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:
{dF_=`.
CqkY_z 一、实现方法
@7j$$ z 7
s&7)a 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:
N" =$S|Gs XJI
ff$K #pragma data_seg("shareddata")
h:3^FV HHOOK hHook =NULL; //钩子句柄
:)eU)r"s4 UINT nHookCount =0; //挂接的程序数目
B65"jy static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
~(~
y=M static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
WPpS? static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
_ \LPP_ static int KeyCount =0;
t 8,VR FV static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
4/J"}S #pragma data_seg()
FIEA'kUy OKO+(>AQ 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。
|K,[[D<R .s8u?1b 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]ic(74c? &s>E~M0+J BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
?Tr\r1s] cKey,UCHAR cMask)
}VDJ {
5xIOi(3`Q BOOL bAdded=FALSE;
'Xb?vOU for(int index=0;index<MAX_KEY;index++){
N}rc3d# if(hCallWnd[index]==0){
XKQ\Ts2<k hCallWnd[index]=hWnd;
P'<D0 HotKey[index]=cKey;
31)eDs HotKeyMask[index]=cMask;
_>=QZ`!r bAdded=TRUE;
'U/X<LCl KeyCount++;
'irHpN6n break;
>= VCKN2'j }
nSR<( -j! }
1 LUvs~Qu return bAdded;
@5:#J! }
}*>xSb1 //删除热键
3Q\k!$zq BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
*Al`QEW {
l/6$BPU` BOOL bRemoved=FALSE;
t[=teB v< for(int index=0;index<MAX_KEY;index++){
ul!e!^qwx if(hCallWnd[index]==hWnd){
FNy-&{P2 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
S #6:! hCallWnd[index]=NULL;
iQ#dWxw4 HotKey[index]=0;
$s,Az_bs HotKeyMask[index]=0;
<[Y@< bRemoved=TRUE;
9>7w1G# KeyCount--;
<C{uodFll break;
dR@XwEpP }
bb}$7v`G }
7:$zSj#y }
&++tp5 return bRemoved;
FL?Ndy"I }
h4geoC_W2 G+V?c1Me \yKYBfp-p DLL中的钩子函数如下:
?j|i|WUD + )lkHv$R LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
DNmP> ~ {
(*Fb/ BOOL bProcessed=FALSE;
2'T uS? if(HC_ACTION==nCode)
MNWuw;:v {
=Yt)b/0b9 if((lParam&0xc0000000)==0xc0000000){// 有键松开
xI(t!aYp switch(wParam)
>yr1wVS {
<
s1 case VK_MENU:
k+;XQEH MaskBits&=~ALTBIT;
P&.-c _ break;
U{?#W case VK_CONTROL:
ibL MaskBits&=~CTRLBIT;
JthW"{E break;
Q)L6+gW^ case VK_SHIFT:
W~Ae&gcn# MaskBits&=~SHIFTBIT;
v FWg0 $, break;
]!'9Y}9a default: //judge the key and send message
7j~}M(s" break;
&{zRuF }
(>M?
iB for(int index=0;index<MAX_KEY;index++){
Gq0Q}[53 if(hCallWnd[index]==NULL)
I|/\ L|vo continue;
j&w4yY if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
o|bm=&f {
FQqk+P! SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
V PaW-o bProcessed=TRUE;
rPXy(d1<`S }
;JV(!8[ }
[iGL~RiXtn }
>))K%\p
else if((lParam&0xc000ffff)==1){ //有键按下
6#upBF: switch(wParam)
_]6n]koD, {
AoFxh o case VK_MENU:
{No
Y`j5S MaskBits|=ALTBIT;
#2*6esP break;
Q1^kU0M } case VK_CONTROL:
v)s;
wD MaskBits|=CTRLBIT;
Gz kvj:(V break;
cTu"Tu\Qw case VK_SHIFT:
:>3/*"vx?G MaskBits|=SHIFTBIT;
*EllE+M{n break;
r31)Ed$ default: //judge the key and send message
~tB#Q6`nB break;
~d"9?K^# }
kmu r={IR for(int index=0;index<MAX_KEY;index++){
@;`d\lQ if(hCallWnd[index]==NULL)
"U o~fJ continue;
BVe c if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Pt\GVWi_t {
HMl
M!Xk? SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
H}PZJf_E bProcessed=TRUE;
lqZUU92; }
FfpP<(4 }
TaNcnAY>9 }
{jOV8SVL if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
GFfZ TA for(int index=0;index<MAX_KEY;index++){
3fd?xhWbN if(hCallWnd[index]==NULL)
7;3;8Q FX continue;
$9rQ w1#e if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
D]NJ^.X SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
k4+ Q$3" //lParam的意义可看MSDN中WM_KEYDOWN部分
Ux+UcBKm- }
9`T2 }
qLa6c2o, }
