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:
rr],DGg+B]
U]H#MiC! 一、实现方法
) j#`r/ PUMXOTu] 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:
2lH& nS }<-s #pragma data_seg("shareddata")
{HltvO%8 HHOOK hHook =NULL; //钩子句柄
pP&7rRhw UINT nHookCount =0; //挂接的程序数目
O:;w3u7;u static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
c_$=-Khk static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
-P$PAg5"2 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
%rL.|q9
static int KeyCount =0;
NX*Q F+ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
O`IQ(,yef #pragma data_seg()
'T*&'RQr dVtG/0 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。
6_GhO@lOG itt3.:y 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:
S6Q qZ}^;)a^ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
vxBgGl cKey,UCHAR cMask)
C!<Ou6}!b {
H(ARw'M BOOL bAdded=FALSE;
~D j8z+^ for(int index=0;index<MAX_KEY;index++){
_YhES-Ff if(hCallWnd[index]==0){
l` lk-nb hCallWnd[index]=hWnd;
{T$9?`h~M HotKey[index]=cKey;
Cgk<pky1 HotKeyMask[index]=cMask;
y@S$^jk. bAdded=TRUE;
3) <yod= KeyCount++;
A4x]Qh3OO break;
*SJ_z(CZm }
{#vgtgBB }
>C>.\ return bAdded;
gV's=cQ }
s%7t"-=& //删除热键
~d.Y&b BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
,wb:dj- {
C2kPMB=Xo BOOL bRemoved=FALSE;
X]TG<r for(int index=0;index<MAX_KEY;index++){
)hsgC'H{~] if(hCallWnd[index]==hWnd){
O3,jg|, if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
TQF| a\M' hCallWnd[index]=NULL;
EeE7#$l HotKey[index]=0;
D0-3eV- HotKeyMask[index]=0;
&-)N' bRemoved=TRUE;
0*3R=7_},o KeyCount--;
gh]cXuph break;
]m3HF& }
AofKw }
I5p?
[ }
R`qFg/S return bRemoved;
Qz1E 2yJ }
pI\]6U UcHJR"M~c R B DLL中的钩子函数如下:
yS'I[l -$ls(oot LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
rpha!h>w1% {
q"lSZ;
'E BOOL bProcessed=FALSE;
-=Q*Ml#I if(HC_ACTION==nCode)
~!d\^Z^i {
9s
q if((lParam&0xc0000000)==0xc0000000){// 有键松开
Tx# Mn~xD switch(wParam)
N#_H6TfMG {
L,/%f<wd case VK_MENU:
L~OvY MaskBits&=~ALTBIT;
b{&)6M)zo break;
M'O <h case VK_CONTROL:
pz}.9 yI8 MaskBits&=~CTRLBIT;
%YscBG break;
Czu9o;xr case VK_SHIFT:
)qw&%sO + MaskBits&=~SHIFTBIT;
CY5Z{qiX break;
EI%89i`3^ default: //judge the key and send message
A}9`S6 @@ break;
)*J^K?!S }
0v?"tOT! for(int index=0;index<MAX_KEY;index++){
%J?xRv! if(hCallWnd[index]==NULL)
Ffz,J6b continue;
JX;G<lev if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
FDs>m
#e {
aeJHMHFc SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
YK'<NE3 4 bProcessed=TRUE;
g]H<}4lgq" }
rq].UCj }
BX7kO0j }
D/&o&G96 else if((lParam&0xc000ffff)==1){ //有键按下
T.BW H2gRP switch(wParam)
A?P_DA {
6%_nZvRv case VK_MENU:
IOmfF[ MaskBits|=ALTBIT;
.t!x<B break;
]w8(&,PP case VK_CONTROL:
KkbD W3- MaskBits|=CTRLBIT;
R__OP`! break;
\ Gvm9M case VK_SHIFT:
&j"?\f? MaskBits|=SHIFTBIT;
yR{3!{r3( break;
f.$af4
u default: //judge the key and send message
C_JNX9wv break;
^hM4j{|&M }
*.t7G for(int index=0;index<MAX_KEY;index++){
.W!i7 if(hCallWnd[index]==NULL)
(hbyEQhF continue;
fIU#M]Xx if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
}S-O&Z {
VU3upy< SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
`Ggbi4), bProcessed=TRUE;
JK5gQ3C[ }
8(~h"]`! }
2fd{hJDq;5 }
H<,gU`&R if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
bq*eH (qx for(int index=0;index<MAX_KEY;index++){
\_f(M| if(hCallWnd[index]==NULL)
n{mfn*r. continue;
U'bEL^Jf if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
?Z/V~, SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
b3,
_(;A! //lParam的意义可看MSDN中WM_KEYDOWN部分
H*CW1([ }
/y}xX }
9rf)gU3{+L }
8<Av@9 *} return CallNextHookEx( hHook, nCode, wParam, lParam );
