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:
"M^mJl&*b
Y_~otoSoY 一、实现方法
*u < ZQq +/" \.wYv 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|UUosS-# 2zuQeFsK #pragma data_seg("shareddata")
Yvu?M8aK! HHOOK hHook =NULL; //钩子句柄
,/!^ZS* UINT nHookCount =0; //挂接的程序数目
"z_},TCy static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
rFp>A`TJ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
?0qP6'nWx static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
\m:('^\6o static int KeyCount =0;
. lNf.x#u static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
EG3u)}vI #pragma data_seg()
Ynp#3 r 0]^gT' 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。
Vjd>j; H iO2jT+i 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:
wrsr U JC;&]S. BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
_~S[ cKey,UCHAR cMask)
%joU}G;" {
JU)k+:\a BOOL bAdded=FALSE;
=F
%lx[9Ye for(int index=0;index<MAX_KEY;index++){
U"~W3vwJ if(hCallWnd[index]==0){
-zI9E!24 hCallWnd[index]=hWnd;
Ka<J*
k3 HotKey[index]=cKey;
<Pi#-r., HotKeyMask[index]=cMask;
.1_kRy2*. bAdded=TRUE;
\^jRMIM== KeyCount++;
wyXQP+9G break;
jdx T662q }
~=|QPO(d }
J93xxj return bAdded;
1xSG(! }
#&%>kfeJ)< //删除热键
i?7?I BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
"b%FkD {
<;Tr
BOOL bRemoved=FALSE;
Z#YNL-x for(int index=0;index<MAX_KEY;index++){
RdNLf if(hCallWnd[index]==hWnd){
| IS$Om if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
F07X9s44E hCallWnd[index]=NULL;
p./0N. HotKey[index]=0;
aK7}} HotKeyMask[index]=0;
~@#a*=" bRemoved=TRUE;
+d(|Jid KeyCount--;
iq,rS" break;
e^$JGh2 }
15r=d }
{w7/M]m- }
ExeZj8U return bRemoved;
E=`/}2 }
c5:X$k\ Z[eWey_ 2(m#WK7>F DLL中的钩子函数如下:
sz%_9;`dpL N,3iSH=cN[ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
cv7:5P {
fPPmUM^C9 BOOL bProcessed=FALSE;
T''<y S if(HC_ACTION==nCode)
NB+/S ;` {
m(0X_&&?z if((lParam&0xc0000000)==0xc0000000){// 有键松开
!Lw]aHb switch(wParam)
.8T0OQ4 {
|=MhI5gsx case VK_MENU:
vo%"(! MaskBits&=~ALTBIT;
IDL0!cF break;
ml /S|`Drk case VK_CONTROL:
Yy6$q\@rV MaskBits&=~CTRLBIT;
HxcL3Bh$~} break;
M>}_2G]#F case VK_SHIFT:
Qkhor-f0 MaskBits&=~SHIFTBIT;
$48Z>ij?f break;
1aCpeD4|) default: //judge the key and send message
q'TIN{\.{ break;
&HtTh { }
o"_'cNAz for(int index=0;index<MAX_KEY;index++){
r4<aEj;l if(hCallWnd[index]==NULL)
0m"Ni:KEf continue;
0G0(g,3p if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Hmnxmgx {
{^1'' SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
AWKJ@&pA9m bProcessed=TRUE;
> >KCd }
j#Tl\S!m.I }
%l6E0[ }
c*\;!dbP else if((lParam&0xc000ffff)==1){ //有键按下
;mvVo-r*q switch(wParam)
+.OdrvN4) {
HrfS^B case VK_MENU:
9%1J..c MaskBits|=ALTBIT;
't5`Ni break;
m^=El7+ case VK_CONTROL:
N/--6)5~0 MaskBits|=CTRLBIT;
T[#q0bv break;
y%spI/( case VK_SHIFT:
n?;rWq" MaskBits|=SHIFTBIT;
xu%eg] break;
1<5Ug8q default: //judge the key and send message
HIx%c5^ break;
~_c1h@ }
Vxu V`Plf for(int index=0;index<MAX_KEY;index++){
$mh\` if(hCallWnd[index]==NULL)
D9?.Ru0. continue;
R=F_U if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
]V_A4Df {
:2&"ak>N SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Z#bO}! bProcessed=TRUE;
D W^Zuu/) }
c+ByEP4EG }
:7mHPe}( }
14jN0\ if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
G$%F`R[ for(int index=0;index<MAX_KEY;index++){
.Y"F3
R if(hCallWnd[index]==NULL)
32j}ep.* continue;
,v,rY' if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
0H]{,mVs SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
a@d 15CN //lParam的意义可看MSDN中WM_KEYDOWN部分
9dBxCdpu }
,&qC
R
sw }
t(9q6x3|e }
}m~MN4 l return CallNextHookEx( hHook, nCode, wParam, lParam );
