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:
,>
Ya%;h2k
azhilUD8 一、实现方法
v11Uw?CM !uZ)0R 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:
>X@4wP7l "SMRvi57T #pragma data_seg("shareddata")
hFMJDGCw>Q HHOOK hHook =NULL; //钩子句柄
DT;n)7+, UINT nHookCount =0; //挂接的程序数目
;H' ,PjU static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
_ *l+ze[a static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
'6g;UOx^= static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
lJHU1
gu static int KeyCount =0;
@\*`rl] static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
S_eD1iY2- #pragma data_seg()
PJfADB7Y d/"%fpp^0G 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。
XE#a# plNoI1st 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:
8}M-b6RV $?Km3N\?v BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
fA$2jbGW cKey,UCHAR cMask)
ahh&h1q7| {
3<XP/c"; BOOL bAdded=FALSE;
b6%[?k for(int index=0;index<MAX_KEY;index++){
$.Ia;YBf if(hCallWnd[index]==0){
QLm#7ms*y hCallWnd[index]=hWnd;
O*SJx. HotKey[index]=cKey;
'G1~
A + HotKeyMask[index]=cMask;
R$Rub/b6 bAdded=TRUE;
;NoiH& KeyCount++;
7|@FN7]5NF break;
K' ?`'7 }
_^Z
v[P }
2S return bAdded;
@
^q}.u` }
WJlJD*3 //删除热键
7_9^nDU BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
r@t
\a+
{
>rhqhmh;W" BOOL bRemoved=FALSE;
' Ig:- for(int index=0;index<MAX_KEY;index++){
C6JwJYa if(hCallWnd[index]==hWnd){
-<6b[YA if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
m@i](1*T| hCallWnd[index]=NULL;
l5T0x=y9! HotKey[index]=0;
n-he|u HotKeyMask[index]=0;
t5aX9WIW bRemoved=TRUE;
pP-L{bT KeyCount--;
(VM.]B< break;
G_QV'zQ }
6ys|'<? }
6vfut$)[{ }
{1"kZL return bRemoved;
u0Bz]Ux/Q }
pzT,fmfk
s?JOGu L9]y~[R: DLL中的钩子函数如下:
%N#A1 1f+z[ad&^ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
no$X0ia {
{zI>"%$u BOOL bProcessed=FALSE;
\4j(el if(HC_ACTION==nCode)
kp-`_sDg {
g_3Ozy if((lParam&0xc0000000)==0xc0000000){// 有键松开
84_Y+_9 switch(wParam)
*kt|CXxAS8 {
*qA:%m3 case VK_MENU:
<lZVEg MaskBits&=~ALTBIT;
w5+(A_ break;
:sS4T&@1= case VK_CONTROL:
E{'Y>gB6 MaskBits&=~CTRLBIT;
cK- jN9U break;
`.g'bZ<v/ case VK_SHIFT:
j;<s!A#
MaskBits&=~SHIFTBIT;
]pWn%aGv*Y break;
vX?C9Fr 2 default: //judge the key and send message
d"=)=hm! break;
)GfL?'Z }
sB*!Nf^y for(int index=0;index<MAX_KEY;index++){
v'Pbx if(hCallWnd[index]==NULL)
Nh01NY; continue;
rA|&G' if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
'};mBW4z {
\Ez&?yb/ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
'=+gweM bProcessed=TRUE;
M4n0GWHLy }
gg.lajX }
U]&/F{3
im }
K1=j7 else if((lParam&0xc000ffff)==1){ //有键按下
kpRk.Q* switch(wParam)
)43z(:< {
3F8KF`* case VK_MENU:
l>T]Y MaskBits|=ALTBIT;
v"*c\, break;
Y
8-;eqH case VK_CONTROL:
?jU 3%" MaskBits|=CTRLBIT;
OWp`Wat break;
E&ReQgBft case VK_SHIFT:
-nZDFC8y$ MaskBits|=SHIFTBIT;
R_=fH\c; break;
_ mgu
r default: //judge the key and send message
p@?ud% break;
*Oq&g\K) }
[4Q;5 'Dj for(int index=0;index<MAX_KEY;index++){
OGcW]i if(hCallWnd[index]==NULL)
,ZZ5A;) continue;
h05BZrE if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
YB_fy8Tfx {
l15Z8hYhj SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
6H!l>@a7v bProcessed=TRUE;
\D-X
_.v }
_=9m[
}
wn.UjxX. }
\"X_zM if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
@ %o' for(int index=0;index<MAX_KEY;index++){
!Ld[`d.|R! if(hCallWnd[index]==NULL)
},;Z<( continue;
[M#(su0fv if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
)=!|^M SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
g)}q3-<AK> //lParam的意义可看MSDN中WM_KEYDOWN部分
hGI5^!Cq }
k_nQmU> }
7e[&hea }
