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:
@$9'@")
f>`dF?^6 一、实现方法
Dre2J<QL z2_6??tS/c 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:
$5x ,6[& ryB}b1`D #pragma data_seg("shareddata")
'2^7-3_1 HHOOK hHook =NULL; //钩子句柄
>P6BW UINT nHookCount =0; //挂接的程序数目
PHOP%hI$ static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
0k)rc$eDF+ static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
Q7Iw[=;\ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
yAL[[ static int KeyCount =0;
,R%q}IH# static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
BTgG4F/) #pragma data_seg()
G uz"wY KlRr8G!Z 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
h/?l4iR* ;X*cCb`h DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
}>)[<;M>% wLK07e( BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
(e(:P~Ry cKey,UCHAR cMask)
<-D/O$q {
V |(H|9 BOOL bAdded=FALSE;
8J$|NYv_b for(int index=0;index<MAX_KEY;index++){
#@<9S{F if(hCallWnd[index]==0){
[8tL"G6s hCallWnd[index]=hWnd;
^[:p|U2mA HotKey[index]=cKey;
_SW3_8SuM. HotKeyMask[index]=cMask;
;r c`OZyE bAdded=TRUE;
C8
\5A8c KeyCount++;
M5gWD==uP break;
:#@ = B] }
7}M2bH} \K }
PDs@?nz, return bAdded;
$Y69@s %f }
1UPC e //删除热键
'>r7V BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Ym3\pRFiD {
94B\5I} BOOL bRemoved=FALSE;
hjZKUMG(k for(int index=0;index<MAX_KEY;index++){
'yMF~r3J if(hCallWnd[index]==hWnd){
"g$IP9?U if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
/p8dZ+X hCallWnd[index]=NULL;
DI+fwXeg HotKey[index]=0;
qkiI/nH3 HotKeyMask[index]=0;
ep)>X@t bRemoved=TRUE;
bv&;R KeyCount--;
n2iJ%_zp break;
ty8v
6J# }
.l.a(_R }
X5j1`t, }
~l)-wNqR4r return bRemoved;
J0@X<Lt U }
;q*e=[_DF M5 <@~V/[ ^]TVo\,N DLL中的钩子函数如下:
c%MW\qx <J^MCqp!v LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
%i5M77#Z {
\otWd BOOL bProcessed=FALSE;
4^M if(HC_ACTION==nCode)
y3fGWa*7e {
Ytl4kaYS if((lParam&0xc0000000)==0xc0000000){// 有键松开
yU9DSY\m{ switch(wParam)
+0OLc2
)w {
tCdqh- case VK_MENU:
c@8 93<_ MaskBits&=~ALTBIT;
r-Pkfy( break;
YJ\Xj56gv case VK_CONTROL:
Ft&]7dT{W MaskBits&=~CTRLBIT;
`\}v#2VJ break;
*{L)dW+: case VK_SHIFT:
H !$o$}A MaskBits&=~SHIFTBIT;
#w' kV# break;
{GQ^fu;q default: //judge the key and send message
INJEsz break;
cLLbZ=` }
NxsBX:XDn for(int index=0;index<MAX_KEY;index++){
!wNr3LG if(hCallWnd[index]==NULL)
c-(UhN3WG continue;
]7RD"} if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
d8c=L8~jt {
G|!on<l& SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
?.Ca|H< bProcessed=TRUE;
<$IM8Y5p+w }
.=s&EEF }
EwvoQ$#jv }
]?!mS[X else if((lParam&0xc000ffff)==1){ //有键按下
a ?)NC switch(wParam)
>s<^M|S07 {
ivN&HAxI@ case VK_MENU:
f=WDR m] MaskBits|=ALTBIT;
=,6z4" ) break;
y~U #veY case VK_CONTROL:
pe1R(|H MaskBits|=CTRLBIT;
:g Wu9Y|{ break;
1pgU}sRk case VK_SHIFT:
'Wmx)0) MaskBits|=SHIFTBIT;
T7hcnF$ break;
y.< m#Zzt default: //judge the key and send message
{+Rog/;S' break;
|l]XpWV }
[q8 P~l for(int index=0;index<MAX_KEY;index++){
6\q]rfQ if(hCallWnd[index]==NULL)
rE.;g^4p continue;
RwpdRBb if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
huh6 t ! {
b?tB(if!I SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
P*3BB>FO bProcessed=TRUE;
`xqr{lhL }
>JFO@O5 }
#."-#"0 }
CTq&-l:f if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
:&V h? for(int index=0;index<MAX_KEY;index++){
?kbiMs1;u if(hCallWnd[index]==NULL)
c7x~{V8 continue;
e#$]Y?, if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
j i7[nY SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
Lr~=^{ //lParam的意义可看MSDN中WM_KEYDOWN部分
ix)M`F%P3 }
$QN"wL|| }
4NheWM6 }
