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:
o9D#d\G
OlW5k`B 一、实现方法
5?#AS#TD' .Pe^u%J6F 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:
,mp^t2 U z)G Y #pragma data_seg("shareddata")
0rDQJCm HHOOK hHook =NULL; //钩子句柄
FGMYpapc~ UINT nHookCount =0; //挂接的程序数目
#s=\ static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
wXeJjE%j:3 static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
=6'D/| 3 static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
Hg]iZ,8? static int KeyCount =0;
%E":Wv static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
wuqB['3 #pragma data_seg()
dm83YCdL jA3Ir;a 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。
<UwA5X`0e. *q1sM#;5 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:
KH$o X\v >va9*pdJ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
OYfP!,+bn cKey,UCHAR cMask)
ui*CA^ Y {
"y .(E7 6 BOOL bAdded=FALSE;
#=fd8}9 for(int index=0;index<MAX_KEY;index++){
/h!iLun7I if(hCallWnd[index]==0){
v Dph}Z hCallWnd[index]=hWnd;
bsWDjV~ HotKey[index]=cKey;
G;msq=9| HotKeyMask[index]=cMask;
!E/%Hv1 bAdded=TRUE;
=-uk7uZM KeyCount++;
7:)$oH break;
#0M,g }
XR)I,@i`' }
&2Cu"O'.i return bAdded;
JR/^Go$^ }
SI l<\ //删除热键
q'[yYPDX5x BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
K@=_&A! {
-QydUr/(o BOOL bRemoved=FALSE;
\xtmd[7lb< for(int index=0;index<MAX_KEY;index++){
j98>Jr\ if(hCallWnd[index]==hWnd){
u $T'#p1
if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
<Y#EiC. hCallWnd[index]=NULL;
/I#SP/M&l HotKey[index]=0;
%$(*.o!+8 HotKeyMask[index]=0;
z:tu_5w!, bRemoved=TRUE;
j0K}nS\ P KeyCount--;
;Q8rAsf9 break;
P-lE,X
}
$66 DyK? }
I^y,@EHR }
GmLKg >% return bRemoved;
WXE{uGc }
DvXbbhp (AgM7H0 x42m+5/ DLL中的钩子函数如下:
DU[vLe|Z !bD`2m[Q LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
^,Y#_$oR {
@GR|co BOOL bProcessed=FALSE;
$zV[-d if(HC_ACTION==nCode)
&AlX). {
a@WSIcX*W if((lParam&0xc0000000)==0xc0000000){// 有键松开
0~N2MoOl^ switch(wParam)
`_&7-;)i*\ {
O!\\m0\e case VK_MENU:
V,Br|r$l( MaskBits&=~ALTBIT;
4qEeN-6h break;
JS1''^G&. case VK_CONTROL:
[VwoZX: MaskBits&=~CTRLBIT;
,a,coeL break;
fqU*y 6] case VK_SHIFT:
i(XqoR-x MaskBits&=~SHIFTBIT;
\XlT break;
}Pe0zx.Ge default: //judge the key and send message
wp8ocZ-Gj break;
hGvuA9d~ }
}M9L,O*^ for(int index=0;index<MAX_KEY;index++){
:<Y, f(c if(hCallWnd[index]==NULL)
w873: = continue;
9y"*H2$# if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
+3n07d {
"8Y4;lbN.q SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
ZMXIKN9BF# bProcessed=TRUE;
JB= L\E} }
u=h/l!lR }
p1L8g[\ }
Gvw:h9v else if((lParam&0xc000ffff)==1){ //有键按下
{wx!~K switch(wParam)
Y/_b~Ahn {
`!\`yI$!%w case VK_MENU:
BI-xo}KI MaskBits|=ALTBIT;
MRdZ ' break;
'Nv*ePz case VK_CONTROL:
J@c)SK%2h MaskBits|=CTRLBIT;
k:0HsN!F9 break;
\{[Gdj` case VK_SHIFT:
<M|kOi MaskBits|=SHIFTBIT;
ca1A9fvo break;
AA$-Lx(UJk default: //judge the key and send message
RE(R5n28, break;
u%vq<|~- }
PN n{Rt for(int index=0;index<MAX_KEY;index++){
BK8)'9/ if(hCallWnd[index]==NULL)
e " f/ continue;
^H1B62_ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
8D U|j-I8 {
Zg/ra1n SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
'J&$L c bProcessed=TRUE;
g2v0! }
?_9A`LC*
}
iIoeG_^*Y }
4c*?9r@ if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
wQX,a;Br for(int index=0;index<MAX_KEY;index++){
-*u7MFq_ if(hCallWnd[index]==NULL)
/=}w%-;/; continue;
L}1|R*b if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
>>voL DDd SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
/8i3 I5* //lParam的意义可看MSDN中WM_KEYDOWN部分
gZe(aGh }
9a5x~Z:' }
tTB,eR$ }
x_vaYUl) return CallNextHookEx( hHook, nCode, wParam, lParam );
Z!P7mH\c} }
ljTnxg/?
