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:
(u?s@/e:`/
r'i99~ 一、实现方法
]D6<6OB kHK<~srB 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:
$
DN. sX?arI=_U #pragma data_seg("shareddata")
~D5
-G?%$" HHOOK hHook =NULL; //钩子句柄
}-[l)<F: UINT nHookCount =0; //挂接的程序数目
0hS&4nW static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
IR/S`HD_ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
k7Nx#%xx static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
oypLE=H static int KeyCount =0;
LsR<r1KDJ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
2[w9#6ly #pragma data_seg()
{A}T^q!m] <(E)M@2 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。
uz8eS'8 P0UR{tK 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:
caEIE0H~ 9^Xndo]y BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
+9HU&gQ3 cKey,UCHAR cMask)
{r&r^!K; {
&wNr2PHd# BOOL bAdded=FALSE;
<@7j37,R7V for(int index=0;index<MAX_KEY;index++){
za6 hyd^ if(hCallWnd[index]==0){
R655@|RT hCallWnd[index]=hWnd;
6UIS4_
HotKey[index]=cKey;
^ iu)vED HotKeyMask[index]=cMask;
8z93ETv7` bAdded=TRUE;
q`AsnAzo& KeyCount++;
$;g*s?F* break;
yc0
1\o }
d^'_H>x }
-Ua5anzB return bAdded;
@Hj]yb5 }
|(~IfSE2 //删除热键
.Z7tE? BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
,5 8-h?B0v {
DvWBvs, BOOL bRemoved=FALSE;
_~Lu% for(int index=0;index<MAX_KEY;index++){
|f}wOkl if(hCallWnd[index]==hWnd){
`c:r`Oi? if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
wgSFL6Ei hCallWnd[index]=NULL;
T#E{d HotKey[index]=0;
}r04*P( HotKeyMask[index]=0;
R1*&rjB bRemoved=TRUE;
~&/Nl_# KeyCount--;
K%9!1' break;
-/8V2dv3 }
;4+z~7Je]^ }
2Jo|P A`9 }
(ht"wY#T<( return bRemoved;
n(A;:)W{ }
+46& Zb35 _WV13pnRu b?k,_;\ DLL中的钩子函数如下:
Jn(|.eT| QP%AJ[3ea% LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
3meZ]u {
P'}EZ' BOOL bProcessed=FALSE;
JNU9RxR if(HC_ACTION==nCode)
8f,",NCgc {
yJx,4be if((lParam&0xc0000000)==0xc0000000){// 有键松开
k8Dk;N switch(wParam)
QKk7"2t| {
,9OER!$y case VK_MENU:
w_@6!zm MaskBits&=~ALTBIT;
:4:U\k;QwA break;
M!G/5:VZ case VK_CONTROL:
*"|f!t MaskBits&=~CTRLBIT;
0>Kgz!I break;
~Q- /O~ case VK_SHIFT:
TGpdl`k\T MaskBits&=~SHIFTBIT;
=)#XZ[#F break;
B"7~[,he default: //judge the key and send message
uxW |&q break;
$y)tcVc }
%i&am= for(int index=0;index<MAX_KEY;index++){
MDpx@.A, if(hCallWnd[index]==NULL)
][f 0ZMa continue;
fN`Prs A if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
-6q7ze{@ {
~HctXe' x SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
8pmWw? bProcessed=TRUE;
T+V:vuK }
5=s|uuw/ }
Lxa<zy~b }
0l(G7Ju else if((lParam&0xc000ffff)==1){ //有键按下
n`Ypv{+ {% switch(wParam)
#;2kN
& {
<Rt0
V%}- case VK_MENU:
ziAn9/sT MaskBits|=ALTBIT;
.j!:Hp(z} break;
2V @ pt case VK_CONTROL:
5"#xbvRS0H MaskBits|=CTRLBIT;
j97c@ break;
H8c -/ case VK_SHIFT:
|$T?P*pI. MaskBits|=SHIFTBIT;
BQMo*I>I break;
q|.0Ja default: //judge the key and send message
h#h)=; break;
ud(w0eX }
B)DtJf for(int index=0;index<MAX_KEY;index++){
wh]v{Fi' if(hCallWnd[index]==NULL)
ohPXwp?] continue;
voN, u>U if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
eET1f8B=L {
5IG#-Q(6sp SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
.v) A|{:2 bProcessed=TRUE;
`yXHb }
%H"AHkge:a }
mqQ//$Y
}
<XpG5vV if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
o<S(ODOfi for(int index=0;index<MAX_KEY;index++){
BBoVn^Z*R if(hCallWnd[index]==NULL)
!O,`Z`T? continue;
gA+@p'XnR if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Jl)Q# SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
5X`m.lhUc //lParam的意义可看MSDN中WM_KEYDOWN部分
cTJG1'm }
(
Qk*B }
EU7mP
MxJ }
