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:
4PU@W o
)ytP$,r![S 一、实现方法
k@n L(2 P&Xy6@%[Z 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
DSp~k) :c )R6=v #pragma data_seg("shareddata")
UaQW<6+ HHOOK hHook =NULL; //钩子句柄
z1tCSt}7f UINT nHookCount =0; //挂接的程序数目
VRY@}>W' static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
l_+q a6C* static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
xZV|QVY; static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
b!"qbC1 static int KeyCount =0;
r<P? F static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
&js$qgY #pragma data_seg()
|6Iw\YU 4{6,Sx 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。
o?.VW/" XJS^{=/ 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:
_wW"Tn] $mf6!p4 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
\sW>Y#9] cKey,UCHAR cMask)
!@ AnwV] {
F<2gM#jLB BOOL bAdded=FALSE;
#q&Nd2y for(int index=0;index<MAX_KEY;index++){
k#mL4$]V5N if(hCallWnd[index]==0){
56NDU>j$ hCallWnd[index]=hWnd;
k4:=y9`R}$ HotKey[index]=cKey;
bsI?=lO HotKeyMask[index]=cMask;
YVz,P_\(m bAdded=TRUE;
{ M[iYFg= KeyCount++;
B4m34)EOE break;
=PjdL32 }
R \y
qM;2 }
S!JLy&@ return bAdded;
7eZwpg?K }
Tn>L? //删除热键
@_WZZ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
md : Wx {
%5Elj<eHZ BOOL bRemoved=FALSE;
w/(2fU ( for(int index=0;index<MAX_KEY;index++){
Gh%dVP9B@P if(hCallWnd[index]==hWnd){
('=Q[ua7-( if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
jzZEP4 hCallWnd[index]=NULL;
nnd-d+$ HotKey[index]=0;
y,<\d/YY@ HotKeyMask[index]=0;
"*d%el\63 bRemoved=TRUE;
\[B#dw# KeyCount--;
HXqG;Fds( break;
}Q,BI*}* }
scd}{Y }
SvQj'5~< }
^Ri
;
vM return bRemoved;
A_J!VXq }
T^X um2Ec 2)q$HUIX +]C|y ,r DLL中的钩子函数如下:
eE0nW+i \9:IL9~F LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
_]+
\ B {
*zX^Sg-[ BOOL bProcessed=FALSE;
s8r[U, }( if(HC_ACTION==nCode)
}\ya6Gi8 {
09Z\F^*$F if((lParam&0xc0000000)==0xc0000000){// 有键松开
vFgnbWxG switch(wParam)
f+QDjJ?z {
Jy]}'eE?pr case VK_MENU:
^p\n/#B MaskBits&=~ALTBIT;
M>jk"*hA| break;
FJsg3D*@J case VK_CONTROL:
%w/:mH3FA MaskBits&=~CTRLBIT;
hBW,J$B break;
p;2NO& case VK_SHIFT:
[Ue"#w MaskBits&=~SHIFTBIT;
:&O6Y-/B break;
PV/ hnVUl default: //judge the key and send message
&=-{adm break;
+C=^,B!, }
1-pxM~Y for(int index=0;index<MAX_KEY;index++){
KKw J=za if(hCallWnd[index]==NULL)
~ \7peH% continue;
zids2/_* if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
E-$N!KY {
"Za 'K+4 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
3DZ8-N
S bProcessed=TRUE;
=G1
5eZW }
>t $^U }
0
|Rmb }
lXrAsm$ else if((lParam&0xc000ffff)==1){ //有键按下
sYyya:ykxT switch(wParam)
*U|2u+| F {
<%LN3T case VK_MENU:
Q$^Kf]pD MaskBits|=ALTBIT;
xJE26i break;
~5_>$7L> case VK_CONTROL:
/p[lO g MaskBits|=CTRLBIT;
Sh o] ~)XX break;
:x_;- case VK_SHIFT:
4VlQN$ MaskBits|=SHIFTBIT;
zT _[pa)O` break;
77zDHq= default: //judge the key and send message
)Yw m_f-N break;
X>s'_F? }
!
