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:
>mew"0Q
7\f{'KL 一、实现方法
U(P:J e ~R'BU=!;F 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;(oz]tr$ L2<+#O# #pragma data_seg("shareddata")
C)U #T) HHOOK hHook =NULL; //钩子句柄
A3<^ U UINT nHookCount =0; //挂接的程序数目
XnPJC' static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
=>e?l8`% static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
'Z59<Y a&x static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
98h :X % static int KeyCount =0;
VZt;P%1;h static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
\u{Jf'g #pragma data_seg()
R
!Fx)xj Kyu@>9Ok 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。
,cPkx~w0 [6G=yp 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:
{uEu>D$8 Z4\tY^NI BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
nrI"k2oA@ cKey,UCHAR cMask)
$1b]xQ {
7KeXWW/ d BOOL bAdded=FALSE;
!,Qm for(int index=0;index<MAX_KEY;index++){
SQKi2\8w if(hCallWnd[index]==0){
%7iUlO}}V hCallWnd[index]=hWnd;
:a=ro2NH HotKey[index]=cKey;
N/(ofy HotKeyMask[index]=cMask;
Z(l9>A7! bAdded=TRUE;
%Fs*#S KeyCount++;
K?$9N}+ break;
a^%8QJW }
^dheJ]n=k }
[y_yPOv return bAdded;
r^fxyN2V }
h\/^Aa0 //删除热键
/L)?> tg BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
qwL0~I {
FK-}i|di BOOL bRemoved=FALSE;
-hQ96S8 for(int index=0;index<MAX_KEY;index++){
?OdV1xB if(hCallWnd[index]==hWnd){
/]pX8
d if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
PG\\V$}A( hCallWnd[index]=NULL;
qw6EP C HotKey[index]=0;
n'! -Pv HotKeyMask[index]=0;
Bjurmo bRemoved=TRUE;
|*lH9lWJ KeyCount--;
yW%&_s0 break;
:yd=No@ }
M|1eqR%x-? }
*U( 1iv0n }
zf M<x,XdY return bRemoved;
0Ei\VVK> }
eUX@9eML rdORNlK& QWU5-p9e8 DLL中的钩子函数如下:
&gY;`*< pA*D/P- LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
zfk'>_' {
=4YbVA+( BOOL bProcessed=FALSE;
i)A`Vpn if(HC_ACTION==nCode)
_Cu[s?,kS {
OI)&vQ5k if((lParam&0xc0000000)==0xc0000000){// 有键松开
Q3 K;kS switch(wParam)
k/$Ja; {
SS>:Sw case VK_MENU:
h<PYE]?l MaskBits&=~ALTBIT;
*O2^{ C break;
Se!gs> case VK_CONTROL:
( 1QdZD| MaskBits&=~CTRLBIT;
^hQ:A4@q break;
J`U$b+q6 case VK_SHIFT:
=g{_^^n MaskBits&=~SHIFTBIT;
F2Nb5WT break;
:6\-9m8JM default: //judge the key and send message
1C^HCIH7J break;
O JZ!|J8? }
{ Hktu| for(int index=0;index<MAX_KEY;index++){
!Ei Ze.K if(hCallWnd[index]==NULL)
?K= gg< continue;
O[i2A( if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
31
KDeFg {
V Z4nAG SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
~$ cm9> bProcessed=TRUE;
C=xo&I7 }
A"P\4 }
X=S}WKu }
)?=
kb else if((lParam&0xc000ffff)==1){ //有键按下
ZwY`x') switch(wParam)
m?
