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:
_PP-'^ U
/ >7G 一、实现方法
'(3|hh)Tl `{}DLaD9 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:
"M %WV> !;Ctz'wz #pragma data_seg("shareddata")
E-?JHJloU HHOOK hHook =NULL; //钩子句柄
>bO}sx1? UINT nHookCount =0; //挂接的程序数目
K2tOt7M! static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
lXnv(3j3*s static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
Vr T0S static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
Eqx |k-<a static int KeyCount =0;
RNcnE1= static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
f4|ir3oy #pragma data_seg()
/AUX7
m.8 ? 8S~R 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。
TLz>|gr id1gK(F8H 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:
UGA``;f i/,IG+4vI BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
3nUC,T%
cKey,UCHAR cMask)
'W~6-c9y {
$n::w c
BOOL bAdded=FALSE;
&>}f\ch/ for(int index=0;index<MAX_KEY;index++){
zogl2e+ if(hCallWnd[index]==0){
9tCF m.m hCallWnd[index]=hWnd;
b X/%Q^Y HotKey[index]=cKey;
-}H
EV#ev HotKeyMask[index]=cMask;
=~k#<q1^ bAdded=TRUE;
TO]
cZZ< KeyCount++;
;\Pq break;
dp'k$el }
xK_0@6
}
f!cYLU1e@ return bAdded;
TF@k{_f }
:HH3=.qAp` //删除热键
j$z!kd+% BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
/@LUD= {
=UZQ` { BOOL bRemoved=FALSE;
X@:@1+U for(int index=0;index<MAX_KEY;index++){
1?".R]<{2T if(hCallWnd[index]==hWnd){
1X#gHstD if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
v)v`896S` hCallWnd[index]=NULL;
j[:Iu#VR HotKey[index]=0;
&W>%E!F HotKeyMask[index]=0;
[-3x *?Ju bRemoved=TRUE;
}#` -mRaU KeyCount--;
6CNxb break;
Mqmy*m[U }
[nB4s+NX }
%9T|"\ }
vu_ u\2d return bRemoved;
}h9f(ZyJn }
wf,w%n ">Y(0^^ U)qG]RI DLL中的钩子函数如下:
p9*Ak
U&] Q^oB`)k LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
p+xjYU4^C {
7)l+hZ BOOL bProcessed=FALSE;
"jP{m;p if(HC_ACTION==nCode)
=XZd_v {
?.69nN if((lParam&0xc0000000)==0xc0000000){// 有键松开
c(lG_"q6 switch(wParam)
vC-5_pl {
%d#j%= case VK_MENU:
<;zcz[~ MaskBits&=~ALTBIT;
dZ,~yV break;
Z!oq2,ia case VK_CONTROL:
-D^v:aC MaskBits&=~CTRLBIT;
%j;mDR95 break;
K,f-
w2! case VK_SHIFT:
VNxhv!w MaskBits&=~SHIFTBIT;
h`V#)Q break;
i0{sE default: //judge the key and send message
b|u0a6 break;
q,.@<s W }
Y|F~w~Cb for(int index=0;index<MAX_KEY;index++){
Y86mg7[U/ if(hCallWnd[index]==NULL)
/"7_75
t continue;
G`FY[^: if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
4So
,m0v {
PsyXt5Dk SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
^:^8M4: bProcessed=TRUE;
:<R"Kk@ }
]+@I]\S4 }
$/$ 5{< }
^ <+V[=X else if((lParam&0xc000ffff)==1){ //有键按下
[Qn$i/`J switch(wParam)
Bx ru7E" {
Cg];UB}k case VK_MENU:
Og9:MFI MaskBits|=ALTBIT;
vptBDfzz break;
_"S1>s)X?j case VK_CONTROL:
fO 6Jug MaskBits|=CTRLBIT;
y"Jma`Vjq break;
h)sQ3B.}A case VK_SHIFT:
l]Q<BV MaskBits|=SHIFTBIT;
u=PYm+q{ break;
]"VxEpqhM default: //judge the key and send message
]}>uvl^l break;
{7LNQGiJ }
:Wd@Qy?; for(int index=0;index<MAX_KEY;index++){
5HW'nhE if(hCallWnd[index]==NULL)
g66SCr} continue;
U$=#yg2
: if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Ec l/2 {
LAU\.d SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Yjh02wo bProcessed=TRUE;
'qiDh[ATa }
;.&k zzvJ }
HkdBPMs79 }
ko`.nSZ-k if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
'XW9+jj)/ for(int index=0;index<MAX_KEY;index++){
e>!=)6[* if(hCallWnd[index]==NULL)
p[7?0 ( continue;
%%hG],w if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
]seOc],4 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
?j@(1",=& //lParam的意义可看MSDN中WM_KEYDOWN部分
R9)"%SO<y }
\'-E[xNcWI }
V8"m_ }
