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:
h?b{{
sq%f%?(V 一、实现方法
F&Gb[Q&a8 !Kis,e 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:
Tr8+E;; MB)xL-j O #pragma data_seg("shareddata")
qr*/}F6 HHOOK hHook =NULL; //钩子句柄
A8?>V%b[Y UINT nHookCount =0; //挂接的程序数目
?$?Ni)Z static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
8[k-8h| static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
XxGm,A+>Ty static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
@RC_Ie=#) static int KeyCount =0;
{_Y\Y static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
u=4Rn
#pragma data_seg()
1DX=\BWp 9Ah4N2nL-b 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
h(9K7 jH8F^KJM[ DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
B`vV[w? }\@*A1*X2 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
~HELMS~- cKey,UCHAR cMask)
Vrnx#j-U {
[W2k#-%G BOOL bAdded=FALSE;
#q\C"N5ip for(int index=0;index<MAX_KEY;index++){
uwbj`lpf if(hCallWnd[index]==0){
pCq{F*; hCallWnd[index]=hWnd;
'F@'4[uda HotKey[index]=cKey;
9]Y@eRI< HotKeyMask[index]=cMask;
}}
IvZG& bAdded=TRUE;
&0
@2JS/! KeyCount++;
\t}!Dr+yN break;
4 1Ru@ }
/h_BF\VBs }
H)5]K9D return bAdded;
P%1s6fjU }
rA9"CN //删除热键
{9z EnVfg BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
kWgxswl7H {
s>kzt1,x BOOL bRemoved=FALSE;
qp7>_B for(int index=0;index<MAX_KEY;index++){
+;vfn>^!b if(hCallWnd[index]==hWnd){
-G{}8GM if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
WKN\*N < hCallWnd[index]=NULL;
,ujoGSx} HotKey[index]=0;
1:8ZS HotKeyMask[index]=0;
uoF9&j5E@Z bRemoved=TRUE;
U:_&aY_ KeyCount--;
+~7@K{6q- break;
*r%=p/oQ}B }
s{gdTG6v` }
z7NaW e }
!bQ5CB return bRemoved;
*C$
W^u5h }
u{HB5QqK ^!=+$@< Pj^6.f+ DLL中的钩子函数如下:
D{c`H}/` 6%:N^B=%} LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
}E*#VA0/nY {
/KH3v!G0 BOOL bProcessed=FALSE;
lE /" if(HC_ACTION==nCode)
euQd {
u" nyx0< if((lParam&0xc0000000)==0xc0000000){// 有键松开
XmLHZ,/ switch(wParam)
|XPT2eQ{ {
]@Q14
case VK_MENU:
\T>f+0=4 MaskBits&=~ALTBIT;
gzxLHPiw break;
jytfGE: case VK_CONTROL:
DT;Hr4Z8^" MaskBits&=~CTRLBIT;
YYN=`ST break;
p^NYJV case VK_SHIFT:
!RAyUfS MaskBits&=~SHIFTBIT;
#k*e>d$ break;
T~_+\w default: //judge the key and send message
AS~O*(po break;
"|(+~8[ }
s@Y0"
for(int index=0;index<MAX_KEY;index++){
hK?uGt
d? if(hCallWnd[index]==NULL)
>tYptRP continue;
L=?Yc*vg if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
y1B3F5 {
$yBU
,lu} SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Jk 0;<2j bProcessed=TRUE;
x%5n& B }
%3|0_ }
Y}Y2Vx }
wYPJji
D else if((lParam&0xc000ffff)==1){ //有键按下
vQ$ FMKz7 switch(wParam)
vA*!82 {
{O[a+r.n case VK_MENU:
{b}Ri&oEOH MaskBits|=ALTBIT;
)L<NW{ break;
C5$1K'X@ case VK_CONTROL:
[g`P(? MaskBits|=CTRLBIT;
>iDV8y break;
Y7{IF X case VK_SHIFT:
N[~RWg MaskBits|=SHIFTBIT;
km|;T! break;
D<$,v(- default: //judge the key and send message
ia?{]!7$ break;
\GO^2&g( }
[2"a~o\ for(int index=0;index<MAX_KEY;index++){
%A|9=x* if(hCallWnd[index]==NULL)
kFg@|#0v9 continue;
/PafIq if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
]6bh #N;. {
|Ah'KpL8W SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
T@ (MSgp9 bProcessed=TRUE;
p8aGM-+40W }
^~'tQ}]!" }
G~5EAeG }
<b.?G if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
B4Ko,=pg for(int index=0;index<MAX_KEY;index++){
UzTFT:\ if(hCallWnd[index]==NULL)
R*|y:T,H continue;
?Z9C}t] if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
CoO.. SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
?%-VSL>$w= //lParam的意义可看MSDN中WM_KEYDOWN部分
~)xg7\k }
I|8'#QX }
-.<fGhmU }
R/Y9t8kk return CallNextHookEx( hHook, nCode, wParam, lParam );
