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:
kPO6gdwq$
_3.G\/>[K 一、实现方法
8jjFC9Cbn0 |0L=8~M(j 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:
e?!L}^f6X w#xeua|*I# #pragma data_seg("shareddata")
rv}mD HHOOK hHook =NULL; //钩子句柄
-SvTg{Q{la UINT nHookCount =0; //挂接的程序数目
R VkU+7 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
^`rpf\GX( static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
d@4rD}_Z static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
\TbsoWX static int KeyCount =0;
+5HnZ?E\ static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
V#NG+U.B #pragma data_seg()
~!ZmF(: T A\4uy6o 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。
ou'~{-_xd ^qeY9O 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:
(T|TEt i*S|qX7`` BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
c~^CKgr~R9 cKey,UCHAR cMask)
H|;*_ {
4mN].X[, BOOL bAdded=FALSE;
!/j,hO4Z4 for(int index=0;index<MAX_KEY;index++){
w;
4jx(
if(hCallWnd[index]==0){
i iX\it$s hCallWnd[index]=hWnd;
:reP} Da7q HotKey[index]=cKey;
Xnv@H:$mxk HotKeyMask[index]=cMask;
(#6AKr9K bAdded=TRUE;
+Qh[sGDdY KeyCount++;
](W5.a,-$L break;
D XV@DQ }
7}4'dW. }
<nWKR, return bAdded;
, 3X: ) }
TN35CaSmq //删除热键
ZfPd0 p BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
jt{9e:2% {
>Mvka;T] BOOL bRemoved=FALSE;
~x|aoozL for(int index=0;index<MAX_KEY;index++){
~:>AR` 9G if(hCallWnd[index]==hWnd){
L[?nST18% if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
Kt
W6AZJ hCallWnd[index]=NULL;
"z^(dF| HotKey[index]=0;
q,B3ru.?d HotKeyMask[index]=0;
e~{^oM bRemoved=TRUE;
FR
x6c KeyCount--;
_eJXi, break;
w6T[hZ 9 }
'>j<yaD' }
v6s\Z\v)Q` }
n/QfdAg return bRemoved;
q!6|lZ B3 }
Hm %g_Mt DY9fF4[9a |3}5:k DLL中的钩子函数如下:
2fl4h<V &E
bI Op LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
;%' b;+ {
AZwl fdLB BOOL bProcessed=FALSE;
TQP+>nS, if(HC_ACTION==nCode)
w*50ZS;N {
QR<`pmB~y if((lParam&0xc0000000)==0xc0000000){// 有键松开
43zUN switch(wParam)
*q0`})IQ {
o`bo#A case VK_MENU:
z[fB!O MaskBits&=~ALTBIT;
lT.zNhz:d9 break;
\6sqyWI
% case VK_CONTROL:
zZ%DtxUoU. MaskBits&=~CTRLBIT;
A\K,_&x1Z break;
)^4hQ3BS case VK_SHIFT:
^q
;Cx7T_p MaskBits&=~SHIFTBIT;
KOjluP break;
gQ37> default: //judge the key and send message
![ZmV break;
57~Uqt }
nV}8M for(int index=0;index<MAX_KEY;index++){
_%Bz,C8 if(hCallWnd[index]==NULL)
No)
m/17y continue;
CSL#s^4T if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
gv#4#] {
Ia2(Km SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
mN;+TN'?{ bProcessed=TRUE;
?Gd sOg^ }
eNRs&^ }
!X|k"km" }
$X*mdji else if((lParam&0xc000ffff)==1){ //有键按下
hd
B
|#t switch(wParam)
#,L~w {
8tLHr @%% case VK_MENU:
XS?gn.o\ MaskBits|=ALTBIT;
"PMQyzl break;
o0ZIsrr
case VK_CONTROL:
?aBj# MaskBits|=CTRLBIT;
ak;6z]f8[ break;
n@!wp/J, case VK_SHIFT:
+\0T\;-Xe MaskBits|=SHIFTBIT;
OL'P]=U break;
n`(~OO default: //judge the key and send message
-4w%Iy break;
|uI?ySF }
=m7H)z)i*J for(int index=0;index<MAX_KEY;index++){
igD G}q3jG if(hCallWnd[index]==NULL)
`>6T& continue;
MRfb[p3Cx if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
-DP*q3 {
!9;)N, SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
,_jC$ bProcessed=TRUE;
@x1%)1 }
@o>EBZ7MS }
22
&'@C> }
)%mg(O8uL if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
g5+7p@'fV for(int index=0;index<MAX_KEY;index++){
S]^`woD if(hCallWnd[index]==NULL)
dAc ?O-~ continue;
w{!(r if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
prtK:eGe2 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
x)SralWb //lParam的意义可看MSDN中WM_KEYDOWN部分
m:uPEpcU }
+dk fcG }
[:h5} }