r-}C !aF] return CallNextHookEx( hHook, nCode, wParam, lParam );
n\scOM)3 }
XQ k,xQ :EC[YAK+D 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:
^@maF<Jb $8_b[~%2 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
m!<uY?,hf BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
w##$SaTI 9H%L;C5< 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:
)J|~'{z: J16(d+ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
6$+F5T {
4H%Ai(F}_ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
/;1h-Rc> {
k5Df97\s //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
{Pi]i? SaveBmp();
alQ:'K return FALSE;
(d5kD#.N }
SR'u*u! …… //其它处理及默认处理
Y&b JKX }
>x1?t i\P)P! rcMSso2 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
[tz}H& #F >R5 D 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
mvW,nM1Y Pu|3_3^ 二、编程步骤
z/S}z4o/ bu r0?q 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
&qFy$`" $]]|#}J 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
<bOi } $~.'Tnk) 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
>BlF<
d`X -6>T0- 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
7%^/Jm ^5*9BwH` 5、 添加代码,编译运行程序。
u"1Zv! Y]{~ogsn$: 三、程序代码
|"EQyV w97%5[-T ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
2~*.X^dR #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
S_56! #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
B=+Py% #if _MSC_VER > 1000
_ye74$# #pragma once
>a2i%j/T #endif // _MSC_VER > 1000
Sy`7 })[ #ifndef __AFXWIN_H__
CrI:TB>/" #error include 'stdafx.h' before including this file for PCH
[E|% #endif
iwnFCZVS #include "resource.h" // main symbols
/jv4#9 class CHookApp : public CWinApp
t5WW3$Nf {
6{PlclI ! public:
-|A`+1-R+ CHookApp();
q*4=sf,> // Overrides
q'[q] // ClassWizard generated virtual function overrides
vTU*6) //{{AFX_VIRTUAL(CHookApp)
J9*$@&@S public:
hE>%LcP virtual BOOL InitInstance();
leJ\ virtual int ExitInstance();
,O/ t6' //}}AFX_VIRTUAL
$Q< >MB7 //{{AFX_MSG(CHookApp)
<C,lHt // NOTE - the ClassWizard will add and remove member functions here.
wLz@u$u? // DO NOT EDIT what you see in these blocks of generated code !
&C=[D_h //}}AFX_MSG
f^?k?_~PN DECLARE_MESSAGE_MAP()
[kyIF\0 };
aaM76; LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
6#/v:;bF BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
f+Ht BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
W #kOcw BOOL InitHotkey();
R<n'v.~"A BOOL UnInit();
xF8^#J6> #endif
1MnT*w jou741 //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
a"&Gs/QKSC #include "stdafx.h"
m3E`kW| #include "hook.h"
j>-O'CO #include <windowsx.h>
7[?{wbq #ifdef _DEBUG
"nEfk{ g #define new DEBUG_NEW
qt!0#z8 #undef THIS_FILE
Ryrvu 1 k static char THIS_FILE[] = __FILE__;
P4S]bPIp #endif
YZ0Jei8+- #define MAX_KEY 100
@is !VzE
#define CTRLBIT 0x04
TO~Z6NA0 #define ALTBIT 0x02
^J-\s_)" #define SHIFTBIT 0x01
NhYce> #pragma data_seg("shareddata")
B78e*nNS#2 HHOOK hHook =NULL;
_)?59 UINT nHookCount =0;
B6#^a static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
%RS8zN static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
X1PXX!]lo[ static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
oF0BBs$ static int KeyCount =0;
p`-Oz] static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
FH}2wO~ _ #pragma data_seg()
J-wF2*0r< HINSTANCE hins;
Td/J6Q90 void VerifyWindow();
cg]>*lH BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
txp^3dZ`^ //{{AFX_MSG_MAP(CHookApp)
&3_.k // NOTE - the ClassWizard will add and remove mapping macros here.
qlgo#[i // DO NOT EDIT what you see in these blocks of generated code!
