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:
k/+-Tq;
%-? :'F!1 一、实现方法
fFD:E} >5 / d
S! 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:
QG\lXY, k%w5V>]1 #pragma data_seg("shareddata")
G#.(%, HHOOK hHook =NULL; //钩子句柄
ns_5|*' UINT nHookCount =0; //挂接的程序数目
!6_lD0 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
YxH"*)N static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
Kp")
%p# static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
(g2?&b
iuz static int KeyCount =0;
1
h(oty2p static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
V"n0"\k, #pragma data_seg()
I(fq4$ O!+LM{>
F 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。
M7"I]$|\ V>}@--$c-r 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:
]PVPt,c k|W =kt$ P BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
'LZF^m _<< cKey,UCHAR cMask)
uLV@D r {
~@ZdO+n? BOOL bAdded=FALSE;
'Z LGt# for(int index=0;index<MAX_KEY;index++){
fu|N{$h%X if(hCallWnd[index]==0){
J%']t$AR hCallWnd[index]=hWnd;
jRN*W2]V HotKey[index]=cKey;
0raVC=[ HotKeyMask[index]=cMask;
.uzg2Kd_ bAdded=TRUE;
]_NN,m>z KeyCount++;
"oZ]/( break;
Hl"rGA> }
55xv+|k }
iq$edq[ return bAdded;
|ubDudzp }
?c)PBJ+] //删除热键
V6l*!R BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
ZN!OM)@:! {
?vL\VI9 BOOL bRemoved=FALSE;
IWeQMwg for(int index=0;index<MAX_KEY;index++){
@/}{Trmg/ if(hCallWnd[index]==hWnd){
sGIY\% if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
:A35?9E? hCallWnd[index]=NULL;
1Sox@Ko HotKey[index]=0;
E@\e37e HotKeyMask[index]=0;
X%"P0P bRemoved=TRUE;
+5Z0-N@ KeyCount--;
o)'u%m break;
6'y+Ev$9 }
}49X
N }
0wZ_;FN*- }
!xoN%5! return bRemoved;
dzDh V{ }
I}/o`oc grEmp9Q ? <{@?c DLL中的钩子函数如下:
MdK!Y .J' 8d"+ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
7kU:91zR {
REnd#
V2x BOOL bProcessed=FALSE;
Z qX U if(HC_ACTION==nCode)
fq/F|c {
%]%.{W\j3 if((lParam&0xc0000000)==0xc0000000){// 有键松开
\&\_[y8U switch(wParam)
v{Cts3?Br {
}$u]aX< case VK_MENU:
%C=^
h1t% MaskBits&=~ALTBIT;
"sF&WuW| break;
d;&'uiS case VK_CONTROL:
g~_cYy MaskBits&=~CTRLBIT;
24{!j[,q@ break;
f !t2a// case VK_SHIFT:
F\!;}z MaskBits&=~SHIFTBIT;
D+{h@^C9Z break;
?&Si P-G default: //judge the key and send message
0gPz|v>z break;
($*bwqp]} }
M.1bRB for(int index=0;index<MAX_KEY;index++){
]Po9a4w# if(hCallWnd[index]==NULL)
X}'3N'cbkU continue;
FRI<A8 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
$Ch!]lJA {
0'O; H[nrl SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
5;{d*L bProcessed=TRUE;
:)}iWKAse }
"!<Kmh5 }
6'W79 }
j &)Xi^^ else if((lParam&0xc000ffff)==1){ //有键按下
:P`sK&b_ switch(wParam)
RC Fb&,51 {
3F2> &p|7 case VK_MENU:
7k{Oae\$ MaskBits|=ALTBIT;
DG8]FhD^b break;
Et@= <g case VK_CONTROL:
.!0),KmkK MaskBits|=CTRLBIT;
@K36?d]e break;
V ~w(^;o@ case VK_SHIFT:
pH.wCD:1n MaskBits|=SHIFTBIT;
{:40Jf
break;
qF=D,Dlz default: //judge the key and send message
P8!Vcy938 break;
CYrVP%xRA }
B9|!8V for(int index=0;index<MAX_KEY;index++){
zR
h1 if(hCallWnd[index]==NULL)
9,Zg'4",d continue;
|Q:$G!/ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
qgrRH' {
{'Nvs_{6 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
`Bx3grZ
7& bProcessed=TRUE;
p?X.I]=vRv }
i;xH }
NylN-X7[# }
/s& xI if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
QlIg'B6 for(int index=0;index<MAX_KEY;index++){
p3 I{ if(hCallWnd[index]==NULL)
L~A"%T,/h continue;
T[>h6d if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
N( E\ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
;RZ@t6^ //lParam的意义可看MSDN中WM_KEYDOWN部分
W3*BdpTw }
<.(IJ }
Yo;/7gG> }
