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:
x#VUEu]8
1>{-wL4rc 一、实现方法
\k-juF80 iC2nHZ*, 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:
z(68^-V=:
x`l;
; #pragma data_seg("shareddata")
{YTF]J$ HHOOK hHook =NULL; //钩子句柄
kU>|E<c* UINT nHookCount =0; //挂接的程序数目
trt\PP:H% static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
zFQkUgb static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
Y rnqi-P static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
|^{" 2l"j static int KeyCount =0;
/\I%)B47^9 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
l#.,wOO{ #pragma data_seg()
;!sGfrs0$
r@UY$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。
qyfxT Q5 {S(T1ua 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:
$s!meg@s 7V``f:#d BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
FQ1oqqr cKey,UCHAR cMask)
*lF%8k"Al {
nQ3goVRFP BOOL bAdded=FALSE;
WN1-J(x6 for(int index=0;index<MAX_KEY;index++){
C
P v}A if(hCallWnd[index]==0){
4ux5G`oL hCallWnd[index]=hWnd;
<t@*[Aw HotKey[index]=cKey;
oF^hq-xcP HotKeyMask[index]=cMask;
,lM2BXz% bAdded=TRUE;
cBf{R^>Fd KeyCount++;
c)fp;^ break;
8{t&8Ql n }
6u;(R0n }
umn^QZ, return bAdded;
n9-[z2n }
`:O.g9 //删除热键
@!O{>` BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Z"T(8>c;g {
.LHe*J C BOOL bRemoved=FALSE;
T
bWZw for(int index=0;index<MAX_KEY;index++){
>vy+U if(hCallWnd[index]==hWnd){
2MeavTr if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
gOAluP hCallWnd[index]=NULL;
rcT<OiYuig HotKey[index]=0;
TvwIro HotKeyMask[index]=0;
:!hH`l}p bRemoved=TRUE;
1=.kH[R KeyCount--;
0E1)&f break;
ZfikNQU9r }
C;>Ll~f_ }
RtL'fd }
/=} vPey return bRemoved;
^4NH.q{ }
nP31jm+A j-|0&X1C l/NK.Jr DLL中的钩子函数如下:
XS/TYdXB8 !YHu LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
ZW%`G@d"H- {
"ukbqdKD BOOL bProcessed=FALSE;
J)NpG9iN if(HC_ACTION==nCode)
HArYL}l {
eO G%6C%a if((lParam&0xc0000000)==0xc0000000){// 有键松开
)>p6h]]a switch(wParam)
>FNt*tX<0 {
6P|neb} case VK_MENU:
]Jqe)o MaskBits&=~ALTBIT;
sAlgp2- break;
ztpb/9J9 case VK_CONTROL:
k]g\`
gc MaskBits&=~CTRLBIT;
k({8C`&tK/ break;
,cEcMaJ case VK_SHIFT:
UC@ "<$'C MaskBits&=~SHIFTBIT;
pC8i&_A break;
[NcOk, default: //judge the key and send message
ic#drpl, break;
@eWx4bl }
i-b7 for(int index=0;index<MAX_KEY;index++){
6'zy"UkH if(hCallWnd[index]==NULL)
rOT8!" continue;
q4=RE if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
hNy S {
?2;G_P+ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
)I4t l/ bProcessed=TRUE;
r kl7p? }
V
"" }
vxx3^;4p }
6 -}gqkR else if((lParam&0xc000ffff)==1){ //有键按下
*93 N0m4Rl switch(wParam)
uX[
"w| {
Ex3woT- case VK_MENU:
+n dyR MaskBits|=ALTBIT;
qQ_QF break;
D6WsEd> case VK_CONTROL:
\2!$HA7P MaskBits|=CTRLBIT;
<~OyV5:6 break;
ND>}t#^$ case VK_SHIFT:
_#:1Axx1 MaskBits|=SHIFTBIT;
0*^Fk=>ej break;
u@B"*V~K default: //judge the key and send message
n21J7;\/+ break;
lTXU }
#UQ[8e for(int index=0;index<MAX_KEY;index++){
sh1()vT if(hCallWnd[index]==NULL)
e+[J9;g continue;
2}t wt if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
icmDPq {
f]}F_] SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
}UrtDXhA bProcessed=TRUE;
xo$ZPnf(zv }
Ipe; %as# }
85mQHZ8aR }
E_oe1C: if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
U?QO'H5 for(int index=0;index<MAX_KEY;index++){
rL=$WxdPU if(hCallWnd[index]==NULL)
j*{bM{~T< continue;
cx|j
_5%i if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
$/H'Dt6x SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
d9(F wmE //lParam的意义可看MSDN中WM_KEYDOWN部分
zBbTj IFQ }
?*4zNhL }
A?/?9Gr }
\<} nn?~n return CallNextHookEx( hHook, nCode, wParam, lParam );