5PPaR|c3 return CallNextHookEx( hHook, nCode, wParam, lParam );
e&ci\x% }
X.J$
5b I|vfxf 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:
N7mYE hmr 2(f%U BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
G?5Vj_n BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
NRDXWscb -~WDv[[ 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 ^Ro 54i ,^uQw/ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
Q>
J9M`a {
}C<$q if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
9UE)4*5 {
7~m[:Eg6[s //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
v)%0`%nSR SaveBmp();
%>!$eCX return FALSE;
R 9b0D>Lxt }
u E<1PgW …… //其它处理及默认处理
,<!v!~Iy }
Vl%UT@D| (u-eL#@ ]lZg }7h 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。
eizni\ eR>|1s%^ 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。
V&Q_iE fOt?2Bh 二、编程步骤
Ln"D .gpq vMeB2r< 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";
ZFNg+H/k u{%dm5 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
;U]Ym48 *dPG[ } 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;
[SU;U['7 %ZM"c 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;
1}ws@hU -xL^UcG0 5、 添加代码,编译运行程序。
|wGmu&fY EClx+tz;` 三、程序代码
\x<i6&. -SUK [<=X ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
aXh~w<5F #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
)8*}-z #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
\"1%>O* #if _MSC_VER > 1000
@cu#rWiG #pragma once
\/F*JPhy #endif // _MSC_VER > 1000
XWag+K #ifndef __AFXWIN_H__
c)4L3W-x= #error include 'stdafx.h' before including this file for PCH
^"] ]rZ) #endif
ob]j1gYb #include "resource.h" // main symbols
A\ r}V- class CHookApp : public CWinApp
j] J-#J {
m"GgaH3, public:
C_S2a0? CHookApp();
KtD
XB> // Overrides
Hb3t|<z // ClassWizard generated virtual function overrides
rk
&ME#<r //{{AFX_VIRTUAL(CHookApp)
7\[)5j public:
u{LtyDnik virtual BOOL InitInstance();
iaHL&)[YK virtual int ExitInstance();
4)?s?+ //}}AFX_VIRTUAL
RwUosh\W //{{AFX_MSG(CHookApp)
TW-^C;
// NOTE - the ClassWizard will add and remove member functions here.
_0"s6D$ // DO NOT EDIT what you see in these blocks of generated code !
bi[g4,`Z; //}}AFX_MSG
@ |D#lBm DECLARE_MESSAGE_MAP()
1 RVs!; };
d'@i8N["{ LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
W<>R;~) BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
W0XfU` BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
W5Vh+'3 BOOL InitHotkey();
(/KeGgkhv BOOL UnInit();
QB;jZpF #endif
G124!^ SA%uGkm:e //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
oaG;i51! #include "stdafx.h"
5QP`2I_n #include "hook.h"
0( q:K6zI} #include <windowsx.h>
)3.=)?XW #ifdef _DEBUG
[xo-ZDIoG #define new DEBUG_NEW
{$Z
S
27 #undef THIS_FILE
Tly*i"[& static char THIS_FILE[] = __FILE__;
SvQ!n4 $ #endif
17#t 7Yk #define MAX_KEY 100
VI]~uTV #define CTRLBIT 0x04
V-dyeb #define ALTBIT 0x02
Y 2[ik< #define SHIFTBIT 0x01
c!N#nt_< #pragma data_seg("shareddata")
7n]ukqZ HHOOK hHook =NULL;
TjicltQi4 UINT nHookCount =0;
X}g"_wN,g> static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
W:hTRq static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
2`J#)f| static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
('Ha$O72 static int KeyCount =0;
[*1:?mD$ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
M)3'\x: #pragma data_seg()
)v\ A8)[ HINSTANCE hins;
'm0_pM1:D void VerifyWindow();
NZz^* Ela BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
hWi2S!*Y //{{AFX_MSG_MAP(CHookApp)
m-]F]c=)w< // NOTE - the ClassWizard will add and remove mapping macros here.
Cd|rDa // DO NOT EDIT what you see in these blocks of generated code!