W _Jc[`2Uv_c 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:
rn7eY {]/}3t BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
%(,Kj
~0 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
XP"lqyAi 7Rf${Wv0 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#_(suo64 I]|X6 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
P"LbWZ6Nj {
6;g"`l51 if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
%(IkUD {
9"3 7va //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
:O}= $[ SaveBmp();
Ccld;c&+ return FALSE;
T\VKNEBo }
b Z0mK$B …… //其它处理及默认处理
p^~AbU'6~ }
@-9I<)Z/2 "|yuP1;L Qx-/t 9`!Z 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。
3: 'eZcM oz(V 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。
*E0dCY$ /*)zQ?N 二、编程步骤
E({W`b~_f <
`r+ZyM 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";
=ILE/pC-| I'Dc9&2 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
fD<9k B zmmE2~* 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;
A{Jp>15AVg diF-`~ 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;
p0jQQg roDE?7x1 5、 添加代码,编译运行程序。
0drt,k AM4lAq_ 三、程序代码
_yi`relcq- h\#\hx ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
u]K&H&AxT #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
4NaL#3 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
E-Nc|A #if _MSC_VER > 1000
Cku#[?G #pragma once
tA2Py #endif // _MSC_VER > 1000
'O%itCy) #ifndef __AFXWIN_H__
&DQyJJ`k #error include 'stdafx.h' before including this file for PCH
[ZC{eg+D #endif
v803@9@ #include "resource.h" // main symbols
=]k0*\PS class CHookApp : public CWinApp
),ur!v {
cn62:p]5 public:
m5c?A+@fZ CHookApp();
3mI(5~4A]? // Overrides
tI42]:z // ClassWizard generated virtual function overrides
5G!0Yy[' //{{AFX_VIRTUAL(CHookApp)
>/@wht4- j public:
TYv'#{ virtual BOOL InitInstance();
J?]wA1 virtual int ExitInstance();
k1l\Rywp //}}AFX_VIRTUAL
kjVUG >e> //{{AFX_MSG(CHookApp)
TI^W=5W@@ // NOTE - the ClassWizard will add and remove member functions here.
}^!8I7J. // DO NOT EDIT what you see in these blocks of generated code !
HjCWsQM //}}AFX_MSG
PE $sF]/ DECLARE_MESSAGE_MAP()
i2]7Bf)oV };
5G$N LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
(X=JT BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
P%VEJ5,]b BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
6V{Sf9V| BOOL InitHotkey();
wKxw|Fpn BOOL UnInit();
LH7m >/LJr #endif
F|+Qi BO .
V5Pr}"y //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
<'n'>@ #include "stdafx.h"
)ry7a
.39b #include "hook.h"
+ZFw3KEkz #include <windowsx.h>
#m
x4pf{ #ifdef _DEBUG
}q<p;4<\F #define new DEBUG_NEW
0 &M~lJ #undef THIS_FILE
`fTH"l1zn static char THIS_FILE[] = __FILE__;
eh\_;2P #endif
S#h-X(4 #define MAX_KEY 100
{zd07!9y #define CTRLBIT 0x04
52X[{ #define ALTBIT 0x02
BK$cN>J #define SHIFTBIT 0x01
o#GZ|9IL #pragma data_seg("shareddata")
Qt-7jmZw1 HHOOK hHook =NULL;
f4%Z~3P UINT nHookCount =0;
Z^tTR]u\$ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
>A5*=@7bY? static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
0R2KI,WI static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
|/^ KFY" static int KeyCount =0;
S2y_5XJ<D static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
tx` Z?K[ #pragma data_seg()
V{jQ=<)@e HINSTANCE hins;
JRti2Mu void VerifyWindow();
bsuGZ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
z):LF< //{{AFX_MSG_MAP(CHookApp)
e}f#dR+( // NOTE - the ClassWizard will add and remove mapping macros here.
dC'8orFG+ // DO NOT EDIT what you see in these blocks of generated code!
