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:
%p
L$_%T 一、实现方法
2YZ>nqy \OkZ\!<hg 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
)TiM>{ XjL3Ar* #pragma data_seg("shareddata")
/.7RWy` HHOOK hHook =NULL; //钩子句柄
njxLeDe- UINT nHookCount =0; //挂接的程序数目
N gF7$@S static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
gyAJ#N| static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
ZN)EbTpc\a static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
?lD)J?j static int KeyCount =0;
46NuT]6/4 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
:po6%}hn #pragma data_seg()
_*e_?]G- LJ
<pE;`d 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。
I9G^T' W Skci;4T( 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:
gC2}?nq* xgcJEox! BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
+U<YM94? cKey,UCHAR cMask)
\B~g5}= {
!@Qk=Xkg BOOL bAdded=FALSE;
y*^UGJC: for(int index=0;index<MAX_KEY;index++){
*tj(,:! if(hCallWnd[index]==0){
[(x<2MTj hCallWnd[index]=hWnd;
3ArHaAv{y HotKey[index]=cKey;
*KDTBd HotKeyMask[index]=cMask;
%:`v.AG bAdded=TRUE;
=>5Lp KeyCount++;
.+(V</ break;
d*s*AV }
7uc\AhOk6 }
!gW`xVGv return bAdded;
td7(444] }
%dPk,Ylz //删除热键
bT 42G[x BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
?SgFD4<~P {
&6OY^6< BOOL bRemoved=FALSE;
_1E c54D for(int index=0;index<MAX_KEY;index++){
xP'0a if(hCallWnd[index]==hWnd){
1z7+:~;l if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
N 5Om~D hCallWnd[index]=NULL;
I ==)a6^ HotKey[index]=0;
;iX~3[] HotKeyMask[index]=0;
p*lP9[7 bRemoved=TRUE;
zGU MH7 M KeyCount--;
id9QfJ9t break;
z9IW&f~~P }
%OgK{h }
JR]elRR }
;&J>a8B$ return bRemoved;
,V
52Fj }
N}U+K -(TC' #3
E"Ame DLL中的钩子函数如下:
=JE<oVP8 nD/B:0' LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
eGQ4aQhi {
3LfF{ED@ BOOL bProcessed=FALSE;
r~T!$Tb if(HC_ACTION==nCode)
1(Vv-bq$ {
`&c[s%0 if((lParam&0xc0000000)==0xc0000000){// 有键松开
S\N l|U[ switch(wParam)
s:6K'* {
(v?@evQ case VK_MENU:
M**Sus87Q MaskBits&=~ALTBIT;
>4wigc break;
9J7yR}2-F case VK_CONTROL:
S>x@9$( ym MaskBits&=~CTRLBIT;
Y<W9LF break;
#g$I>\O< case VK_SHIFT:
!b!An; ', MaskBits&=~SHIFTBIT;
d>F7i~W break;
mr}o0@5av default: //judge the key and send message
axC{azo| break;
-x6_HibbD }
QmSj6pB> for(int index=0;index<MAX_KEY;index++){
;q-c[TZC if(hCallWnd[index]==NULL)
NqF*hat continue;
5:gpynE| if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
I52nQCXi {
N:3=G`Ws SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
+$ djX=3 bProcessed=TRUE;
l,Q`;v5| }
U>!TM##1QD }
.a2R2~35 }
j7_,V?5z else if((lParam&0xc000ffff)==1){ //有键按下
8t=H switch(wParam)
?84f\<" {
+?6]Vu&|f case VK_MENU:
C&0f8PnD MaskBits|=ALTBIT;
^3sv2wh^|8 break;
y'>9'/& case VK_CONTROL:
}!fIY7gv MaskBits|=CTRLBIT;
W!ug^2" break;
Yl au case VK_SHIFT:
^~l@ _r MaskBits|=SHIFTBIT;
]v:,<=S break;
/z^v%l default: //judge the key and send message
^[[@P(e> break;
n,2 p)#? }
ES,JdImZ| for(int index=0;index<MAX_KEY;index++){
uYs45 G if(hCallWnd[index]==NULL)
OF1^_s; continue;
W="pu5q$5 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
,O.iOT0=; {
+ rB3\R"d SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
.&]3wB~ bProcessed=TRUE;
$U ._4 }
&'e+`\ }
_\dC<K *> }
ecl6>PS$' if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
aC9iNm8w for(int index=0;index<MAX_KEY;index++){
ysp,:)-%G@ if(hCallWnd[index]==NULL)
^WWr8- continue;
u7J:ipyiq2 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
|;V-;e* SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
8yI4=P"F, //lParam的意义可看MSDN中WM_KEYDOWN部分
0*P-/)o x }
-[>J"l }
