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:
8oGRLYU N
H PVEnVn 一、实现方法
[-w%/D%@ ueNS='+m 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:
pxi3PY? ckn(`I #pragma data_seg("shareddata")
uxz^/Gk HHOOK hHook =NULL; //钩子句柄
2~V*5~fb UINT nHookCount =0; //挂接的程序数目
4+tEFxvX& static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
*Pr )% static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
='jT~\ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
pgo$61 static int KeyCount =0;
E{(;@PzE static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
a+QpM*n7Lq #pragma data_seg()
\U_@S. Zd+bx*rD 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。
Hn:Crl y# zuCSj~ 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:
MQ2_`pi b,@/!ia BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
eS!/(#T cKey,UCHAR cMask)
Q2>gU# {
,r}6iFu BOOL bAdded=FALSE;
d;>QhoiL for(int index=0;index<MAX_KEY;index++){
lhJ'bYI if(hCallWnd[index]==0){
73-p*o(pt hCallWnd[index]=hWnd;
$cgcX HotKey[index]=cKey;
=~gvZV-< HotKeyMask[index]=cMask;
Dv6}bx( bAdded=TRUE;
7p[n KeyCount++;
<3
uNl break;
VU#7%ufu& }
&,/S`ke= }
@)}L~lb[) return bAdded;
Gm`8q}<I }
W*G<X.Hf //删除热键
/{2,zW BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
_0I@xQj- {
@VI@fN BOOL bRemoved=FALSE;
iow"n$/ for(int index=0;index<MAX_KEY;index++){
n{jGOfc if(hCallWnd[index]==hWnd){
n+p }\msH if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
)5H?Vh>36 hCallWnd[index]=NULL;
A}w/OA97RO HotKey[index]=0;
}B^tL$k HotKeyMask[index]=0;
_v:SP
L U bRemoved=TRUE;
GX%g9f!O KeyCount--;
AFn7uW!9Gw break;
(At$3b6 }
tX[WH\(xI }
g{LP7D;6 }
eH,or ,r return bRemoved;
_dU\JD }
w(F%^o\ a.Vuu)+Quw !~Z"9(v'C DLL中的钩子函数如下:
}a/Cro.~4 @]0%L0u LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
(%9$! v{3 {
0 {mex4 BOOL bProcessed=FALSE;
Zd&S@Z if(HC_ACTION==nCode)
?cZlN! {
[Qr"cR^ if((lParam&0xc0000000)==0xc0000000){// 有键松开
!m$jk2< switch(wParam)
tp|d*7^i {
$Q0n case VK_MENU:
31)&vf[[ MaskBits&=~ALTBIT;
fy$1YI>!Q break;
t,'<gI case VK_CONTROL:
.C(tMF]D, MaskBits&=~CTRLBIT;
'>"
4 break;
^@]3R QB case VK_SHIFT:
`mqMLo* MaskBits&=~SHIFTBIT;
\NC3'G:Ii break;
Mihg: default: //judge the key and send message
P;*(hY5& break;
}7X%'Bg=M }
5dg(e3T for(int index=0;index<MAX_KEY;index++){
p[cX O= if(hCallWnd[index]==NULL)
adw2x pj continue;
.V*^|UXbHi if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
\v/[6&|X0s {
Ss`LLq0LO SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
_f{{( 7 bProcessed=TRUE;
Xr{v~bf }
s`UJ1eJ }
28nFRr }
SAz else if((lParam&0xc000ffff)==1){ //有键按下
OJxl<Q=z switch(wParam)
}\LQ3y"[ {
F!do~Z case VK_MENU:
i9$ Av MaskBits|=ALTBIT;
$8FUfJ1@ break;
snJ129}A case VK_CONTROL:
7o4\oRGV MaskBits|=CTRLBIT;
3a|\dav% break;
m kexc~l case VK_SHIFT:
?4B`9<j8% MaskBits|=SHIFTBIT;
cNH7C"@GVu break;
_G0x3 default: //judge the key and send message
54/=G(F break;
(w{j6).3Dj }
%3rP`A for(int index=0;index<MAX_KEY;index++){
-HuA
\0J if(hCallWnd[index]==NULL)
/(LL3cZK continue;
`x|?&Ytmf9 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
+n)9Tz5 {
(#'>(t(4 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
@@%ataUSBT bProcessed=TRUE;
q*KAk{kR(v }
n*$ g]G$ }
U6VKMxSJ }
Yw9GN2AG if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
S[N5 ikg for(int index=0;index<MAX_KEY;index++){
T;uX4,|( if(hCallWnd[index]==NULL)
6nQq continue;
+q oRP2 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
b]y2+A.n SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
_g.{MTQ //lParam的意义可看MSDN中WM_KEYDOWN部分
f5r0\7y0 }
@.C2LIb }
% `3jL7| }
.u:GjL'$ return CallNextHookEx( hHook, nCode, wParam, lParam );
a
=QCp4^ }
z:;CX@)* ,s(,S 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:
HP=+<]?{G 8_8l.!~ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
=Uh$&m BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
^s=8!=A( L$-T,Kze 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:
Ned."e KSvE~h[#+ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
<qSC#[xu {
40/Y\ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
%LV9=!w {
..qCPlK; //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
YMgNzu SaveBmp();
G?ZXWu. return FALSE;
;fJ.8C }
TN.rrop`#g …… //其它处理及默认处理
uc=B,3 }
Fp:'M X @VBcJ{e, "#] $r 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
:0ep(<|; OnK4] S5 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
R8Tx[CJ5 z}@7'_iJ 二、编程步骤
G#CXs:1pd+ liZxBs
:%i 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
q@&6#B J1vR5wbu 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
(=$x.1 R2; 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;
1,~D4lD| y^k$Us 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
/,dz@ 8QK&_n* 5、 添加代码,编译运行程序。
S:Hl/:iV 74u&%Rj 三、程序代码
<[phnU^
8 yuVs
YV@" ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
GmG5[?) #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
AdmC&!nH #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
:+Z%; Dc #if _MSC_VER > 1000
=I4lL]> #pragma once
>Q/Dk7 # #endif // _MSC_VER > 1000
/mHqurB #ifndef __AFXWIN_H__
4W])}C % #error include 'stdafx.h' before including this file for PCH
@,}UWU #endif
(mOtU8e #include "resource.h" // main symbols
v^iAD2X/F class CHookApp : public CWinApp
XG?8s
& {
yX5\gO6G public:
FlQGgVN CHookApp();
)1z@ // Overrides
=v\.h=~~ // ClassWizard generated virtual function overrides
lMt=|66 //{{AFX_VIRTUAL(CHookApp)
9$Y=orpWxr public:
No$3"4wk virtual BOOL InitInstance();
pdMc}=K virtual int ExitInstance();
<$YlH@;)`a //}}AFX_VIRTUAL
5^cCY'I //{{AFX_MSG(CHookApp)
=*Lfl'sr_ // NOTE - the ClassWizard will add and remove member functions here.
Q/?$x*\> // DO NOT EDIT what you see in these blocks of generated code !
NRuNKl.v //}}AFX_MSG
/}$+uBgJm DECLARE_MESSAGE_MAP()
~~.}ah/_d };
]iWRo' LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
<%^&2UMg BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
fJ\[*5eiS BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
\*da6Am BOOL InitHotkey();
SJLis"8 BOOL UnInit();
l}h!B_P' #endif
"tZe>>I :3PH8TL //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
m~|40) #include "stdafx.h"
"MsIjSu #include "hook.h"
/1 dT+> #include <windowsx.h>
#Y!a6h+ #ifdef _DEBUG
}vuARZ> #define new DEBUG_NEW
;a/E42eN; #undef THIS_FILE
u
+hX static char THIS_FILE[] = __FILE__;
mq l
Z?- #endif
sKWfXCd #define MAX_KEY 100
im8 CmQ #define CTRLBIT 0x04
S/ *E,))m #define ALTBIT 0x02
W_=f'yb:E #define SHIFTBIT 0x01
(:_$5&i7 #pragma data_seg("shareddata")
dr(*T HHOOK hHook =NULL;
|)&%A%m UINT nHookCount =0;
e.C)jv6qr static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
=l6mL+C static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
uRvP hkqm static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
TjH][bH5 static int KeyCount =0;
x5Bk/e' static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
>:-$+I #pragma data_seg()
j#|ZP-=1_ HINSTANCE hins;
vh^VxS void VerifyWindow();
Lbgi7|& BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
.v
K-LHs //{{AFX_MSG_MAP(CHookApp)
p K*TE5] // NOTE - the ClassWizard will add and remove mapping macros here.