0CROq} }
;
F=_ozWV* @4i DN 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
i?>"}h ?HY0@XILI BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
dQ[lXV[}v BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
<_![~n$H _OY ;SJ( 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:
|1D`v9 D fea<5~^z LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
aI{[W;43T {
/2:r}O if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
L2qF@!Yy= {
llzl-2`/ //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
2Y+*vN s3 SaveBmp();
"hfwj`U return FALSE;
,>$#e1!J }
OjN]mp-q …… //其它处理及默认处理
Ssj'1[% }
sCUPa-cHF Cv| :.y
vzw\f 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。
A-W7!0
URAipLvN 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。
Q%7EC>V g_=Q=y@, 二、编程步骤
&l Q j?] [Ue>KG62= 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";
Bg`b*(Q _5zR!|\^ 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
EP[
gq rnr7t \a~] 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;
bYtF#Y 6"DvdJ0MB 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;
G>,rf
]N +,MzD'(D 5、 添加代码,编译运行程序。
[ACYd/ $OT:J 三、程序代码
#_E8>;)k \||PW58j ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
O7.Is88! #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
,y0kzwPR1 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
VY F4q9 #if _MSC_VER > 1000
D,hl+P{^K #pragma once
DxYu #endif // _MSC_VER > 1000
p])km%zB( #ifndef __AFXWIN_H__
|!}$V #error include 'stdafx.h' before including this file for PCH
78X;ZMY #endif
&EQov9P7 #include "resource.h" // main symbols
_uBf.Qfs class CHookApp : public CWinApp
! yxb< {
a%AU9?/q# public:
C{c (K! CHookApp();
:70oO}0m. // Overrides
u4S3NLG) // ClassWizard generated virtual function overrides
dlWw=^ //{{AFX_VIRTUAL(CHookApp)
p?}Rolk7 public:
j#*K[ virtual BOOL InitInstance();
M6e"4Gh virtual int ExitInstance();
zYep
V //}}AFX_VIRTUAL
os2yiF", //{{AFX_MSG(CHookApp)
u%|VmM> // NOTE - the ClassWizard will add and remove member functions here.
X)yTx8v4 // DO NOT EDIT what you see in these blocks of generated code !
lu >>~vy6 //}}AFX_MSG
nhIITfJJ DECLARE_MESSAGE_MAP()
aA:Ky&5e };
lyib+Sa ?` LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
RH`m=?~J, BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
KAe)
X_R7 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
l"cYW9 BOOL InitHotkey();
}n<dyX:a BOOL UnInit();
"evLI? #endif
|6&"r& sOHh&e //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
pZH
bj2~ #include "stdafx.h"
$)'{+1 #include "hook.h"
vOqYt42
#include <windowsx.h>
97
1qr #ifdef _DEBUG
eSvu:euv #define new DEBUG_NEW
eZUK<&0x5 #undef THIS_FILE
UL oTPx@N static char THIS_FILE[] = __FILE__;
.z_^_@qdm #endif
2/;KZ+U& #define MAX_KEY 100
vj#gY2qZ #define CTRLBIT 0x04
4
Hu+ljdjB #define ALTBIT 0x02
jReI+
pS #define SHIFTBIT 0x01
(Q@m;i> #pragma data_seg("shareddata")
o]]Q7S= HHOOK hHook =NULL;
4TLh'?Xu9 UINT nHookCount =0;
i} q6^;uTF static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
_gc2h@x1O static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
[0 W^|=#K static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
Edjh* static int KeyCount =0;
{L8SDU{P static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
&;y(@e}D #pragma data_seg()
4gYP .h:, HINSTANCE hins;
I\[*vgjm3G void VerifyWindow();
vbSz&+52; BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
>z(6ADq //{{AFX_MSG_MAP(CHookApp)
fxc~5~$> // NOTE - the ClassWizard will add and remove mapping macros here.
<
*XC`Ii // DO NOT EDIT what you see in these blocks of generated code!
