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$]6
~i5YqH0 一、实现方法
3}fOb \9VF)Y.ke 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
+)sX8zb*gY f$xXR$mjf #pragma data_seg("shareddata")
mQ:{>` HHOOK hHook =NULL; //钩子句柄
:snO*Zg UINT nHookCount =0; //挂接的程序数目
$ZBYOA static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
yDafNH static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
A9MM^jV8 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
<giBL L! static int KeyCount =0;
QM0B6F static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
t>\sP #pragma data_seg()
a_>|Ny6{ =b%}x >> 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
\;X7DK2 7Bp7d/R- DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
H#SQ>vyAV @(,1}3s BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
M/?,Qii cKey,UCHAR cMask)
XDemdMy$ {
l*1|B3#m! BOOL bAdded=FALSE;
k7CKl;Fck for(int index=0;index<MAX_KEY;index++){
' P?h?w^T if(hCallWnd[index]==0){
faQmkO hCallWnd[index]=hWnd;
!RI _Uph HotKey[index]=cKey;
|3' HotKeyMask[index]=cMask;
7Z< ~{eD, bAdded=TRUE;
FDz`U:8 KeyCount++;
HT;^u"a~ break;
]3_b3@k }
,;`f* # }
Tlw'05\{J return bAdded;
7Z6=e6/\ }
,|]JaZq //删除热键
~#pATPW@( BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
FJ;I1~?? {
YaC%69C' BOOL bRemoved=FALSE;
FH~:&; for(int index=0;index<MAX_KEY;index++){
!T`oHs if(hCallWnd[index]==hWnd){
dJ"M#X!Zu if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
'#'noB;,
hCallWnd[index]=NULL;
4VJUu`[ HotKey[index]=0;
o!M8V ^vW HotKeyMask[index]=0;
4Z)s8sD KW bRemoved=TRUE;
~bLx2=-" KeyCount--;
\R#SoOd break;
)'djqpM. }
%k!CjW3 }
a`!Jq' }
"n%s>@$ return bRemoved;
Oidf\%!mvR }
Qm%PpQ^Lz3 ^m qEKy< JusU5 e| DLL中的钩子函数如下:
EwP2,$; 'UX.Q7W LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
OIcXelS:@k {
`z|0O BOOL bProcessed=FALSE;
#a8kA"X if(HC_ACTION==nCode)
.IeO+RDQ {
bKQho31a'
if((lParam&0xc0000000)==0xc0000000){// 有键松开
M-o'`e' switch(wParam)
WMB%?30 {
2*:q$ c case VK_MENU:
C96/ MaskBits&=~ALTBIT;
~aob@( break;
8z9{H case VK_CONTROL:
#{cy( &cz MaskBits&=~CTRLBIT;
aB,-E>+ break;
5'zXCHt case VK_SHIFT:
}Le]qR9Y] MaskBits&=~SHIFTBIT;
HlGSt$woX break;
+,76|oMsQ% default: //judge the key and send message
`b?uQ\#-M break;
4>KF`?%4 }
;*(-8R/ for(int index=0;index<MAX_KEY;index++){
7~7L5PRW if(hCallWnd[index]==NULL)
QN:v4,$d continue;
vF72#BNs if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
kK? SG3 {
^ ""edCs SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
I|@+O# bProcessed=TRUE;
/DQYlNa }
gEh/m.L7 }
da$FY7 }
zxyl+tU & else if((lParam&0xc000ffff)==1){ //有键按下
:`bC3Mr switch(wParam)
>US*7m } {
$L/`nd case VK_MENU:
'}.Yf_ MaskBits|=ALTBIT;
/R#zu_i break;
">H*InF case VK_CONTROL:
{9x_E { MaskBits|=CTRLBIT;
<Ky-3:pxeM break;
}9fa]D-a? case VK_SHIFT:
/_C2O"h MaskBits|=SHIFTBIT;
=nEP:7~{ break;
&\h7E
default: //judge the key and send message
98[uRywI break;
B~Sj#(WEa }
&LLU@ | for(int index=0;index<MAX_KEY;index++){
]eL# bJ if(hCallWnd[index]==NULL)
RTOA'|[0M continue;
fLDrit4_Q if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
!_Lmrs {
:#rP$LSYC SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
-&Rv=q> bProcessed=TRUE;
{;yO3];Hqw }
yM_/_V|G }
A}9Z%U }
.t8)`MU6. if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
a'J0}j! for(int index=0;index<MAX_KEY;index++){
+-izC%G if(hCallWnd[index]==NULL)
LF dvz0 continue;
L:i&OCU2k if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
?
