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:
fB80&G9
C. BlB 一、实现方法
6r|=^3{ W#)X@TlE 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:
F r!FV4 -MRX@ a^1 #pragma data_seg("shareddata")
5JHWt<n{P HHOOK hHook =NULL; //钩子句柄
V/3@iOwD UINT nHookCount =0; //挂接的程序数目
FsO_|r static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
Fw\g\ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
\TZSn1isZX static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
e)= "Fq! static int KeyCount =0;
b'``0OB ) static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
7Db}bDU1
| #pragma data_seg()
k#bG&BF FDFwx| 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。
<UF0Xc&X' iC3C~?,7 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:
|Fz ^(US o$eo\X?J? BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
QChncIqc cKey,UCHAR cMask)
Q 0G5<:wc {
gu6%$z BOOL bAdded=FALSE;
]#Cc7wa
for(int index=0;index<MAX_KEY;index++){
9: .m]QN if(hCallWnd[index]==0){
,z<1:st]< hCallWnd[index]=hWnd;
N]eBmv$| HotKey[index]=cKey;
3&>0'h HotKeyMask[index]=cMask;
Y)@Y$_ bAdded=TRUE;
EK=
y!> KeyCount++;
iciKjXJ: break;
NRny]! }
xP_/5N=f }
"u]&~$ return bAdded;
GeDI\- }
,]:Gn5~ //删除热键
~`Rar2%B BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
?JG^GD7D {
k 3H0$1 BOOL bRemoved=FALSE;
DF_wMv:>^ for(int index=0;index<MAX_KEY;index++){
GGnlkp& E if(hCallWnd[index]==hWnd){
/o%VjP"< if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
; >>n#8` hCallWnd[index]=NULL;
Th$Z9+() HotKey[index]=0;
@R}3f6@67 HotKeyMask[index]=0;
9/!1J bRemoved=TRUE;
<#J5.I 1 KeyCount--;
OLPY<ax break;
$[}EV(#y }
F~i ~%f, }
k_{?{:X;y }
JO`r)_ return bRemoved;
J$sBfOD }
5RvE ), 1
_Oc1RM PWZd< DLL中的钩子函数如下:
T>]T= s;YbZ*oaMe LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
{1Y@%e {
}% f7O BOOL bProcessed=FALSE;
0
zK{)HZ if(HC_ACTION==nCode)
q8&l%-d` {
xu_,0ZT]{ if((lParam&0xc0000000)==0xc0000000){// 有键松开
'B{FRK switch(wParam)
3:MJKS02OD {
A+!,{G case VK_MENU:
WPkKbF MaskBits&=~ALTBIT;
2cUT bRm break;
/q+;!EM case VK_CONTROL:
ax>j3HKi MaskBits&=~CTRLBIT;
m3BL break;
5L:-Xr{ case VK_SHIFT:
,%
QhS5e MaskBits&=~SHIFTBIT;
'UUj(1
f break;
f+Acs*.GQ default: //judge the key and send message
WB?HY?[r break;
:IU7dpwDl }
#gqh0 27 for(int index=0;index<MAX_KEY;index++){
m0As t<u if(hCallWnd[index]==NULL)
zxx\jpBBk continue;
xI1{Wo*2C} if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
yw$4Hlj5 {
n8F~!|lQ0 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
k'PvTWR bProcessed=TRUE;
Lj(cCtb) }
|mE;HvQF }
?"r=08 }
3r,~-6 else if((lParam&0xc000ffff)==1){ //有键按下
9M;t4Um switch(wParam)
RSe4lw {
Go)g}#.& case VK_MENU:
^t5My[R MaskBits|=ALTBIT;
r":anR( ; break;
?9a%g\`?: case VK_CONTROL:
F^'$%XK V MaskBits|=CTRLBIT;
^L5-2;s<U' break;
3q}j"x? case VK_SHIFT:
fCx( MaskBits|=SHIFTBIT;
+x=)Kp> break;
VO8rd>b4 default: //judge the key and send message
jOVF+9M break;
_ Lb"yug }
UPU$SZAIx for(int index=0;index<MAX_KEY;index++){
HK8sn1j if(hCallWnd[index]==NULL)
gr SF}y!3 continue;
GM0Q@`d if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
@2/|rq {
OIL8'xY.w SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
NDP"
@ bProcessed=TRUE;
[p9v#\G; [ }
dv>n38&mDQ }
bO2?DszT5 }
HKXC=^}x' if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
M/quswn1 for(int index=0;index<MAX_KEY;index++){
8^>c_%e} if(hCallWnd[index]==NULL)
l P3|h* continue;
Si>38vCJ* if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
VFL^-tXnA^ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
"vSKj/] //lParam的意义可看MSDN中WM_KEYDOWN部分
A,9JbX }
X}v*"`@Q }
7Hr_ZwO/^ }