\#vw$ {
G#_(7X& case VK_MENU:
e8WPV MaskBits|=ALTBIT;
-jcrXskb&N break;
"6|'&6& case VK_CONTROL:
7v4-hfN MaskBits|=CTRLBIT;
Jgi{7J break;
Z7K!"I case VK_SHIFT:
^*$WZMMJ1 MaskBits|=SHIFTBIT;
qiwQUm{ break;
$G^H7|PzdC default: //judge the key and send message
\rw'QAi8r break;
cG~_EX$ }
T1g:gfw@ for(int index=0;index<MAX_KEY;index++){
s5_1}KKCs if(hCallWnd[index]==NULL)
^^j|0qshL continue;
J8`1V`$ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
tA;ZW2$# {
bKZAJLnd SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
g%<{G/Tz bProcessed=TRUE;
<uWJ>sg^6 }
Gc3PN }
P~b%;*m}8 }
vl#V-UW$4P if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
9fr&Yb=_o@ for(int index=0;index<MAX_KEY;index++){
+ik N) D if(hCallWnd[index]==NULL)
.q'FSEkMJ continue;
9v5.4a} if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
y7}~T!UyfF SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
1*eWvYo1 //lParam的意义可看MSDN中WM_KEYDOWN部分
MO(5-R` }
T^f&58{ 7 }
B4M'Er{v }
Nt,]00S\w return CallNextHookEx( hHook, nCode, wParam, lParam );
`qYc#_ELv }
ej??j<] ni 02N3R 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
st1M.} m8j#{[NE BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
<T=o]M$ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
J[_?>YJ Q%b46" 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:
'KN!m|
z Xf' LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
M#22Zfxq {
@?($j)9} if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
)Lv6vnT> {
}~0{1& //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
8)2u@sx% SaveBmp();
Ug[F3J|Mu return FALSE;
p_kTLNZd9 }
9BgQoK@ …… //其它处理及默认处理
-^SD6l$ }
)I0g&e^Tzy b "AHw?5F v*T@<]f3j 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。
;tIIEc 0$dY;,Q . 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
'rcsK :fMM-?s] 二、编程步骤
5tbiNm^X v|hKf6 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
70 DQ/b @rDv
(W 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
#IciNCIrG ZBh@%A 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
q?b)zeJ i\c^h;wX 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
^<H#dkECG v+,
w{~7RH 5、 添加代码,编译运行程序。
U1@P/ @zpHemdB 三、程序代码
dIe 6:s ]&%X(jWyn ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
U*#E aL #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
]{ l
O #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
;Q%19f3,6 #if _MSC_VER > 1000
ckkM)|kK #pragma once
pRfHbPV? #endif // _MSC_VER > 1000
Wn)A/Z ^r #ifndef __AFXWIN_H__
.m
% x-i #error include 'stdafx.h' before including this file for PCH
N_~Wu #endif
v,O&UrZ #include "resource.h" // main symbols
4iB)oR class CHookApp : public CWinApp
3_['[}
{
a>e
1jM[ public:
L&F\"q9q71 CHookApp();
;@$, "
P // Overrides
nHL>}Yg // ClassWizard generated virtual function overrides
pl? J<48 //{{AFX_VIRTUAL(CHookApp)
SF}L3/C&h public:
kA$;vbm virtual BOOL InitInstance();
>w'?DV>u| virtual int ExitInstance();
xo@/k //}}AFX_VIRTUAL
w[7HY@[ //{{AFX_MSG(CHookApp)
l=G#gKE // NOTE - the ClassWizard will add and remove member functions here.
'Rf#1ls# // DO NOT EDIT what you see in these blocks of generated code !
T"jDq1C/,E //}}AFX_MSG
oz7udY=]0 DECLARE_MESSAGE_MAP()
OTbjZ( };
{d5ur@G1 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
G7#~=W
2M BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
xn#I7]]G BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
-)c"cgx. BOOL InitHotkey();
l<:)rg^, BOOL UnInit();
eFI9S.6 #endif
Le+8s LE`Y m_W.r+s~C4 //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
~V)VGGOL$v #include "stdafx.h"
9n2%7dLQ* #include "hook.h"
8YkH #include <windowsx.h>
YRX2^v ^[ #ifdef _DEBUG
5 s2}nIe #define new DEBUG_NEW
sJ*U Fm{ #undef THIS_FILE
Bc`A]U static char THIS_FILE[] = __FILE__;
gf8U &; #endif
)=y6s^} #define MAX_KEY 100
2G*#Czr" #define CTRLBIT 0x04
IOsDVIXL\ #define ALTBIT 0x02
7o%|R2mL} #define SHIFTBIT 0x01
N>#P
1!eP #pragma data_seg("shareddata")
ymJw{&^am HHOOK hHook =NULL;
B~?Q. <M UINT nHookCount =0;
U0=zuRr n static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
246!\zf static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
mLdyt-1 static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
eyp\h8!u_ static int KeyCount =0;
hndRgCo static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
bGLp0\0[ #pragma data_seg()
>.sN?5}y HINSTANCE hins;
?v*7!2; void VerifyWindow();
4C*=8oe_ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
nqW:P$ //{{AFX_MSG_MAP(CHookApp)
im%3*bv- // NOTE - the ClassWizard will add and remove mapping macros here.