JK{2hr_a }
#bGYHN return CallNextHookEx( hHook, nCode, wParam, lParam );
ZiKO|U@/ }
hUi5~;Q5Fi +{6:] 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:
Qj
[p/H$ ffB<qf)?G BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
r.LO j6c BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
b[&ri:AC -
]We|{ 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:
?gU-a :O,,fJ<x.O LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
o|84yT!~ {
=dKk #* if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
-H\j-k {
JeVbFZ8 //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
v8uUv%Hkd SaveBmp();
&2y9J2aA return FALSE;
'Q7t5v@FF }
WzdlrkD …… //其它处理及默认处理
., thdqOO }
='Oxy g-x;a0MQx DKlHXEt> 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。
#"C*dNAB jtpk5 fJB 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。
|Cfo(]>G 1G(wESe 二、编程步骤
Q[`2?j? dj,lbUL 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";
h52+f 1-4[w
*u> 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
kd
p*6ynD )=N.z6? 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;
e \kR/<L oe9S$C;$' 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;
I2z7}*<u KJ-Q$
M 5、 添加代码,编译运行程序。
u91 4^6Oh#p0 三、程序代码
RzB64 b?9'-hK< ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
>X>]QMfh #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
0eCjK. #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
tJGPkeA #if _MSC_VER > 1000
SN QLEe #pragma once
lvk*Db$ #endif // _MSC_VER > 1000
<dk9n}y<, #ifndef __AFXWIN_H__
<(qdxdUp #error include 'stdafx.h' before including this file for PCH
1-! |_<EW1 #endif
[h\_yU[P #include "resource.h" // main symbols
wDh&S{N class CHookApp : public CWinApp
3fop.%( {
@:9mTP7 public:
KA`)dMWL CHookApp();
.=
8Es# // Overrides
fG7-07 // ClassWizard generated virtual function overrides
F<6{$YI //{{AFX_VIRTUAL(CHookApp)
A_6Dol=J@ public:
@6b;sv1W virtual BOOL InitInstance();
"yXqf%CGE virtual int ExitInstance();
*EtC4sP //}}AFX_VIRTUAL
WN#dR~> //{{AFX_MSG(CHookApp)
OL&VisJ{75 // NOTE - the ClassWizard will add and remove member functions here.
.vMi<U; // DO NOT EDIT what you see in these blocks of generated code !
dZmq //}}AFX_MSG
|3m%d2V*hF DECLARE_MESSAGE_MAP()
z?,5v`,t2 };
e_TDO LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
9G~P)Z!0 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
)K~nZLULY BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
7l3q~ dQ BOOL InitHotkey();
/$(D>KU BOOL UnInit();
zn|}YovY+ #endif
n4johV.# qa6~N3* //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
+$5^+C\6A #include "stdafx.h"
{wI0 =U #include "hook.h"
n}{cs #include <windowsx.h>
l1WVt} #ifdef _DEBUG
{'!~j!1'j #define new DEBUG_NEW
v<1;1m #undef THIS_FILE
p~IvkW>ln) static char THIS_FILE[] = __FILE__;
^ a:F*<D #endif
qv\yQ&pj #define MAX_KEY 100
p<4':s;* #define CTRLBIT 0x04
#SueT"F #define ALTBIT 0x02
~_%[j8o&l #define SHIFTBIT 0x01
u:ISwAp #pragma data_seg("shareddata")
^iNR(cwgX HHOOK hHook =NULL;
1zRO==b UINT nHookCount =0;
Q*:
Ow] static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
zdCt#=QV?R static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
7f>n`nq? static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
>pKI' static int KeyCount =0;
D$HxPfDZ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
h%%'{^>~ #pragma data_seg()
Lrq&k40y HINSTANCE hins;
$G3P3y:
[ void VerifyWindow();
bX,Z<BvbF BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
}_ E //{{AFX_MSG_MAP(CHookApp)
Wm 61 // NOTE - the ClassWizard will add and remove mapping macros here.