9J>DLvl; //}}AFX_MSG_MAP
+oyc9PoXF END_MESSAGE_MAP()
&AoWT:Ea TzIgEn~ CHookApp::CHookApp()
x.d9mjLN8m {
Jb0]!*tV // TODO: add construction code here,
02S Uyv(Mt // Place all significant initialization in InitInstance
]qXfgc }
@]cpPW-b wngxVhu8Ld CHookApp theApp;
!1!uB } LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
VB[R!S= {
4 ba1c BOOL bProcessed=FALSE;
:}E*u^v K if(HC_ACTION==nCode)
QJ$]~)w?H {
_/KW5 if((lParam&0xc0000000)==0xc0000000){// Key up
vK6bpzI
3 switch(wParam)
OnG!5b {
ag] nVE/ case VK_MENU:
R
z[- MaskBits&=~ALTBIT;
~M <4HC break;
7C&`i}/t case VK_CONTROL:
#!<x|N?_< MaskBits&=~CTRLBIT;
u'=#~'6 break;
SK-|O9Ki case VK_SHIFT:
q6osRK*20 MaskBits&=~SHIFTBIT;
K7CiICe break;
xvgIYc{ default: //judge the key and send message
N'^ 0:zK: break;
[V1gj9t=, }
{(t (}-:Z for(int index=0;index<MAX_KEY;index++){
f(9w FT if(hCallWnd[index]==NULL)
h>\}-|Ek continue;
!FO92 P16 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
y{kXd1, {
dso\+s SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
zO!`sPP bProcessed=TRUE;
A]R"C:o }
BL]^+KnP }
S?D2`b }
^%\p; yhL else if((lParam&0xc000ffff)==1){ //Key down
RI%*5lM8; switch(wParam)
P~?u2,.E[ {
#ReW#?P%b/ case VK_MENU:
@GGyiK@ MaskBits|=ALTBIT;
~r!j VK>^ break;
|px4a" case VK_CONTROL:
G"J6X e MaskBits|=CTRLBIT;
I2zSoQ1P break;
Jq.26I= case VK_SHIFT:
#{N#yReh MaskBits|=SHIFTBIT;
\Z)'':},C break;
u |#ruFR default: //judge the key and send message
vnIxI a break;
J :, }
DrW]`%Ql for(int index=0;index<MAX_KEY;index++)
FxD" z3D {
z.{yVQE if(hCallWnd[index]==NULL)
b5yb~;0 continue;
);=JoRQ{ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
}p&aI?-B {
|4dNi1{Zd SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
9WBDSx_(Q bProcessed=TRUE;
|z5olu$gVc }
VM-J^ }
M`"2; }
W>+<r9Rt4 if(!bProcessed){
c5U1N&k5& for(int index=0;index<MAX_KEY;index++){
9N9|h y if(hCallWnd[index]==NULL)
hf%W grO. continue;
ib&
|271gG if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
Q>||HtF$A SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
)L_jR%2j }
5nEvnnx0 }
C?b Mj[$ }
~-.q<8
return CallNextHookEx( hHook, nCode, wParam, lParam );
!hJ%{. }
p|W:;( rNI3_|a BOOL InitHotkey()
4
9#I {
aHb,4 wY if(hHook!=NULL){
sYXVSNonm nHookCount++;
J|3CG;+ return TRUE;
bEPXNN }
s'/ug else
64zO%F* hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
D4`7,JC}< if(hHook!=NULL)
vlE#z nHookCount++;
$|AvT;4 return (hHook!=NULL);
O:D`6U+0 }
|Z!C`G[ BOOL UnInit()
?5Lom#^ {
vR:t4EJ` if(nHookCount>1){
q!NwfXJM nHookCount--;
qf
]ax!bK return TRUE;
{'{ssCL }
ysvn*9h+& BOOL unhooked = UnhookWindowsHookEx(hHook);
.llAiv if(unhooked==TRUE){
S,J'Z:spf nHookCount=0;
.H9!UQ&It hHook=NULL;
3{,Mpb@ }
|" l
g4S% return unhooked;
x~KS;hA }
I /RvU, (A"oMnjWd BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
vW~_+:),e {
mb?yG:L=0b BOOL bAdded=FALSE;
4?8GK for(int index=0;index<MAX_KEY;index++){
A7ck-9dT/L if(hCallWnd[index]==0){
60QElJ9D hCallWnd[index]=hWnd;
% #|S HotKey[index]=cKey;
~*G I<n HotKeyMask[index]=cMask;
BXm{x6\ bAdded=TRUE;
Be?mIwc_g KeyCount++;
hydn" 9; break;
-@AGQ+e }
c[ =9Z;| }
r`6XF return bAdded;
8CMI\yk }
QULrE+@ 4yjAi@ /2 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
_3ZZ-=J:=* {
P]INYH BOOL bRemoved=FALSE;
>YPfk=0f0 for(int index=0;index<MAX_KEY;index++){
>oLM2VJ if(hCallWnd[index]==hWnd){
c-`&e-~XKL if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
`/Z8mFs Y hCallWnd[index]=NULL;
{T.$xiR HotKey[index]=0;
A:k`Ykr[ HotKeyMask[index]=0;
#]n[ bRemoved=TRUE;
TS@EE&W