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:
[2H(yLw O
mGyIr kE 一、实现方法
{dSU
\': qeO6}A"^| 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:
k~s>8N:&G C6=;(=?C #pragma data_seg("shareddata")
}RP 9%n^ HHOOK hHook =NULL; //钩子句柄
|{|r?3 UINT nHookCount =0; //挂接的程序数目
g9r5t'; static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
'y@ 2,9v static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
r@@eC[' static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
.1? i'8TF static int KeyCount =0;
p~zTRnm static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
Qmc;s{-r; #pragma data_seg()
{HJ`%xN| Go+,jT- 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。
DSG +TA" $q@RHcj DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
8!fAv$g0 @aPu}Hi BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
:>-sITeY cKey,UCHAR cMask)
RO3e {
KL\=:iWA BOOL bAdded=FALSE;
rxK[CDM, for(int index=0;index<MAX_KEY;index++){
-0J<R;cVs if(hCallWnd[index]==0){
E?5B>Jer# hCallWnd[index]=hWnd;
s1b\I6&:J HotKey[index]=cKey;
E$yf2Q~k HotKeyMask[index]=cMask;
wTuRo
J bAdded=TRUE;
% |Gzht\ KeyCount++;
]~x/8%e76 break;
,xM*hN3A }
y42T.oK8c }
.$}zw|,q return bAdded;
~322dG }
?;7>`F6ld //删除热键
VqT[ca\ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
O
NzdCgY {
^WYG?/{4 BOOL bRemoved=FALSE;
w
I
7 for(int index=0;index<MAX_KEY;index++){
M]zNW{Xt if(hCallWnd[index]==hWnd){
vh3iu+ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
Z42 Suy hCallWnd[index]=NULL;
.8xacVyK2 HotKey[index]=0;
RpXG gw HotKeyMask[index]=0;
?U[nYp}"v bRemoved=TRUE;
)s[S.`STz KeyCount--;
>-WOw break;
%lW:8ckL }
+uXnFf d^ }
Pb&+(j }
_;RD-kv return bRemoved;
-^yc yZ }
yFtf~8s3 dllf~:b Yzx0 [_'u DLL中的钩子函数如下:
_( /lBf{| | (9FV^_ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
e[o
;l
{
9rc
n*sm BOOL bProcessed=FALSE;
4^9_E&Fa if(HC_ACTION==nCode)
vyy\^nL {
mV]g5>Q\ if((lParam&0xc0000000)==0xc0000000){// 有键松开
|W];v@b\y switch(wParam)
-\v8i.w0 {
L uKm case VK_MENU:
Y\S^DJy MaskBits&=~ALTBIT;
dR{
V,H7N break;
.Sw'Bo!Ee case VK_CONTROL:
I"?&X4%e MaskBits&=~CTRLBIT;
|^!@ break;
xM,(|p( case VK_SHIFT:
eZ$1|Sj]j MaskBits&=~SHIFTBIT;
%*}f<k{6 break;
h(up1(x default: //judge the key and send message
N'.+ezZ;h break;
"A3xX&9-q }
ogbdt1 for(int index=0;index<MAX_KEY;index++){
1OS3Gv8jc~ if(hCallWnd[index]==NULL)
5aQg^f%\ continue;
8"^TWzg}L if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
5nb6k,+E {
bd}SB -D SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
wB"Gw` D bProcessed=TRUE;
OUMr}~/ }
1ki"UF/ }
NQ=YTRU }
)5x?Qn (B else if((lParam&0xc000ffff)==1){ //有键按下
CgE5;O switch(wParam)
\(L^ /]}G) {
3/05ee;| case VK_MENU:
-C<aB750O) MaskBits|=ALTBIT;
t,nB`g? break;
$vz%
case VK_CONTROL:
2_v>8B MaskBits|=CTRLBIT;
R0'EoX break;
3J<,2 case VK_SHIFT:
l0)uu4| MaskBits|=SHIFTBIT;
;_\P;s break;
~G:7*:[b default: //judge the key and send message
l[ k$O$jo break;
9f`Pi:*+/ }
@Iu-F4YT for(int index=0;index<MAX_KEY;index++){
-}o;Y)
if(hCallWnd[index]==NULL)
*6tN o-)^ continue;
2oLa`33c1 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
UtN>6$u
{
F)Lbr>H?I SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
sd%~pY} bProcessed=TRUE;
/G ;yxdb }
>Z%`&D~u }
Y2n*T
KXI, }
M='Kjc>e if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
`m^OnH for(int index=0;index<MAX_KEY;index++){
qZe"'"3M if(hCallWnd[index]==NULL)
VWa(@A continue;
Y{=@^4|] if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
=d}3>YHS SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
v!Z 9T //lParam的意义可看MSDN中WM_KEYDOWN部分
CgC wM=!r }
~l~g0J }
-s"lW 7N^ }
