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:
K#X/j'$^
QdQ1+*/+U 一、实现方法
Y.Z:H!P);$ mS![J69( 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:
{xov8M #m?)XB^_ #pragma data_seg("shareddata")
5toa@#Bc% HHOOK hHook =NULL; //钩子句柄
AL3iNkEa UINT nHookCount =0; //挂接的程序数目
J9]cs?`) static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
z5M6 static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
-40X3 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
_ ~\} fY static int KeyCount =0;
HNBmq>XDc static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
&b5(Su #pragma data_seg()
0^o/cSF W~D_+[P|_ 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。
u|Mx} +D]raU 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:
[{u3g4`} v7./u4S|V BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
LFHJj-nk cKey,UCHAR cMask)
t4v'X}7q] {
Q#SQ@oUzD BOOL bAdded=FALSE;
v=lW5%r,' for(int index=0;index<MAX_KEY;index++){
!1=OaOT if(hCallWnd[index]==0){
6V JudNA hCallWnd[index]=hWnd;
$'Mf$h HotKey[index]=cKey;
;2&" HotKeyMask[index]=cMask;
+#BOWz bAdded=TRUE;
^ `Ozw^~ KeyCount++;
QNU~G3 break;
fpo{`;&F }
]gcOMC }
\2a;z<( return bAdded;
8/dMvAB1So }
s[0` //删除热键
_Wg}#r BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
4^2>KC_ {
Q9O_>mZy BOOL bRemoved=FALSE;
HV/:OCK for(int index=0;index<MAX_KEY;index++){
!a F~5P7% if(hCallWnd[index]==hWnd){
$B%KkD if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
Zc1x"j hCallWnd[index]=NULL;
si6CWsb_ f HotKey[index]=0;
yFDeYPZP HotKeyMask[index]=0;
Z)E)-2U$@ bRemoved=TRUE;
,jis@]: KeyCount--;
=cjO] break;
]Rxo}A }
X=]utn }
~r8<|$; }
0@cIj
] return bRemoved;
pIcg+~ }
qNj?Rwc 4y7_P0}:B -]zb3P DLL中的钩子函数如下:
nD*iSb* uWdF7|PN7 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
04|ZwX$>+ {
<.4(#Ebd BOOL bProcessed=FALSE;
Bgc]t if(HC_ACTION==nCode)
<F0^+Pf/ {
EA6l11{Gk1 if((lParam&0xc0000000)==0xc0000000){// 有键松开
[q[37;ZEQ switch(wParam)
H"AL@= {
")uKDq case VK_MENU:
~ `qWEu MaskBits&=~ALTBIT;
L@(. i break;
nI6ompTX case VK_CONTROL:
!mUJ["# MaskBits&=~CTRLBIT;
^)>( <6 break;
PtW2S 1?j case VK_SHIFT:
m#RJRuZ|2V MaskBits&=~SHIFTBIT;
`K.B` break;
(Fzy8
s default: //judge the key and send message
'A:Y&w"r break;
:\"0jQ.y| }
)f:i4.M for(int index=0;index<MAX_KEY;index++){
2\1+M) if(hCallWnd[index]==NULL)
'|ntwK*f continue;
I{(!h90 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
lgU!D |v {
cHF W"g78 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
)>FAtE bProcessed=TRUE;
"PI;/(kR }
Ex
p?x }
{\1bWr8!U }
=exCpW> else if((lParam&0xc000ffff)==1){ //有键按下
e*}zl>f switch(wParam)
uKk#V6t# {
'D5J5+.z case VK_MENU:
:zKW[sF MaskBits|=ALTBIT;
a4^hC[a break;
[6mK<A,/ case VK_CONTROL:
rueaP MaskBits|=CTRLBIT;
I &iyj99n break;
$oQOOa@;i) case VK_SHIFT:
-@w,tbc$ MaskBits|=SHIFTBIT;
:V+rC]0 break;
#2_FM!e default: //judge the key and send message
u5}:[4N%I break;
]ouoRlb/ }
N+c|0 for(int index=0;index<MAX_KEY;index++){
q%;cu1^"M if(hCallWnd[index]==NULL)
q][kD2 continue;
n&;JW6VQS if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
U%:%. Bys {
[l5jPL}6 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
~q566k!Ll! bProcessed=TRUE;
:
Z<\R0 }
PDD2ouv4 }
`S|F\mI~
}
l.pxDMY if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
~wW]ntZm for(int index=0;index<MAX_KEY;index++){
2Cp4aTGv# if(hCallWnd[index]==NULL)
Bn&P@C$7 continue;
8m
iJQIq if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
^;PjO|mD
Z SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
f<bB= 9J //lParam的意义可看MSDN中WM_KEYDOWN部分
{k.:DH) }
fKY-@B[| }
Cu#n5SF* }
