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:
k1oJ<$Q
D'vaK89\ 一、实现方法
~M8|r!_ Cf9{lhE8 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
`a83bF35 E*`PD<:)H #pragma data_seg("shareddata")
0G6aF" HHOOK hHook =NULL; //钩子句柄
qajZ~oB{ UINT nHookCount =0; //挂接的程序数目
#/o~h|g static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
3E^qh03( static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
}79O[& static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
T~k @Z static int KeyCount =0;
-gm5Eqi static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
-fXQ62:S #pragma data_seg()
xT]t3'y|- yo/;@}g}
关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
g'b|[ q K4jHha DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
g e(,>xB G%FZTA6a BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
jU~ x^Y cKey,UCHAR cMask)
e5 L_<V^Jo {
#-@Uq6Y BOOL bAdded=FALSE;
DH%PkGn for(int index=0;index<MAX_KEY;index++){
\8=)X} ) if(hCallWnd[index]==0){
}8"
|q3k hCallWnd[index]=hWnd;
a6j& po HotKey[index]=cKey;
b>VV/j4!/ HotKeyMask[index]=cMask;
^3BPOK[*gB bAdded=TRUE;
i%[ gNh KeyCount++;
.|^Gde break;
,dR.Sacv }
z=) m6\ }
V:'F_/&X? return bAdded;
q)L4*O }
*Z^`H!& //删除热键
A&)2m BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
}oA>0Nw$K {
) WbWp4 BOOL bRemoved=FALSE;
NXFi* for(int index=0;index<MAX_KEY;index++){
51b%uz if(hCallWnd[index]==hWnd){
Y|><Ls6Q if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
:ujpLIjvVG hCallWnd[index]=NULL;
:CW^$Zvq HotKey[index]=0;
""jW'%wR HotKeyMask[index]=0;
\cCH/ bRemoved=TRUE;
(;;ji!i KeyCount--;
^h$*7u"^y break;
]t~.?)Ad+2 }
tiE|%jOzt }
[U/h'A.j }
iuGwc086 return bRemoved;
NI#]#yM+ }
Fz';H "A"YgD#t Qy0w'L/@ DLL中的钩子函数如下:
'I&0$< F5RL+rU(h LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
T>'O[=UWh {
d}zh.O5P!
BOOL bProcessed=FALSE;
^n0;Q$\ if(HC_ACTION==nCode)
\.}T_,I {
XQ9W
y if((lParam&0xc0000000)==0xc0000000){// 有键松开
V%s7*`U switch(wParam)
>fzyD(> {
j!>P7 8 case VK_MENU:
~Ym_ { MaskBits&=~ALTBIT;
Q;8z&4s@ break;
$uDgBZA\ case VK_CONTROL:
Qgj# k MaskBits&=~CTRLBIT;
6vsA8u(|V# break;
eZAMV/]jH case VK_SHIFT:
'0+~]4&}q MaskBits&=~SHIFTBIT;
pQBn8H|Y break;
tngB;9c+w default: //judge the key and send message
M%`CzCL
u break;
k\.9iI'6 }
`
= O for(int index=0;index<MAX_KEY;index++){
%S;AM\o4 if(hCallWnd[index]==NULL)
NOQ^HEi continue;
,M.}Q ak^ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
o& FOp' {
.)b<cH~% SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
(cOe*>L; bProcessed=TRUE;
|Q3d7y }
&L$9Ii }
ZI!: }
}6%XiP| else if((lParam&0xc000ffff)==1){ //有键按下
r[i^tIv6As switch(wParam)
B223W_0"o {
(l^7EpNs case VK_MENU:
O'wmhLa"W MaskBits|=ALTBIT;
JE-*o"& break;
Bk~C$'x4 case VK_CONTROL:
?h&XIM( MaskBits|=CTRLBIT;
5<dg@,\ break;
MSQ^ovph case VK_SHIFT:
]nUr E6 MaskBits|=SHIFTBIT;
!vAmjjB break;
/S"jO[n9b default: //judge the key and send message
bPxL+
+ break;
%US&`BT! }
sQ#e 2 for(int index=0;index<MAX_KEY;index++){
hz4?ku if(hCallWnd[index]==NULL)
n8<?<-2 continue;
9)1Ye if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
j+gxn_E {
=|z:wlOs SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
]##aAh-P4& bProcessed=TRUE;
hU""YP~y }
*uyP+f2O }
#
-luE }
]qT&6:;-] if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
U<w8jVE for(int index=0;index<MAX_KEY;index++){
H KrENk if(hCallWnd[index]==NULL)
"iK=
8 continue;
=4eJ@EVM if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
6P{^j SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
?Tc#[B //lParam的意义可看MSDN中WM_KEYDOWN部分
E)$>t}$ }
*I(6hB }
3@I0j/1#k1 }
/>S^`KSTM return CallNextHookEx( hHook, nCode, wParam, lParam );
- j3Lgm }
w li cuY? OKMdyyO<l 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:
sr6BC. {h+8^ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Wn=sF,c BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