wS}' SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
:j\7</uu //lParam的意义可看MSDN中WM_KEYDOWN部分
&jqaW2 }
)x.%PUA }
iU)I"#\l'k }
t~Q9}+ return CallNextHookEx( hHook, nCode, wParam, lParam );
r.C6`
a }
+3v)@18B1 Rh="<'d 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:
e5L+NPeM6v l<=;IMWd BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
59E9K)c3 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
s(,S~
=ZgueUz, 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:
iE%" Q? Q/ JF=R$! 5 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
[|]J8o@u^ {
{[y6qQm if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
$WA wMS, {
IiYL2JS;t| //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
xR+vu>f SaveBmp();
G~9m,l+ return FALSE;
]2AOW}= }
@Z5q2Q …… //其它处理及默认处理
&^=Lr:I }
s QDgNJbU 'HA{6v,y #6 M]tr 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
5y#,z`S 8v$q+Wic 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。
E0Wc8m " T7[@ lMa? 二、编程步骤
r%,?uim# N ,~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";
{cK<iQJ ]H1mj#EWU 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
#xIg(nG QkrQM&Im 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;
V?mP7 bWFa{W5! 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;
?ANWI8'_j ~f<']zXv 5、 添加代码,编译运行程序。
~ k*]Z8Z 2yN!yIPR 三、程序代码
15:9JVH3D !0{SVsc) ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
]kj^T?&n. #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
{*xE+ | #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
4^7 v@3
#if _MSC_VER > 1000
/}:{(Go #pragma once
!(d]f0 #endif // _MSC_VER > 1000
%YG?7PBB #ifndef __AFXWIN_H__
g~U(w #error include 'stdafx.h' before including this file for PCH
{yn,u)@r9S #endif
, ZsZzZ# #include "resource.h" // main symbols
7[ ovEE54 class CHookApp : public CWinApp
+gl\l?>sr {
FXCBX:LnvU public:
&L6Ivpj- CHookApp();
ZFZ'&"+ // Overrides
K+3-XhG // ClassWizard generated virtual function overrides
J;4x$BI //{{AFX_VIRTUAL(CHookApp)
UP](1lAf public:
%
km<+F=~ virtual BOOL InitInstance();
!BQt+4G7 virtual int ExitInstance();
$QJ3~mG2 //}}AFX_VIRTUAL
*i"9D: //{{AFX_MSG(CHookApp)
m6Dm1'+ // NOTE - the ClassWizard will add and remove member functions here.
Tmg C {_ // DO NOT EDIT what you see in these blocks of generated code !
r)<A YX]J //}}AFX_MSG
,np=m17 DECLARE_MESSAGE_MAP()
2Kxb(q" };
jWdviS9&g LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
] \yIHdcDi BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Ib(C`4% BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
is;g`m BOOL InitHotkey();
prJd' BOOL UnInit();
ne#dEUD #endif
'|C%X7 J(1Tl //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
(-C)A-Uo& #include "stdafx.h"
A 3 V #include "hook.h"
b4L7M1l #include <windowsx.h>
196aYLE #ifdef _DEBUG
u]ms~rO #define new DEBUG_NEW
,%pCcM) #undef THIS_FILE
[@i:qB>B static char THIS_FILE[] = __FILE__;
>.<VD7p #endif
6[m~xegG #define MAX_KEY 100
#Xg;E3BM #define CTRLBIT 0x04
^ :VH?I= #define ALTBIT 0x02
CHnclT #define SHIFTBIT 0x01
F^l1WX6 #pragma data_seg("shareddata")
gT}H B. HHOOK hHook =NULL;
1AJ6NBC&c UINT nHookCount =0;
{B$CqsvJ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
80nE QT
y static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
7L~*%j static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
WwmYJl0 static int KeyCount =0;
'm<Lx _i static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
zs=3e~o3 #pragma data_seg()
0cm34\* HINSTANCE hins;
IMM;LC%rD9 void VerifyWindow();
#|9W9\f, BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
D]~K-[V?l //{{AFX_MSG_MAP(CHookApp)
rWht},-|1 // NOTE - the ClassWizard will add and remove mapping macros here.
&8IBf8 // DO NOT EDIT what you see in these blocks of generated code!
