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:
w@:o:yLS
-x_iqrB 一、实现方法
>8AtT=}w 8dZH&G@; 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:
.`h+fqa O3BU.X1'% #pragma data_seg("shareddata")
to?"{ HHOOK hHook =NULL; //钩子句柄
hXrvb[6 UINT nHookCount =0; //挂接的程序数目
pP/o2 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
}bnkTC static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
Xr)d;@yi static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
pH~JPNng static int KeyCount =0;
gRqz8UI static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
{W4t]Ff #pragma data_seg()
{(MG:
B |y=gp 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。
cEQa 6 [c W 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:
{
o;0Fx ih;TQ!c+b BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
x)U; cKey,UCHAR cMask)
(CV=0{] {
R;.WOies4 BOOL bAdded=FALSE;
-"nYCF for(int index=0;index<MAX_KEY;index++){
G7=8*@q>: if(hCallWnd[index]==0){
a #0{tZd hCallWnd[index]=hWnd;
7r;A
wa HotKey[index]=cKey;
'{u#:TTj HotKeyMask[index]=cMask;
kg@J. bAdded=TRUE;
O71rLk; KeyCount++;
}N|/b"j9 break;
e.kt]l }
{r}}X@|5 }
v}mmY>M% return bAdded;
c]&VUWQ }
W2B=%`sC //删除热键
pxC5a i BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
f
0#V^[%Q {
^R$dG[Qf BOOL bRemoved=FALSE;
DtN6.9H2` for(int index=0;index<MAX_KEY;index++){
h
,n!x:zy@ if(hCallWnd[index]==hWnd){
zF$wz1
% if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
Cwh;+3?C| hCallWnd[index]=NULL;
[*<&]^ HotKey[index]=0;
VA%i_P, HotKeyMask[index]=0;
0q;] ;m bRemoved=TRUE;
7U7 i2 4 KeyCount--;
"O
'I break;
;C<A} }
n)H0;25L }
)K6{_~Kc\ }
'[E_7$d return bRemoved;
xr2:bu }
}<S2W\,G #lC{R^SL x M[#Ah) DLL中的钩子函数如下:
\*
#4 .KSGma6] LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
?!66yn {
`qgJE_GC BOOL bProcessed=FALSE;
,'6GG+ if(HC_ACTION==nCode)
<>oW f {
iau&k`b` if((lParam&0xc0000000)==0xc0000000){// 有键松开
R}Y=!qjYE= switch(wParam)
:F\f}G3 {
E;Hjw0M'k case VK_MENU:
{cI<4>< MaskBits&=~ALTBIT;
J)->
7h= break;
A~>=l= case VK_CONTROL:
y_&XF>k91 MaskBits&=~CTRLBIT;
X9j+$X\j break;
=R"tnjR case VK_SHIFT:
$gTPW,~s[ MaskBits&=~SHIFTBIT;
5S?yj break;
m t^1[ default: //judge the key and send message
QMY4%uyY! break;
1hWz%c| }
4{g|$@s( for(int index=0;index<MAX_KEY;index++){
iE`aGoA if(hCallWnd[index]==NULL)
l :"*]m7o_ continue;
7KIQ)E'kG| if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
:[39g;V}c {
c53`E U SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
"U.=A7r bProcessed=TRUE;
:JIPF=]fc }
*ZGN!0/ }
0}V'\=F454 }
y<b0z\ else if((lParam&0xc000ffff)==1){ //有键按下
Y5CE#& switch(wParam)
'1
$ ({{R {
]l'ki8 case VK_MENU:
{@%(0d{n} MaskBits|=ALTBIT;
>cb
gL% break;
WXU6J?tIm case VK_CONTROL:
6f!mk:\T. MaskBits|=CTRLBIT;
"tARJW break;
^'4uTbxP_! case VK_SHIFT:
m~eWQ_a]C@ MaskBits|=SHIFTBIT;
h6N}sLM{0 break;
"-?Y UY` default: //judge the key and send message
z-G (!]: break;
lz 6 Aj }
r|@?v , for(int index=0;index<MAX_KEY;index++){
m5X=P5U if(hCallWnd[index]==NULL)
Se8y-AL6x> continue;
`.g8JC\_m if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
K;y\&'E {
?g4|EV-56 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
>JOvg*a?" bProcessed=TRUE;
uyj*v]AE' }
}0RFo96)v }
rg}kxvu }
a6E" if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
qS|VUy4 for(int index=0;index<MAX_KEY;index++){
gj^]}6-P if(hCallWnd[index]==NULL)
NN'<-0~ continue;
auW]rwY if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
O$/swwB! SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
I+t38un% //lParam的意义可看MSDN中WM_KEYDOWN部分
T}[vfIJD }
C>dJ:.K%H }
E5{)d~q }
Dt.Wb&V_w return CallNextHookEx( hHook, nCode, wParam, lParam );
/nFw }
X)OP316yx Qu _T& 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:
hp4(f W %Qz`SO8x? BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
;%alZ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
v6\2mc. 3+5\xRq 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:
i%8&g2 J*X.0&Toc LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
J9.p8A^^2 {