-\V!f6Q //}}AFX_MSG_MAP
84}Pu% END_MESSAGE_MAP()
tlJ@@v&= \&Zp/;n CHookApp::CHookApp()
T@)|0M {
+1o4l i // TODO: add construction code here,
T>2_ r6; // Place all significant initialization in InitInstance
#%$U-ti }
70BLd(? 7uW=f kxT CHookApp theApp;
+<1MY'>y LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
sOUQd-!" {
1r LK1X BOOL bProcessed=FALSE;
oDBv5 if(HC_ACTION==nCode)
9`X}G` {
b>Em~NMu_ if((lParam&0xc0000000)==0xc0000000){// Key up
/_l$h_{DH switch(wParam)
o!-kwtw`l {
cA8A^Iv:0 case VK_MENU:
6A23H7 MaskBits&=~ALTBIT;
C_ 4(-OWq break;
JULns#tx} case VK_CONTROL:
y8arFG MaskBits&=~CTRLBIT;
y1c2(K>tu break;
M!)~h<YL case VK_SHIFT:
#M~6A^) MaskBits&=~SHIFTBIT;
a*(,ydF|L break;
l}MVk%[ default: //judge the key and send message
yJn<S@)VT: break;
lzDA0MPI: }
'`nf7b( for(int index=0;index<MAX_KEY;index++){
VY|'7in"M if(hCallWnd[index]==NULL)
:'0. continue;
ziTE*rNJ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
[.j&~\AG {
x=%wPVJ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
tEFbL~n bProcessed=TRUE;
b[s=FH]#N }
L }L"BY3$ }
J,Rp&tavt: }
O
!
iN else if((lParam&0xc000ffff)==1){ //Key down
&A!?:?3%O switch(wParam)
Mj5&vs~n; {
[wv;CUmgc case VK_MENU:
eWWtMnq MaskBits|=ALTBIT;
)N'rYS'9 break;
sRKoM case VK_CONTROL:
k|D =Q MaskBits|=CTRLBIT;
,|G~PC8 break;
I:Q3r"1 case VK_SHIFT:
cfhiZ~."T MaskBits|=SHIFTBIT;
_k O<|ev break;
\;bDDTM default: //judge the key and send message
8qF OO3c\V break;
*1c1XN<7 }
e61e|hoX\ for(int index=0;index<MAX_KEY;index++)
q)rxv7Iu\ {
]7DS>%mY( if(hCallWnd[index]==NULL)
jWNF3\ continue;
KzWqHq if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
M>g%wg7Ah {
i8|0zI SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
bTep TWv bProcessed=TRUE;
_y5J]Yu`j }
O3~7 }
Xn= }
f{+n$Cos if(!bProcessed){
g?OC-zw for(int index=0;index<MAX_KEY;index++){
7+;CA+; if(hCallWnd[index]==NULL)
/k^!hI"4c continue;
WinwPn+9 if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
?w5>Z/V SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
L|]!ULi$d }
B6J< }
>& `;@ZOH }
94Q?)0W$ return CallNextHookEx( hHook, nCode, wParam, lParam );
*w5xC5* }
*wp>a?sG\ _Y _v& BOOL InitHotkey()
q>f|1Pf {
fq4[/%6,O if(hHook!=NULL){
JS2h/Y$ nHookCount++;
Zt/4|&w return TRUE;
HVH <S }
7v]9) W=y else
S2<evs1d hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
Lm1
- if(hHook!=NULL)
ESi'3mbeC nHookCount++;
/Xf_b.ZM& return (hHook!=NULL);
B
x-"<^< }
,,+iPGa< BOOL UnInit()
Wi<g {
CKy/gTN if(nHookCount>1){
WWjc.A$ nHookCount--;
, .]1N:
return TRUE;
D/&nEMp6 }
\#7@"~< BOOL unhooked = UnhookWindowsHookEx(hHook);
J-5E# v if(unhooked==TRUE){
eJ+@<+vr;x nHookCount=0;
[Ufx=BPx3 hHook=NULL;
}UX0 eI4 }
|f{(MMlj return unhooked;
u{8:VX }
Bv{DZ?{s O/Mx$Q3re BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
JyDg=%-$2 {
V)jF]u~g BOOL bAdded=FALSE;
,-`A6ehg for(int index=0;index<MAX_KEY;index++){
^^(!>n6r^ if(hCallWnd[index]==0){
d*R('0z{ hCallWnd[index]=hWnd;
@XQItc< HotKey[index]=cKey;
8>AST, HotKeyMask[index]=cMask;
V(wANvH bAdded=TRUE;
0x,NMS KeyCount++;
hQ\W~3S55 break;
HApjXv!U[ }
5ggsOqH }
LOi/+;> return bAdded;
,t@B]ll }
ZVni'ym ?5j}&Y3 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
QE4TvnhK {
=58:e7(df BOOL bRemoved=FALSE;
6rBP,\m for(int index=0;index<MAX_KEY;index++){
1<F6{?,z if(hCallWnd[index]==hWnd){
ypLt6(1j% if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
d^qTY?k. hCallWnd[index]=NULL;
|"aop| HotKey[index]=0;
Ef\&