yP0XA=,Y return CallNextHookEx( hHook, nCode, wParam, lParam );
0+ 3{fD/ }
6)[gF1 u}eLf'^ZCe 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
#j4jZBOTM G^2%F5@ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
^
RIWW0 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
S:{`eDk\A_ kj/v$m 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:
>bbvQb+j P&5kO;ia LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
Yx':~ {
nNpXkI: if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
'tn-o {
UoOxGo //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
<RJ+f- SaveBmp();
(,;4f7\ return FALSE;
/j"aOLL| }
x9 i^_3Z …… //其它处理及默认处理
TxvvCV^
}
6L, "gF<n s7"5NU- s}g3*_" 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。
tf4clzSTa ]:}x 4O# 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。
6oy[0hj /0(c-Dv 二、编程步骤
BNq6dz$ J ;X%8I$Ba, 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";
C8AR^FW T07 AH 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
80"oT'ZFh 1HBWOV7z.? 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;
bEB9J-
Q +O!4~k^ 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;
7_c/wbA#me tKYg 5、 添加代码,编译运行程序。
I]6,hygs $ 9
k5a 三、程序代码
3"LT '' "w{$d&+?ag ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
_WN\9< #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
0;tu}]jnN #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
>Y=qSg>Ik #if _MSC_VER > 1000
$/"QYSF #pragma once
v{pW/Fu~ #endif // _MSC_VER > 1000
EnP> #ifndef __AFXWIN_H__
q]#j,}cN9 #error include 'stdafx.h' before including this file for PCH
LX{mr{ #endif
uxbLoE #include "resource.h" // main symbols
K:b^@>XH class CHookApp : public CWinApp
#+(@i|!ifo {
N ,nvAM public:
6[\1Nzy> CHookApp();
\:9<d@? // Overrides
VfkQc$/ // ClassWizard generated virtual function overrides
L7nW_ //{{AFX_VIRTUAL(CHookApp)
BE)&.}l public:
MN[D)RKh; virtual BOOL InitInstance();
& {=}U virtual int ExitInstance();
GsU.Lkf //}}AFX_VIRTUAL
bwe)_<c //{{AFX_MSG(CHookApp)
9v?rNJs // NOTE - the ClassWizard will add and remove member functions here.
}#phNn6 // DO NOT EDIT what you see in these blocks of generated code !
R#4f_9e<Z //}}AFX_MSG
Mw|lEctN0 DECLARE_MESSAGE_MAP()
hp$1c };
p
Cgm!t?/ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
0y3C
/>a BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
DqA$%b
yyE BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
FYIz_GTk BOOL InitHotkey();
GC7W7B BOOL UnInit();
yi*EE% #endif
hCob^o g"v6UZ\ //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
_*-b0 }T #include "stdafx.h"
+zZ]Txb( #include "hook.h"
5#mHWBGd7 #include <windowsx.h>
&Y1RPO41J #ifdef _DEBUG
z-^/<u1p #define new DEBUG_NEW
WXd#`f % #undef THIS_FILE
;jh.\a_\ static char THIS_FILE[] = __FILE__;
Oar%LSkPRz #endif
,:%
h`P_ #define MAX_KEY 100
{hVc,\A #define CTRLBIT 0x04
: eFyd`Syw #define ALTBIT 0x02
~~}8D" #define SHIFTBIT 0x01
/Nns3oE #pragma data_seg("shareddata")
%e+{wU}w?2 HHOOK hHook =NULL;
E&>;a!0b] UINT nHookCount =0;
9F7}1cH7g@ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
XwDt8TxL static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
8@r>`c static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
!im%t9 static int KeyCount =0;
wU-Cb<^ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
zICAV -& #pragma data_seg()
DaqlL HINSTANCE hins;
oF_
'<\ly= void VerifyWindow();
;i!$rL BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
{v*X}`.h //{{AFX_MSG_MAP(CHookApp)
H/l,;/q]b
// NOTE - the ClassWizard will add and remove mapping macros here.
lcXo> // DO NOT EDIT what you see in these blocks of generated code!