^J^,@Hf_ //}}AFX_MSG_MAP
Sca"LaW1 END_MESSAGE_MAP()
7Kw'Y8 4[lFurH CHookApp::CHookApp()
l7QxngWw {
~,lt^@a // TODO: add construction code here,
')jItje| // Place all significant initialization in InitInstance
y
4i3m(S }
R ]Ev=V'U :1 +Aj
( CHookApp theApp;
@.;+WQE LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
}geb959 {
^4sfVpD2! BOOL bProcessed=FALSE;
fD!c t; UK if(HC_ACTION==nCode)
G)vNMl {
Nj9A-*0g6N if((lParam&0xc0000000)==0xc0000000){// Key up
FC0fe_U(F switch(wParam)
_c-3eQ1 {
g*$2qKm case VK_MENU:
12`u[O}\}- MaskBits&=~ALTBIT;
ztVTXI%Kz break;
$>)0t@[f case VK_CONTROL:
9=j9vBV MaskBits&=~CTRLBIT;
\ eHOHHAGW break;
ZSf &M case VK_SHIFT:
v ,")XPY MaskBits&=~SHIFTBIT;
8maWF.xq break;
x/,;:S default: //judge the key and send message
:FAPH8] break;
\HGf!zZ }
R+LKa Z for(int index=0;index<MAX_KEY;index++){
dN2JOyS if(hCallWnd[index]==NULL)
NK|UeL7ght continue;
GxdAOiq; if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
15ailA&(Qm {
fRS;6Jc SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Cm[}DB bProcessed=TRUE;
e:O,$R#g }
e)sR$]i:v }
wfo, r 7 }
Xs2}n^#i else if((lParam&0xc000ffff)==1){ //Key down
NQ{(G8x9 switch(wParam)
)oIh?-WL {
H07\z1?.K case VK_MENU:
#eW
T-m MaskBits|=ALTBIT;
`n&:\Ib break;
*OLqr/ yb case VK_CONTROL:
1Q@]b_"Xh MaskBits|=CTRLBIT;
ImN'o4vo break;
/8GdCac case VK_SHIFT:
/1OCK= MaskBits|=SHIFTBIT;
.`Rt break;
z +MH co" default: //judge the key and send message
D4VDWv break;
y_m+&Oe }
aHN"I
for(int index=0;index<MAX_KEY;index++)
,AnD%#o {
K6DN>0sY if(hCallWnd[index]==NULL)
5Zq
hyv= continue;
l<6GZ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
>.meecE?Q {
VWft/2p~ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
5/"$_7"{a bProcessed=TRUE;
f~VlCdf+ }
}n^Rcz6HeO }
Qx)b4~F? }
*(9Tl]w if(!bProcessed){
GLsa]}m,9 for(int index=0;index<MAX_KEY;index++){
vT?^# if(hCallWnd[index]==NULL)
NY7yk3 continue;
+d3|Up8= if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
NzgG77> SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
A3eCI }
yd;e;Bb7* }
k%6CkCw }
:a }](Wn return CallNextHookEx( hHook, nCode, wParam, lParam );
T.da!!'B
f }
v0DDim?cc /p
!A:8 BOOL InitHotkey()
bWTfP8gT {
'|[!I!WB` if(hHook!=NULL){
1_+ h"LE nHookCount++;
NWf=mrS8@$ return TRUE;
h%/BZC^L]| }
Sgi`&;PF else
G4(R/<J,BQ hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
?Bf>G]zx if(hHook!=NULL)
Yc[umn^K nHookCount++;
`w!XO$"]Z return (hHook!=NULL);
AR[m+E }
u`'"=Y_E BOOL UnInit()
E0ED[d, {
9,?~dx if(nHookCount>1){
WE\TUENac( nHookCount--;
p!pf2}6Fd return TRUE;
X.b8qbnq[ }
=v:?rY} BOOL unhooked = UnhookWindowsHookEx(hHook);
gkr9+ if(unhooked==TRUE){
81Z;hO"~ nHookCount=0;
f"s_dR hHook=NULL;
\]>YLyG }
x?L[*N_ml return unhooked;
FJ3S
}
@1*^ttC 3L&: BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
3m>YR-n$ {
7${<u 0((! BOOL bAdded=FALSE;
#
55>? for(int index=0;index<MAX_KEY;index++){
i(.e=
if(hCallWnd[index]==0){
D
/QLp3+o hCallWnd[index]=hWnd;
Ja6 KO2}p HotKey[index]=cKey;
=gj?!d` HotKeyMask[index]=cMask;
2F2Hl bAdded=TRUE;
Wk[a|> KeyCount++;
k!Yc_ZB:*l break;
cC-8.2 }
AlQhKL}|s }
mG1~rI return bAdded;
C~2!@<y }
p]kEH\
sh @_do<'a BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
}#^Cj; {
YdhV
a!Y BOOL bRemoved=FALSE;
6 - 3?&+ for(int index=0;index<MAX_KEY;index++){
'C5id7O& if(hCallWnd[index]==hWnd){
h7#\]2U$[5 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
)Q=u[ p hCallWnd[index]=NULL;
<H^jbK HotKey[index]=0;
GlJ[rD HotKeyMask[index]=0;
^("b~-cJ bRemoved=TRUE;
&@lfr623 KeyCount--;
e* [wF})) break;
w-Ph-L/ }
xeF>"6\ }
Zv@qdY<: }
`PARZ| return bRemoved;
E^)FnXe5 }
Ll|-CY $ .?u<|4jE6 void VerifyWindow()
iYr)Ao5X {
lrE"phYk for(int i=0;i<MAX_KEY;i++){
TdPd8ig8{ if(hCallWnd
!=NULL){ "}3sL#|z
if(!IsWindow(hCallWnd)){ PSJj$bt;<+
hCallWnd=NULL; *tv&