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:
]7QRelMiz+
X7I"WC1ncz 一、实现方法
C] <K s VQm)32' 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:
cT8`l!RD< qsB,yckml #pragma data_seg("shareddata")
-%&_LE9ZtS HHOOK hHook =NULL; //钩子句柄
-fl?G%:(!0 UINT nHookCount =0; //挂接的程序数目
FtUO gL)| static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
&S}i)Nu6J static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
TzXivE@mm static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
uC3o@qGW< static int KeyCount =0;
\dyJ=tg static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
_Ee`Uk #pragma data_seg()
{gE19J3 *t;'I -1w^ 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。
:*bmc /c Gs*FbrY 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:
U9D4bn D {emO=@CP BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
w ' E cKey,UCHAR cMask)
zN(fZT}K5 {
g)*[W>M BOOL bAdded=FALSE;
f-9&n4=H for(int index=0;index<MAX_KEY;index++){
yZ[H&> if(hCallWnd[index]==0){
[)}F4Jsz% hCallWnd[index]=hWnd;
`;7^@ k HotKey[index]=cKey;
u,:GJU HotKeyMask[index]=cMask;
(C#9/WO? bAdded=TRUE;
{:&t;5qz^ KeyCount++;
DiK@>$v break;
i|X ;n }
1 l'Wb2g>A }
%nJ^0X_] return bAdded;
t[B\'f! }
5oQy
$Y //删除热键
Y{X79Rd BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
^|@t 2Rp@ {
h+k:G9;sS BOOL bRemoved=FALSE;
tT}*%A for(int index=0;index<MAX_KEY;index++){
AL/q6PWi if(hCallWnd[index]==hWnd){
\UI7H1XDH if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
]X,C9 hCallWnd[index]=NULL;
[&n2 yt HotKey[index]=0;
m~ %\f8w-x HotKeyMask[index]=0;
p=U*4[9k bRemoved=TRUE;
*0)vsBi KeyCount--;
6(4FC?Y7 break;
+'abAST
t }
:\x)`lu }
/TTmMx* }
U2=l; R{ return bRemoved;
,K Ebnk|i }
Z(p kj }EmNSs`$r 6P=6E DLL中的钩子函数如下:
VLW<"7I 6\ 0c4H2RW LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
i]8HzKuiW {
Rh-e
C6P BOOL bProcessed=FALSE;
!/G2vF" if(HC_ACTION==nCode)
TI-8I) {
@Otom'O if((lParam&0xc0000000)==0xc0000000){// 有键松开
oD]tHuDa switch(wParam)
cq`v8 {
B&&:A4 case VK_MENU:
-QL_a8NL MaskBits&=~ALTBIT;
{D1"bDZ break;
Ml1sE,BT case VK_CONTROL:
<rc? EV MaskBits&=~CTRLBIT;
/
%}Xiqlrd break;
q]3bGO; case VK_SHIFT:
^9zL[R MaskBits&=~SHIFTBIT;
V3WHp'1 break;
+]-~UsM default: //judge the key and send message
bCY8CIF break;
tz-, |n0 }
ec/1Z8}p for(int index=0;index<MAX_KEY;index++){
=$6z1] ;3 if(hCallWnd[index]==NULL)
\ Tf845 continue;
smQ<lwA if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
=Jfo=`da {
tgy*!B6a~ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
|Id0+-V
? bProcessed=TRUE;
8%]o6'd4 }
h.@5vhD }
Q?KWiFA}' }
FU9q|!2Y else if((lParam&0xc000ffff)==1){ //有键按下
p9k'.H^:_ switch(wParam)
H(U`S {
4(>|f_$ case VK_MENU:
K^j7T[pR MaskBits|=ALTBIT;
\EF^Ag break;
4$LVl case VK_CONTROL:
G9ku(2cq MaskBits|=CTRLBIT;
+CL`]'~;E- break;
8 SII>iL{ case VK_SHIFT:
xMNUyB{? MaskBits|=SHIFTBIT;
1e.V%!Xk break;
.6Tan2[% default: //judge the key and send message
H^{Eh break;
?|LR@M!S7 }
{fe[$KQ for(int index=0;index<MAX_KEY;index++){
<eP`Lu" if(hCallWnd[index]==NULL)
9frLYJz" continue;
[%'yHb~< if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
{/SUfXq {
5[3vup? SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
a"gZw9m@ bProcessed=TRUE;
H1iewsfzH }
U_ELeW5@ }
555j@ }
,83%18b if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
?5(Cwy ? for(int index=0;index<MAX_KEY;index++){
z+IBy+ if(hCallWnd[index]==NULL)
{%W'Zx continue;
y/57 >.3 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
I;xrw?=\L SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
c\cPmj@ //lParam的意义可看MSDN中WM_KEYDOWN部分
o
NX-vN- }
2fIHFo\8 }
/<7'[x< }
?7>G\0G return CallNextHookEx( hHook, nCode, wParam, lParam );
KITC,@xE_O }
)Y.H*ca [w&B>z=g$ 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:
.}
al s +?r,Nn BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
PhTMXv<cE BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
J?VMQTa/+ /U\k<\1~m 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:
s`Z|
A .!|\Y!]^r LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
XS+2OutVo {
Aw#@}TGT if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
C sXV0 {
4eOS+& //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
(JV [7u - SaveBmp();
-JgN$Sf return FALSE;
L-.