@un+y9m[C }
S2_(lS+R L+(ng 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:
zsJermF,O |ns?c0rM BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
)>S,#_e*b BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
%W)pZN} $(Mz@#% 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
7.6L1srV ?s3S$Ih LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
`fTM/" {
,"XiI$Le if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
O#^H.B {
d]"4aS //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
4=MjyH|[Jx SaveBmp();
CgrQ"N5 return FALSE;
J}:.I> }
lM{f ld …… //其它处理及默认处理
xZlCFu }
(6Z^0GL +E_yEH7_) {svo!pN: 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
mPk'a XW" 0:}`J 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
]|+M0:2? >( [,yMIY 二、编程步骤
3m`>D
e ~IS8DW$; 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";
fyA-*)oHv kMMgY? 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
}Mt1C~{( 7K:V<vX5 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;
HP1QI/*v (rkg0 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;
bAGKi. G9 O6Fi 5、 添加代码,编译运行程序。
ow.!4kx{ d wz*iwd- 三、程序代码
RbXR/Rd O6R)>Y4 ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
ElV!C}g #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
PD-&(ka. #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
"8{A4N1B5 #if _MSC_VER > 1000
}:
HG)V #pragma once
.'gm2 #endif // _MSC_VER > 1000
x9 %=d #ifndef __AFXWIN_H__
4^F%bXJ) #error include 'stdafx.h' before including this file for PCH
N+rU|iMa. #endif
'#Au~5 #include "resource.h" // main symbols
=I@t%Y class CHookApp : public CWinApp
r(46jV.sD: {
"+-
'o+ public:
K+F"V W*? CHookApp();
_!@:@e)yB{ // Overrides
czuIs|_K* // ClassWizard generated virtual function overrides
p;w&}l{{ //{{AFX_VIRTUAL(CHookApp)
+*:mKx@Nw public:
/[.V( K
D virtual BOOL InitInstance();
-HG.GA virtual int ExitInstance();
:~vodh //}}AFX_VIRTUAL
At4\D+J{Vs //{{AFX_MSG(CHookApp)
1x:W 3. // NOTE - the ClassWizard will add and remove member functions here.
9Yv:6@. F // DO NOT EDIT what you see in these blocks of generated code !
VP~2F
E //}}AFX_MSG
d?2ORr|m= DECLARE_MESSAGE_MAP()
Cp6S2v I };
T8x)i\< LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
Og/aTR<;= BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
$`E?=L`$ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
%
/VCjuV BOOL InitHotkey();
&uK(. @ BOOL UnInit();
6*q1%rs:w #endif
^{4BcM7eH ;7QXs39S //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
Mh.1KI[t #include "stdafx.h"
10Ik_L=' #include "hook.h"
<\~v$=G #include <windowsx.h>
_SAM8!q4, #ifdef _DEBUG
,X4+i8Yc #define new DEBUG_NEW
&*=!B9OBI #undef THIS_FILE
U]=yCEb8p static char THIS_FILE[] = __FILE__;
z'EQdQ) #endif
hul,Yd) Z #define MAX_KEY 100
Sfz1p #define CTRLBIT 0x04
+[!S[KE #define ALTBIT 0x02
vW1^ #define SHIFTBIT 0x01
Y 3BJ@sqz #pragma data_seg("shareddata")
$3^M-w HHOOK hHook =NULL;
\yr9j$ UINT nHookCount =0;
p%I'd^}.! static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
N}?|ik static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
GfE>?mG static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
d:(Ex^^ static int KeyCount =0;
hv|a8=U!R static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
=:gKh #pragma data_seg()
QnWE;zN[7A HINSTANCE hins;
5H0qMt P void VerifyWindow();
@:C)^f" BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
cag 5w~Px //{{AFX_MSG_MAP(CHookApp)
Lq2Q:w' // NOTE - the ClassWizard will add and remove mapping macros here.
e= IdqkJ% // DO NOT EDIT what you see in these blocks of generated code!