E(_I3mftm if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
nk
9 K\I
{
re J?38( //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
0 _}89:- SaveBmp();
x{V>(d'p return FALSE;
|7x^@i9w }
[frD
L) …… //其它处理及默认处理
R} 9jgB }
2z# @:Q EsB'nf r 2(//slP 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。
$yFuaqG`Wo KocXSh U 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
{WOfT6y+ G5J ZB7C 二、编程步骤
%esZ}U (1j$*?iGA 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";
<9tG_ \<x_96jt!\ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
#@s~V<rW <" l;l~Y1 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;
, %O3^7i `f+g A 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;
E*CQG;^=N !BuJC$ 5、 添加代码,编译运行程序。
TcmZ0L^O Bl\kU8O- 三、程序代码
Atq2pL" L)Ar{*xC ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
}QW~.>` #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
0a6z"K} #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
G$9|aaf`1# #if _MSC_VER > 1000
Z*)Y:tk)b #pragma once
B2qq C-hw? #endif // _MSC_VER > 1000
.r%|RWs6W #ifndef __AFXWIN_H__
S&]<;N_B #error include 'stdafx.h' before including this file for PCH
'/gwC7*-& #endif
hcc-J)=m #include "resource.h" // main symbols
N/{Yi
_n class CHookApp : public CWinApp
dS_)ll.6z {
{59VS
Nl public:
Mv`L F CHookApp();
L9?/ -@M // Overrides
2X c // ClassWizard generated virtual function overrides
E(kb!Rz //{{AFX_VIRTUAL(CHookApp)
p<fgUVR public:
7"NJraQ6 virtual BOOL InitInstance();
)K%O/H virtual int ExitInstance();
Fd,+(i D //}}AFX_VIRTUAL
`Mp7}) //{{AFX_MSG(CHookApp)
Bp{`%86SE // NOTE - the ClassWizard will add and remove member functions here.
7+hF; // DO NOT EDIT what you see in these blocks of generated code !
~w9=Fd6 //}}AFX_MSG
MGKeD+=5 DECLARE_MESSAGE_MAP()
2$W,R/CLh };
8Pr7aT:, LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
#L=
eK8^e BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
[d~bZS|(T( BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
(Cd{#j< BOOL InitHotkey();
z "$d5XR BOOL UnInit();
!Fg4Au #endif
EQOP?>mWx! v:Z4z6M- //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
N?{1'=Om #include "stdafx.h"
pW--^aHu #include "hook.h"
+y4AUU:Q #include <windowsx.h>
^pV>b(?qw #ifdef _DEBUG
.C;_4jE #define new DEBUG_NEW
n,:.]3v% #undef THIS_FILE
_AB9BQm static char THIS_FILE[] = __FILE__;
?&<o_/`-H5 #endif
c[RLYu #define MAX_KEY 100
a(DZGQ-as
#define CTRLBIT 0x04
Y{2d4VoW6 #define ALTBIT 0x02
XL/o y'_ #define SHIFTBIT 0x01
=>ztB w\ #pragma data_seg("shareddata")
<CKmMZ{ HHOOK hHook =NULL;
OC>_=i$' UINT nHookCount =0;
Ar7mH4M static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
Z t+FRR= static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
|}p}`Mb)a static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
~& WN)r'4y static int KeyCount =0;
eGSp(o5 6 static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
sqpOS!] #pragma data_seg()
hB}h-i(u HINSTANCE hins;
R~5*#r@f void VerifyWindow();
]F*a PV BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
CndgfOF //{{AFX_MSG_MAP(CHookApp)
27 145
// NOTE - the ClassWizard will add and remove mapping macros here.
;!JX-J q // DO NOT EDIT what you see in these blocks of generated code!
fw|+7 O //}}AFX_MSG_MAP
oBNX8%5w END_MESSAGE_MAP()
T'b/]&0Tio 11y.z^ CHookApp::CHookApp()
=6:L +V {
T<e7(= // TODO: add construction code here,
d:<H?~ // Place all significant initialization in InitInstance
MjXE|3& }
hN_f h J Am4^v?q CHookApp theApp;
W6Aj<{\F LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
6;[/9 {
1S(\2{Ylo BOOL bProcessed=FALSE;
[&pW&>p3 if(HC_ACTION==nCode)
X:``{!~geo {
u|OzW}xb7j if((lParam&0xc0000000)==0xc0000000){// Key up
G>w?9:V} switch(wParam)
D_n}p8blT {
0+<eRR9- case VK_MENU:
4o4 = MaskBits&=~ALTBIT;
4`U0">gY break;
24jtJC,7 case VK_CONTROL:
o!toO&= MaskBits&=~CTRLBIT;
^>X)"'0+ break;
c@ZS|U*( case VK_SHIFT:
w*u{;v# MaskBits&=~SHIFTBIT;
8 ih;#I=q break;
]C
~1]7vb default: //judge the key and send message
bH\C5zt6( break;
mYh5#E41J }
%`?;V;{= for(int index=0;index<MAX_KEY;index++){
?)'
2l6 if(hCallWnd[index]==NULL)
9XoQO 9*Q continue;
^K.u
~p if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
phgexAq {
6vgBqn[ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
5`E`Kb+@ bProcessed=TRUE;
'{0[&i* }
EY)Gi`lK }
a%T -Z.rd }
gM3]%L_ else if((lParam&0xc000ffff)==1){ //Key down
/$9BPjO{ switch(wParam)
%/y`<lJz( {
Z6^QB@moj case VK_MENU:
@1qdd~B} MaskBits|=ALTBIT;
9:%n=U Rd break;
`D)Lzm R case VK_CONTROL:
AUxM)H MaskBits|=CTRLBIT;
(/SGT$#8 break;
jWXR__>. case VK_SHIFT:
%0yS98']g MaskBits|=SHIFTBIT;
k6O.H break;
%-#
qO default: //judge the key and send message
SY'2A) break;
x*h?%egB!p }
[Y$5zeA for(int index=0;index<MAX_KEY;index++)
3duG.iUlL {
zUs~V`0 if(hCallWnd[index]==NULL)
l@N;sI<O- continue;
OQ(D5GR:4 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
o#xgrMB {
LZM,QQ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
\T`["< bProcessed=TRUE;
.73zik }
aUW/1nQHa }
kG)2% }
wqlcLIJPR if(!bProcessed){
IX<r5!
for(int index=0;index<MAX_KEY;index++){
L6:W'u^ if(hCallWnd[index]==NULL)
#M5_em4kN continue;
i s L{9^ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
{[2tG U9 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
}pMP!%| }
"F-Y^ }
E
&7@#'l }
c[VrC+e m return CallNextHookEx( hHook, nCode, wParam, lParam );
?&znUoB }
,Z>wbMJig e=t<H"& BOOL InitHotkey()
P_p6GT:5 {
Ys-Keyg if(hHook!=NULL){
?fK^&6pI nHookCount++;
FXx.$W return TRUE;
q*6q}s3n }
JbE?a[Eg? else
E-~mOYea hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
iOT)0@f' if(hHook!=NULL)
[J0*+C9P* nHookCount++;
^
<qrM return (hHook!=NULL);
CQdBf3q }
E'5Ajtw; BOOL UnInit()
UvkJ?Bu {
1GtOA3,~;- if(nHookCount>1){
07x=`7hs} nHookCount--;
j$@?62)6 return TRUE;
[@m[V1D }
F`!TV(,bY BOOL unhooked = UnhookWindowsHookEx(hHook);
c[SU5 66y if(unhooked==TRUE){
zwK
}7h6] nHookCount=0;
[tUv*jw % hHook=NULL;
AG]WO8f) }
e:N7BZl'c9 return unhooked;
g b -Bxf }
ngP7'1I 2~f6~\4GL+ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
a{h%DpG {
Zj qA30! BOOL bAdded=FALSE;
NuU'0_")/ for(int index=0;index<MAX_KEY;index++){
W_^>MLq if(hCallWnd[index]==0){
]}Pl%. hCallWnd[index]=hWnd;
[ S5bj]D HotKey[index]=cKey;
`f@{Vcr%i HotKeyMask[index]=cMask;
%drJ p6n% bAdded=TRUE;
3&es]1b KeyCount++;
}wG,BB %N break;
wGPotPdE2 }
EMLx?JnP }
osl=[pm return bAdded;
\}Dpb%^\ }
D%-{q>F!gf JwZ?hc BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
TfJL+a0 {
kLJlS,nh\r BOOL bRemoved=FALSE;
wG+=}1X for(int index=0;index<MAX_KEY;index++){
o]A XT8 if(hCallWnd[index]==hWnd){
;Xqn-R if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
d7* CwY9" hCallWnd[index]=NULL;
XdpF&B&K7Q HotKey[index]=0;
[4p=X=B HotKeyMask[index]=0;
(Akd8}nf~ bRemoved=TRUE;
`)6>nPr7P KeyCount--;
?cJY
B) break;
~z5@V5z }
F)
?o, }
\/!ZA[D|E\ }
<P1rqM9^ return bRemoved;
<"?*zx&