?{TWsuP7 return CallNextHookEx( hHook, nCode, wParam, lParam );
\ 2y/: }
PM84Z@Y Jl\xE`-7 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
n zaDO-2! #VX]trh, BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
wd*B3 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
j67a?0<C2U 9y6u&!PZ\ 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
L D[\eJ_ _)5E= LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
45.ks. {
/Kli C\ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
OoA!N-Q {
K@1gK<,a //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
S&UP;oc SaveBmp();
_oc6=Z return FALSE;
q&@s/k }
-M=BD-_.h …… //其它处理及默认处理
xFp$JN }
4utwcXL m=9b/Nr4 RM_%u=jC 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。
9)tb= ?+hEs =Xs 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。
|k6+-
1~_ N/0aO^"V 二、编程步骤
:} =lE"2 [ x{$f7CEh 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
SV t~pE+Y 1<m`38' 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
L-?ty@-i x*z[(0g! 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
+C!GV.q[ WZ?>F 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
kBk>1jn"
s*gqKQ; 5、 添加代码,编译运行程序。
<MG&3L.[ kNWTM%u9 三、程序代码
'M6+(`x G)s.~ T ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
ri4z^1\ #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
"|(.W3f1 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
m@kLZimD #if _MSC_VER > 1000
6inAnC@I #pragma once
>C_G~R #endif // _MSC_VER > 1000
3mU~G}ig #ifndef __AFXWIN_H__
O1o>eDE5A #error include 'stdafx.h' before including this file for PCH
Zm*d)</> #endif
CJN~p]\ #include "resource.h" // main symbols
bh5D}w class CHookApp : public CWinApp
_}p[(sTV {
>+7{PF+sB public:
k#pO+[ x CHookApp();
Mu/(Xp6 2 // Overrides
:u9'ZHkZ // ClassWizard generated virtual function overrides
L3\#ufytb //{{AFX_VIRTUAL(CHookApp)
ZbT$f^o}M] public:
*yT> virtual BOOL InitInstance();
k^ZP~.G virtual int ExitInstance();
W6>t!1oO+ //}}AFX_VIRTUAL
Ci-Ze j //{{AFX_MSG(CHookApp)
FLG"c690 // NOTE - the ClassWizard will add and remove member functions here.
tcoG;ir // DO NOT EDIT what you see in these blocks of generated code !
A^).i_ //}}AFX_MSG
'8)kFR^9 DECLARE_MESSAGE_MAP()
8'@5X-nD };
15J"iN2"W LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
Y910\h@V BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
]CLM'$ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
DQK?y=vf BOOL InitHotkey();
[(Z(8{3i BOOL UnInit();
tx
d0S! #endif
Z#@ Zfk]Z9YO //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
2LN6pu #include "stdafx.h"
X7-*`NI^ #include "hook.h"
w.58=Pr #include <windowsx.h>
b}NNkM #ifdef _DEBUG
AJB
NM #define new DEBUG_NEW
sm'_0EUg #undef THIS_FILE
j=T8b static char THIS_FILE[] = __FILE__;
bDl#806P L #endif
!0lk}Uzkh #define MAX_KEY 100
N4,oO H~ #define CTRLBIT 0x04
F<{,W-my ` #define ALTBIT 0x02
Az y`4 #define SHIFTBIT 0x01
.g}N@ #pragma data_seg("shareddata")
BNJ0D HHOOK hHook =NULL;
Z:^#9D{ UINT nHookCount =0;
M>5OC)E static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
+ Fo^NT static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
BAXu\a-C_ static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
(/$-2.@ static int KeyCount =0;
Y _`JS; static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
z4_B/Q #pragma data_seg()
36{OE!,i HINSTANCE hins;
;SI (5rS? void VerifyWindow();
eEBNO*2 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
^k7I+A //{{AFX_MSG_MAP(CHookApp)
@4UX~=:686 // NOTE - the ClassWizard will add and remove mapping macros here.
hK)'dG* // DO NOT EDIT what you see in these blocks of generated code!
