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:
+7
j/.R
N:#$S$ 一、实现方法
MY z!zI =,qY\@fq 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:
Fe$o*r, QR~4Fe #pragma data_seg("shareddata")
gVJh@]8) HHOOK hHook =NULL; //钩子句柄
/|h+,]<
> UINT nHookCount =0; //挂接的程序数目
4k<U5J static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
8ql<7RTM! static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
x{So static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
2,Z@< static int KeyCount =0;
~d,$nZ"z static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
$/(``8li_ #pragma data_seg()
Rp:I&f$Hk/ Q[H4l({E 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。
t%k`)p7O ~+Cl9:4T 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:
@(N}
{om Z?9G2<i BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
a%6=sqxE cKey,UCHAR cMask)
jJ2{g> P0P {
\S?-[v*{ BOOL bAdded=FALSE;
~-%z:Re'_ for(int index=0;index<MAX_KEY;index++){
G@T_o4t if(hCallWnd[index]==0){
f8f3[O!x hCallWnd[index]=hWnd;
@ IDY7x27 HotKey[index]=cKey;
Z
R~2Y?Wt9 HotKeyMask[index]=cMask;
e~,+rM bAdded=TRUE;
/%t`0pi KeyCount++;
f/0k,~,* break;
h:FN&E c} }
d}Y#l}!E6 }
A5%Now;.cf return bAdded;
E\9HZ;}G }
W&I:z-VH //删除热键
QMX BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
XC}2GHO< {
H3iYE~^# BOOL bRemoved=FALSE;
qzZ;{>_f
for(int index=0;index<MAX_KEY;index++){
!g|[A7<| if(hCallWnd[index]==hWnd){
dg+"G|nr if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
ALInJ{X hCallWnd[index]=NULL;
}y(cv}8Y HotKey[index]=0;
pMAFZfte!x HotKeyMask[index]=0;
h*Mi/\ bRemoved=TRUE;
[3tU0BU" KeyCount--;
dww4o~hO break;
GQjU="+ }
*8u<?~9F }
~0Zy$L/D }
;uZeYY? return bRemoved;
kaECjZ_&+ }
{8%KO1xB cb. -AlqQ =dWqB& DLL中的钩子函数如下:
4JH^R^O<n
-y$<fu9
e LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
-&%!
4(Je {
n%QWs1 b BOOL bProcessed=FALSE;
$}0\sj% if(HC_ACTION==nCode)
V9>$M= {
jG#e%`' if((lParam&0xc0000000)==0xc0000000){// 有键松开
AJ#YjkO>] switch(wParam)
4O{,oN~7 {
q+?q[:nR- case VK_MENU:
YWk+}y}^d MaskBits&=~ALTBIT;
mMCd break;
f|j<Mj+\ case VK_CONTROL:
srKEtd" MaskBits&=~CTRLBIT;
W}Rzn break;
{817Svp@ case VK_SHIFT:
>I+p;V$@ MaskBits&=~SHIFTBIT;
f]Rh<N$ break;
rfh`;G5s default: //judge the key and send message
lpbcpB break;
"837b/>/ }
nH+wU;M for(int index=0;index<MAX_KEY;index++){
|`AJP if(hCallWnd[index]==NULL)
G//hZwf0 continue;
%T}*DC$&S if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
_]0<G8|Rv {
2f rwU~y SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
?MSV3uODb bProcessed=TRUE;
' Yy+^iCus }
b
|ijkys }
M~.1:%khM }
mWMtz]M} else if((lParam&0xc000ffff)==1){ //有键按下
p$Floubh] switch(wParam)
d-H03F@N {
tU.~7f#+A case VK_MENU:
xo!2GPD. MaskBits|=ALTBIT;
.k,,PuP break;
60xL.Z case VK_CONTROL:
/3;]e3x MaskBits|=CTRLBIT;
3/,}&SX break;
kJCeQK:W case VK_SHIFT:
EO/41O MaskBits|=SHIFTBIT;
/:C<{m.[} break;
bUuQ"!>ppu default: //judge the key and send message
Jpn= ^f[rm break;
?YF2Uc8z%2 }
zu,Yuq for(int index=0;index<MAX_KEY;index++){
E!=Iz5 if(hCallWnd[index]==NULL)
Wo5%@C#M continue;
tLP
Er@ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
;B{oGy. {
_9<Mo;C SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
,@zw
bProcessed=TRUE;
]\/"-Y#4Q }
$gCN[%+j }
xiqeKoAD }
" z -tL if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
mH)8A+us for(int index=0;index<MAX_KEY;index++){
F;T;'!mb if(hCallWnd[index]==NULL)
nXERj; Q" continue;
7ab'q&Y[ if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
00yWk_w SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
f @Vd'k< //lParam的意义可看MSDN中WM_KEYDOWN部分
eZ
7Atuv }
v]T?xo~@' }
XI,= W }
@h/-P'Lc=7 return CallNextHookEx( hHook, nCode, wParam, lParam );
S.pXo'} }
.Y^pDR12 b)r;a5"<5 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
Xi w U6YHq2< BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
S#T u/2<} BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
Zu94dFP CV2#G *
为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
.0MY$ 0s 4E+8kz' LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
(B03f$8}*_ {
Qkc9X0J! if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
$lAdh {
;s8\F]K //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
t[MM=6|Wb SaveBmp();
**.23<n^W return FALSE;
~g;)8X;;+ }
BnaI30- …… //其它处理及默认处理
MeAY\V%G=o }
]@ }o"Td $'yWg_( t3=K>Y@w 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
xc7Rrh]} dV-6 l6 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
d<E2=WVB6 IYa(B+nB) 二、编程步骤
)19#g1rn5 B9H.8+~( 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
O9N+<sU=X s4 Vju/ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
:)FNhx3 ZP-9KA$" 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;
Qh*}v!3Jo K??jV&Xor 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;
E )2/Vn2 rje;Bf 5、 添加代码,编译运行程序。
dTte4lh V}Oz!