6[b'60CuZL }
.0+=#G> a|?& 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
t.Q}V5t{g Fjch<gAofS BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
X67^@~l BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
jGy%O3/ z=%&?V 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
jeLRS8]; Lu?MRF
f LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
5ar2Y$bY {
qw?#~"Ca. if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Ya~*e;CW2 {
6bPoC$<Z //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
{;mT.[ SaveBmp();
9bu}@#4* return FALSE;
3kqO5+,C }
q9+`pj …… //其它处理及默认处理
VS`
tj }
.Z?@;2<l 8.JFQ/)i p6S{OUiG 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。
[l#
8}dy v\lhbpk 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。
b-!+Q) oW
! Z=; 二、编程步骤
J)o.@+Q} j}s<Pn%4 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";
qe^d6 M9~eDw'Pr 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
JJC YM
Z2P DT 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;
Z01BzIsR ~t=73fwB 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;
1F|e/h%^ ^lvYj
E 5、 添加代码,编译运行程序。
Q+<{2oVz G.{)#cR 三、程序代码
-ElK=q ~?6M4!u
///////////////////////////////////// Hook.h : main header file for the HOOK DLL
meF.`fh #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
LI~ofCp #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
CU`yi.)T{ #if _MSC_VER > 1000
Xmb001 #pragma once
vQH6CB" #endif // _MSC_VER > 1000
LC>bZ!(i# #ifndef __AFXWIN_H__
simD<&p #error include 'stdafx.h' before including this file for PCH
dgEH]9j& #endif
rd_!'pG #include "resource.h" // main symbols
=# /BCL7 class CHookApp : public CWinApp
^QG;:.3v {
/`kM0=MMa public:
B+VD53 V CHookApp();
?zpN09e // Overrides
X;/5Niv32q // ClassWizard generated virtual function overrides
uD=FTx //{{AFX_VIRTUAL(CHookApp)
1Zo"Xb public:
N\{{:<Cp\ virtual BOOL InitInstance();
2%Mgg,/~ virtual int ExitInstance();
L#|6Lnp^ //}}AFX_VIRTUAL
/_(q7:<ZF //{{AFX_MSG(CHookApp)
Mn<#rBE B // NOTE - the ClassWizard will add and remove member functions here.
>OxSrc@A // DO NOT EDIT what you see in these blocks of generated code !
b[/uSwvi //}}AFX_MSG
EP'I DECLARE_MESSAGE_MAP()
w<|Qezi3
w };
5 (cgHr" LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
huat,zLS BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
lKSd]:3Xm BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
dCn'IM1 BOOL InitHotkey();
4:0y\M5u BOOL UnInit();
U(6=;+q #endif
qP5'&!s&! al1Nmc# //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
o;"Phc. #include "stdafx.h"
V48o+ O #include "hook.h"
V;IV2HT0J" #include <windowsx.h>
/%{Qf #ifdef _DEBUG
(:r80: #define new DEBUG_NEW
/H'F4-> #undef THIS_FILE
cii!
WCu static char THIS_FILE[] = __FILE__;
U9t-(`[j? #endif
e-EY]%JO #define MAX_KEY 100
mmvo
>F" #define CTRLBIT 0x04
9#MY(Hr #define ALTBIT 0x02
Hs`j6yuc9 #define SHIFTBIT 0x01
o>jM4sk$ #pragma data_seg("shareddata")
231,v,X[ HHOOK hHook =NULL;
SCL8.%z D UINT nHookCount =0;
#`o]{UfW static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
_q
z^|J static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
n\w2e_g;N static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
x^V9;V@6 static int KeyCount =0;
PBOZ^%k static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
7GDrH/yK #pragma data_seg()
4S1\5C9 HINSTANCE hins;
.H#<yPty void VerifyWindow();
kNk$[Yfs BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
tDQuimYu7 //{{AFX_MSG_MAP(CHookApp)
k];NTALOG // NOTE - the ClassWizard will add and remove mapping macros here.
sL!+&Id| // DO NOT EDIT what you see in these blocks of generated code!