bE~lc}% return CallNextHookEx( hHook, nCode, wParam, lParam );
':3KZ4/C }
D2bUSRrb >.|gmo>b 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
0J~4
nmr>Aj8[ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
7}k8-:a% BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
5mU_S\)4:z CggEAi~ 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:
`Z-`-IL SCij5il% LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
q]x@q {
Cmj)CJ- if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
|k+^D : {
YVT^}7# //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
N"TD$NrK\ SaveBmp();
i7FEjjGtG return FALSE;
Cp%|Q.? }
rAKdf?? …… //其它处理及默认处理
C7#$s<>TO }
KVuv%? lK-I[i! iwbjjQPr 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。
*D,T}N jKzjTn9{E 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。
C7{w I`~ |NI0zd 二、编程步骤
(k?OYz]c -LyIu# 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";
>L%%B- /?sV\shy 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
mIyaoIE|$ b{&@Lm0Tn 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;
$[Fk>d .qZ<ROZ 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
mWh:,[o S'txY\ 5、 添加代码,编译运行程序。
1 !sYd@iD@ M-NR!? 9 三、程序代码
sdb#K?l 7P ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
jzQgDed ] #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
.MKxHM7 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
1WU-gQki! #if _MSC_VER > 1000
>a<;)K^1 #pragma once
-8]$a6`{_ #endif // _MSC_VER > 1000
m*1=-"P #ifndef __AFXWIN_H__
[Y[|:_+5 #error include 'stdafx.h' before including this file for PCH
BsJClKp/ #endif
?IK[]=! #include "resource.h" // main symbols
C-8@elZ1 class CHookApp : public CWinApp
J? C"be= {
EB\\
F public:
avQwbAh[ CHookApp();
e.[h // Overrides
+U[A.^t // ClassWizard generated virtual function overrides
=vR>KE //{{AFX_VIRTUAL(CHookApp)
IMj{n.y4 public:
i9d.Ls virtual BOOL InitInstance();
7XaRi@uG virtual int ExitInstance();
]c08` //}}AFX_VIRTUAL
r'&VH]m //{{AFX_MSG(CHookApp)
5( 3tPbm{ // NOTE - the ClassWizard will add and remove member functions here.
Lx.X#n.]T // DO NOT EDIT what you see in these blocks of generated code !
L9T|* ?|| //}}AFX_MSG
?Pa5skqR DECLARE_MESSAGE_MAP()
V[#jrwhA };
kxh
$R> LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
&T{+B:*v BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
[j):2 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
d;K,2 BOOL InitHotkey();
%k9GoX_ BOOL UnInit();
eKt~pzXwm #endif
'Je;3"@ _k&vW(O=: //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
X4gs{kx}| #include "stdafx.h"
Z<`QDBN"4 #include "hook.h"
^]K_k7`I #include <windowsx.h>
)KG.:BO< #ifdef _DEBUG
3>ytpXUEGx #define new DEBUG_NEW
[:Sl^ Z&6M #undef THIS_FILE
QN":Qk(,q static char THIS_FILE[] = __FILE__;
b}WU #endif
*4]}_ .rG# #define MAX_KEY 100
H+` Zp #define CTRLBIT 0x04
K1Mn_)% #define ALTBIT 0x02
`#R[x7bA1 #define SHIFTBIT 0x01
^tI
,eZ #pragma data_seg("shareddata")
w=,bF$:fIW HHOOK hHook =NULL;
UZz/v#y~ UINT nHookCount =0;
zt6GJz1q static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
!#3v<_]#d static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Ejmpg_kux static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
JD9)Qelw^$ static int KeyCount =0;
dSkM A static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
6o6I]QL #pragma data_seg()
&sJ -&7YZ HINSTANCE hins;
508v:?^' void VerifyWindow();
:<hM@>eFn BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
Q\rf J|| //{{AFX_MSG_MAP(CHookApp)
=bgWUu\F // NOTE - the ClassWizard will add and remove mapping macros here.
l|v`B6( // DO NOT EDIT what you see in these blocks of generated code!