O 三、程序代码
}G!'SZ$F 5 {wO.nOB ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
`,4YPjk^ #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
7e D`
is #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
"W_E!FP]r #if _MSC_VER > 1000
4ywtE}mp #pragma once
)Lk2tvr #endif // _MSC_VER > 1000
RN;#H_
q #ifndef __AFXWIN_H__
e-.(O8 #error include 'stdafx.h' before including this file for PCH
Ec }9R3 m #endif
, 10+Sh #include "resource.h" // main symbols
UQWv) class CHookApp : public CWinApp
O"_QDl<ya {
XXQC`%-]<i public:
G/w@2lYx CHookApp();
n"Jj'8k // Overrides
dkSd
Y+Q // ClassWizard generated virtual function overrides
@Y+kg //{{AFX_VIRTUAL(CHookApp)
oeI[x public:
*$/Go8t4u virtual BOOL InitInstance();
f/Z-dM\e virtual int ExitInstance();
jP<6Q|5F //}}AFX_VIRTUAL
?*<1B //{{AFX_MSG(CHookApp)
5r;)Ppo // NOTE - the ClassWizard will add and remove member functions here.
CurU6x1 // DO NOT EDIT what you see in these blocks of generated code !
/Wdrpv-%,1 //}}AFX_MSG
]eTp?q%0 DECLARE_MESSAGE_MAP()
0t*PQ% };
"g(q)u > LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
n"R$b: BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
Z$35`:x&h BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
.RS BOOL InitHotkey();
:73T9/ BOOL UnInit();
`eGp.[ffT #endif
.li)k[] ts ol_&epG;ST //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
kjSzuqB #include "stdafx.h"
h}S2b@e| #include "hook.h"
E#kH>q@K`$ #include <windowsx.h>
3[~LmA #ifdef _DEBUG
[y<s]C6E #define new DEBUG_NEW
ADMeOdgca #undef THIS_FILE
&((04<@e static char THIS_FILE[] = __FILE__;
.0|_J|{ #endif
q@4Cw&AI+ #define MAX_KEY 100
gUp9yV #define CTRLBIT 0x04
~{6}SXp4U #define ALTBIT 0x02
-{yG+1 #define SHIFTBIT 0x01
E,4*a5Fi #pragma data_seg("shareddata")
YKx+z[A/p HHOOK hHook =NULL;
BpF}H^V- UINT nHookCount =0;
y! j>_m){w static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
qtP*O#1q static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
W5&KmA static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
zS?DXE static int KeyCount =0;
_G)x\K]N static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
&(20*Vn,O #pragma data_seg()
Z,F1n/7 HINSTANCE hins;
7re4mrC void VerifyWindow();
t"6u BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
pf3- //{{AFX_MSG_MAP(CHookApp)
+H!aE} // NOTE - the ClassWizard will add and remove mapping macros here.
vE~<R // DO NOT EDIT what you see in these blocks of generated code!