Dg`W{oj // DO NOT EDIT what you see in these blocks of generated code!
y+a&swd2(U //}}AFX_MSG_MAP
#LiC@> END_MESSAGE_MAP()
o=ex{g( 3 &3<]FK CHookApp::CHookApp()
/NZR| {
x>cu<,e$d\ // TODO: add construction code here,
sC>8[Jatd // Place all significant initialization in InitInstance
C$8=HM3 }
6%TV X h(BN6ZrzKd CHookApp theApp;
!SnpesTn LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
3?:}lY<, {
":OXs9Yg BOOL bProcessed=FALSE;
ScEM#9T | if(HC_ACTION==nCode)
8Xr"4;}f+ {
lI9 3{!+> if((lParam&0xc0000000)==0xc0000000){// Key up
RW5T} switch(wParam)
+xMDm_TGLA {
$\H>dm case VK_MENU:
_>s.V`N' MaskBits&=~ALTBIT;
fOfp.`n break;
g(1'i 1 case VK_CONTROL:
l<5!R;?$ MaskBits&=~CTRLBIT;
XZhhr1-<a break;
{PZe!EQ case VK_SHIFT:
t1kD5^ MaskBits&=~SHIFTBIT;
95}"AIi break;
}U9e#>ex default: //judge the key and send message
;RXv%ML break;
,Fb#%r% }
rie1F, for(int index=0;index<MAX_KEY;index++){
I8m(p+Z= if(hCallWnd[index]==NULL)
SLW1]ZaG continue;
Gv`PCA@/d if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
yDPek*#^"q {
QFMS] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
DGcd|>q bProcessed=TRUE;
[X|P(&\hQd }
2l9_$evK~ }
Epx.0TA= t }
d97wiE/i< else if((lParam&0xc000ffff)==1){ //Key down
fy-(B; switch(wParam)
"YivjHa7H {
GFvOrRlP\ case VK_MENU:
7Ev~yY;N MaskBits|=ALTBIT;
Q,>AT$| break;
Q,scjt[ case VK_CONTROL:
kY|<1Ht MaskBits|=CTRLBIT;
hSxf;>(d break;
O?P6rXKr case VK_SHIFT:
3 Tt8#B MaskBits|=SHIFTBIT;
9vXrC_W9 break;
g%K3ah
v default: //judge the key and send message
t JJaIb6Xj break;
nF=h|rN }
#6JG#!W for(int index=0;index<MAX_KEY;index++)
{L#Pdj{ {
'E9\V\bi if(hCallWnd[index]==NULL)
]1X];x&e continue;
!aLL|}S if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
$ #CkI09 {
{&xKSWNc SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
X4jtti bProcessed=TRUE;
g1Aq;Ah / }
&",pPuq }
(i { }
F*QGzbv) if(!bProcessed){
WO|#`HM2 for(int index=0;index<MAX_KEY;index++){
\MnlRBUM, if(hCallWnd[index]==NULL)
f)>=.sp continue;
U`xjau+ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
'En 6h" { SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
lOql(ZH`w }
Y}PI{PN }
YqYCW}$ }
9\V^q9l return CallNextHookEx( hHook, nCode, wParam, lParam );
tv5SQ+AI3
}
fF;-d2mF Wfp[)MM; BOOL InitHotkey()
`C,47 9~J {
='a$>JVJ5 if(hHook!=NULL){
/aP`|&G,) nHookCount++;
7Y:1ji0l return TRUE;
@`)A) }
kA fkQy(~ else
*U8Pjb1 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
Po% V%~ if(hHook!=NULL)
"+p_{J/P nHookCount++;
VGkwrS;+I return (hHook!=NULL);
N\rbnr }
+Ibcc8Qud BOOL UnInit()
s~,Y po? {
OQA}+XO if(nHookCount>1){
UE5T%zd / nHookCount--;
FgLV>#)- return TRUE;
&0~E+
9b }
LJ9^:U BOOL unhooked = UnhookWindowsHookEx(hHook);
+Uq$'2CT if(unhooked==TRUE){
YuFJJAJ nHookCount=0;
*zJ}=%)f hHook=NULL;
p1q"[)WVn^ }
n)gzHch return unhooked;
Ab/gY$l }
|X0h-kX4 `J#(ffo- BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
V^[o{'+ {
h#a,<B| BOOL bAdded=FALSE;
:>] =YE for(int index=0;index<MAX_KEY;index++){
eNR>W>;' if(hCallWnd[index]==0){
*Mgl X< hCallWnd[index]=hWnd;
u?i_N0H HotKey[index]=cKey;
1ve
%xF HotKeyMask[index]=cMask;
{%*,KB>b bAdded=TRUE;
x=(Q$Hl5 KeyCount++;
N[:;f^bH49 break;
$C#G8Ck, }
4cDjf~n }
N*y09?/h return bAdded;
1^jGSB.%A }
@lRTp A!\g!* BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Y j;KKgk {
f%<kcM2 BOOL bRemoved=FALSE;
nep0<&