fN&@y$ //}}AFX_MSG_MAP
Y7BmW+ END_MESSAGE_MAP()
$t0o*i{ jl9hFubwW CHookApp::CHookApp()
AT%6K. {
{>g{+Eq // TODO: add construction code here,
>e^bq/' // Place all significant initialization in InitInstance
,Wv+Ek }
[n4nnmM 9:R3+,ZN CHookApp theApp;
$7" Y/9Y LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
nr&bpA/ {
iYD5~pK8 BOOL bProcessed=FALSE;
Qp7h|< if(HC_ACTION==nCode)
.d I".L {
o%7-<\qS if((lParam&0xc0000000)==0xc0000000){// Key up
'Fy"|M;2 switch(wParam)
ulE5lG0c {
oR7[[H.4 case VK_MENU:
t W+"/<U MaskBits&=~ALTBIT;
Bv<aB(c break;
.' }jd# case VK_CONTROL:
yIhPB8QL MaskBits&=~CTRLBIT;
T*:w1*: break;
9#TD1B/ case VK_SHIFT:
{n|ah{_p| MaskBits&=~SHIFTBIT;
f0vO(@I break;
<8(=Lv`)q default: //judge the key and send message
XLC9B3Jt break;
![;={d0 }
EB|
iW2' for(int index=0;index<MAX_KEY;index++){
( +Sv3h if(hCallWnd[index]==NULL)
P0y DL:X[ continue;
eZEk$W% if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
b"WF]x|^ {
Q7rBc
wm5 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
/v^'5j1o bProcessed=TRUE;
<3!Al,!ej@ }
Vm|KL3}NRv }
w i[9RD@ }
4j~q,#$LW else if((lParam&0xc000ffff)==1){ //Key down
/cb`%"Z switch(wParam)
?h6|N%U' {
t5%cpkgh4 case VK_MENU:
gu3iaM$W MaskBits|=ALTBIT;
hH 5}%/vF break;
u8T@W}FX case VK_CONTROL:
yfK}1mx)j MaskBits|=CTRLBIT;
kV+^1@" break;
*#'j0;2F case VK_SHIFT:
5]>*0#C
S MaskBits|=SHIFTBIT;
@oE
5JM break;
`mzlOB default: //judge the key and send message
y92R}e\M break;
uG^CyM>R` }
RqgN<&g? for(int index=0;index<MAX_KEY;index++)
:a6LfPEAX {
`*Yw-HL if(hCallWnd[index]==NULL)
\rFS^# continue;
=}0Uw4ub(u if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
4~,Z ' k {
Up{[baWF SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
nd]SI;< bProcessed=TRUE;
*Jgi=,!m }
E
+_n@t" }
j:h}ka/!p }
A#.
%7S if(!bProcessed){
N[po)}hp for(int index=0;index<MAX_KEY;index++){
{1)A"lQu if(hCallWnd[index]==NULL)
rZKfb}ANQ continue;
^ +SE_ -+] if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
jc&k-d>=G SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
+4s]#{mP }
m+0yf(w }
j|t=%* }
J?9jD:x return CallNextHookEx( hHook, nCode, wParam, lParam );
I/`"lAFe }
wb0$FZzh inWLIXC,
BOOL InitHotkey()
lS4r pbU_ {
fOV_ >]u if(hHook!=NULL){
JM3[
yNSN@ nHookCount++;
=6u@JpOl return TRUE;
M]s\F(*ib }
B&]`OO>O else
}R%H?&P hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
P.y +jyu if(hHook!=NULL)
4yyw:" nHookCount++;
suY47DCX) return (hHook!=NULL);
XwY,xg&o }
:C:6bDQ BOOL UnInit()
7*l$i/! {
'JOUx_@z if(nHookCount>1){
k =5k)}i nHookCount--;
$aV62uNf return TRUE;
6KMO*v }
"`>6M&`U BOOL unhooked = UnhookWindowsHookEx(hHook);
|V a:*3u if(unhooked==TRUE){
qYK^S4L nHookCount=0;
YnEyL2SuU hHook=NULL;
.KrLvic }
D0Dz@25- return unhooked;
B[N]=V }
0V:H/qu8> ^&qK\m_A BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
B!wN%>U {
e$[O J<t BOOL bAdded=FALSE;
LCivZ0?|X for(int index=0;index<MAX_KEY;index++){
p*Z<DEh# if(hCallWnd[index]==0){
QTHY{:Rmu hCallWnd[index]=hWnd;
K(+=V)'Dz HotKey[index]=cKey;
%g9ym@s HotKeyMask[index]=cMask;
Jh-yIk bAdded=TRUE;
}>{R<[I!G KeyCount++;
k4']q break;
A%^?z. }
k8s)PN }
f Fi=/} return bAdded;
Ue}1(2.v }
hk?i0#7W Q`k;E}x_- BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
5gf
~/Zr {
q /JC\ BOOL bRemoved=FALSE;
sX"L\v for(int index=0;index<MAX_KEY;index++){
A|"T8KSMB if(hCallWnd[index]==hWnd){
<V^o.4mOg> if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
uH89oA/H hCallWnd[index]=NULL;
EB3/o7)L HotKey[index]=0;
Zf$mwRS[_ HotKeyMask[index]=0;
[A~?V.G bRemoved=TRUE;
02,t KeyCount--;
-53c0g@X break;
-|V#U`mwF }
e#oK%
{A }
,a>Dv@$Y }
Zq4%O7% return bRemoved;
&k'<