YDEb MEMd/ //}}AFX_MSG_MAP
g#5t8w END_MESSAGE_MAP()
<H1e+l{8$ CTc#*LJx>j CHookApp::CHookApp()
W'Qy4bl7C {
Ft>, // TODO: add construction code here,
TG.\C8;vFh // Place all significant initialization in InitInstance
Btc[ }
v)'Uoe"R% J!zL)u| CHookApp theApp;
C,{ Ekbg LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
w1= f\ {
X-%91z:o58 BOOL bProcessed=FALSE;
"+BuFhSLf if(HC_ACTION==nCode)
VO*fC {
)KY U[ if((lParam&0xc0000000)==0xc0000000){// Key up
lq27^K switch(wParam)
1,6Y)_ {
|%=c<z+8 case VK_MENU:
?:RWHe.P MaskBits&=~ALTBIT;
}cg 1CT5 break;
w)gMJX/0yw case VK_CONTROL:
B 5va4@ MaskBits&=~CTRLBIT;
FsfP^a break;
"o<&3c4 case VK_SHIFT:
(m=F MaskBits&=~SHIFTBIT;
iP?=5j=4 break;
<P
c;8[ default: //judge the key and send message
E%)3{#.z break;
L4Si0 K }
5%R$7>`Z for(int index=0;index<MAX_KEY;index++){
}h\]0'S~J~ if(hCallWnd[index]==NULL)
Oxh.& continue;
U6_GEBz~y if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
p%CcD]o {
t$*CyYb{@ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
n UD;y}}n bProcessed=TRUE;
; <|m0>X }
@X#e }
z)pp{ }
T@DT|lTI else if((lParam&0xc000ffff)==1){ //Key down
\H.1I=< switch(wParam)
<:`x> _ {
K]Q1VfeL= case VK_MENU:
&?yVLft MaskBits|=ALTBIT;
>)iCKx break;
>J@hqW case VK_CONTROL:
C)0JcM MaskBits|=CTRLBIT;
ITEd[
@^d break;
A(qy>x-BI case VK_SHIFT:
.tRWL! MaskBits|=SHIFTBIT;
o2NU~Ub break;
uVV;"LVK~ default: //judge the key and send message
NxQ+z^o\ break;
%NfbgJcL_ }
1\BQq for(int index=0;index<MAX_KEY;index++)
[|\BuUT' {
Qxh 1I?h if(hCallWnd[index]==NULL)
O[#pB.
4 continue;
1t7S:IZ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
N6_<[` {
K~Hp%. SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
uWKc
. bProcessed=TRUE;
dzPwlCC%- }
! <xe Ao%8 }
^3
'7 }
r(QjVLjj`k if(!bProcessed){
:If1zB) for(int index=0;index<MAX_KEY;index++){
+gQoYlso if(hCallWnd[index]==NULL)
Y!|*`FII continue;
4RV5:&ALLS if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
W{2(fb SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
8_@#5 }
~&Gw[Nd1 }
PI0[ }
DpaPRA)x return CallNextHookEx( hHook, nCode, wParam, lParam );
@4N@cM0
}
vg5;F[e 0*KU"JcXd BOOL InitHotkey()
lC ^NhQi {
sA u ;i if(hHook!=NULL){
n-7|{1U nHookCount++;
?lYi![.o return TRUE;
T6g(,xPcL }
UlN+ else
GX+o A] hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
?Rj)x%fN if(hHook!=NULL)
jJF(*D nHookCount++;
qh)o44/
$ return (hHook!=NULL);
A9[ELD>p }
4M&6q(389 BOOL UnInit()
+)4_1i4"x {
gL+8fX2G6 if(nHookCount>1){
C=6 Vd nHookCount--;
lxpi return TRUE;
+8 avA:o }
NyTv~8A`) BOOL unhooked = UnhookWindowsHookEx(hHook);
?-P]m&nh| if(unhooked==TRUE){
G#&R/Tc5N nHookCount=0;
6+9inWTT( hHook=NULL;
gZ*8F|sg }
1}{bHj return unhooked;
{VPF2JFB[ }
A3C#wJ mRT`'fxK BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
b NBpt}$ {
%z&=A%'a BOOL bAdded=FALSE;
, wT$L3 for(int index=0;index<MAX_KEY;index++){
&xlz80% if(hCallWnd[index]==0){
BK>uJv-qU hCallWnd[index]=hWnd;
9WaKs d f HotKey[index]=cKey;
ei>8{v&g
HotKeyMask[index]=cMask;
AKVll bAdded=TRUE;
}>\+eG KeyCount++;
|RBgJkS;8 break;
6_a42# }
C< GS._V& }
Q]7Rqslz return bAdded;
xA DjQ%B }
2-9'zN0u }%B^Vl%ZZ BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
[.O3z*[9# {
X0Q};, BOOL bRemoved=FALSE;
%,-oxeM1u for(int index=0;index<MAX_KEY;index++){
FTx&] QN? if(hCallWnd[index]==hWnd){
D&f(h][hH? if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
)E<<