d " i for(int index=0;index<MAX_KEY;index++){
:*E#w"$,j if(hCallWnd[index]==NULL)
!K_ ke h continue;
7|pF(sb0 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
jb!15Vlt" {
@ u2P&|:{ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
|(UkI?V bProcessed=TRUE;
c_.4~>qw }
w 8oIq* }
L
t.Vo }
;rJ/Diz!g if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
ZS?4<lXF for(int index=0;index<MAX_KEY;index++){
+Zi@+|"BCN if(hCallWnd[index]==NULL)
$pYT#_P!/ continue;
'0E^th#u-0 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
/Es&~Fn SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
PQ`~qM:3st //lParam的意义可看MSDN中WM_KEYDOWN部分
;{Su:Ixg }
dW2Lvnh!>/ }
dIRSgJ` }
ZNTOI]P& return CallNextHookEx( hHook, nCode, wParam, lParam );
^)[jBUT }
~z*A%vp6ER orr6._xw 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:
; Uf]-uS DM)%=C6< BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
?Y#x`DMh BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
$tFmp) d"hW45L 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
" ll
TVB xO` O$ie LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
Oxhc!9F {
dQH9NsV7g if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
P[bj{lo {
XCU>b[Cj, //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
(cEjC`] SaveBmp();
Q GQ}I return FALSE;
;chz};zY }
k_%"# …… //其它处理及默认处理
d(8X?k.S }
Y1h)0_0 x5)YZ~5 h`%}5})= 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。
h oL"K CYWL@<p, 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。
2<' 1m{ BD ( 二、编程步骤
@
wJ|vW_. bQu1L>c,Uw 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";
2n8spLZYGY Iw-3Z'hOX 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
%N
}0,a0 j6{9XIRo_ 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;
:")iS?l 4!
V--F 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;
u!WjG@ Yr9!</;T 5、 添加代码,编译运行程序。
{E+o+2L idh5neyL 三、程序代码
} :8{z`4H vpl>
5 % ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
3BWYSJ| #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
y&$v@]t1 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
xsIuPL#_ #if _MSC_VER > 1000
XAf,k&f3 #pragma once
uzpW0(_i3a #endif // _MSC_VER > 1000
QCvz| ) #ifndef __AFXWIN_H__
)cd5iE:FO #error include 'stdafx.h' before including this file for PCH
JVgV,4 1 #endif
BYBf`F)4 #include "resource.h" // main symbols
Q-M"+ HO class CHookApp : public CWinApp
%qf ?_2v {
W8R"X~!V public:
_R?:?{r, CHookApp();
ic_q<Y} // Overrides
LmQS;/: // ClassWizard generated virtual function overrides
Sx", Zb //{{AFX_VIRTUAL(CHookApp)
$8"G9r public:
ggn:DE" virtual BOOL InitInstance();
a*gzVE7W#n virtual int ExitInstance();
@3F 4Lg6H| //}}AFX_VIRTUAL
-l#h^ //{{AFX_MSG(CHookApp)
a
J&)-ge // NOTE - the ClassWizard will add and remove member functions here.
3Bk_4n // DO NOT EDIT what you see in these blocks of generated code !
FV->226o% //}}AFX_MSG
#nOS7Q#uW DECLARE_MESSAGE_MAP()
}pzUHl> };
Fs,#d%4 @% LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
?UGA-^E1 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
bdUe,2Yi n BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
$ 3/G)/A BOOL InitHotkey();
Vo2{aK; BOOL UnInit();
3RyB 0
n #endif
A/zZ%h Rt^~db //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
@1UC9}> #include "stdafx.h"
~Kr_[X:d5 #include "hook.h"
Nhnw'9 #include <windowsx.h>
);zLy?n #ifdef _DEBUG
hkhk,bhI #define new DEBUG_NEW
mDT"%I"4j #undef THIS_FILE
<:rbK9MIl static char THIS_FILE[] = __FILE__;
!b0ANIp #endif
U)n+j}vi #define MAX_KEY 100
O*8.kqlgt #define CTRLBIT 0x04
`Z3p( G #define ALTBIT 0x02
A*r6 #define SHIFTBIT 0x01
L\u6EMyV #pragma data_seg("shareddata")
cU^Z=B HHOOK hHook =NULL;
L&WhX3$u UINT nHookCount =0;
p*_^JU(<p static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
u\9t+wi}< static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
im6Rx=}E{ static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
@FBlF$vG static int KeyCount =0;
3{wmKo|_X static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
XsVp7zk\ #pragma data_seg()
<lBY HINSTANCE hins;
*)6:yn void VerifyWindow();
O~1vX9 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
).BZPyV< //{{AFX_MSG_MAP(CHookApp)
~$O.KF: // NOTE - the ClassWizard will add and remove mapping macros here.
#:yh2y7a% // DO NOT EDIT what you see in these blocks of generated code!