1EK*g;H // DO NOT EDIT what you see in these blocks of generated code!
dO'(2J8 //}}AFX_MSG_MAP
{: /}NpA$ END_MESSAGE_MAP()
Txu/{M, 6K^#?Bn; CHookApp::CHookApp()
BPrt'Nc {
{ 6il`>=C // TODO: add construction code here,
w)f#V s // Place all significant initialization in InitInstance
:WEDAFq0 }
C|bET >4TO=i CHookApp theApp;
i-1op> Y LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
&C}*w2]0S {
=_CzH(=f# BOOL bProcessed=FALSE;
rq{$,/6. if(HC_ACTION==nCode)
/ZX}Nc g {
6ujWNf if((lParam&0xc0000000)==0xc0000000){// Key up
I9^x,F"E] switch(wParam)
&oNAv-m^GD {
Z,gk|M3. case VK_MENU:
F9^S"qv$ MaskBits&=~ALTBIT;
203s^K61 break;
mh%VrAq case VK_CONTROL:
z{q`G wW MaskBits&=~CTRLBIT;
).O)p9 break;
KNl$3nX case VK_SHIFT:
w0.
u\ MaskBits&=~SHIFTBIT;
]Ljf?tk break;
4g/dP^ default: //judge the key and send message
mpyt5#f break;
'/p4O2b, }
Py<}S-: for(int index=0;index<MAX_KEY;index++){
gGYKEq{j( if(hCallWnd[index]==NULL)
R2NZ{"h
continue;
(Ld i|jL if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
bA 2pbjg= {
@ Qe0! (_= SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Z+SRXKQ bProcessed=TRUE;
\U0Q<ot/7 }
S:}7q2: }
+T ?NH9 }
'u658Tj else if((lParam&0xc000ffff)==1){ //Key down
Om&Dw|xG8 switch(wParam)
/Oono6j {
Ri'n case VK_MENU:
+ZYn? #IQ MaskBits|=ALTBIT;
qs6aB0ln break;
iZ%yd- case VK_CONTROL:
9WHddDA MaskBits|=CTRLBIT;
gw(z1L5
n break;
K3C <{#r case VK_SHIFT:
x-c"%Z| MaskBits|=SHIFTBIT;
!>tL6+yj break;
d9ihhqq3} default: //judge the key and send message
Bvj0^fSm break;
2%1hdA< }
PF2nLb2- for(int index=0;index<MAX_KEY;index++)
I fir ,8 {
INf&4!&h if(hCallWnd[index]==NULL)
CLSK'+l continue;
Xj*Wu_ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
& kIFcd@ {
'qi}|I SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
^Cmyx3O^ bProcessed=TRUE;
9Flb|G% }
k9R9Nz|J }
6zkaOA46V }
V~bD)?M if(!bProcessed){
kza5ab for(int index=0;index<MAX_KEY;index++){
V]&\fk-{ if(hCallWnd[index]==NULL)
g}i61( continue;
c,22*.V/ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
zi:BF60]= SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
=sFTxd_"iQ }
)Z$!PqRw@u }
4 :=]<sc, }
,Q,^3*HX9} return CallNextHookEx( hHook, nCode, wParam, lParam );
H]!"Zq k }
%\DX#. ,[Fb[#Qqb BOOL InitHotkey()
l,:F {
Q&&@v4L if(hHook!=NULL){
JRFtsio* nHookCount++;
hSMH,^Io$ return TRUE;
p'fYULYE }
{$r[5%L\H else
5IN(|B0 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
ddo#P%sH' if(hHook!=NULL)
23?rEhKe nHookCount++;
:]c3|J return (hHook!=NULL);
h~26WLf. }
/bEAK- BOOL UnInit()
fh{`Mz,o {
_6Ha if(nHookCount>1){
9kojLqCT nHookCount--;
q=G+Tocv return TRUE;
&{RDM~ }
zJXplvaL;
BOOL unhooked = UnhookWindowsHookEx(hHook);
z=FZiH if(unhooked==TRUE){
.-=vx r nHookCount=0;
.o8t+X'G hHook=NULL;
&R siVBA }
q =Il|Nb> return unhooked;
':}\4j&{E }
ExM,g' 7 *dF>_F BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
OH"XrCX7n {
e%6QTg5# BOOL bAdded=FALSE;
HqTjl4ai for(int index=0;index<MAX_KEY;index++){
nd(S3rct& if(hCallWnd[index]==0){
cFv8 Od hCallWnd[index]=hWnd;
8D].MI^ HotKey[index]=cKey;
8] ikygt" HotKeyMask[index]=cMask;
E e]-qN*8 bAdded=TRUE;
Th[dW<