]F4QZV(
M //}}AFX_MSG_MAP
,|:.0g[n END_MESSAGE_MAP()
qzUiBwUi@ *#T:
_ CHookApp::CHookApp()
S hI1f {
.~f )4'T 9 // TODO: add construction code here,
mr\,"S-` // Place all significant initialization in InitInstance
(p-q>@m }
Kjd3!%4mB Qr$'Q7 CHookApp theApp;
:y-;V LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
.<%tu 0 {
xE:jcA
d$} BOOL bProcessed=FALSE;
1=R$ RI if(HC_ACTION==nCode)
9zwD%3Ufn {
L|CdTRgRCB if((lParam&0xc0000000)==0xc0000000){// Key up
$ZM'dIk? switch(wParam)
#n>U7j9`O {
4z0gyCAC A case VK_MENU:
.l1x~( MaskBits&=~ALTBIT;
NnLK!Q break;
oy^-?+ case VK_CONTROL:
$hhXsu= MaskBits&=~CTRLBIT;
XV]N}~h o` break;
sgfqIe1 case VK_SHIFT:
z
&EDW5I MaskBits&=~SHIFTBIT;
@]l|-xGCWn break;
$6rm;UH default: //judge the key and send message
W%L'nR~w$ break;
wQ+pVu?6_ }
J!uG/Us for(int index=0;index<MAX_KEY;index++){
"ko*-FrQ if(hCallWnd[index]==NULL)
fsL9d} continue;
@+b$43^ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Msqqjhoy {
9\Jc7[b SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
1K Fd
~U bProcessed=TRUE;
LYDiqOrx }
4 Ej->T. }
TKB8%/_p }
\3JCFor/ else if((lParam&0xc000ffff)==1){ //Key down
1/M^7Vb. switch(wParam)
Tb i?AJa} {
YV.' L case VK_MENU:
`K{} MaskBits|=ALTBIT;
1>Sfv|ZP, break;
)'+[,z ;s case VK_CONTROL:
2;v:Z^& MaskBits|=CTRLBIT;
w+)${|N?
break;
<:9ts@B case VK_SHIFT:
.LDZqWr- MaskBits|=SHIFTBIT;
//7YtK6 break;
fd'kv default: //judge the key and send message
+``vnC break;
rCPIz< }
%'KRbY for(int index=0;index<MAX_KEY;index++)
HMd?` {
Nc\DXc-N
if(hCallWnd[index]==NULL)
*Jsb~wta continue;
XDPR$u8hM if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
,Cr%2Wg- {
&>jz[3 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Q!l(2nva bProcessed=TRUE;
Y$JVxly }
/8l-@P.o }
+=($mcw#[ }
"'v+*H 3 if(!bProcessed){
s<YN*~ for(int index=0;index<MAX_KEY;index++){
M/o?D <' if(hCallWnd[index]==NULL)
BN 9e S continue;
=8]`-( if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
x=DxD&I!J SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
Bp^LLH }
wkp2A18n }
hz:7W8 }
~@'wqGTp return CallNextHookEx( hHook, nCode, wParam, lParam );
+xYu@r%R }
YS|Dw'%g / $Tbsre\MJ BOOL InitHotkey()
5;)^o3X> {
[Mu9"kF if(hHook!=NULL){
0F)v9EK(W4 nHookCount++;
$mJv\;t return TRUE;
.z#eYn%d }
};'@'
else
B:"D)/\ hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
7NvKpinQ if(hHook!=NULL)
gv67+Mf nHookCount++;
`3\aX|4@ return (hHook!=NULL);
2K:A4)jZ }
AS;Sz/YP BOOL UnInit()
yY#h1 {
EXSJ@k6=8s if(nHookCount>1){
6{)pF nHookCount--;
_^_3>}y5op return TRUE;
og";mC }
xT>9ZZcE BOOL unhooked = UnhookWindowsHookEx(hHook);
V|YQhd0kv if(unhooked==TRUE){
6:8s,a3&[k nHookCount=0;
GN_L"|#)= hHook=NULL;
FAM{p=t]HT }
Au2?f~#Fv return unhooked;
Htgo=7!?\3 }
YrL(4 Nt8 UBL{3s^" BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Z1fY' f {
()aCE^C BOOL bAdded=FALSE;
U`6|K$@ for(int index=0;index<MAX_KEY;index++){
e=&~6bs1U if(hCallWnd[index]==0){
~xqiasE#K hCallWnd[index]=hWnd;
&PJ;B)b HotKey[index]=cKey;
!.UE} ^TV HotKeyMask[index]=cMask;
$`lWW6>P bAdded=TRUE;
W` x.qumN KeyCount++;
,7wYa& break;
xKu#OH }
znrO~OK }
{F<0e^* return bAdded;
2Hd\>{* }
/l<(i+0 Vit-)o{zr BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
EV( F!& {
n3p@duC4 BOOL bRemoved=FALSE;
)%^l+w+& for(int index=0;index<MAX_KEY;index++){
h\!8*e;RAW if(hCallWnd[index]==hWnd){
G' U_I if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
]$2 yV&V