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:
Kz v*`
fF~3"!1#\I 一、实现方法
'Dh+v3O
*jAw 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:
^+v6?%m "0ITW46n #pragma data_seg("shareddata")
QH?}uX'x)G HHOOK hHook =NULL; //钩子句柄
vmV<PK- UINT nHookCount =0; //挂接的程序数目
tks3xS static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
'Fe1]B"Y static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
9)_fH6r static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
W0++q=F static int KeyCount =0;
^5"2s:vP static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
4sj:%%UE #pragma data_seg()
ISp'4H7R+N Oyfc! 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。
d|nJp-%V @D<KG 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:
^p'iX4M gEejLyOag BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
Hg~O0p}[ cKey,UCHAR cMask)
Cfz020u`g {
]i}3`e? BOOL bAdded=FALSE;
8Z^9r/%*Z for(int index=0;index<MAX_KEY;index++){
Wq4>!| if(hCallWnd[index]==0){
( k@%04c hCallWnd[index]=hWnd;
C2~t HotKey[index]=cKey;
*1Q~/<W HotKeyMask[index]=cMask;
.x
1& bAdded=TRUE;
%*>ee[^L , KeyCount++;
";I|\ T break;
LLa72HW }
eyx;8v cM }
4h|48</ return bAdded;
H;&^A5 }
(#4 //删除热键
T8ga)BA BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
q#8$@*I {
qkCj33v BOOL bRemoved=FALSE;
tkN5|95 for(int index=0;index<MAX_KEY;index++){
UuNcBzB2d if(hCallWnd[index]==hWnd){
0a#2 Lo if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
GzJ("RE0)v hCallWnd[index]=NULL;
QQ+? J~ HotKey[index]=0;
uC_&?
HotKeyMask[index]=0;
?A[q/n:K bRemoved=TRUE;
sCX 8 KeyCount--;
) o)k~6uT break;
l7{Xy_66 }
LX4*3c|i, }
+1 K9R\ }
DI P( return bRemoved;
{=(GY@yU/ }
yv.UNcP? ]F,mj-?4x ^%^~:<N DLL中的钩子函数如下:
%fS__Tb#u ?a8 o.&`l LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
w8|38m {
~w<u! BOOL bProcessed=FALSE;
xMk0Xf'_ if(HC_ACTION==nCode)
+Om(&\c(6 {
B&l5yI
b if((lParam&0xc0000000)==0xc0000000){// 有键松开
,ux?wa+ switch(wParam)
*c\:ogd {
:hre|$@{a case VK_MENU:
HG(J+ocn MaskBits&=~ALTBIT;
";jj` break;
g~5$X{ case VK_CONTROL:
~ccwu MaskBits&=~CTRLBIT;
ZDVz+L|p break;
L-7?: case VK_SHIFT:
n'<FH<x MaskBits&=~SHIFTBIT;
_m;#+`E break;
MGH(= w1 default: //judge the key and send message
xWY%-CWY. break;
aS^
4dEJ }
f'hrS}e for(int index=0;index<MAX_KEY;index++){
O|t@p=] if(hCallWnd[index]==NULL)
DKd:tL24& continue;
|1sl>X, if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
dgLE/r? {
l_K=7\N SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
mnKSO bProcessed=TRUE;
#nQZ/[| }
aCu 8
D! }
xPFNH`O& }
{rQSB;3 else if((lParam&0xc000ffff)==1){ //有键按下
;^waUJ\Z
switch(wParam)
s?=v@|vz) {
:'*;>P
.( case VK_MENU:
Pr
|u_^ MaskBits|=ALTBIT;
![=C`O6K break;
+!dWQ=W case VK_CONTROL:
4Wz@^7|V5 MaskBits|=CTRLBIT;
*]<M%q!<6 break;
Z=VAjJ;i[ case VK_SHIFT:
inO)Y]|f MaskBits|=SHIFTBIT;
8lG@8tbW^ break;
ao2NwH## default: //judge the key and send message
T%{qwZc+mJ break;
)bJS*# }
jH+ddBVA for(int index=0;index<MAX_KEY;index++){
^gP pmb<x if(hCallWnd[index]==NULL)
G}!dm0s$ continue;
wc&%icF*cr if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
,(h:0L2v7d {
<m;idfn SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
jNKu5"HB bProcessed=TRUE;
PL;PId<9w }
HYd&.*41rE }
A 9I5 }
CCZ'(Tkq if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
T(Q(7 for(int index=0;index<MAX_KEY;index++){
x+? P/Ckg if(hCallWnd[index]==NULL)
L>4!@L5) continue;
JHF<vyt5< if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
A .]o&S} SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
{bQi
z //lParam的意义可看MSDN中WM_KEYDOWN部分
o>(I_3J[p }
AoL2Wrk]\B }
'@~\(SH }
;5i~McH#