;HNq>/{ return CallNextHookEx( hHook, nCode, wParam, lParam );
c 6"Ib) }
;au*V5a% %'bJ: 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:
VfSj E.| e_.Gw"/Yl BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
6)qp*P$L BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
rh!;|xB|+ #(KDjnP[ 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
HeLG?6 tIc 7:th LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
PT'MNH {
m^V5*JIh if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
_V2xA88 {
|A\a4f'G //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
j.m(ltGh SaveBmp();
#Ex p51 return FALSE;
+D&Pp0xe }
[Wi1|]X"G …… //其它处理及默认处理
?Q0I'RC }
KkcXNjPVS h|D0z_f zF`3gl. 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
rf.`h{!! 8)L*AdDAW! 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
WBr59@V 5'KA'>@ 二、编程步骤
aUc|V{Jp pTJX""C 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
MHU74//fe E5</h"1 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
M5g\s;y; SJ?cI!=x 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
MSw$_d >yB(lKV 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;
>6<q8{* #wY0D_3@1 5、 添加代码,编译运行程序。
dOFD5}_ .ubE2X[ ][ 三、程序代码
@n-r-Q )5_jmW`n ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
i#/]KsSp #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
"%qzj93>
#define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
mh.+."<)F #if _MSC_VER > 1000
&@% $2O.3 #pragma once
Qm4o7x{q #endif // _MSC_VER > 1000
A1"SLFY #ifndef __AFXWIN_H__
x79Ha, #error include 'stdafx.h' before including this file for PCH
CyDV r #endif
cxIk<&i~( #include "resource.h" // main symbols
a5YIUVCv class CHookApp : public CWinApp
424(3-/v; {
/,@p\Ae5 public:
piy`zc-yu CHookApp();
q%Yn;g|_ // Overrides
up>c$jJ // ClassWizard generated virtual function overrides
asHxL! //{{AFX_VIRTUAL(CHookApp)
30>3 !Xqa public:
*`_{ virtual BOOL InitInstance();
r [ : virtual int ExitInstance();
n/~A`%E@ //}}AFX_VIRTUAL
zCv"]% //{{AFX_MSG(CHookApp)
#bH_Dg5I // NOTE - the ClassWizard will add and remove member functions here.
c(#;_Ve2P // DO NOT EDIT what you see in these blocks of generated code !
MUnEuhXTr //}}AFX_MSG
4_A0rveP DECLARE_MESSAGE_MAP()
A@hppaP! };
U8.7>ENnP& LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
_>+8og/%@ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
]hos+;4p BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
+{<#(} BOOL InitHotkey();
^ D%FX!$ BOOL UnInit();
U*3J+Y #endif
YNwp/Y km~Ll //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
br-]fE.be #include "stdafx.h"
AN!s{7V3 #include "hook.h"
Ae]sGU|?' #include <windowsx.h>
oVFnlA #ifdef _DEBUG
;oZ)Wt #define new DEBUG_NEW
R;,g1m|] #undef THIS_FILE
>/[GTqi static char THIS_FILE[] = __FILE__;
ApBWuXp|u #endif
AIMSX]m #define MAX_KEY 100
R^?/' dr #define CTRLBIT 0x04
H0m|1
7 #define ALTBIT 0x02
tW
WWx~k #define SHIFTBIT 0x01
KlRr8G!Z #pragma data_seg("shareddata")
7frTTSZ HHOOK hHook =NULL;
%\]*OZ7 UINT nHookCount =0;
L:XC static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
X+UJzR90 static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
*na?n2Yzt static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
c\a_VRN>r static int KeyCount =0;
'5&s=M_ static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
8NyJc"T<. #pragma data_seg()
[
ol9|sdu HINSTANCE hins;
kuyjnSo9i void VerifyWindow();
hxQqa 0B BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
y@0E[/O //{{AFX_MSG_MAP(CHookApp)
BauU{:Sh // NOTE - the ClassWizard will add and remove mapping macros here.
!*RqCS, // DO NOT EDIT what you see in these blocks of generated code!