C)z4Cn9# return CallNextHookEx( hHook, nCode, wParam, lParam );
dHUbaf:e)T }
GYx0U8MJ[e )Xjn: 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
Q+=pP'cV tO8\} u4c BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
W~/d2_|/ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
CpO_p%P aX^T[ 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
Zk%@GOu\ x/umwT,o v LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
Bz/Vzc( {
yx5e if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
SlG v {
E7fQ9] //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
t1adS:)s SaveBmp();
e4tIO return FALSE;
MqnUym }
0I)$!1~O) …… //其它处理及默认处理
{siOa%;* }
G kjfDY: 172 G eo0-aHs 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。
_-TplGSO=c $+'H000x 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
T+v*@#iJ_ WFOJg& 二、编程步骤
x,,y}_YX ;7lON-@BI 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
ZwS:Te9- ma~#E$i& 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
\b"rf697, E$)| Kv^ 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;
-I|xW J,yKO(}<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;
R ZY=c w(Z ?j%b 5、 添加代码,编译运行程序。
m1X7zU Cy 5l6/5 三、程序代码
x%}D+2ro-t K3?5bT_{ ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
kh
W. #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
/|
v.A\: #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
{cm?Q\DT #if _MSC_VER > 1000
~T1W-ig4[* #pragma once
+
Q-b} #endif // _MSC_VER > 1000
1Z# $X` #ifndef __AFXWIN_H__
2I-d.{ #error include 'stdafx.h' before including this file for PCH
b/'bhE= #endif
Ga7E}y% #include "resource.h" // main symbols
&kg^g%% class CHookApp : public CWinApp
+`
Md5.w {
@t9HRL?T~ public:
GJ,&$@8) CHookApp();
l_^OdQ9D // Overrides
KZppQ0 // ClassWizard generated virtual function overrides
p;+O/'/j //{{AFX_VIRTUAL(CHookApp)
4[gmA public:
l 00i2w virtual BOOL InitInstance();
A[Mke virtual int ExitInstance();
=w$&n%~ //}}AFX_VIRTUAL
y]j.PT`Cw //{{AFX_MSG(CHookApp)
YN8x|DLi? // NOTE - the ClassWizard will add and remove member functions here.
Mn0.!J
" // DO NOT EDIT what you see in these blocks of generated code !
2)f_L|o,m //}}AFX_MSG
*2/Jg'de DECLARE_MESSAGE_MAP()
axC|,8~tq };
,;g%/6X LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
P@7>R7gS BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
P(D>4/f3" BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
rnIjpc F BOOL InitHotkey();
#A/OGi BOOL UnInit();
OyTK,i<n #endif
-r\jIO_ >yO/p(/;jR //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
vzIo2,/7 #include "stdafx.h"
S<nF>JRJa #include "hook.h"
tu
-a`h_NJ #include <windowsx.h>
ZJ/528Ju #ifdef _DEBUG
J>Ar(p #define new DEBUG_NEW
LDt6<D8,Q #undef THIS_FILE
$plk>Khg static char THIS_FILE[] = __FILE__;
f;e#7_ #endif
FuHBzBoM= #define MAX_KEY 100
%ih\|jRt #define CTRLBIT 0x04
i KSRr#/ #define ALTBIT 0x02
51k}LH #define SHIFTBIT 0x01
d0aXA+S% #pragma data_seg("shareddata")
Qte5E}V` HHOOK hHook =NULL;
Cj0r2^` UINT nHookCount =0;
]rG=\>U3~ static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
bY~K)j
v3& static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
?qjdmB|w static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
/@9Q:'P static int KeyCount =0;
pv]@}+<Dt static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
g NI1W@) #pragma data_seg()
q[$>\Nfg>B HINSTANCE hins;
ytcLx77`: void VerifyWindow();
<XeDJ8
' BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
N^;lp<{6? //{{AFX_MSG_MAP(CHookApp)
J
n.7W5v // NOTE - the ClassWizard will add and remove mapping macros here.
iXWHI3
// DO NOT EDIT what you see in these blocks of generated code!