2n,73$s // DO NOT EDIT what you see in these blocks of generated code!
833t0Ml1A/ //}}AFX_MSG_MAP
mqxy(zS] END_MESSAGE_MAP()
y^fU_L?p sX?7`n1U CHookApp::CHookApp()
UjK&`a;V {
^d=@RTyo/ // TODO: add construction code here,
Jm^jz // Place all significant initialization in InitInstance
nf^k3QS\ }
V'4}9J 0X6o CHookApp theApp;
qOanu LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
{;~iq {
'%7]xp BOOL bProcessed=FALSE;
{Z;GNMO: if(HC_ACTION==nCode)
jCa;g{#@ {
,3[<C)'[ if((lParam&0xc0000000)==0xc0000000){// Key up
`)P_X4e]` switch(wParam)
b,sc {
c3BL2>c case VK_MENU:
`h]f( MaskBits&=~ALTBIT;
=&xoyF break;
<08 V- case VK_CONTROL:
Kt0Tuj@CY MaskBits&=~CTRLBIT;
S,>n'r[ break;
''YjeX case VK_SHIFT:
LxDhthZi_ MaskBits&=~SHIFTBIT;
_YUF /B' break;
Q*(C)/ QW default: //judge the key and send message
Rb*\A7o|; break;
':dHYvP/UX }
d8I:F9 for(int index=0;index<MAX_KEY;index++){
]jrxrUl if(hCallWnd[index]==NULL)
fL:Fn"Nv continue;
BS.6d}G4 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
.`RC,R`C {
%05a>Rf& SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
_L.yt5_ bProcessed=TRUE;
ZJm^znpw6 }
"xI[4~'`: }
,6L>f.V^(U }
|g!#
\ else if((lParam&0xc000ffff)==1){ //Key down
~(S4/d5 switch(wParam)
"|rqt.f2[ {
V0(ABi:d case VK_MENU:
1\kehCt MaskBits|=ALTBIT;
u'."E7o# break;
GC3L2C0)k case VK_CONTROL:
8B9zo& MaskBits|=CTRLBIT;
#{1fb%L{i break;
.9QQ]fLs case VK_SHIFT:
%q^]./3p MaskBits|=SHIFTBIT;
v\FD~ break;
z$b!J$A1 default: //judge the key and send message
CxV%/ChJ# break;
B.jYU }
5w9<_W0d for(int index=0;index<MAX_KEY;index++)
v,B\+q/ {
8m0sEV> if(hCallWnd[index]==NULL)
Y6a|\K| continue;
]^<~[QK_C if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
l"8YI sir {
aoS1Yt'@ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
J>35q'nN]F bProcessed=TRUE;
U4JN,`p{ }
_{%H*PxTn= }
^eii
4 }
<i-RF-*S if(!bProcessed){
N%+M+zEJ for(int index=0;index<MAX_KEY;index++){
cO9Aw ! if(hCallWnd[index]==NULL)
{VG6m
Hw continue;
jK53-tF~I if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
%b9M\ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
).xWjVC }
P9vROzXK }
'-=?lyKv }
X*Zv,Wm return CallNextHookEx( hHook, nCode, wParam, lParam );
|~Iw }
|*i-Q @
D vCM'nkXY BOOL InitHotkey()
b8&9pLl {
zAewE@N#_ if(hHook!=NULL){
_NFJm(X. nHookCount++;
g,nE iL return TRUE;
p
WH u[Fu }
Y|F);XXIl else
]Ea-?IhD hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
||f4f3R' if(hHook!=NULL)
\N30SG?o nHookCount++;
.PgkHb=l@ return (hHook!=NULL);
uY,FugWbl }
^_uzr}LE` BOOL UnInit()
z5I<,[` {
{8Ll\j@ " if(nHookCount>1){
Dp8(L ]6 nHookCount--;
eR
CGr?e4 return TRUE;
C;` fOCz^ }
)8;'fE[p} BOOL unhooked = UnhookWindowsHookEx(hHook);
^^m%[$nw&r if(unhooked==TRUE){
SzgVvmM} nHookCount=0;
ctGjqHo hHook=NULL;