c9-$^yno <l5i%? 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
=tP9n ;D nv:Qd\UM LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
T%eBgseS {
JI-i7P if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
cpjwc@UMe {
G{} 2"/ //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
bXnUz?1!d SaveBmp();
UUV5uDe>i return FALSE;
(&e!u{I }
ki'$P.v{$w …… //其它处理及默认处理
fIoc)T }
4$KDf;m@ tS2&S 6u 031"D*W'i 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。
{Ge{@1 o0R?vnA= 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。
ur}'Y^0iR
B(;MI` 二、编程步骤
_&/`-"3y /^.S
nqk 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";
8${n}}
1c0'i 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
X,v.1#[ U.<j2Kum 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
+^Xf:r`
G bZYayjxZ5i 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
ZG^<<V$h ]
]U )wg 5、 添加代码,编译运行程序。
.#QE*<T)] @A1f#Ed< 三、程序代码
$t;:"i> r1r$y2v~ ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
?wB_fDb} #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
ytIPY7E #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
oVpZR$ #if _MSC_VER > 1000
WoZU} T- #pragma once
;W?#l$R #endif // _MSC_VER > 1000
j?N<40z #ifndef __AFXWIN_H__
Mr)t>4 #error include 'stdafx.h' before including this file for PCH
f7_(C0d #endif
?y-^Fq|h #include "resource.h" // main symbols
TGF$zvd class CHookApp : public CWinApp
RTc@`m3 M {
4^W!,@W public:
Ku,wI86 CHookApp();
z{W Cw // Overrides
u4Nh_x8\Nr // ClassWizard generated virtual function overrides
F=Bdgg9s //{{AFX_VIRTUAL(CHookApp)
@Y/&qpo$#W public:
2#.s{ Bv virtual BOOL InitInstance();
/yG7!k]Eg virtual int ExitInstance();
12Oa_6<\0; //}}AFX_VIRTUAL
m%[e_eS //{{AFX_MSG(CHookApp)
.}\8Y= // NOTE - the ClassWizard will add and remove member functions here.
*K|~]r(F? // DO NOT EDIT what you see in these blocks of generated code !
=VD],R) //}}AFX_MSG
>_2~uF@pb DECLARE_MESSAGE_MAP()
n&:ohOH% };
n*7^lAa2 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
+c~&o83[ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
zTa5N BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
x:FZEyalG BOOL InitHotkey();
9w=7A>.U BOOL UnInit();
XjN4EDi+E #endif
KmNnW1T 2GptK"MrD //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
V;%ug'j #include "stdafx.h"
_;k<=ns(= #include "hook.h"
V$ H(a`! #include <windowsx.h>
'SFAJ #ifdef _DEBUG
,'s}g,L #define new DEBUG_NEW
Lu}jk
W* #undef THIS_FILE
%nZ:)J>kz static char THIS_FILE[] = __FILE__;
c~vhkRA #endif
%hSQ\T<8[o #define MAX_KEY 100
j,j|'7J% #define CTRLBIT 0x04
>aAM&4 #define ALTBIT 0x02
eNd&47lJ #define SHIFTBIT 0x01
Lk !)G'42 #pragma data_seg("shareddata")
-V}oFxk]q HHOOK hHook =NULL;
nFQuoU]ux UINT nHookCount =0;
%LrOGr static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
wtYgHC}X static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
Fx:38Ae static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
>%tG[jb static int KeyCount =0;
|SOLC static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
k'st^1T #pragma data_seg()
relt7 sK HINSTANCE hins;
q!c=f!U?\l void VerifyWindow();
a$=~1@ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
@s1T|}AJ //{{AFX_MSG_MAP(CHookApp)
NT+.E[J6 // NOTE - the ClassWizard will add and remove mapping macros here.
=^KgNQ // DO NOT EDIT what you see in these blocks of generated code!
|6Q5bV //}}AFX_MSG_MAP
H{Ewj_L END_MESSAGE_MAP()
X)KCk2Ax /JS_gr@DK CHookApp::CHookApp()
zFjz%:0 {
.P1WY // TODO: add construction code here,
@5^&&4>N // Place all significant initialization in InitInstance
^)-[g }
w-n}&f <MbhBIejr CHookApp theApp;
,ucRQ&P LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
e#*3X4<\K {
/
dJz?0 BOOL bProcessed=FALSE;
"9_$7.q<y if(HC_ACTION==nCode)
3:iEt (iCI {
S"&Gutu3o if((lParam&0xc0000000)==0xc0000000){// Key up
D&):2F^9. switch(wParam)
?h[HC"V/2 {
{'M<dI$ case VK_MENU:
-Rpra0o.