`O+}$wP //}}AFX_MSG_MAP
=Msr+P9Ai END_MESSAGE_MAP()
6zbqv 6 h^QLvOuR CHookApp::CHookApp()
]rNM3@bVy {
!uZ)0R // TODO: add construction code here,
>X@4wP7l // Place all significant initialization in InitInstance
"SMRvi57T }
+ d?p? v DT;n)7+, CHookApp theApp;
;H' ,PjU LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
CvOji1 {
'6g;UOx^= BOOL bProcessed=FALSE;
(YV]T!q if(HC_ACTION==nCode)
qjr:(x / {
scc+r if((lParam&0xc0000000)==0xc0000000){// Key up
84f(B E switch(wParam)
X%C`('"R {
7sX#6`t case VK_MENU:
B4
k5IS MaskBits&=~ALTBIT;
*A&A V||q break;
PF+ F^;C case VK_CONTROL:
@23?II$=@ MaskBits&=~CTRLBIT;
I K9plsd* break;
,=a+;D]' case VK_SHIFT:
]F{F+r MaskBits&=~SHIFTBIT;
$)YalZ break;
"xI70c{ default: //judge the key and send message
'048Qykt; break;
t6q7w }
tZXq<k9 for(int index=0;index<MAX_KEY;index++){
(Sv=R(_s if(hCallWnd[index]==NULL)
\sn
wR continue;
O#_\@f#[ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
:Bh7mF-1 {
QBYY1)6S, SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
/KTWBcs 7 bProcessed=TRUE;
d[F3"b% }
E8/Pi>QW }
BT^Im=A }
sB@9L L]&| else if((lParam&0xc000ffff)==1){ //Key down
Nf5zQ@o_y switch(wParam)
~0@uR {
$x/VO\Z{- case VK_MENU:
-<6b[YA MaskBits|=ALTBIT;
m@i](1*T| break;
FfRvi8 case VK_CONTROL:
Od("tLIO}I MaskBits|=CTRLBIT;
Dz3~cuVb break;
@?n~v^ case VK_SHIFT:
r1&eA% eh MaskBits|=SHIFTBIT;
iBPIj;, break;
H2S/!Q;K default: //judge the key and send message
$jg~a break;
]>/oo =E }
H73 r3BH for(int index=0;index<MAX_KEY;index++)
Pk3b#$+E {
gJH^f3 if(hCallWnd[index]==NULL)
79z/(T+ continue;
@ N@
!Q if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
yHo#v:>?p {
Eo`'6
3 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Bh UGMK bProcessed=TRUE;
5yL\@7u` }
g [u*`]-;v }
03n+kh }
{^.q6,l if(!bProcessed){
>:bXw#w] for(int index=0;index<MAX_KEY;index++){
TV Zf@U if(hCallWnd[index]==NULL)
?!.L#]23f continue;
% !>@m6JK if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
s7(1|}jh SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
:sS4T&@1= }
E{'Y>gB6 }
a"{b}UP }
OI,F,4e return CallNextHookEx( hHook, nCode, wParam, lParam );
ok1w4#%, }
_G$21=
0}`0!Kv BOOL InitHotkey()
WR9-HPF {
_oHxpeM if(hHook!=NULL){
P\y ZcL nHookCount++;
0Of6$` return TRUE;
V)fF|E~0 }
GP(nb, else
12V-EG i hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
#~o<9O if(hHook!=NULL)
~#dfZa& nHookCount++;
*EPJeblAV return (hHook!=NULL);
6o1[fr }
9T\\hM)k BOOL UnInit()
!S'!oinV {
J'%W_?wZ if(nHookCount>1){
cK,&huk nHookCount--;
t>2EZ{N+y return TRUE;
*^iSP(dg }
Xb~i?T;f BOOL unhooked = UnhookWindowsHookEx(hHook);
Elt"tJ if(unhooked==TRUE){
9+b){W nHookCount=0;
tmQ,> hHook=NULL;
#bS}?fj }
!y862oKD return unhooked;
t9.| i H }
(+nnX7V?I vW0U~(XlN BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
ck$> {
q>6RO2, BOOL bAdded=FALSE;
GF36G?iEi for(int index=0;index<MAX_KEY;index++){
5,BvT>zFY if(hCallWnd[index]==0){
KP`Pzx hCallWnd[index]=hWnd;
WQ9VcCY HotKey[index]=cKey;
Ri3*au/Q HotKeyMask[index]=cMask;
5S ) N&% bAdded=TRUE;
zCS&