X?'v FC //}}AFX_MSG_MAP
(rM-~h6g END_MESSAGE_MAP()
}?0At<(d tTzPT< CHookApp::CHookApp()
=/J{>S>(i {
?=22@Q}g // TODO: add construction code here,
I}&`IUP // Place all significant initialization in InitInstance
0"*!0s~
}
rLU+-_ Y30e7d* qr CHookApp theApp;
E9]/sFA-] LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
"5+x6/9b {
q
(?%$u. BOOL bProcessed=FALSE;
0KQDw if(HC_ACTION==nCode)
8hK\Ya:mP {
Z+qTMm if((lParam&0xc0000000)==0xc0000000){// Key up
+~6Nq(kV switch(wParam)
1m52vQSo3l {
jgfl|;I?pg case VK_MENU:
w*E0f?s MaskBits&=~ALTBIT;
Aw38Tw break;
nsRZy0@$t case VK_CONTROL:
wstH&^ MaskBits&=~CTRLBIT;
R*v~jR/ break;
Oc|`<^m case VK_SHIFT:
yt+"\d MaskBits&=~SHIFTBIT;
tdl Y break;
<d$L}uQwg default: //judge the key and send message
a2{nrGD break;
phT|w
H }
/:YJ2AARY for(int index=0;index<MAX_KEY;index++){
9
2e?v8 if(hCallWnd[index]==NULL)
Od?M4Ed( continue;
o:E_k#Fi if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
<K$X>&Ts {
?x*Ve2+] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
-t<8)9q( bProcessed=TRUE;
O[tOpf@s. }
]Tb ?k+a }
Vh.9/$xQ }
JwkMRO else if((lParam&0xc000ffff)==1){ //Key down
7(q EHZEr switch(wParam)
ymIjm0jVh {
LV^V`m0# case VK_MENU:
zSpL^:~ MaskBits|=ALTBIT;
MS Ml break;
?\
qfuA9. case VK_CONTROL:
'q#$^='o MaskBits|=CTRLBIT;
j"8 f,er break;
@dy<=bh~ case VK_SHIFT:
_* xjG \! MaskBits|=SHIFTBIT;
tKnvNOhn break;
,}("es\b default: //judge the key and send message
x"n!nT%Z break;
aetK<9L$ }
A@-A_=a, for(int index=0;index<MAX_KEY;index++)
YkPc& {
Ly?%RmHK if(hCallWnd[index]==NULL)
(Hr_gkGtM continue;
Mn-f if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Qj?qWVapA {
-FAAP&LG SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
Au q) bProcessed=TRUE;
0X`sQNx }
}\9elVt'2 }
"kE$2Kg }
\Bg;^6U if(!bProcessed){
),G?f {`! for(int index=0;index<MAX_KEY;index++){
Q\P?[i] if(hCallWnd[index]==NULL)
'w'PrM,: continue;
( 5^bU< if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
6vx0F?>_ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
+YL9gNN>P }
ZQZBap" }
=~OH.=9\ }
NA%(ZRSg( return CallNextHookEx( hHook, nCode, wParam, lParam );
Z*Sa%yf }
SMMV$;O{9 DrG9Kky{ BOOL InitHotkey()
X&B2&e; {
$_j\b4]% if(hHook!=NULL){
qdlz#-B nHookCount++;
.,)C^hs@ return TRUE;
.pP{;:Avpn }
mSw$?
> else
l>KkK|!T^i hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
Fq]ht* if(hHook!=NULL)
}b//oe7 nHookCount++;
)FNvtLZ return (hHook!=NULL);
'7+e!>" }
/[[_}\xI% BOOL UnInit()
rmX'Ym9# {
]BY^.!Y if(nHookCount>1){
#cN0ciCT' nHookCount--;
7e{w)m:A return TRUE;
5hVp2w- }
GI&XL'K& BOOL unhooked = UnhookWindowsHookEx(hHook);
\S[7-:Lu^ if(unhooked==TRUE){
E>/kNl nHookCount=0;
.L,xqd[zC hHook=NULL;
0i76(2 }
7J
0=HbH return unhooked;
@Axwj }
`zr%+ r%M.rYLG{ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
mkA1Sh{hX> {
RXMzwk BOOL bAdded=FALSE;
u7rA8u|TO for(int index=0;index<MAX_KEY;index++){
aoLYw 9 if(hCallWnd[index]==0){
XZ@;Tyn0, hCallWnd[index]=hWnd;
lJ+05\pE HotKey[index]=cKey;
P/BWFN1 HotKeyMask[index]=cMask;
e <Hbm bAdded=TRUE;
;.=ZwM]C KeyCount++;
(+@
Lnz\ break;
r<Il;?S6 }
we6kV-L. }
n=HId:XT return bAdded;
`Qf$]Eoft }
"bO\Wt#Mf y^7ol;t BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
{Vc%g a|E {
fl{wF@C6 BOOL bRemoved=FALSE;
ogcEv>0 for(int index=0;index<MAX_KEY;index++){
!"*!du28jo if(hCallWnd[index]==hWnd){
54TW8y `h if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
k{*IR hCallWnd[index]=NULL;
2v
^bd^]u: HotKey[index]=0;
EhEUkZE3) HotKeyMask[index]=0;
&<!DNXQ bRemoved=TRUE;
<