@<ILF69b //}}AFX_MSG_MAP
2Fc>6]:* END_MESSAGE_MAP()
Yaix\*II EPiZe- CHookApp::CHookApp()
2>*b.$g {
@;t6Slc"~ // TODO: add construction code here,
Nv5)A=6#AA // Place all significant initialization in InitInstance
vhd +A }
%CIRN} 3L^]J}| CHookApp theApp;
O6"S=o& LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
/C
{
*?3c2Jg=E BOOL bProcessed=FALSE;
?rxq//S2 if(HC_ACTION==nCode)
.K`EflN {
),(HCzK` if((lParam&0xc0000000)==0xc0000000){// Key up
{$QkerW3 switch(wParam)
6olJ7`* {
&>A<{J@VL case VK_MENU:
2(i|n= MaskBits&=~ALTBIT;
Ox%p"xuP, break;
$5\+QW case VK_CONTROL:
:^rt8>~ MaskBits&=~CTRLBIT;
N;S1s0FN break;
m[DCA\Mo@ case VK_SHIFT:
!:wA\mAd MaskBits&=~SHIFTBIT;
*2>kic
aH break;
ib- H
jJ8 default: //judge the key and send message
Q N]y.(S)y break;
7q(A& }
W <u,S for(int index=0;index<MAX_KEY;index++){
IXv9mr?H} if(hCallWnd[index]==NULL)
)F_nK f"a continue;
RXRoMg!-P if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
G|b
I$ {
'E"W;#% SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
7yQw$zG,Iz bProcessed=TRUE;
2EiE5@ }
4n} a%ocv^ }
xmi@
XL@t }
6d(D>a else if((lParam&0xc000ffff)==1){ //Key down
hsHbT^Qm switch(wParam)
U:0Ma6< {
Y?ZzFd,i& case VK_MENU:
\}71pzw( MaskBits|=ALTBIT;
L+8{%\UPd break;
m "96%sB case VK_CONTROL:
$wC'qV
* MaskBits|=CTRLBIT;
UM<!bNz` break;
X?U'GLm case VK_SHIFT:
=&F~GCZ> MaskBits|=SHIFTBIT;
[@_W-rA break;
)4TP{tp default: //judge the key and send message
&2bqL!k break;
Eh*(N(` }
?I$- im for(int index=0;index<MAX_KEY;index++)
ejc> {
t:"3MiM=c if(hCallWnd[index]==NULL)
<$u\PJF7_^ continue;
DTlId~Dyq if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
/gn!="J {
x\oSD1t, SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
[RF 6mWQ bProcessed=TRUE;
wjfq"7Q }
}T-'""* }
^J;rW3#N8 }
qw
03]a if(!bProcessed){
U;j\FE^+> for(int index=0;index<MAX_KEY;index++){
!;;7:!)P if(hCallWnd[index]==NULL)
*M/:W =,t continue;
aS``fE;O if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
KP&xk13) SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
m%=*3gH]& }
gD2P)7: }
s(KSN/ }
BOWBD@y return CallNextHookEx( hHook, nCode, wParam, lParam );
pD('6C; }
Nz}PcWF/ FA+"t^q BOOL InitHotkey()
5+Ao.3Xn {
}[R-)M if(hHook!=NULL){
`?O0) nHookCount++;
>7PNl\=gG return TRUE;
{PR "}x }
.)SR3? else
[N12X7O3 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
:_tt9J if(hHook!=NULL)
ITg<u?z_ nHookCount++;
~Hu!iZ2] return (hHook!=NULL);
Z #T }
3)OQgeKU BOOL UnInit()
uuxVVgWp{ {
}8POm# if(nHookCount>1){
^,,}2dsb> nHookCount--;
kIX1u<M~ return TRUE;
4v`IAR?&K; }
l&}}Io$?@
BOOL unhooked = UnhookWindowsHookEx(hHook);
xH&hs$= if(unhooked==TRUE){
dOa9D nHookCount=0;
OQ-
Hn-H hHook=NULL;
AL.psw-Il }
'_^T]fr} return unhooked;
+<j7^AEG }
0|J_'-< 9Msy=qvYG BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
'&'m#H*: {
*ziR &Fr! BOOL bAdded=FALSE;
L,[Q{:C S for(int index=0;index<MAX_KEY;index++){
tc<uS%XT4^ if(hCallWnd[index]==0){
y)U?.@ hCallWnd[index]=hWnd;
g;v;xlY`N HotKey[index]=cKey;
Pc_aEBq HotKeyMask[index]=cMask;
8;V9%h`P> bAdded=TRUE;
OQ7 `n<I<) KeyCount++;
Ml7
(<J break;
<S041KF.{6 }
P RWb6 }
LP=j/qf| return bAdded;
jx]P: ] }
Y}1c>5{bE TI8r/P?
]V BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
!t^DN\\# {
PO`p.("h BOOL bRemoved=FALSE;
Aeb(b+= for(int index=0;index<MAX_KEY;index++){
QYboX~g~p if(hCallWnd[index]==hWnd){
>
[J. if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
=9X1 +x hCallWnd[index]=NULL;
\gk.[={^P HotKey[index]=0;
tqZ+2c<W3 HotKeyMask[index]=0;
EU %,tp bRemoved=TRUE;
@Fb1D"! KeyCount--;
L%T(H<