RJ-J/NhWyI return CallNextHookEx( hHook, nCode, wParam, lParam );
jw)c|%r> }
";upu a{Y8hR 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:
|9[)-C~N7 /2cn`dR, BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
wauM|/KG BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
D|2lBU hP_{$c{4:g 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
i&-g _z\qtl~3 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
DG,m;vg+ {
'8LHX6FXK if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
F5H]$AjW {
Q6p75$SVq //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
R8Dn
GR SaveBmp();
0S\HO<~k return FALSE;
)>N=B 2P }
lI3d
_cU …… //其它处理及默认处理
p::`1 }
@vO~'Xxq! Hn]6re ItE)h[86 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
@>F`;'_*z !>fi3#Fi 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
[7l5p(= N_p^DP 二、编程步骤
8\bZ?n#dn N.vkM`Z 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
A{wk$`vH >+%p}l:<\ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
WV;[v g] sUZ2A1J} 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;
XUK%O8N#9 XcKyrh;i 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;
BPu>_$C n>YgL}YZ? 5、 添加代码,编译运行程序。
9 LUk[V +WvW#wpH 三、程序代码
GPAz#0p ig'4DmNC ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
JY9hD;`6y #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
1#x@ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
lgC^32y #if _MSC_VER > 1000
D7C%Y^K]>E #pragma once
7H. HiyppW #endif // _MSC_VER > 1000
6W'2w?qj?4 #ifndef __AFXWIN_H__
CWkAc5 #error include 'stdafx.h' before including this file for PCH
9abn6S(XpJ #endif
LufZ, #include "resource.h" // main symbols
OQ _wsAA class CHookApp : public CWinApp
3ZqtIQY` {
<7oZV^nd * public:
8u Z4[ CHookApp();
C7!=LiK} // Overrides
Yt;@@xe& // ClassWizard generated virtual function overrides
F5<GGEQb //{{AFX_VIRTUAL(CHookApp)
,]=Qgn public:
J|b:Zo9<f" virtual BOOL InitInstance();
?D]T|=EZY virtual int ExitInstance();
HgRfMiC //}}AFX_VIRTUAL
)Ju$PrO //{{AFX_MSG(CHookApp)
LESF*rh= // NOTE - the ClassWizard will add and remove member functions here.
u_S>`I // DO NOT EDIT what you see in these blocks of generated code !
\JGRd8S[ //}}AFX_MSG
RvYH(!pQ DECLARE_MESSAGE_MAP()
m[C-/f^u| };
Dm6}$v'0 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
tqE LF BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Dqe/n_Z BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
p
IXBJk BOOL InitHotkey();
5yO6szg BOOL UnInit();
j3rBEQ,R #endif
OZ1+` 4 v OedL?4 //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
(KHTgZ6 #include "stdafx.h"
ZgLO[Bj #include "hook.h"
E{d Mdz #include <windowsx.h>
oQ 5g0(J~ #ifdef _DEBUG
iZQwo3"8r #define new DEBUG_NEW
](vshgp2 #undef THIS_FILE
Z
xLjh static char THIS_FILE[] = __FILE__;
l,*v/95h #endif
=/"Of #define MAX_KEY 100
\CL |=8[2 #define CTRLBIT 0x04
cX@~Hk4=\ #define ALTBIT 0x02
o*\kg+8 #define SHIFTBIT 0x01
T"'"T]^
X #pragma data_seg("shareddata")
I -i)D HHOOK hHook =NULL;
oq=D9 UINT nHookCount =0;
qu8i Jq static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
sf]y\_zU static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
jNV2o static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
~!'%m(g static int KeyCount =0;
> >wbyj8 static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
,*r"cmz #pragma data_seg()
cU5x8[2 HINSTANCE hins;
>/EmC3?b! void VerifyWindow();
(^Xp\dyZL BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
{!xPq% //{{AFX_MSG_MAP(CHookApp)
4-=> >#
P // NOTE - the ClassWizard will add and remove mapping macros here.
3~BL!e, // DO NOT EDIT what you see in these blocks of generated code!