)Ql%r?(F+ }
Vt#.eL)Ee e(t\g^X 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:
@:#eb1<S p<"m[Dt] BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
/a4{?? #e BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
XW]tnrs (O3nL. 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:
-uf|w? [7Oe3= LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
UP,c | {
83#mB:^R if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
}o`76rDN {
(f"4,b^] //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
yY q,*<G SaveBmp();
[{,1=AB return FALSE;
`[i r}+S }
C LRdm^B …… //其它处理及默认处理
MQ8J<A Pf- }
wnC81$1l~ $xN|5;+ fNFY$:4X 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*b|ilvc C~/a- 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。
J)-x!y> }BP;1y6-r 二、编程步骤
KbeC"mi Qvhl4-XjZa 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";
H/M@t\$Dc cbTm'}R(G 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
Pd Wx|y{% /j.9$H'y 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
>4CbwwMA Q\Vgl(;lX 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
gg2(5FPP w\O;!1iU 5、 添加代码,编译运行程序。
4o[{>gW sfl<qD+? 三、程序代码
= dN@Sa/ N;`n@9BF ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
Z7Hbj!d/Sz #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
=T7.~W #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
0o&5]lEe #if _MSC_VER > 1000
]D\D~!R #pragma once
VI*$em O0 #endif // _MSC_VER > 1000
>XfbP] #ifndef __AFXWIN_H__
}O
p;
g^W #error include 'stdafx.h' before including this file for PCH
u>vL/nI #endif
X^j fuA #include "resource.h" // main symbols
Xsa]. class CHookApp : public CWinApp
3!_XEN[ {
3=oDQ&UFt public:
dSHDWu& CHookApp();
jnwu9PQ // Overrides
TB31-
() // ClassWizard generated virtual function overrides
^U/O!GK //{{AFX_VIRTUAL(CHookApp)
u=e{]Ax#} public:
N8df8=.kw virtual BOOL InitInstance();
"3J}b?u_[ virtual int ExitInstance();
_|`S3}q|d //}}AFX_VIRTUAL
;!Fn1|) //{{AFX_MSG(CHookApp)
r5^eNg k // NOTE - the ClassWizard will add and remove member functions here.
k+*u/neh // DO NOT EDIT what you see in these blocks of generated code !
x]j W<A //}}AFX_MSG
UJ2U1H54h DECLARE_MESSAGE_MAP()
xskz)kk };
2&cT~ZX&' LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
.T`%tJ-Em BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
<1TAw. BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
<F'\lA9 BOOL InitHotkey();
J<lW<:!3] BOOL UnInit();
g<qaXv #endif
uPvEwq*
C <C*hokqqP //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
{{!-Gr #include "stdafx.h"
~"A0Rs= #include "hook.h"
r9XZ(0/p #include <windowsx.h>
s5.CFA #ifdef _DEBUG
1xvu<|F #define new DEBUG_NEW
r.U`Kh]K #undef THIS_FILE
Q,Eo mt static char THIS_FILE[] = __FILE__;
|w3M7;~eF #endif
gRzxLf`K #define MAX_KEY 100
VIbq:U #define CTRLBIT 0x04
E{vbO/|kf #define ALTBIT 0x02
#\ErY3k 6& #define SHIFTBIT 0x01
lU]nd[x #pragma data_seg("shareddata")
7t3!)a|lI HHOOK hHook =NULL;
+ZX{>:vo UINT nHookCount =0;
# f\rt
static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
8 zb/xP> static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
n=q76W\ static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
7xR\kL., static int KeyCount =0;
G#$-1"!` static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
_yT Ed"$
#pragma data_seg()
!<F3d`a HINSTANCE hins;
fV~[;e;U. void VerifyWindow();
J[kTlHMD BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
Dt1jW //{{AFX_MSG_MAP(CHookApp)
4I[P> // NOTE - the ClassWizard will add and remove mapping macros here.
B<C&xDRZ0 // DO NOT EDIT what you see in these blocks of generated code!