UCB/=k^m return CallNextHookEx( hHook, nCode, wParam, lParam );
5YeM%%-S }
I
8`VNA&b
3KlbP 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
gd`!tRcNY i:Y^{\Z?V BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
+M\`#i\g> BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
q_A!'sm@) 3TeY%5iVt 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
vqDu(6!2 (MxQ+D\ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
MOQ*]fV: {
v$?+MNks if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
|
*2w5iR {
1WxK#c-) //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
$P/~rZ@M@ SaveBmp();
Vc\MV0lr return FALSE;
lrlgz[ }
W$hx,VEy` …… //其它处理及默认处理
1\
o59Y }
DgId_\Ze sBvzAVBL Ezc?#<+7 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。
e>+i>/Fn{h 3no%E03p 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。
x[~b2o Lt?lv2k=L 二、编程步骤
gmw|H?] cQCSe,$ W 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";
G|!Tj X7s |"ls\ 7 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
qouhuH_WtJ %Nlt H/I 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;
0l )~i'' n'n/Tu 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;
6F!+T= xpV|\2C 5、 添加代码,编译运行程序。
a*lh)l<KV pjKWtY@=X 三、程序代码
`VA"vwz wh$sn:J ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
naG=Pq< #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
?+@n3]`0 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
Lb:g4A" #if _MSC_VER > 1000
]!?;@$wx #pragma once
e^6)Zz1\ #endif // _MSC_VER > 1000
9-&Ttbb4)0 #ifndef __AFXWIN_H__
sJL&:!}V> #error include 'stdafx.h' before including this file for PCH
^a0um/+M} #endif
EN<F# Y3E #include "resource.h" // main symbols
JVvs-bK5 class CHookApp : public CWinApp
Ns>-
o {
+~m46eI public:
XixL R CHookApp();
?uzRhC_)! // Overrides
7zXvnxYE // ClassWizard generated virtual function overrides
)WNzWUfn=z //{{AFX_VIRTUAL(CHookApp)
4Tb
#fH% public:
HSjlD{R virtual BOOL InitInstance();
'f!8DGix virtual int ExitInstance();
V,lOt4b //}}AFX_VIRTUAL
Q{s H3Y#l //{{AFX_MSG(CHookApp)
#xsE3Wj-X // NOTE - the ClassWizard will add and remove member functions here.
wN_Vfb // DO NOT EDIT what you see in these blocks of generated code !
MU@UfB|;u //}}AFX_MSG
rK' L6o DECLARE_MESSAGE_MAP()
EH+"~-v)ae };
u^@f&BIG]: LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
}eCw6 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
H%qsjB^ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
'\l" BOOL InitHotkey();
'.IW.{;$ BOOL UnInit();
#++lg{ #endif
sEp"D+f R1adWBD> //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
+ [iQLM?zo #include "stdafx.h"
DU0zez I9 #include "hook.h"
M'?,] an #include <windowsx.h>
"h{q#~s #ifdef _DEBUG
! E<[JM #define new DEBUG_NEW
g/ T
#undef THIS_FILE
| k&Ck static char THIS_FILE[] = __FILE__;
\(?rQg@U #endif
CM/H9Kz. #define MAX_KEY 100
$O&b`` #define CTRLBIT 0x04
9&-dTayIz #define ALTBIT 0x02
Sq>dt[7 #define SHIFTBIT 0x01
cvn@/qBq*t #pragma data_seg("shareddata")
"%`1]Fr HHOOK hHook =NULL;
dU&a{$ku[ UINT nHookCount =0;
<Th6r.#? static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
}MJy
+Z8& static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
w$3,A$8 static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
.0zY}` static int KeyCount =0;
}^ApJS(FQ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
Sj%u)#Ub #pragma data_seg()
>{q]&}^U HINSTANCE hins;
C)um9} void VerifyWindow();
faEt6 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
Go5J%&E9 //{{AFX_MSG_MAP(CHookApp)
TH%Qhv\] // NOTE - the ClassWizard will add and remove mapping macros here.
;v}GJ<3 // DO NOT EDIT what you see in these blocks of generated code!
j$M h+5 //}}AFX_MSG_MAP
q }i]'7 END_MESSAGE_MAP()
F|SXn\ U$O\f18 CHookApp::CHookApp()
m ifxiV {
\r/rBa\ // TODO: add construction code here,
? ^0:3$La // Place all significant initialization in InitInstance
Z)I+@2 }
29;?I3<
* G?L HmTHg CHookApp theApp;
Lu?C-$a C LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
.p<:II:6 {
nD_GL BOOL bProcessed=FALSE;
|U:k,YH if(HC_ACTION==nCode)
r<9Iof4 {
j@n)kPo,1 if((lParam&0xc0000000)==0xc0000000){// Key up
k$ 4y9{ switch(wParam)
Z+*9#!?J {
9g9HlB&Ze case VK_MENU:
Xpr?Kgz MaskBits&=~ALTBIT;
Yxr>"KH6a break;
:y'Ah# case VK_CONTROL:
v"y-0$M MaskBits&=~CTRLBIT;
JA %J$d break;
\ ZgE case VK_SHIFT:
/Wi[OT14 MaskBits&=~SHIFTBIT;
I:=S0&%) break;
:tz#v`3o default: //judge the key and send message
*z5.vtfu! break;
3lf=b~Zi) }
Zd3S:),& for(int index=0;index<MAX_KEY;index++){
2Z+Wu3# if(hCallWnd[index]==NULL)
xs{3pkTYD continue;
]N~2 .h if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
)1]ZtU {
GA$V0YQX SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
`LrHKb
aP bProcessed=TRUE;
bBiE }
JgxtlYjl }
\Z?9{J }
R|6Cv3: else if((lParam&0xc000ffff)==1){ //Key down
bZ dNibN switch(wParam)
@3>u@ {
f/ U` case VK_MENU:
W\>fh&!) MaskBits|=ALTBIT;
Cz9xZA{[M break;
mUNn%E:7@{ case VK_CONTROL:
q_MPju&* MaskBits|=CTRLBIT;
[8Y:65 break;
_'#n6^Us< case VK_SHIFT:
ayn) 5q/z MaskBits|=SHIFTBIT;
:">!r.Q break;
Uf1!qP/H? default: //judge the key and send message
T(#J_Y break;
ts,ZvY] }
K%,2=. for(int index=0;index<MAX_KEY;index++)
RFi
S@.7 {
4)S,3G if(hCallWnd[index]==NULL)
.UQzPnK continue;
0.\/\V:H6 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
uu-PJTNZ {
-"R2 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
?j'7l=94A bProcessed=TRUE;
;!>rnxB?4 }
x,'(5* }
&u]8IEv}u }
} +TORR? if(!bProcessed){
a[>/h3 for(int index=0;index<MAX_KEY;index++){
Q0)#8Rcm if(hCallWnd[index]==NULL)
oTEL?hw5 continue;
4svBzZdr if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
HCIU!4rH SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
_mj,u64 }
Yz'K]M_Dq }
y8d]9sX{ }
[meO[otb return CallNextHookEx( hHook, nCode, wParam, lParam );
;o
6lf_ }
#oS<E1 ;(b9#b. BOOL InitHotkey()
`Syl:rU~y@ {
Mc?Qx if(hHook!=NULL){
^a/gBC82x nHookCount++;
]MqMQLG0t return TRUE;
OsTc5K.U~ }
H[NSqu.s else
7!evm;A hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
ntu5{L'8 if(hHook!=NULL)
v3*_9e nHookCount++;
D.r<QO~6B return (hHook!=NULL);
2+RUTOv/d }
VRVO-Sk BOOL UnInit()
M f}~{+ {
Rm2yPuOU}A if(nHookCount>1){
~G)S
nHookCount--;
I
)~GZ return TRUE;
;d@#XIS&-( }
'S20\hwt- BOOL unhooked = UnhookWindowsHookEx(hHook);
<kfnpB= if(unhooked==TRUE){
({ +!`}GY nHookCount=0;
B~?*?Z' hHook=NULL;
kS %Ydy#:' }
6{@w="VT return unhooked;
k6;?)~. }
1;JEc9#h l94b^W}1)W BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
2VPdw@"~} {
55G+; BOOL bAdded=FALSE;
UZWioxsKr+ for(int index=0;index<MAX_KEY;index++){
:W"~
{~#? if(hCallWnd[index]==0){
I~[F|d> hCallWnd[index]=hWnd;
el&0}`K HotKey[index]=cKey;
{IjF+@I HotKeyMask[index]=cMask;
bc7/V#W bAdded=TRUE;
3BzNi' KeyCount++;
Ve8=b0&Y#j break;
&r[`>B{tP }
<S5BDk }
UgRhWV~f0 return bAdded;
|{&{ }
ww)<E`eGi -r!. 9q BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
dydc}n {
.fn\]rUv BOOL bRemoved=FALSE;
FK^p")i for(int index=0;index<MAX_KEY;index++){
\|n-
O=}=2 if(hCallWnd[index]==hWnd){
gGR"Z]DBk if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
*~2,/D hCallWnd[index]=NULL;
OP;v bZ HotKey[index]=0;
_Mi5g_ HotKeyMask[index]=0;
j9m_jv bRemoved=TRUE;
~Q*%DRd&Z- KeyCount--;
>|J`s~? break;
T*I{WW }
]q\b,)4
e }
<c*FCblv }
4aug{}h(" return bRemoved;
w3N[9w?1 }
0}<