SDkN }
j^gF~Wz^ return unhooked;
LHps2, }
F3q5!1 LPC7Bdjz BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
J0IK=Y {
A.[T#ZB.4 BOOL bAdded=FALSE;
=LR UasF for(int index=0;index<MAX_KEY;index++){
{q^KlSjm if(hCallWnd[index]==0){
DQSv'!KFO hCallWnd[index]=hWnd;
T(6S~;,Z HotKey[index]=cKey;
="`y<J P HotKeyMask[index]=cMask;
X^ovP'c2 bAdded=TRUE;
08Q:1 ' KeyCount++;
-?uwlpm# break;
0*q:p`OLw* }
eMs`t)rQ }
sb1/4u/W return bAdded;
HwHI$IB }
)~6974 m5S/T\,X BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
gI]Vyg<{d {
\vI_%su1N BOOL bRemoved=FALSE;
|l9AgwDg for(int index=0;index<MAX_KEY;index++){
%UmE=V if(hCallWnd[index]==hWnd){
bnlL-]]9z if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
R~`Y6>o~9: hCallWnd[index]=NULL;
gVGq HotKey[index]=0;
G 6][@q HotKeyMask[index]=0;
z#y<QH bRemoved=TRUE;
hm&~6rB KeyCount--;
ZrTq)BZ break;
thh, V }
?F-,4Ox{/ }
1xw},y6T2 }
Z1Ms~tch return bRemoved;
:!%oQQO }
X**wRF R{T4AZ@,' void VerifyWindow()
6c2fqAF>i {
F?UL0Q|u v for(int i=0;i<MAX_KEY;i++){
\1tce`+ if(hCallWnd
!=NULL){ nP}/#Wy
if(!IsWindow(hCallWnd)){ |aZ^K\yI F
hCallWnd=NULL; {Z|C
HotKey=0; /:S.("Unv
HotKeyMask=0; eA!aUu
KeyCount--; w:qwU\U>x
} .N%$I6w
} |Oo
WGVc
} f~]5A%=cZ
} WYq, i}S
\UXQy{Ex
BOOL CHookApp::InitInstance() PgVM>_nHk
{ ar6Z?v$
AFX_MANAGE_STATE(AfxGetStaticModuleState()); U*-%V$3+w5
hins=AfxGetInstanceHandle(); kr3ZqMfeI
InitHotkey(); l!oU9
return CWinApp::InitInstance(); u",
[ulP
} KmMt:^9
8J)x>6
int CHookApp::ExitInstance() O".#B
{ ZI8p(e
VerifyWindow(); C}M0KDF
UnInit(); pM>.z9
return CWinApp::ExitInstance(); C4b3ZcD2
} *bR _
C"-
FCg,p2
////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file 0hPm,H*Y]
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_) .9`.\v6R
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_ 0py0zE6,,
#if _MSC_VER > 1000 Sna7r~j
#pragma once 2^|*M@3r
#endif // _MSC_VER > 1000 }@x0@sI9
o<x2,uT
class CCaptureDlg : public CDialog p}C3<[Nk
{ RlpW)\{j?
// Construction `/0FXb
8h
public: tf>?;
BOOL bTray; C3D1rS/I
BOOL bRegistered; ~V (WD;Mk
BOOL RegisterHotkey(); k&9
b&-=fk
UCHAR cKey; P*\.dAi
UCHAR cMask; }APf^Ry
void DeleteIcon(); f9;M"Pd
void AddIcon(); A6-JV8^
UINT nCount; `>K;S!z
void SaveBmp(); T;I a;<mfE
CCaptureDlg(CWnd* pParent = NULL); // standard constructor CnJO]0Op3
// Dialog Data q'PA2a:
//{{AFX_DATA(CCaptureDlg) yXlzImPn
enum { IDD = IDD_CAPTURE_DIALOG }; 'GAjx{gM
CComboBox m_Key; ,KZ_#9[>
BOOL m_bControl; @*F
NWT6
BOOL m_bAlt; `?~pk)<C].
BOOL m_bShift; 9HWtdJ+^C=
CString m_Path; 'DVPx%p
CString m_Number; ~~>D=~B0'
//}}AFX_DATA >YD?
pDPb/
// ClassWizard generated virtual function overrides "MlY G6
//{{AFX_VIRTUAL(CCaptureDlg) ptX;-'j(
public: >i=mw5`D]
virtual BOOL PreTranslateMessage(MSG* pMsg); ^G=s<