DL$@?.?I //}}AFX_MSG_MAP
:#@ = B] END_MESSAGE_MAP()
FEVEp PDs@?nz, CHookApp::CHookApp()
~e6Brq {
1UPC e // TODO: add construction code here,
4R18A=X // Place all significant initialization in InitInstance
Ym3\pRFiD }
'Ut7{rZ5 hjZKUMG(k CHookApp theApp;
6DH~dL_",% LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
"g$IP9?U {
/p8dZ+X BOOL bProcessed=FALSE;
DI+fwXeg if(HC_ACTION==nCode)
qkiI/nH3 {
ep)>X@t if((lParam&0xc0000000)==0xc0000000){// Key up
bv&;R switch(wParam)
n2iJ%_zp {
ty8v
6J# case VK_MENU:
.l.a(_R MaskBits&=~ALTBIT;
X5j1`t, break;
~l)-wNqR4r case VK_CONTROL:
J0@X<Lt U MaskBits&=~CTRLBIT;
Q~Hy%M%R3 break;
M5 <@~V/[ case VK_SHIFT:
@Y1s$,=xB MaskBits&=~SHIFTBIT;
c%MW\qx break;
l1f\=G?tmU default: //judge the key and send message
%i5M77#Z break;
\otWd }
4^M for(int index=0;index<MAX_KEY;index++){
gLOEh6 if(hCallWnd[index]==NULL)
AvfNwE continue;
y&V@^"` if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
9I4K}R {
rx] @A SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
ax (c# bProcessed=TRUE;
?#fu.YE\ }
J:Qa5MTWp }
Z'\h }
k |eBJ% else if((lParam&0xc000ffff)==1){ //Key down
2AMo:Jqv switch(wParam)
u:=7l {
g*_cPU0~m case VK_MENU:
VIv&ofyAR MaskBits|=ALTBIT;
<ZNzVnVA break;
9b9$GyI case VK_CONTROL:
ME*LHr, MaskBits|=CTRLBIT;
zzX_q(:S break;
b45-:mi! case VK_SHIFT:
~{jcH MaskBits|=SHIFTBIT;
"hsb8- break;
LU={")TdQ default: //judge the key and send message
]"?)Z break;
sVOyT*GY }
PK `D8)=u for(int index=0;index<MAX_KEY;index++)
t+!$[K0/ {
JsODzw if(hCallWnd[index]==NULL)
^zQ/mo,Z continue;
`Tv[DIVW if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
a6uJYhS~ {
|>dI/_' SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
fTK3,s1= bProcessed=TRUE;
?`PvL!' }
lE4HM$p
}
$w`=z<2yo1 }
=`H@% if(!bProcessed){
NU5.o$
for(int index=0;index<MAX_KEY;index++){
OG>}M$Ora if(hCallWnd[index]==NULL)
% ~H=sjg continue;
u)+8S/ ) if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
E?
;0)'h SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
T7hcnF$ }
|R/%D%_g }
A;]}m8(* }
vVFy*#I#_[ return CallNextHookEx( hHook, nCode, wParam, lParam );
+l<5#pazx }
V<T9&8l+: <h:x= BOOL InitHotkey()
6\q]rfQ {
rE.;g^4p if(hHook!=NULL){
]QlwR'&j/n nHookCount++;
huh6 t ! return TRUE;
b?tB(if!I }
P*3BB>FO else
`xqr{lhL hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
|}Nn!Sj>#; if(hHook!=NULL)
#."-#"0 nHookCount++;
CTq&-l:f return (hHook!=NULL);
:&V h? }
?kbiMs1;u BOOL UnInit()
#_^Lb]jkM {
e#$]Y?, if(nHookCount>1){
j i7[nY nHookCount--;
#Y
a4ps_ return TRUE;
ix)M`F%P3 }
RC7]'4o BOOL unhooked = UnhookWindowsHookEx(hHook);
4NheWM6 if(unhooked==TRUE){
UCB/=k^m nHookCount=0;
5YeM%%-S hHook=NULL;
I
8`VNA&b }
3KlbP return unhooked;
gd`!tRcNY }
i:Y^{\Z?V +M\`#i\g> BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
q_A!'sm@) {
3TeY%5iVt BOOL bAdded=FALSE;
vqDu(6!2 for(int index=0;index<MAX_KEY;index++){
(MxQ+D\ if(hCallWnd[index]==0){
MOQ*]fV: hCallWnd[index]=hWnd;
d928~y
W HotKey[index]=cKey;
|
*2w5iR HotKeyMask[index]=cMask;
}v}P
.P bAdded=TRUE;
>UiYL}'br6 KeyCount++;
^
*k?pJ5 break;
jFL #s&ft }
P}n_IV*@ }
,Z&xNBX return bAdded;
'"0'Oua }
1ySk;;3 'YmIKIw BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
w0rRSD4S8B {
f
e\$@- BOOL bRemoved=FALSE;
G\2CR* for(int index=0;index<MAX_KEY;index++){
/Kql>$I if(hCallWnd[index]==hWnd){
gY/"cq if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
{Aw#?#GPW hCallWnd[index]=NULL;
iT3BF"ZqBO HotKey[index]=0;
/R]U}o^/(% HotKeyMask[index]=0;
C~,a!qY bRemoved=TRUE;
! >(7+B3E* KeyCount--;
GfoLae break;
[8 ]z|bM }
{FeDvhv }
t5\-v_mG=& }
Cjm`|~&e+ return bRemoved;
IA8f*]? }
&Cr: