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:
[}mx4i
eYpK!9 一、实现方法
,8tk]W[C ro%Jg 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:
l;~b:[r 8q}955Nl #pragma data_seg("shareddata")
4X}.aZO&b HHOOK hHook =NULL; //钩子句柄
rf ?\s/#OY UINT nHookCount =0; //挂接的程序数目
wr) \GJ#> static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
A$7j B4 static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
;4%Co)Rw static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
3J3Yt` static int KeyCount =0;
;4:[kv@ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
9I|D"zXn #pragma data_seg()
pO_$ 8=G+ :{g;J 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。
&1 BACKu 6zZT5
Kn 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:
)/p=ZH0[ ?LwBF;Y BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
H(QbH)S$6 cKey,UCHAR cMask)
^o LMgz {
^b;3Jj BOOL bAdded=FALSE;
0XSMby?t` for(int index=0;index<MAX_KEY;index++){
` P,-NVB if(hCallWnd[index]==0){
"9^OT hCallWnd[index]=hWnd;
(zmLMG(R HotKey[index]=cKey;
Ue?mb$ykC. HotKeyMask[index]=cMask;
=$wQA bAdded=TRUE;
K!<3|d KeyCount++;
83i;:cn break;
>d9b"T }
)wM881_! }
Q2)CbHSz return bAdded;
aA6m5 }
75"&"*R/*G //删除热键
>7$h BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
<K:L.c! {
~_]i'ii8 BOOL bRemoved=FALSE;
3nbTK3, for(int index=0;index<MAX_KEY;index++){
1_B;r9x if(hCallWnd[index]==hWnd){
[.Y]f.D if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
hN U.y hCallWnd[index]=NULL;
Y(/y,bJ?jp HotKey[index]=0;
k^{}p8;3 HotKeyMask[index]=0;
N0V`xrS bRemoved=TRUE;
/*G-\| KeyCount--;
DUMC4+i break;
W}iDT?Qi }
x,fX mgE }
TB%NHq-! }
GQ8A}gwH return bRemoved;
"Q.KBX v/ }
n|'}W+ CxV$_J wZs jbNf`K DLL中的钩子函数如下:
ZWb\^N r @URs;O= LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
Yma-$ytp {
f{w[H S,z BOOL bProcessed=FALSE;
KLpFW} if(HC_ACTION==nCode)
!<UdG+iV {
hcT5> w[ if((lParam&0xc0000000)==0xc0000000){// 有键松开
*JA0Vs5 switch(wParam)
?58*#'r {
iGw\A!}w\ case VK_MENU:
XE`u MaskBits&=~ALTBIT;
l|S_10x5 break;
b^'>XT~1J& case VK_CONTROL:
(o2.*x MaskBits&=~CTRLBIT;
.)|2^ 'W break;
nhLw&V3y case VK_SHIFT:
\^3cNw MaskBits&=~SHIFTBIT;
@M)" break;
]A,Og_g default: //judge the key and send message
q71V]! break;
,KaO8^PB }
~(-df> for(int index=0;index<MAX_KEY;index++){
mum4Uj if(hCallWnd[index]==NULL)
cq4sgQ?sW continue;
b~C^cM if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
iTVepYv4m {
C5^9D SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
{wptOZ
bProcessed=TRUE;
BMH?BRi }
U1=]iG<% }
[<JY[o= }
fD#!0^ else if((lParam&0xc000ffff)==1){ //有键按下
e8U6D+jY switch(wParam)
zxrbEE Q {
T( CTU/a-, case VK_MENU:
'p&q}IO MaskBits|=ALTBIT;
5n1T7-QCL break;
D9r4oRkP* case VK_CONTROL:
>l =;6QL MaskBits|=CTRLBIT;
:OD-L)Or break;
h/NI5 case VK_SHIFT:
#^9a[ZLj0 MaskBits|=SHIFTBIT;
tKCX0UZ' break;
2!nz>K default: //judge the key and send message
mc|8t0+1` break;
<.U(%`| }
>@.:9}Z for(int index=0;index<MAX_KEY;index++){
^TqR0a-* if(hCallWnd[index]==NULL)
t&MLgu continue;
bmw"-W^U[ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Ih%LKFT {
uC5W1LyI SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
p&lT! 5P!A bProcessed=TRUE;
PcEE@W9 }
,F?O} ijk }
;tWi4iT+. }
1v'|%B;O if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
K}!YXy h for(int index=0;index<MAX_KEY;index++){
wF)g@cw if(hCallWnd[index]==NULL)
"q7pkxEuJ continue;
[W8?ww%qT if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
n7,LfO# SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
'&F
PkT:5 //lParam的意义可看MSDN中WM_KEYDOWN部分
!4}Wp. }
RX,c 4; }
#OsUF,NU }
xeKfc}:&z return CallNextHookEx( hHook, nCode, wParam, lParam );
g)=-%n'RoE }
BUU ) Sz #F:\_!2c 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:
>]/aG! tREC)+*\ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
hEfFMi=a` BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
S*(ns<L (2'q~Z+>' 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:
?dQ#%06mn ?#J;[y\^ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
D)J'xG_<O {
f=Kt[|%'e if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
~?:Xi_3Lo {
mO@Sl(9 //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
PaBqv] SaveBmp();
dk@iAL*v return FALSE;
#QKgY7 }
vf
h*`G$ …… //其它处理及默认处理
M*<Bp }
r=ht:+m r95$( N ? W2Wy\ 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。
rE4qPzL rB-}<22. 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。
skBzwVW I X m%aT 二、编程步骤
7=@MnF` +KHk`2{y~ 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";
2D"\Ox -"w&g0Z 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
)Zit6I W%P0X5YQ 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,Dcg2ZM" RRJN@|" 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;
F!&_ h2mU 5、 添加代码,编译运行程序。
k4BiH5\hA Kv#TJn 三、程序代码
$6yr:2Xvt XV0t
8#T2 ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
#brV{dHV, #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
%^<A`Q_ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
S0mF%" #if _MSC_VER > 1000
Yc~c(1VRz #pragma once
*egAx #endif // _MSC_VER > 1000
H^0`YQJ3 #ifndef __AFXWIN_H__
FW!1 0K? #error include 'stdafx.h' before including this file for PCH
82~ZPZG #endif
!_LRuqQ?" #include "resource.h" // main symbols
D(^ |'1 class CHookApp : public CWinApp
vV /fTO {
`yWWX.` public:
^*+-0b;[G CHookApp();
6ZwFU5)QE/ // Overrides
D3kx&AR // ClassWizard generated virtual function overrides
UZ3oc[#D=] //{{AFX_VIRTUAL(CHookApp)
=]hPX public:
=U<6TP]{ virtual BOOL InitInstance();
I
DtGtkF virtual int ExitInstance();
\:d|'r8OCM //}}AFX_VIRTUAL
h2fTG //{{AFX_MSG(CHookApp)
bx%P-r31 // NOTE - the ClassWizard will add and remove member functions here.
.LEn~ 8 // DO NOT EDIT what you see in these blocks of generated code !
2 NrMse //}}AFX_MSG
o0Pc^ DECLARE_MESSAGE_MAP()
+}@6V4BRn };
#e(P~'A0 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
2_#Vw&v BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
ZHW|P BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
h]#bPb BOOL InitHotkey();
pxO?:B BOOL UnInit();
]WP[hF #endif
DeL7sU E/N*n!sV //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
yct^AN|% #include "stdafx.h"
/Jw65 e #include "hook.h"
<-m?l6 #include <windowsx.h>
uZ7~E._ #ifdef _DEBUG
0G"I}Jp{ #define new DEBUG_NEW
~pj/_@S@x #undef THIS_FILE
lhLE)B2a2 static char THIS_FILE[] = __FILE__;
K/+w6d #endif
y|E{] #define MAX_KEY 100
fxL0"Ry #define CTRLBIT 0x04
~LuR)T=%es #define ALTBIT 0x02
4'ymPPY #define SHIFTBIT 0x01
Xv1mjHZCC #pragma data_seg("shareddata")
JYU0&nZl4 HHOOK hHook =NULL;
=/]d\JSp UINT nHookCount =0;
,6FmU$
Kn static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
6Y(Vs> static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
0(~,U!g[= static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
3-Xc3A=w static int KeyCount =0;
Ib665H7w static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
3gzcpFNqX #pragma data_seg()
tZn=[X~Vw@ HINSTANCE hins;
yvz2eAXa void VerifyWindow();
FD*w4U5 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
}I;5yk,o //{{AFX_MSG_MAP(CHookApp)
><Z`)}f // NOTE - the ClassWizard will add and remove mapping macros here.
;p}X]e l} // DO NOT EDIT what you see in these blocks of generated code!
0/Wo":R: //}}AFX_MSG_MAP
LVX01ox$ END_MESSAGE_MAP()
p .^#mN 7ZVW7%,zF CHookApp::CHookApp()
T2V#
fYCc {
#`9D,+2iB% // TODO: add construction code here,
'aoHNZfxw // Place all significant initialization in InitInstance
'WW[' }
{_i.IPp~ ;+/[<bv d" CHookApp theApp;
,/ P)c*at5 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
O-ZB4hN8 {
|p1pa4%} BOOL bProcessed=FALSE;
0aS&!"o! if(HC_ACTION==nCode)
C3
m#v[+ {
"|:I]ZB if((lParam&0xc0000000)==0xc0000000){// Key up
!@<>S>uGG switch(wParam)
>nL9%W}8M {
`*nK@: case VK_MENU:
eVYUJ, MaskBits&=~ALTBIT;
e~,/Z\i break;
6s"Erq5q case VK_CONTROL:
Py)'%e MaskBits&=~CTRLBIT;
uBe1{Z break;
xe3t_y case VK_SHIFT:
O]Mz1 ev| MaskBits&=~SHIFTBIT;
4&c7^ 4w~ break;
_(<D*V[ default: //judge the key and send message
9-9:]2~g! break;
cNd2XQB9= }
FGP~^Dr/ for(int index=0;index<MAX_KEY;index++){
68^5X"OGF if(hCallWnd[index]==NULL)
m%hUvG| i continue;
q3s
+?& if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
t,2Q~ied= {
8VwByk8
SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
`Oc`I9 bProcessed=TRUE;
A%G
\
AT }
ul',!js? }
1JU1XQi }
+AT!IZrB2i else if((lParam&0xc000ffff)==1){ //Key down
/{~cUB,Um switch(wParam)
S}rW=hO {
?kvkdHEO_ case VK_MENU:
?OU+)kgzh MaskBits|=ALTBIT;
u$Za hN! break;
D*oJz3[ case VK_CONTROL:
\y%:[g}Fvw MaskBits|=CTRLBIT;
/_rg*y* break;
jR^>xp; case VK_SHIFT:
AF
qut MaskBits|=SHIFTBIT;
>qSaF break;
8\~IwtSk default: //judge the key and send message
p?X`f# break;
G([!(8&2Y }
:X`Bc" for(int index=0;index<MAX_KEY;index++)
=m4_8)-8u {
3??*G8Yp if(hCallWnd[index]==NULL)
om"q[Tudc continue;
*Iu
.>nw if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
ZhWtY {
$z9z'^HqO SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
b (,X3x* bProcessed=TRUE;
7x%0^~/n }
C(-bh]J }
pEjA*6v|, }
H:ar&o#( if(!bProcessed){
GA{Q6]B for(int index=0;index<MAX_KEY;index++){
J! @$lyH if(hCallWnd[index]==NULL)
TT429 continue;
&S.zc@rN if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
(BgO< SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
%EuXL% B }
od- 0wJN-m }
I499Rrw#E }
1f 0"z1 return CallNextHookEx( hHook, nCode, wParam, lParam );
T#1>pED }
] Qp0|45= }31z
35 BOOL InitHotkey()
<mc[-To {
MK]S205{ if(hHook!=NULL){
0;-S){ nHookCount++;
{.We%{4V return TRUE;
1R/=as,R }
7/;Xt& else
=W9;rQm hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
&/7AW(? if(hHook!=NULL)
"jVMk nHookCount++;
T
x_n$ & return (hHook!=NULL);
13]sZ([B%| }
vXnTPjbE BOOL UnInit()
K%<Z"2!+ {
<!\J([NM8 if(nHookCount>1){
Riq5Au?*) nHookCount--;
%aX<p{EY return TRUE;
BPnZ"w_ }
,=tVa]) BOOL unhooked = UnhookWindowsHookEx(hHook);
`@{qnCNQ if(unhooked==TRUE){
A$RN7# nHookCount=0;
9-+6Ed^2 hHook=NULL;
Ed|7E_v }
n>X return unhooked;
%S22[;v{N }
cI3uH1;# z(^p@&r)F BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
U~SK 'R {
TA=Ij,z~ BOOL bAdded=FALSE;
S:] w@$ for(int index=0;index<MAX_KEY;index++){
Vkex&?>v$ if(hCallWnd[index]==0){
bw{%X
hCallWnd[index]=hWnd;
>RxZ-.,a HotKey[index]=cKey;
T7YzO,b/
HotKeyMask[index]=cMask;
VGBL<X bAdded=TRUE;
SZ-% 0z KeyCount++;
l[^bo/ break;
Mg95us }
]"^GRFK5 }
(jCE&'?} return bAdded;
EkV v }
nX>k}&^L /Mf45U< BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
s&vOwPmV {
U %Aj~K^b BOOL bRemoved=FALSE;
il-v>GJU7{ for(int index=0;index<MAX_KEY;index++){
T7n;Bf if(hCallWnd[index]==hWnd){
K/Axojo if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
;W#G<M&n' hCallWnd[index]=NULL;
+bd/*^ HotKey[index]=0;
MQ"<r,o?: HotKeyMask[index]=0;
cGC&O%`i,\ bRemoved=TRUE;
A20_a;V KeyCount--;
.+aSa?h_ break;
P/t$xqAL }
A]BD2 }
NF0} eom }
2P9h x5PiV return bRemoved;
<