+yNX) }
r6_g/7.- …… //其它处理及默认处理
/>^ sGB }
GHeucG}? Sep/N"7~t w)}' {]P"c 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
/G*]3=cSe >1luLp/,$ 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。
;ED` 7 })~M}d2LXB 二、编程步骤
yR?S]
{vCB$@/o 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";
;1x(~pD*o =+>cTV 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
Cn6<I {`\ R^u 1(SF 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;
O7D aVlln n{'LF #4l 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;
vH14%&OcN >#pZ`oPEAv 5、 添加代码,编译运行程序。
FYe#x]ue P_e9>t@ 三、程序代码
>+}yI}W;e E}-Y!,v^ ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
Lt'FA #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
LT+QW #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
=(]yl_ #if _MSC_VER > 1000
3`
,u^ w #pragma once
AN)exU ? #endif // _MSC_VER > 1000
B h<DqN #ifndef __AFXWIN_H__
{N.JA= #error include 'stdafx.h' before including this file for PCH
\3K%> #endif
*z?Vy<u G #include "resource.h" // main symbols
P|U9f6^3 class CHookApp : public CWinApp
/[V} {
nC6 ;:uM public:
wlC7;u CHookApp();
<D}yqq@| // Overrides
#/"?.Z;SSH // ClassWizard generated virtual function overrides
>]dH1@@ //{{AFX_VIRTUAL(CHookApp)
$0[t<4K`yn public:
#{f%b,.yxt virtual BOOL InitInstance();
/+
yIcE(&3 virtual int ExitInstance();
58]C``u@Y //}}AFX_VIRTUAL
bf4QW JZD //{{AFX_MSG(CHookApp)
OV>JmYe1{/ // NOTE - the ClassWizard will add and remove member functions here.
;*+wg5| // DO NOT EDIT what you see in these blocks of generated code !
5EX
Ghc' //}}AFX_MSG
4CH/~b1( DECLARE_MESSAGE_MAP()
d
U}kimz };
I9VU,8~ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
7cMHzhk^ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
m7$t$/g BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
G*N}X3H:o BOOL InitHotkey();
==!k99`f, BOOL UnInit();
h85kQ^% #endif
%+8"-u cPp<+ ts //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
z79c30y]" #include "stdafx.h"
+H**VdM6s #include "hook.h"
%3kS;AaA #include <windowsx.h>
Y[~Dj@Q< #ifdef _DEBUG
tS[@3h #define new DEBUG_NEW
|#i|BVnoE #undef THIS_FILE
<>71;%e;' static char THIS_FILE[] = __FILE__;
+eUWf{(_ #endif
i8nzPKF2$3 #define MAX_KEY 100
BbCaIt #define CTRLBIT 0x04
+{b3A@f|F #define ALTBIT 0x02
T8t_+|(
G #define SHIFTBIT 0x01
)&px[Dbx #pragma data_seg("shareddata")
3'jH,17lWV HHOOK hHook =NULL;
YJm64H,[ UINT nHookCount =0;
!5^&?plC@ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
qK-\`m static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
-hU1wX%U static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
\c(Z?`p]R1 static int KeyCount =0;
"K)ue@? static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
JIOeDuw+ #pragma data_seg()
wSPwa,)7s HINSTANCE hins;
7;rf$\-& void VerifyWindow();
B;Dl2k^L BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
. UaLP //{{AFX_MSG_MAP(CHookApp)
'_fj:dy // NOTE - the ClassWizard will add and remove mapping macros here.
h anS8 // DO NOT EDIT what you see in these blocks of generated code!