C MaskBits&=~ALTBIT;
LFax$CZc break;
3Z?ornS case VK_CONTROL:
5mZ2CDV MaskBits&=~CTRLBIT;
;].X;Ky< break;
NA0nF8ek case VK_SHIFT:
D|ceZ <9x MaskBits&=~SHIFTBIT;
Eiu/p&ct break;
2K9X (th1 default: //judge the key and send message
r!&174DSR1 break;
B@(d5i{h }
_Q1p_sdg for(int index=0;index<MAX_KEY;index++){
^4fvV\ne_~ if(hCallWnd[index]==NULL)
+mWf$+w continue;
c -k3<|H` if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
P*6m~`"5 {
!.'D"Me> SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
xqX3uq bProcessed=TRUE;
A`uHZCwJ5 }
r
&.~
{ }
T_S3_-|{== }
v*!N}1+J else if((lParam&0xc000ffff)==1){ //Key down
+;~N; BT switch(wParam)
"s0,9;
} {
(vG*)a case VK_MENU:
Dz0D ^(;V MaskBits|=ALTBIT;
_8.TPB]no break;
5!?5S$> case VK_CONTROL:
e6taQz@} MaskBits|=CTRLBIT;
w x]?D%l break;
Onq^|r's& case VK_SHIFT:
`PbY(6CF MaskBits|=SHIFTBIT;
Z+v,o1 break;
`^[k8Z( default: //judge the key and send message
oJ4HvrUO break;
tY;<S}[@7w }
0I.KHIBk for(int index=0;index<MAX_KEY;index++)
a]r+np]vTy {
t)&U'^ if(hCallWnd[index]==NULL)
4J5 zSTw continue;
o4" [{LyT if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
J]U_A/f {
<mFDC?j SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
m+!.H\ bProcessed=TRUE;
HFFG4' }
DT`HS/~fH }
*V kaFQZ$, }
M*0^<e~]F if(!bProcessed){
q? "> for(int index=0;index<MAX_KEY;index++){
q5_zsUR= if(hCallWnd[index]==NULL)
:XhF:c[.: continue;
I#2$CSJ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
qj;i03 +@ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
=_`q;Tu= }
X\m\yv}} }
/F;2wT; }
T#qf&Q Z return CallNextHookEx( hHook, nCode, wParam, lParam );
,Wd=!if }
xeFx!$3 S=,czs3N BOOL InitHotkey()
[P+kQBLpL {
P4#i]7% if(hHook!=NULL){
3Rb#!tx9 nHookCount++;
,cNe-KJk return TRUE;
NVx>^5QV }
{N}az"T4f else
$sY'=S hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
h\[@J rDa if(hHook!=NULL)
`o{ Z;-OF nHookCount++;
uLzE'ZmV return (hHook!=NULL);
JPZp*5c6A }
iHhdoY[] BOOL UnInit()
nriSVGi {
OdFF)-K>~ if(nHookCount>1){
nms[No? nHookCount--;
nod&^%O" return TRUE;
rNk'W, FU }
b,+Sa\j)( BOOL unhooked = UnhookWindowsHookEx(hHook);
+%XByY5 if(unhooked==TRUE){
1Rd|P<y nHookCount=0;
-rU_bnm hHook=NULL;
%nkP" Z# }
;D~#|CB return unhooked;
NWn*_@7; }
QQW}.>N :6(\: BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
)G)6D"5,+G {
RyK~"CWT BOOL bAdded=FALSE;
|p/*OFC6 for(int index=0;index<MAX_KEY;index++){
w8X5kk
if(hCallWnd[index]==0){
y-26\eY^P hCallWnd[index]=hWnd;
l+6c|([ HotKey[index]=cKey;
8e-nzc,] HotKeyMask[index]=cMask;
A8.noV bAdded=TRUE;
6m$X7;x} KeyCount++;
<KX9>e break;
LY0f`RX*& }
Ibz9juY }
yo[Sh6r/9b return bAdded;
|^-D&C(Eu }
7nT|yL? `+n0a@BVB BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
&j:e<{@ {
:O413#8 BOOL bRemoved=FALSE;
Pp }Z" for(int index=0;index<MAX_KEY;index++){
?TpjU*Cxy if(hCallWnd[index]==hWnd){
2FuV%\p if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
=W7-;& hCallWnd[index]=NULL;
gfK_g)'2U HotKey[index]=0;
+\Vw:~e HotKeyMask[index]=0;
~+1mH bRemoved=TRUE;
KfjWZ4{v KeyCount--;
_+48(QF<