3}s]F/e //}}AFX_MSG_MAP
n*$g1 HG6 END_MESSAGE_MAP()
"{vWdY|" wG MhKZE CHookApp::CHookApp()
qvu1 u
GCc {
mvH8hvD9 // TODO: add construction code here,
?3K~4-!?/ // Place all significant initialization in InitInstance
$\*Z }
tf 7HhOCYX Gn4b*Y&M]3 CHookApp theApp;
?=4oxPe LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
=YVxQj {
!HU$V9C BOOL bProcessed=FALSE;
YK{J"Kof if(HC_ACTION==nCode)
'8zd]U {
7+f6? if((lParam&0xc0000000)==0xc0000000){// Key up
[err$ switch(wParam)
R.WB.FP {
d #1&"( case VK_MENU:
40MKf/9 MaskBits&=~ALTBIT;
|U1 [R\X break;
]cP%d-x} case VK_CONTROL:
*w0|`[P+h MaskBits&=~CTRLBIT;
*(5;5r break;
@!oN]0`F; case VK_SHIFT:
\(
V1-, MaskBits&=~SHIFTBIT;
I,#E`) break;
i[9gcL" default: //judge the key and send message
\?t8[N\_[( break;
@`
Pn<_L }
`lE&:) for(int index=0;index<MAX_KEY;index++){
=(hBgNH if(hCallWnd[index]==NULL)
mD7NQ2:wA continue;
`AE6s.p? if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
:Ef!gpS}?R {
zqt<[=O SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
sE&nEc bProcessed=TRUE;
r=3`Eb"t }
iJhieNn }
e eN`T&cI }
7r?,wM else if((lParam&0xc000ffff)==1){ //Key down
Y>aVnixx< switch(wParam)
U/{t" e {
sryA(V case VK_MENU:
X=-= z5 MaskBits|=ALTBIT;
!VIxEu^ke break;
}iDRlE, case VK_CONTROL:
C ibfuR MaskBits|=CTRLBIT;
Dti-*LB1 break;
PTe$dPB case VK_SHIFT:
5P<1I7d MaskBits|=SHIFTBIT;
0vLx={i break;
1J1Jp|j. default: //judge the key and send message
*A!M0TK?i, break;
A4(L47^ }
XM!oN^ for(int index=0;index<MAX_KEY;index++)
"Cxj_V@\ {
16eP7s if(hCallWnd[index]==NULL)
[dLc+h1{B continue;
`:Wyw<^ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
!NNPg?Y {
z =H?@z SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
`f}ZAX bProcessed=TRUE;
!-T#dU }
037\LPO }
B /3~[ ' }
}N-UlL( if(!bProcessed){
XelFGT E for(int index=0;index<MAX_KEY;index++){
W20- oZ8 if(hCallWnd[index]==NULL)
XOqHzft h6 continue;
dEXhn if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
A4l"^dZc SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
_:Q^mV=;j }
[wSoZBl }
wT+60X' }
hb~d4J=S return CallNextHookEx( hHook, nCode, wParam, lParam );
=CFg~8W }
*g}==o` OO/>}? ob BOOL InitHotkey()
zx"EAF{ {
Bi fI.2| if(hHook!=NULL){
D_<B^3w) nHookCount++;
JfJ ln[ return TRUE;
yD3vq}U! }
}mp`!7?>O else
P JKY$s. hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
oIOeX1$V if(hHook!=NULL)
B> i^ w1 nHookCount++;
N%:uOX8{ return (hHook!=NULL);
7.NL>:lu }
kKbbsB BOOL UnInit()
H4v%$R;K {
`4@`G:6BL if(nHookCount>1){
:,H_
e!
X nHookCount--;
.Sw4{m[g return TRUE;
</<z7V,{ }
{DvWa| BOOL unhooked = UnhookWindowsHookEx(hHook);
vr47PM2al if(unhooked==TRUE){
_`QME r? nHookCount=0;
myXGMN$i hHook=NULL;
4ybOK~z }
HSG9|}$ return unhooked;
#F
.8x@ }
< :eKXH2 PTpCiiA@ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
$aXYtHI {
A+Je?3/. BOOL bAdded=FALSE;
FhH*lO& for(int index=0;index<MAX_KEY;index++){
bU}!bol if(hCallWnd[index]==0){
-{eiV0<^ hCallWnd[index]=hWnd;
7 je1vNs HotKey[index]=cKey;
T;3~teVYB HotKeyMask[index]=cMask;
)`5-rm~* bAdded=TRUE;
D//58z& KeyCount++;
O{]}{Ss break;
4byh,t }
)}w-;HX }
2s 9U& return bAdded;
'uUa|J1mu }
Jz;`L3m zSsogAx BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
$3#oA.~R/ {
~U?vB((j! BOOL bRemoved=FALSE;
&n6
|L8 for(int index=0;index<MAX_KEY;index++){
Z+J~moW ` if(hCallWnd[index]==hWnd){
N9 )ERW2`* if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
T^xp2cZ hCallWnd[index]=NULL;
gJOswN;([ HotKey[index]=0;
#@5 jOi HotKeyMask[index]=0;
mW_A3S5 bRemoved=TRUE;
g=v[@{9Pw KeyCount--;
/s:akLBaD break;
|("5 :m }
hW cM. }
=(k0^#++G }
m}
=<@b:l return bRemoved;
[qt^gy) }
v#sx9$K T ~0.@1zEXj void VerifyWindow()
-gS/ {
K&