`l //}}AFX_MSG_MAP
dQ
Lo,S8( END_MESSAGE_MAP()
Kl]l[!c7$ \qJ cs'D CHookApp::CHookApp()
r=# v@]zB {
`$ pJ2S // TODO: add construction code here,
@ 1FWBH~ // Place all significant initialization in InitInstance
jQ['f\R }
[nLd> 2P `KUL4) g~ CHookApp theApp;
g ,yB^^% LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
GW2v&Ul7( {
K~+x@O* BOOL bProcessed=FALSE;
A>6_h1 if(HC_ACTION==nCode)
Awe'MG p% {
h9QQ8}g if((lParam&0xc0000000)==0xc0000000){// Key up
7%W@Hr,%F switch(wParam)
ihD|e& {
'![VA8 case VK_MENU:
G0(A~Q" MaskBits&=~ALTBIT;
e}ivvs2 break;
$]MOAj"LH case VK_CONTROL:
U04)XfO;] MaskBits&=~CTRLBIT;
!,{-q)'D break;
-BH T'zq1S case VK_SHIFT:
\~.elKw<U MaskBits&=~SHIFTBIT;
n<Ki.;-ZE break;
rB_ESNx default: //judge the key and send message
Mo\nY5 break;
([]\7}+8 }
vH@$?b3VP for(int index=0;index<MAX_KEY;index++){
5uU{!JuSa if(hCallWnd[index]==NULL)
E//*bmww continue;
6>b'g
~I if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
u zL|yxt {
zLg_0r*h1 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
pIY3ft\ bProcessed=TRUE;
ceAefKdb }
Ryn@">sVI }
u?KG% }
M1I4Ot else if((lParam&0xc000ffff)==1){ //Key down
tDtqTB} switch(wParam)
Qm4cuV-0{ {
5Zl7crA [ case VK_MENU:
}DQ[C& MaskBits|=ALTBIT;
9`!#5i)VU8 break;
/Q'O]h0a case VK_CONTROL:
le2 v"Y MaskBits|=CTRLBIT;
-l{ wB" break;
Oyp)Wm;@ case VK_SHIFT:
9mEhZ" MaskBits|=SHIFTBIT;
S9 @*g3 break;
5K00z?kD2V default: //judge the key and send message
M] W5%3do break;
LP) IL~ }
QY$4D;M`g6 for(int index=0;index<MAX_KEY;index++)
^?T,>ZI {
Q`Ug tL if(hCallWnd[index]==NULL)
Nrc-@ ] continue;
>Vb V<ak if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
;(IAhWE?7 {
|^l17veA@ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Nfv.v1Tt+ bProcessed=TRUE;
@">^2 }
?|4Y(0N }
%gBulvg }
w[ )97d if(!bProcessed){
e_U1}{=t for(int index=0;index<MAX_KEY;index++){
dsJMhB_41U if(hCallWnd[index]==NULL)
:g&9v_}&K{ continue;
s{g^K#BoFi if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
R( 2,1f=d SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
vwF#;jj\ }
O_vCZW
a3 }
jEK{QOq0 }
h{ xq return CallNextHookEx( hHook, nCode, wParam, lParam );
8v{0=9,Z }
'PO+P~|oa& }4$k-,1S BOOL InitHotkey()
'Cr2&
dy {
w3hG\2)[HS if(hHook!=NULL){
dgbqMu" nHookCount++;
-hy`Np return TRUE;
%=w@c }
o2'^MxKb T else
{"rYlN7, hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
{&u`d.Lk2p if(hHook!=NULL)
2!@ER i nHookCount++;
hYvWD.c} return (hHook!=NULL);
]lQLA
IQ }
A^L8" BOOL UnInit()
Y8i'=Po%, {
9Rf})$o+ if(nHookCount>1){
#_(t46 nHookCount--;
@%"+;D return TRUE;
3lh^maQ] }
L0^rw|Z%' BOOL unhooked = UnhookWindowsHookEx(hHook);
Nw3K@Ge if(unhooked==TRUE){
[hhPkJf|f nHookCount=0;
ve3-GWT{C hHook=NULL;
tBB\^xq: }
Hl|EySno return unhooked;
-F->l5 }
cc0e(\ v35!?
5{ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
gdj,e ^ {
b79z<D BOOL bAdded=FALSE;
g$?kL for(int index=0;index<MAX_KEY;index++){
wC&+nS1 if(hCallWnd[index]==0){
v%
c-El% hCallWnd[index]=hWnd;
vV$6fvS HotKey[index]=cKey;
vx7wW<e%D HotKeyMask[index]=cMask;
"aT"o bAdded=TRUE;
tKP
zM KeyCount++;
oS0rP'V^ break;
_6Z}_SiOl }
0?80V' }
;NoD4* return bAdded;
fkHCfcU }
ov xX.hO x<=<Lx0B; BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
jhx @6[ {
6s<w}O BOOL bRemoved=FALSE;
gH
u!~l for(int index=0;index<MAX_KEY;index++){
Au"7w=G`f if(hCallWnd[index]==hWnd){
C@F3iwTtp if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
(@(rz/H hCallWnd[index]=NULL;
_N1UL? HotKey[index]=0;
P`$Y73L HotKeyMask[index]=0;
[kp# bRemoved=TRUE;
be+]kp KeyCount--;
yN/Uyhq break;
i
w(4!,4~ }
b^dBX }
9zKbzT] }
=5kTzH. return bRemoved;
UmNh0nS }
g[D`. }"\jB void VerifyWindow()
&Jf67\N {
\L5h&