Sce} |q q29dS? 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;
cavzXz 4&`d$K 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
T=pKen/ 2&F H8 5、 添加代码,编译运行程序。
AAc2u^spx +2s][^-KV 三、程序代码
&v+Hl^ cn_ *,\} ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
oR<;Tr~{q #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
-$D#u #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
7{f{SIB #if _MSC_VER > 1000
GIUyW #pragma once
]jP0Z# #endif // _MSC_VER > 1000
o-]8)G>~M #ifndef __AFXWIN_H__
B :1r;8{j #error include 'stdafx.h' before including this file for PCH
\&Oc}] #endif
]#$rTWMl' #include "resource.h" // main symbols
ob(~4H- class CHookApp : public CWinApp
k@2@%02o9C {
]5eZLXM public:
n(Ry~Xu_ CHookApp();
[>kzQYT[ // Overrides
FzFP 0 // ClassWizard generated virtual function overrides
FOX0 //{{AFX_VIRTUAL(CHookApp)
~T'$gl public:
')E4N+h/ virtual BOOL InitInstance();
X,+N/nku virtual int ExitInstance();
Otm7j>w //}}AFX_VIRTUAL
"I[uD)$ //{{AFX_MSG(CHookApp)
{=E,.%8 // NOTE - the ClassWizard will add and remove member functions here.
]LSlo593 // DO NOT EDIT what you see in these blocks of generated code !
0 9*?'^s4 //}}AFX_MSG
mC`U"rlK~ DECLARE_MESSAGE_MAP()
y@]:7 };
x[YW 3nF LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
4p`z%U~=u BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
OV $|!n BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
dxWG+S BOOL InitHotkey();
DGx<Nys@B BOOL UnInit();
"& q])3h = #endif
3#c0p790 xgB-m[Xi //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
'C1yqkIa` #include "stdafx.h"
K6oQx)| #include "hook.h"
A)o%\j #include <windowsx.h>
+}!FP3KgT #ifdef _DEBUG
AaJnRtBS~ #define new DEBUG_NEW
lO^YAOY #undef THIS_FILE
K>`*JJ, static char THIS_FILE[] = __FILE__;
0]t7(P"F6 #endif
dIvvJk8 #define MAX_KEY 100
T9Pu V #define CTRLBIT 0x04
? `# #define ALTBIT 0x02
Tn\59 ( #define SHIFTBIT 0x01
@>hXh
+!2h #pragma data_seg("shareddata")
>U[YSsFt6 HHOOK hHook =NULL;
je~gk6}Y UINT nHookCount =0;
JztSP? static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
T#R*] static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
UL\gcZ
Zkl static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
Vb8{OD3PK static int KeyCount =0;
QU^?a~r static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
$T}Dn[. #pragma data_seg()
*Y9' tHI HINSTANCE hins;
*[wj ) void VerifyWindow();
L@LT *M BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
WzO[-csy //{{AFX_MSG_MAP(CHookApp)
V]A*' ke/ // NOTE - the ClassWizard will add and remove mapping macros here.
;"DI)hdz // DO NOT EDIT what you see in these blocks of generated code!
&<S]=\ //}}AFX_MSG_MAP
hvU\l`m END_MESSAGE_MAP()
{}v<2bS }VXZM7@u CHookApp::CHookApp()
/7XVr"R {
D,;6$Pvg^ // TODO: add construction code here,
G_n~1? // Place all significant initialization in InitInstance
yM*<BV }
$iAd)2LT _^u^@.Q'i< CHookApp theApp;
C*,PH!$k LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
_8nT$!\\ {
$ &fm^1 BOOL bProcessed=FALSE;
dRnO5
7+{ if(HC_ACTION==nCode)
M/a5o|>8 {
3D"?|rd~ if((lParam&0xc0000000)==0xc0000000){// Key up
Fo[=Dh*AqU switch(wParam)
k8ej. {
p3z%Y$!Tm case VK_MENU:
I=Xj;\b MaskBits&=~ALTBIT;
d7Devs
k break;
%W]"JwRu case VK_CONTROL:
^G]H9qY-e MaskBits&=~CTRLBIT;
SB2Ij', break;
` z!?!"= case VK_SHIFT:
_i+7O^=d6X MaskBits&=~SHIFTBIT;
?o6\>[O break;
CaqMLi% default: //judge the key and send message
1q;r4$n break;
l>:\%
ol }
rA#Ji~ for(int index=0;index<MAX_KEY;index++){
Y!L<&
sl if(hCallWnd[index]==NULL)
M-+=t8 continue;
piKR*|F if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
DANndXQLH {
07tSXl5! SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
{oc7Chv=/H bProcessed=TRUE;
23=SXA! }
nvnJVkL9s }
?e+$?8l[3 }
\Z ms else if((lParam&0xc000ffff)==1){ //Key down
#mcU);s switch(wParam)
dX:#KdK {
maTZNzy case VK_MENU:
_Zs]za.#)| MaskBits|=ALTBIT;
gdfG3d$4 break;
rCdf*; case VK_CONTROL:
1$G'Kg/ MaskBits|=CTRLBIT;
G@;I^_gN break;
1(12`3 case VK_SHIFT:
;Q} H'Wg, MaskBits|=SHIFTBIT;
%R[X_n= break;
9,zM.g9Qv default: //judge the key and send message
d9sqO9Ud8 break;
t.E3Fh!o }
bZsg7[: C for(int index=0;index<MAX_KEY;index++)
3teanU` {
f.SmCgG if(hCallWnd[index]==NULL)
z ''-AH, continue;
SR\F2@u if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
<E.$4/T {
{Lm%zdk*k SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
y?s8UEC bProcessed=TRUE;
Nt#a_ }
'+{dr\nJ }
l]o)KM< }
PC}m.tE if(!bProcessed){
SQd`xbIuL for(int index=0;index<MAX_KEY;index++){
rCa2$#Z if(hCallWnd[index]==NULL)
z7P]g
C$\ continue;
!%{s[eO\ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
^U4|TR6mub SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
CD+2
w
cy }
h8lI#Gs }
v/B:n
}
rv?d3QqIC return CallNextHookEx( hHook, nCode, wParam, lParam );
~NtAr1 }
v
lsS 8^Ov.$rP BOOL InitHotkey()
!p~K;p, {
L7lRh=D if(hHook!=NULL){
XUyoZl? nHookCount++;
ib%x&?|| return TRUE;
\7Fkeo+ }
E5b JIC(
else
';z5]O~ hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
-'OO6mU if(hHook!=NULL)
NJglONO nHookCount++;
h8MkfHH7{ return (hHook!=NULL);
sB,>4*Zd }
9k@`{+wmZ BOOL UnInit()
X519}
l3 {
Qb;5:U/x if(nHookCount>1){
SAEV " nHookCount--;
32sb$|eQq return TRUE;
$q6'VLPo }
s *B-| BOOL unhooked = UnhookWindowsHookEx(hHook);
`1[GY){?) if(unhooked==TRUE){
D<