80K"u[ //}}AFX_MSG_MAP
-ufaV# END_MESSAGE_MAP()
'LYN{ PLq]\y CHookApp::CHookApp()
o)+C4f[G4 {
AnoA5H // TODO: add construction code here,
|h& q // Place all significant initialization in InitInstance
Ml6}47n }
'EC0|IT)c N
;Cs? C CHookApp theApp;
+/ ?oyC+Z LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
(-xVW#39 {
}=A+W2D BOOL bProcessed=FALSE;
eOahr:Db if(HC_ACTION==nCode)
1BSn#Dnj {
C!Jy;Z=+u if((lParam&0xc0000000)==0xc0000000){// Key up
\+"Jg/)ij switch(wParam)
[9yd29pQ] {
]e$n ;tuW case VK_MENU:
9<.8mW^68 MaskBits&=~ALTBIT;
Ld
0j!II( break;
`4wy
*!] case VK_CONTROL:
0-p
%.}GE
MaskBits&=~CTRLBIT;
4kR;K!@k break;
Q)\[wYMt case VK_SHIFT:
2V*;=cv~z MaskBits&=~SHIFTBIT;
r`i.h ^2De break;
8X/SNRk6p default: //judge the key and send message
=.l>Uw! break;
Z/q'^PB
p }
yji>vJHu for(int index=0;index<MAX_KEY;index++){
?*6Q;.f< if(hCallWnd[index]==NULL)
ni6zo~+W] continue;
{vk%&{D0) if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
N'0nt]&a {
!QCErE;r SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
h6?o)Q>N bProcessed=TRUE;
"n{JH9sA: }
l!": s:/' }
L s+zJ1 }
yq!peFu else if((lParam&0xc000ffff)==1){ //Key down
+_jM$?:F} switch(wParam)
:lu "14 {
bI8')a case VK_MENU:
^4xl4nbx MaskBits|=ALTBIT;
U+aiH U9 break;
&{q< case VK_CONTROL:
OW#G{#.6R MaskBits|=CTRLBIT;
";^_[n break;
7Rd(,eWE@ case VK_SHIFT:
c*i,z MaskBits|=SHIFTBIT;
\eAV: qV break;
J!">L+Zcx default: //judge the key and send message
k>~D break;
$01~G?:]` }
wbI1~/ for(int index=0;index<MAX_KEY;index++)
AmJdZs|/ {
1GPBqF if(hCallWnd[index]==NULL)
"LH3ZPD continue;
/S @iF if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
R
G~GVf {
di7cCn SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
x6ayFq= bProcessed=TRUE;
5Q: %f }
?)Je%H }
7>F [7_ }
.3#Xjhebvu if(!bProcessed){
) )t]5Ys%; for(int index=0;index<MAX_KEY;index++){
%'VzN3Q5V if(hCallWnd[index]==NULL)
^1<i7u continue;
&Lbwx&!0b if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
?!.J0q SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
S+*>""= }
,$U~<Zd }
!pHI`FeAV }
1$^r@rP return CallNextHookEx( hHook, nCode, wParam, lParam );
/FjdcH= }
G-,0mo TD78&a# BOOL InitHotkey()
jvpv1>KYV {
X~/-,oV=A if(hHook!=NULL){
[.6bxK nHookCount++;
B
]sVlbt return TRUE;
M.bkFuh }
?}= $zN else
~_IQ:]k hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
"'/+}xM"5 if(hHook!=NULL)
; P$ _:-C nHookCount++;
BkY#wJ' return (hHook!=NULL);
ab#z&jg! }
P@%L.y
B BOOL UnInit()
jy_4W!4a {
:Ys
;)W+R if(nHookCount>1){
X":2o|R nHookCount--;
d=
?lPEzSA return TRUE;
GkI{7GD:z }
s3'kzwX BOOL unhooked = UnhookWindowsHookEx(hHook);
Vv+ oq5hf if(unhooked==TRUE){
=#A/d`2
b nHookCount=0;
@Kw&XK e` hHook=NULL;
D *IeG>% }
L+eK)Q return unhooked;
@ZrNV*&< }
|C5{[ z JY,oXA6O BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
FlY"OU* {
j`K0D65 BOOL bAdded=FALSE;
,?`kYPZ for(int index=0;index<MAX_KEY;index++){
ly6dl if(hCallWnd[index]==0){
:_`Yrx5 hCallWnd[index]=hWnd;
n xR\tBv HotKey[index]=cKey;
+q+JOS]L HotKeyMask[index]=cMask;
F&B E+b/# bAdded=TRUE;
m=Mk@xfQ# KeyCount++;
=
uepg@J break;
=@q,/FR- }
UMT}2d% }
B\l 0kiNT return bAdded;
q(4Ny<=,'K }
.u`A4;;Gw {xOzxLB; BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
}SyK)W5Y {
THB[(3q BOOL bRemoved=FALSE;
zU!d(ge.E
for(int index=0;index<MAX_KEY;index++){
q8,,[R_ if(hCallWnd[index]==hWnd){
*I}_g4 if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
hS>=pO+y hCallWnd[index]=NULL;
66$hdT$ HotKey[index]=0;
DF'~ #G8 HotKeyMask[index]=0;
4 /v[.5 bRemoved=TRUE;
~QUN O~ KeyCount--;
9l:[jsk<d break;
BB ::zBg }
ZwiXeD+4 }
<*P)"G }
.ud&$-[a return bRemoved;
xsN OjHk }
3JqGLR`z3 &