t return CallNextHookEx( hHook, nCode, wParam, lParam );
x4b.^5"`: }
bFV+|0 $~$NQe!/ 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:
{#-I;I: zk\YW'x|r BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
>!o||Yn BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
|f9fq~'1e lCyBdY9n 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:
oP[R?zN $2tPqZ> LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
<=1nr@L {
#0;H'GO?c if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
UbWeE,T~S {
w;e42.\ //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
;M)l7f SaveBmp();
\J]qd4tF return FALSE;
mA{G:
d }
gb_r <j:w …… //其它处理及默认处理
S,I|8
YE }
BQ[,(T`+R !(%^Tg= UKfC!YR2J8 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
cJIA/HQe N;\G=q]
9 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
qD#E, "% W
zKaLyM 二、编程步骤
am+'j5`Ys D@-'<0= 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
Qp]-:b 8w 2$H 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
cx+li4v Or({|S9d2 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;
Cp`>dtCd }]fJ[KbDp 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;
:)djHPP* <Z0N)0| 5、 添加代码,编译运行程序。
qG Abh l.Psh7B2 三、程序代码
:!fP~(R'm r.JY88" ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
dg(fD>+ #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
sKIpL(_I$ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
l^LYSZg'R8 #if _MSC_VER > 1000
vX9B^W||x #pragma once
Ts~MkO #endif // _MSC_VER > 1000
g^`;B" #ifndef __AFXWIN_H__
4ONou&T #error include 'stdafx.h' before including this file for PCH
N9|v%-_?) #endif
WNE=|z#| #include "resource.h" // main symbols
{j0c)SETN class CHookApp : public CWinApp
,(D:cRN {
!awsQ!e| public:
j/C.='?% CHookApp();
A,WZ}v}_ // Overrides
D>HX1LV // ClassWizard generated virtual function overrides
b`TA2h //{{AFX_VIRTUAL(CHookApp)
dx<KZR$!V public:
N~Kl{">` virtual BOOL InitInstance();
\Y?ByY virtual int ExitInstance();
t7(#Cuv- //}}AFX_VIRTUAL
=Nc}XFq //{{AFX_MSG(CHookApp)
GadZ!_.f // NOTE - the ClassWizard will add and remove member functions here.
]O\m(of
R // DO NOT EDIT what you see in these blocks of generated code !
Fq-AvU //}}AFX_MSG
ne~=^IRB DECLARE_MESSAGE_MAP()
A.D@21py };
J7p'_\ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
e1
yvvi BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
RCgn\ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
F$!K/Mm[ BOOL InitHotkey();
[q<Vm- BOOL UnInit();
,g"[7Za #endif
+O2z&a;q 7I_1Lnnf //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
K<_bG<tm_ #include "stdafx.h"
]P5|V4FXo #include "hook.h"
)J['0DUrZK #include <windowsx.h>
t:SME'~.P #ifdef _DEBUG
RTEzcJ> #define new DEBUG_NEW
Pd~{XM,yfW #undef THIS_FILE
nO{m2&r+ static char THIS_FILE[] = __FILE__;
3Dm`8Xt
#endif
G<8d=} #define MAX_KEY 100
X=W.{? #define CTRLBIT 0x04
k3w(KH@ #define ALTBIT 0x02
YyF=u~l #define SHIFTBIT 0x01
|#)S`Ua1 #pragma data_seg("shareddata")
_>k&,p]y HHOOK hHook =NULL;
V"r2 t9A UINT nHookCount =0;
^J[r<Dm8F static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
]{/1F:bcQ static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
8vuA`T!~G static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
\'BA}v
&/ static int KeyCount =0;
15 /lX static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
_tJm0z! #pragma data_seg()
\MY`R HINSTANCE hins;
+W8L^Wl void VerifyWindow();
#7Pnw.s3zz BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
m"r=p //{{AFX_MSG_MAP(CHookApp)
uE}A-\G // NOTE - the ClassWizard will add and remove mapping macros here.
%:DH_0 // DO NOT EDIT what you see in these blocks of generated code!
$&C~Qti|G //}}AFX_MSG_MAP
?KKu1~a_ END_MESSAGE_MAP()
'&OJ hLE !qQB}sAf CHookApp::CHookApp()
?|`Ba- {
)5O E~}> // TODO: add construction code here,
!I8m(axW // Place all significant initialization in InitInstance
~kJ}Z<e }
EV$$wrohQ` qSg=[7XOO CHookApp theApp;
p:/#nmC< LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
K4{1}bU{> {
k\NwH?ppu BOOL bProcessed=FALSE;
2j UEL=+Y if(HC_ACTION==nCode)
3rUuRsXn {
W{v{sQg if((lParam&0xc0000000)==0xc0000000){// Key up
gpe/ dfyJ9 switch(wParam)
:|V`QM {
fGz++;b<S case VK_MENU:
uDWxIP,m MaskBits&=~ALTBIT;
B}&9+2M break;
kW!`vQm~ case VK_CONTROL:
W|yFjE&dr MaskBits&=~CTRLBIT;
xeGl}q| break;
"~|;XoMU case VK_SHIFT:
!go$J]T MaskBits&=~SHIFTBIT;
V(5=-8k break;
B9[eLh! default: //judge the key and send message
WC pCWtmy break;
!gKz=-C }
!SxZN d v for(int index=0;index<MAX_KEY;index++){
yltzf
#% if(hCallWnd[index]==NULL)
N"M?kk, continue;
Ol@ssm if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
p[J 8
r{' {
p3L0'rY|+ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
WYayr1 bProcessed=TRUE;
v1m'p:7uGB }
GcpAj9 }
]5_6m;g }
rZt7C(FM$7 else if((lParam&0xc000ffff)==1){ //Key down
?L'4*S] switch(wParam)
,Q2?Z:l {
$X;wj5oj case VK_MENU:
Vo; B#lK MaskBits|=ALTBIT;
AvxP0@.` break;
{Iu9%uR>@ case VK_CONTROL:
CB1AL]|3 MaskBits|=CTRLBIT;
$zR[2{bg break;
TSp;VrOP case VK_SHIFT:
-2\%?A6L MaskBits|=SHIFTBIT;
U&\2\z3{ break;
3!OO_ default: //judge the key and send message
UojHlTg#bT break;
`H7V[' }
aglW\LT^ for(int index=0;index<MAX_KEY;index++)
=64%eF {
{TWgR2?{C if(hCallWnd[index]==NULL)
fK'qc L continue;
-$8M#n, if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
j. m(Z} {
82q_"y>6 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
MUs~ZF bProcessed=TRUE;
"V>7u{T }
u>cU*E4/ }
jxt^d }
yVP 1=pz_[ if(!bProcessed){
a33SY6. for(int index=0;index<MAX_KEY;index++){
"?yu^ if(hCallWnd[index]==NULL)
S[_Hc$7U continue;
u3Jsu=Nx- if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
&7gE=E(M SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
v.aSf`K }
KioD/
}
h>l }
z3lMD'uU3 return CallNextHookEx( hHook, nCode, wParam, lParam );
MvO!p }
!{L6
4qI 0tzMu# BOOL InitHotkey()
BU|bo") {
c20'{kH if(hHook!=NULL){
=}G `i** nHookCount++;
SLiQHWw*J return TRUE;
B_B~Y8=3` }
I2b\[d else
8+b ?/Rn0 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
<^Hh5kfS' if(hHook!=NULL)
r|bvpZV nHookCount++;
I'_.U]An return (hHook!=NULL);
$jDp ^ - }
A#"AqNVWv BOOL UnInit()
^<@9ph {
4~G++|NQ if(nHookCount>1){
[}/\W`C nHookCount--;
mh4NZ @; return TRUE;
D:uBr|(' }
@'K+ BOOL unhooked = UnhookWindowsHookEx(hHook);
Jk.Ec)w if(unhooked==TRUE){
"~f=7
nHookCount=0;
SGU~LW& hHook=NULL;
GUe&WW:Sqk }
XZaei\rUn) return unhooked;
jocu=Se@ }
[-@Lbu-| X3KPN BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
A@@Z?t. {
]i=\5FH e BOOL bAdded=FALSE;
k++Os'hSEY for(int index=0;index<MAX_KEY;index++){
ak?XE4-N if(hCallWnd[index]==0){
+yq Z\$ii hCallWnd[index]=hWnd;
B=:7N;BT HotKey[index]=cKey;
K4vl#*qn HotKeyMask[index]=cMask;
C^po*(W6 bAdded=TRUE;
Q<y&*o3YF| KeyCount++;
<B;l).[6 break;
3N) bJ }
5o~;0K] }
89>U Koc? return bAdded;
29?{QJb }
:bLLN mis
cmD BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
yIwAJl7Xf {
^/wvHu[# BOOL bRemoved=FALSE;
R4<