hd%O\D? //}}AFX_MSG_MAP
/6@$^paB END_MESSAGE_MAP()
H"b}lf s`dwE*~ CHookApp::CHookApp()
9D`p2cO {
YZ(tjIgQ // TODO: add construction code here,
aH'=k?Of; // Place all significant initialization in InitInstance
8#h~J>u. }
HceZT e@ V jqs\ CHookApp theApp;
|T+YC[T#v LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
W6&mXJ^3L {
fN_Ilg)t?5 BOOL bProcessed=FALSE;
ozUsp[W> if(HC_ACTION==nCode)
f=cj5T:[ {
@.8FVF if((lParam&0xc0000000)==0xc0000000){// Key up
`gE_u switch(wParam)
u"5
hlccH {
aB ^`3J case VK_MENU:
Aa!#=V1d MaskBits&=~ALTBIT;
.T*89cEu break;
j21>\K!p case VK_CONTROL:
@g%^H)T MaskBits&=~CTRLBIT;
u;Rm/. break;
ZOzwO6(_ case VK_SHIFT:
/VHQ!Wi MaskBits&=~SHIFTBIT;
4NDT5sL break;
}!^`%\ %\ default: //judge the key and send message
Xf6\{ break;
S]g`Ds< }
9Ac4'L for(int index=0;index<MAX_KEY;index++){
pT<}n 9yB5 if(hCallWnd[index]==NULL)
,7os3~Mk9 continue;
e\95X{_' if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
zW:r7
P. {
\H{UJ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
%(ms74R+ bProcessed=TRUE;
KYM%U"j D }
A|<i7QVY }
Lgrpy }
a_(fqoW else if((lParam&0xc000ffff)==1){ //Key down
^X|Bzz) switch(wParam)
&'"dYZj{ {
vT;~\,M case VK_MENU:
U}c05GiQw MaskBits|=ALTBIT;
z|v/hUrD break;
5-! Zm] case VK_CONTROL:
{1L{ MaskBits|=CTRLBIT;
\qw1\-q break;
q vGP$g case VK_SHIFT:
=v6qr~ MaskBits|=SHIFTBIT;
JLh{>_Rr break;
v<:/u(i default: //judge the key and send message
RN ~pC break;
/ TAza9a }
Rc#c^F< for(int index=0;index<MAX_KEY;index++)
?X nKKw\ {
UI_u:a9Q/ if(hCallWnd[index]==NULL)
`2a7y]? continue;
f"aqg/l if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Jl@YBzDfF {
8fC5O SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
HImQ.y!B bProcessed=TRUE;
fDrjR6xV }
4|/=]w }
qK,PuD7i" }
Ry`Y + if(!bProcessed){
6fV;V:1{ for(int index=0;index<MAX_KEY;index++){
^+u/Lw& if(hCallWnd[index]==NULL)
UhbGU G continue;
1JY3c
M if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
UUR` m SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
+qee8QH }
5K {{o'' }
{(_>A\zi }
AI9#\$aGV return CallNextHookEx( hHook, nCode, wParam, lParam );
@%gth@8 }
k[8{N 8Uoqj=5F BOOL InitHotkey()
3}nkTZ G {
!"bU|a if(hHook!=NULL){
-^WW7 g` nHookCount++;
W3y9>]{x^ return TRUE;
[_1K1i"m }
q4]Qvf> else
`Oe"s_O# hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
*ulkqpO if(hHook!=NULL)
H'x)[2 nHookCount++;
}HxC~J" return (hHook!=NULL);
]?UK98uS\A }
6GsB*hW BOOL UnInit()
2<TpNGXM_ {
E=RX^ 3+} if(nHookCount>1){
KCi0v nHookCount--;
gmdA1$c return TRUE;
nrJW.F]S8[ }
EzGO/uZ] BOOL unhooked = UnhookWindowsHookEx(hHook);
*4O9W8Qz if(unhooked==TRUE){
j)Y68fKK nHookCount=0;
^wMZG'/ hHook=NULL;
8~:s$~&r }
0jMS!"k
return unhooked;
zTW)SX_O }
wG",Obja f_;6uCCO BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
&m{vLw {
_)-y& BOOL bAdded=FALSE;
3?uah'D5 for(int index=0;index<MAX_KEY;index++){
O%m>4OdH if(hCallWnd[index]==0){
3\H0Nkubts hCallWnd[index]=hWnd;
jI45X22j HotKey[index]=cKey;
.aD=d\ HotKeyMask[index]=cMask;
6&[rATU+ bAdded=TRUE;
7Lx=VX#]q KeyCount++;
lzK,VZ=mM break;
C>Cb }
:z a:gs0 }
W,|JocDq return bAdded;
e)2w&2i`(F }
-b'a-? B;^YHWJ6i BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
d/l>~%bR {
/YD2F BOOL bRemoved=FALSE;
ebIRXUF}> for(int index=0;index<MAX_KEY;index++){
C$7dmGjZ if(hCallWnd[index]==hWnd){
(x/xqDpmBS if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
-(l/.yE{X hCallWnd[index]=NULL;
p[:E$#W~; HotKey[index]=0;
{/q4W; D HotKeyMask[index]=0;
G&d