X4&{/;$ //}}AFX_MSG_MAP
tOwwgf END_MESSAGE_MAP()
Fm{Ri=X<: Fg?Gx(g4 CHookApp::CHookApp()
1&Rz'JQ+ {
\*!?\Ko`W // TODO: add construction code here,
@h([c // Place all significant initialization in InitInstance
B @UaaWh }
X^?<, Y)1. }?#<)|_5 CHookApp theApp;
RM-|?% LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
UMo=bs {
x';6 BOOL bProcessed=FALSE;
G[r_|-^S if(HC_ACTION==nCode)
4*lShkL {
%]>c4"H if((lParam&0xc0000000)==0xc0000000){// Key up
WhSQ>h!@s switch(wParam)
0X`Qt[ {
ss% ahs case VK_MENU:
jio1#& MaskBits&=~ALTBIT;
p(%7|' break;
Dz]&|5'N case VK_CONTROL:
"}Ch2K MaskBits&=~CTRLBIT;
A(W%G|+ break;
<dD}4c+/t case VK_SHIFT:
~kYUp5f MaskBits&=~SHIFTBIT;
?BQZ\SXU break;
v@LK3S/!3 default: //judge the key and send message
EkEM|<GNd break;
AASw^A3p }
z*YkD"]B for(int index=0;index<MAX_KEY;index++){
%z J)mOu if(hCallWnd[index]==NULL)
NM/?jF@j* continue;
5Qo\0YH if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
~LuZpV {
N/TUcG|m\ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
}qG{1Er bProcessed=TRUE;
&'N{v@Oi) }
d%81}4f: }
c7q1;X{: }
%(Nu"3|$K= else if((lParam&0xc000ffff)==1){ //Key down
._~_OVU switch(wParam)
(X,Ua+{ {
za1MSR case VK_MENU:
*|Q'?ty(x MaskBits|=ALTBIT;
e4y dn break;
.rD@Q{e50 case VK_CONTROL:
jB:$+k|~. MaskBits|=CTRLBIT;
KFdV_e5lU break;
Av^{$9yl case VK_SHIFT:
dfiA- h MaskBits|=SHIFTBIT;
A$WE:<^ break;
{^Vkxf] default: //judge the key and send message
BP,"vq $'+ break;
[95(%&k.Q }
PSI5$Vna4p for(int index=0;index<MAX_KEY;index++)
wRgmw
4 {
-f#0$Z/0 if(hCallWnd[index]==NULL)
"8&pT^ continue;
7!#x-KR~5 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
"nU5c4
{
efy65+~GG SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
>zFe) bProcessed=TRUE;
`g<@F^x5 }
7u6o~( }
Ha1E /b]K
}
"2i{ L ' if(!bProcessed){
ZvpcjP for(int index=0;index<MAX_KEY;index++){
sczN0*w&C if(hCallWnd[index]==NULL)
,u#uk7V continue;
=GL}\I if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
}\:3}'S.$ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
xKWqDt }
2xhwi.u }
Sf
B+;i'D }
Yewn return CallNextHookEx( hHook, nCode, wParam, lParam );
cNtGjLpx; }
[pUw(KV2m wV+ W( BOOL InitHotkey()
D!h8NZ;El {
B&Q\J>l9S if(hHook!=NULL){
!lKO|Y nHookCount++;
+J}
wYind return TRUE;
$\Bzp<SN` }
K19/M1~ else
h8Q+fHDYv hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
X]U,`oE)9 if(hHook!=NULL)
Q g"hN nHookCount++;
;gYW!rM return (hHook!=NULL);
=MEv{9_ }
5DK>4H: BOOL UnInit()
K}tl,MMU {
/1F%w8Iqh if(nHookCount>1){
%I9{)'+@x nHookCount--;
mM!'~{r[- return TRUE;
jGl8y!aM }
U s86.@| BOOL unhooked = UnhookWindowsHookEx(hHook);
klxVsx%I{G if(unhooked==TRUE){
PEac0rSW nHookCount=0;
0;2i"mzS\ hHook=NULL;
_T&?H }
R
5-q{ return unhooked;
<`i"5`J }
onRxe\?D( dqnH7okZ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
CnSf GsE> {
j5,1`7\7B BOOL bAdded=FALSE;
DZ92;m for(int index=0;index<MAX_KEY;index++){
k{;"Aj:iL if(hCallWnd[index]==0){
Nz_c]3_j hCallWnd[index]=hWnd;
n0F.Um HotKey[index]=cKey;
$h`(toTyF HotKeyMask[index]=cMask;
<cNXe4( bAdded=TRUE;
^E\{&ka