uKJ:)oyaCP //}}AFX_MSG_MAP
w S END_MESSAGE_MAP()
q<09]i SyL"Bmi CHookApp::CHookApp()
DGTLlBkT
{
#
&v4c // TODO: add construction code here,
c9|4[_&B~ // Place all significant initialization in InitInstance
)M8d\] }
[c?0Q3F ;As~TGiT CHookApp theApp;
% S312=w LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
u3h(EAH> {
g0,~|. BOOL bProcessed=FALSE;
, cxqr3
o if(HC_ACTION==nCode)
$[T~<I {
$JFjR@j if((lParam&0xc0000000)==0xc0000000){// Key up
2Io|? switch(wParam)
0)dpU1B#M {
(TeH)j! case VK_MENU:
~?/7:S MaskBits&=~ALTBIT;
DI0& _, break;
aCU[9Xr? case VK_CONTROL:
Zo=,!@q( MaskBits&=~CTRLBIT;
Ab$E@H# break;
)q$[uS_1[ case VK_SHIFT:
A;Uc&G MaskBits&=~SHIFTBIT;
Q YA4C1h' break;
neEqw+#Z default: //judge the key and send message
BValU break;
(
fFrX_K] }
|gk*{3~y for(int index=0;index<MAX_KEY;index++){
|.; N_i if(hCallWnd[index]==NULL)
Q
8]X continue;
3U6QYD55]] if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
LW=qX%o{ {
*JOK8[Qn SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
1RkN^FZOxq bProcessed=TRUE;
Trirb'qO }
m-{DhJV }
NZGO8u }
gc4o
|x else if((lParam&0xc000ffff)==1){ //Key down
s.z)l$ switch(wParam)
B;bP~e>W {
'M%iS4b{IM case VK_MENU:
}cz58% MaskBits|=ALTBIT;
/IirTmFK break;
RY5e%/bg~U case VK_CONTROL:
wU%uO/sU9 MaskBits|=CTRLBIT;
Md6u4c break;
~cr iZI/ case VK_SHIFT:
X0*+]tRg MaskBits|=SHIFTBIT;
ca=MUm=B break;
.r/s.g default: //judge the key and send message
(s'xO~p break;
P0UR{tK }
caEIE0H~ for(int index=0;index<MAX_KEY;index++)
n^'d8Y( {
aMqt2{f+ if(hCallWnd[index]==NULL)
i7H([b<_m continue;
k2Q[v if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
R5sEQ| E {
C5=^cH8 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
)F9IzR-&m bProcessed=TRUE;
-IIrrY
O }
Qz`evvH }
q`AsnAzo& }
$;g*s?F* if(!bProcessed){
ceg\lE:8 for(int index=0;index<MAX_KEY;index++){
lR?1,yLp if(hCallWnd[index]==NULL)
_3
!s{ continue;
]FR#ZvM>x if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
6?"Gj}|r SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
7:~3B-Tb }
v0'z''KM! }
:{w3l O }
I>MLI=[Kg return CallNextHookEx( hHook, nCode, wParam, lParam );
r[E #JHw }
^3HSw ?a" '(lsJY[-x BOOL InitHotkey()
OBF M70K {
H~[q<ybxr if(hHook!=NULL){
~U<j_j)z4. nHookCount++;
s\'t=}0q return TRUE;
2zo>`;l }
65B&>`H~ else
kU:Q&[/jzH hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
_WV13pnRu if(hHook!=NULL)
V^(W)\ nHookCount++;
|QrVGm@2 return (hHook!=NULL);
%m|BXyf]_B }
S?DMeZ{: BOOL UnInit()
; 180ct4 {
dnANlNMk? if(nHookCount>1){
Z){fie4WM nHookCount--;
|$8N*7UD return TRUE;
6\h*SBI?( }
@sR/l; BOOL unhooked = UnhookWindowsHookEx(hHook);
6/a%%1c1 if(unhooked==TRUE){
=)#XZ[#F nHookCount=0;
]_>38f7h hHook=NULL;
|}l/6WHB }
f`}u9!jVR return unhooked;
0Dd8c\J }
$7-4pW$y x!4<ff. BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
98}l`J=i {
RG1#\d-fE BOOL bAdded=FALSE;
<Rt0
V%}- for(int index=0;index<MAX_KEY;index++){
.j!:Hp(z} if(hCallWnd[index]==0){
5"#xbvRS0H hCallWnd[index]=hWnd;
%z1hXh#+ HotKey[index]=cKey;
^]LWcJ?"^! HotKeyMask[index]=cMask;
2 $Z4 >! bAdded=TRUE;
8LtkP&Wx KeyCount++;
]:6IW: break;
Y
Odwd}M }
5IG#-Q(6sp }
%e:
hVU return bAdded;
P+p:Ed80 }
&>@EfW]( n%dh|j2u BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Mc|UD*Z {
#1>c)_H BOOL bRemoved=FALSE;
r2;+ACwWf_ for(int index=0;index<MAX_KEY;index++){
c}7Rt|`c if(hCallWnd[index]==hWnd){
h*NBSvn if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
uQkFFWS hCallWnd[index]=NULL;
%tz foiJ%P HotKey[index]=0;
p-8x>dmP( HotKeyMask[index]=0;
c+TCC%AJQI bRemoved=TRUE;
:jWQev"/ KeyCount--;
2K(zYv54 break;
ue6&)7:~ }
WGMEZx }
(d5kD#.N }
[M.!7+$o return bRemoved;
~p/1
9/ }
<yEd'Z z!\)sL/" void VerifyWindow()
&FzZpH {
Pu|3_3^ for(int i=0;i<MAX_KEY;i++){
uHO>FM, if(hCallWnd
!=NULL){ ~d6zpQf7>
if(!IsWindow(hCallWnd)){ Oc?]L&a