OQaM4 7" return CallNextHookEx( hHook, nCode, wParam, lParam );
Z_F:H@-& }
.:Bjs* wxpD{P 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:
6~?7CK a#FkoA~M BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
CyO2Z
BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
p%,:U8fOR 3;~1rw=$< 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:
o%X_V!B{V 4IG=mG) LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
>x@]wsj {
W%b<(T;
if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
%1SA!1>j {
qc~6F'?R //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
8#'<SB SaveBmp();
??12
J# return FALSE;
~\4l*$3(^ }
)v;>6( …… //其它处理及默认处理
AuUT 'E@E }
w_pEup\` m9ts&b+TE Xhtc0\0"( 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
*c7kB}/ %]nYv#K 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
@=`Dw/13 ,0NVb7F;k 二、编程步骤
z*ZEw 2\l7=9 ]\3 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
Z"'rc.>a [VIdw92 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
^"v~hjM# UevbLt1Y 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
TYWajcch ^M6v;8EU 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
[ik D4p=
/XS6X 5、 添加代码,编译运行程序。
pBiC [J\5DctX;c 三、程序代码
9_JK. :Gqyj_|< ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
9=@j]g| #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
>T;"bcb #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
]Gow #if _MSC_VER > 1000
UoPd>q4Uj #pragma once
l>h%J,W #endif // _MSC_VER > 1000
~6.AE/ow #ifndef __AFXWIN_H__
fF[n?:VV #error include 'stdafx.h' before including this file for PCH
En8-Hc#NC #endif
qqT6C%Q`kG #include "resource.h" // main symbols
Jx1oK class CHookApp : public CWinApp
6[wej$u {
(*7edc"F public:
P~redX=t@ CHookApp();
1c~c_Cc4 // Overrides
\2-!%i, // ClassWizard generated virtual function overrides
SEXeK2v //{{AFX_VIRTUAL(CHookApp)
<8 Nh dCO6 public:
}|H]>U& virtual BOOL InitInstance();
(`GO@ virtual int ExitInstance();
"6^tG[G% //}}AFX_VIRTUAL
,&
=(DJ //{{AFX_MSG(CHookApp)
tf|/_Y2 // NOTE - the ClassWizard will add and remove member functions here.
flIdL, // DO NOT EDIT what you see in these blocks of generated code !
iHr{
VQ //}}AFX_MSG
:-.R*W DECLARE_MESSAGE_MAP()
|!8[Vg^Wh };
jC
,foqL LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
f3lFpS BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
<i^Bq=E<rJ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
N\=pH{ BOOL InitHotkey();
?'CIt5n+\{ BOOL UnInit();
pA"x4\s #endif
()JM161 DF%\1C> //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
!jMa%;/ #include "stdafx.h"
[0yKd?e #include "hook.h"
hEsCOcEG #include <windowsx.h>
9H2^4D8 #ifdef _DEBUG
YoGnk^$ #define new DEBUG_NEW
`j(\9j ok #undef THIS_FILE
iOPv
% [ static char THIS_FILE[] = __FILE__;
'?E^\\"* #endif
Nz#T)MGO` #define MAX_KEY 100
cbsy&U #define CTRLBIT 0x04
zBay 3a #define ALTBIT 0x02
G5ebb6[+ #define SHIFTBIT 0x01
b=:AFs{ #pragma data_seg("shareddata")
If\u^c HHOOK hHook =NULL;
qW6a|s0} UINT nHookCount =0;
QOlm#S static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
"^ydoRZ static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
dc5w_98o static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
5,I'6$J
static int KeyCount =0;
@JT9utct static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
5(1Zj`>' #pragma data_seg()
8/U=~*`_ HINSTANCE hins;
T.d+@ZV<# void VerifyWindow();
Q7&Yy25 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
#R"9(Q& //{{AFX_MSG_MAP(CHookApp)
iN0pYqY* // NOTE - the ClassWizard will add and remove mapping macros here.
+ Q
If7= // DO NOT EDIT what you see in these blocks of generated code!
zAC //}}AFX_MSG_MAP
l?NRQTG END_MESSAGE_MAP()
7S7gU\qOj /S$p_7N CHookApp::CHookApp()
:HYqm*v;W {
gZ%B9i: // TODO: add construction code here,
= PcmJG] // Place all significant initialization in InitInstance
"BK'<j^q }
Q mOG2 IQMk : CHookApp theApp;
A@j;H| LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
T_\HU*\ {
N)lzX X BOOL bProcessed=FALSE;
$@FD01h.t3 if(HC_ACTION==nCode)
m/|>4~ {
]N NLr;p if((lParam&0xc0000000)==0xc0000000){// Key up
pM@|P,w { switch(wParam)
_Hl[Fit<j1 {
Y]{<IF:
case VK_MENU:
v{i'o4 MaskBits&=~ALTBIT;
q5 I2dNE break;
x|_%R
v case VK_CONTROL:
zPe4WE| MaskBits&=~CTRLBIT;
/[Vaf R! break;
(BVLlOo?J case VK_SHIFT:
M-K<w(,X MaskBits&=~SHIFTBIT;
'C1=(PE%` break;
~&CaC default: //judge the key and send message
Ra'0 ^4t break;
K0@2>nR }
eQx9Vnb for(int index=0;index<MAX_KEY;index++){
@(JcM= if(hCallWnd[index]==NULL)
n }7DL8 continue;
V=VL@= if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
+&jWM-T"- {
[VT& SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
;/N[tO?Q bProcessed=TRUE;
<t,uj.9_ }
?t'ZX~k }
3q R@$pm }
MxuwEV|^ else if((lParam&0xc000ffff)==1){ //Key down
XASoS5 switch(wParam)
lJi'%bOi {
4-eb& case VK_MENU:
-9~kp'_a MaskBits|=ALTBIT;
L5(rP\B break;
%RL\t5TV case VK_CONTROL:
Nm--h$G MaskBits|=CTRLBIT;
_J6|ju\ break;
LZMdW
#,[ case VK_SHIFT:
3%/]y=rA MaskBits|=SHIFTBIT;
%.r{+m break;
r) T^ Td1 default: //judge the key and send message
<GF)5QB break;
VQZ3&]o }
F8 ;M++ for(int index=0;index<MAX_KEY;index++)
GfUIF]X {
(sW:^0 p if(hCallWnd[index]==NULL)
g.kpUs continue;
b,Ed}Ir if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
/R^HRzTO {
6dV@.(][a SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
ge`)sB, bProcessed=TRUE;
'&W`x5`t }
3I^KJ/)A }
brb8C%j}9 }
zid?yuP if(!bProcessed){
#E2`KGCzW for(int index=0;index<MAX_KEY;index++){
bS3qX{5 if(hCallWnd[index]==NULL)
c,Zs.
kC continue;
" 6~pTHT if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
U>(5J,G SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
aa_&WHXkt }
hQ i[7r($8 }
y%|nE(( }
t^&:45~Q return CallNextHookEx( hHook, nCode, wParam, lParam );
Oo`P +S# }
(s
%T18 i92{N$*x BOOL InitHotkey()
&jl'1mZ {
:@wO'
o if(hHook!=NULL){
iH9g5G`O nHookCount++;
l#7,<@) return TRUE;
V-}d-Y }
pco~Z{n else
Xl#vVyO hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
[zm&}$nnN if(hHook!=NULL)
%/oOM\}++ nHookCount++;
t^ Aios~F return (hHook!=NULL);
/R''R:j }
/>Wh BOOL UnInit()
N;F1Z-9 {
0'TqW9P if(nHookCount>1){
+%>s\W+?] nHookCount--;
X9/V;! return TRUE;
C(3yJzg>y }
i`gsT[JQRX BOOL unhooked = UnhookWindowsHookEx(hHook);
eE>3=1d]w if(unhooked==TRUE){
X@b$C~+ nHookCount=0;
\_!FOUPz( hHook=NULL;
E(4ti]'4 }
jHT 4I>\ return unhooked;
.hg<\-:_ }
H
#J"' req=w;E: BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
O*z x{a6 {
-vGyEd7 BOOL bAdded=FALSE;
e=%7tK* for(int index=0;index<MAX_KEY;index++){
1#^[{XlAx if(hCallWnd[index]==0){
Qf414 oW hCallWnd[index]=hWnd;
DHbLS3- HotKey[index]=cKey;
s+[_5n~ HotKeyMask[index]=cMask;
k)[} 3oq bAdded=TRUE;
en=Z[ZIPO KeyCount++;
( iP,F] break;
=gGK24 3 }
(u]ft]z,-B }
*<x]gV return bAdded;
)"m FlS<I }
enF.}fo] C@buewk BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
hEl)BRJ {
?fXg_?+{'g BOOL bRemoved=FALSE;
.!U `,)I for(int index=0;index<MAX_KEY;index++){
XU2HWa if(hCallWnd[index]==hWnd){
nOkX:5 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
zr&K0a{hc hCallWnd[index]=NULL;
]b'K
BAMy HotKey[index]=0;
iEr|?, HotKeyMask[index]=0;
7_S+/2}U* bRemoved=TRUE;
$P^=QN5Bb KeyCount--;
Xr:"8FT break;
N ]}Re$5 }
eoR@5OA& }
C]WVH\Pp }
(*/P~$xIj return bRemoved;
s$C;31k }
vn
.wM {Xwin$C void VerifyWindow()
1;fs`k0p {
`.MM|6 for(int i=0;i<MAX_KEY;i++){
5WO!u:!' if(hCallWnd
!=NULL){ :B$=Pp1
if(!IsWindow(hCallWnd)){ _(
w4 \]
hCallWnd=NULL; KAgiY4
HotKey=0; ZZ!d:1'7
HotKeyMask=0; `vDg~o
KeyCount--; 9=rYzA?)+
} \&R