2`-Bs //}}AFX_MSG_MAP
VxBo1\' END_MESSAGE_MAP()
2Khv>#l
6S{l'!s' CHookApp::CHookApp()
Fk;Rfqq {
ugBCBr // TODO: add construction code here,
%
AgUUn&k // Place all significant initialization in InitInstance
'N(R_q6MW }
{4PwLCy GA.8@3 CHookApp theApp;
z(~_AN M4, LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
D6Wa.,r {
2&5K.Ui% BOOL bProcessed=FALSE;
H,NF;QPPC if(HC_ACTION==nCode)
rT>wg1: {
Alq(QDs if((lParam&0xc0000000)==0xc0000000){// Key up
@}ZVtrz switch(wParam)
L RF103nw {
"Y.y:Vv; case VK_MENU:
OZ&o:/*HM MaskBits&=~ALTBIT;
(tO\)aS= break;
H"F29Pu2 case VK_CONTROL:
(-co. MaskBits&=~CTRLBIT;
#LNED)Vg break;
_VXN#@y case VK_SHIFT:
"gwSJ~:ds MaskBits&=~SHIFTBIT;
*K;~!P break;
-n;}n:wL default: //judge the key and send message
WY]s |2a break;
d"Y{UE }
S8gs-gL#Og for(int index=0;index<MAX_KEY;index++){
d d;T-wa} if(hCallWnd[index]==NULL)
Xnh8e continue;
##ANrG l if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
i@'dH3-kO
{
S]{oPc[7 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
K>
e7pu bProcessed=TRUE;
>R=|Wo`Ri }
FiU#T.`9' }
fXB0j;A }
Z6m)tZVM else if((lParam&0xc000ffff)==1){ //Key down
?@8[e9lLD switch(wParam)
:v 4]D4\o {
IRbfNq^: case VK_MENU:
WF"k[2 MaskBits|=ALTBIT;
DV{=n C break;
?X;RLpEc|A case VK_CONTROL:
hv+zGID7 MaskBits|=CTRLBIT;
;wD)hNLAvR break;
%XTI-B/K case VK_SHIFT:
2T`!v MaskBits|=SHIFTBIT;
=R\]=cRbg break;
Y\tui+?J default: //judge the key and send message
BerwI
7!= break;
K|@G t%Y }
2Rz for(int index=0;index<MAX_KEY;index++)
QS j]ZA {
L%5%T;0'~ if(hCallWnd[index]==NULL)
%>s|j'{ continue;
p4)Q&k! if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
wNX]7wMX {
?%kV?eu' SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
8XbT`y bProcessed=TRUE;
mVmGg, }
I2DpRMy }
!o-@&q }
YbLW/E\T if(!bProcessed){
|nF 8gh~} for(int index=0;index<MAX_KEY;index++){
L=h'Qgk% if(hCallWnd[index]==NULL)
,[;G|et continue;
<\FH fE if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
:H[6Lg\* SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
G/ 5%.Bf@ }
0(btA~'* }
SY8C4vb'h }
U<-D(J return CallNextHookEx( hHook, nCode, wParam, lParam );
CH/rp4NeSy }
^W@5TkkBQq "h ^Z BOOL InitHotkey()
)CyS#j#= {
2BobH_H if(hHook!=NULL){
J-4:H
gx nHookCount++;
MY/}-*| return TRUE;
LIdF 0 }
::F|8 else
Np)lIGE hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
:i7;w%B if(hHook!=NULL)
=qIyqbXz nHookCount++;
)_NO4`ejs/ return (hHook!=NULL);
cS+>J@L }
Vq2$'lY BOOL UnInit()
P
}uOJVQ_ {
-%dCw6aX+ if(nHookCount>1){
u2[w# nHookCount--;
A(0lM`X return TRUE;
{y;n:^ }
4`R(? BOOL unhooked = UnhookWindowsHookEx(hHook);
_tXlF; if(unhooked==TRUE){
%%wNZ{ nHookCount=0;
M@ZI\ hHook=NULL;
9g?(BI^z }
]s748+ return unhooked;
]9,;K;1< }
FGQzoS v9UD%@tZ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
:j`sr {
~v"L!=~G;a BOOL bAdded=FALSE;
1i] ^{;] for(int index=0;index<MAX_KEY;index++){
FCn_^l)EA if(hCallWnd[index]==0){
Tb-F]lg$ hCallWnd[index]=hWnd;
-`t^7pr HotKey[index]=cKey;
wvPk:1wD5 HotKeyMask[index]=cMask;
i 3SHg\~Z bAdded=TRUE;
;S*}WqP, KeyCount++;
m#F`] { break;
&t-kpA|EG }
---N9I }
f
V( J| return bAdded;
cs'{5!i] }
4'Zp-k?5` OUXR BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
rXU\ {
DFTyMB1H BOOL bRemoved=FALSE;
\^%}M!tan for(int index=0;index<MAX_KEY;index++){
<