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:
@<w9fzi
9snyX7/!L 一、实现方法
E_gDwWot 1~xn[acy 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:
+q_lYGTiO PHiX:0zT #pragma data_seg("shareddata")
L};;o+5uJD HHOOK hHook =NULL; //钩子句柄
ga1gd~a UINT nHookCount =0; //挂接的程序数目
}$k`[ivBx( static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
vL=--# static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
luz%FY: static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
|`t!aG8 static int KeyCount =0;
/HJ(Wt
q static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
<QoE_z`76 #pragma data_seg()
;R|#ae@ :mtw}H 'F8 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。
QVRokI`BF Iv|WeSL. 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:
-x%`Wv@L .lF\b A| BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
$E_vCB_ cKey,UCHAR cMask)
U#]eN[ {
U!I_i*:U BOOL bAdded=FALSE;
AoOG[to7 for(int index=0;index<MAX_KEY;index++){
Ho._&az9cT if(hCallWnd[index]==0){
*I1W+W`G hCallWnd[index]=hWnd;
<%#y^_ HotKey[index]=cKey;
Dx# @D# HotKeyMask[index]=cMask;
0S5C7df bAdded=TRUE;
?kFCYZK|" KeyCount++;
S{)n0/_ break;
oY6|h3T=Q$ }
lnC Wu@{ }
gsR9M%mv return bAdded;
_NqT8C4C }
/uz5V/i0 //删除热键
@SG="L BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
-Tkd@ {
wukos5 BOOL bRemoved=FALSE;
=ObtD" for(int index=0;index<MAX_KEY;index++){
`8.32@rUB. if(hCallWnd[index]==hWnd){
CU`Oc>;*T if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
Tl7:}X<? hCallWnd[index]=NULL;
U+r#YE. HotKey[index]=0;
/Vd#q)b%T HotKeyMask[index]=0;
?_j6})2zY bRemoved=TRUE;
/FV6lR!0^ KeyCount--;
4kF . break;
t\bxd`, }
;AB ,:* }
M-K@n$k }
yxUVM`.~ return bRemoved;
(Dh;=xG }
WCl;#= O8N0 ]Mz 14YV#o: DLL中的钩子函数如下:
8Y~T$Yj^ )hJjVitG LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
p}|wO&4h {
rkc%S5we BOOL bProcessed=FALSE;
R/cq00g if(HC_ACTION==nCode)
)[X!/KR90 {
&Wz:-G7<n if((lParam&0xc0000000)==0xc0000000){// 有键松开
2OlC7X{ switch(wParam)
vk+%#w {
J*&=J6 case VK_MENU:
M &EJFpc* MaskBits&=~ALTBIT;
QR$sIu@% break;
\0T*msYQ case VK_CONTROL:
*xTquV$ MaskBits&=~CTRLBIT;
Eq;frnw>q break;
&0Zk3D4 case VK_SHIFT:
KBHKcFk MaskBits&=~SHIFTBIT;
7{F9b0zwk break;
Q09~vFBg default: //judge the key and send message
pYUkd!K" break;
C\@YH] }
pdqa)>$ for(int index=0;index<MAX_KEY;index++){
7:E#c"S
q if(hCallWnd[index]==NULL)
N%E2BJ? continue;
:!15>ML;- if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
?ML<o>OKg {
sl O9H6< SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
i1@g Hk bProcessed=TRUE;
0M2+?aKif }
UzHhU*nW }
vbh#[,lh }
grAL4 else if((lParam&0xc000ffff)==1){ //有键按下
*<QL[qyV switch(wParam)
\1D,Kx;Cb {
&-Er n/[ case VK_MENU:
H4A+Dg, MaskBits|=ALTBIT;
abP?Dj& break;
q[A3$y( case VK_CONTROL:
>(KUYX?p MaskBits|=CTRLBIT;
_!1c.[\T break;
ui0(#2'h% case VK_SHIFT:
&scD) MaskBits|=SHIFTBIT;
2dW-WHaM break;
g]JI}O*5 default: //judge the key and send message
LgKEg90w( break;
oD1=} }
]r5Xp#q2 for(int index=0;index<MAX_KEY;index++){
yE{UV>ry if(hCallWnd[index]==NULL)
Nx
z ,/d continue;
&`W,'qD$ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
k
rjd:*E {
m]pvJJ@ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
o%Q2. bProcessed=TRUE;
Kx!|4ya, }
n:z>l,`C] }
Yr0i9Qow }
|<icx8hbr if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
cu|q& for(int index=0;index<MAX_KEY;index++){
(I
g
*iJ%2 if(hCallWnd[index]==NULL)
Q-CVq_\3I continue;
Py<vN! if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
hV>Ey^Ty SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
R_DQtLI //lParam的意义可看MSDN中WM_KEYDOWN部分
=J\7(0Dz4t }
Yy 1Pipv }
=5F49 }
CcETS}Q0C return CallNextHookEx( hHook, nCode, wParam, lParam );
(b!DJ;(O9 }
q\Z1-sl~s m!if_Iq 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:
5@5="lNjS xSZw, BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
d^>s e'ya BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
cH ?]uu( |V]E8Qt 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:
> xw+2< Xu0*sQK LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
:{<HiJdp {
x$sQ .aT if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
hG)lVo!L4j {
cMAfW3j: ; //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
.quc i(D SaveBmp();
1Btf)y' return FALSE;
I}x*AM 7+ }
"zc!QHpSd …… //其它处理及默认处理
e{/\znBS% }
A}# Mrb O;"%z*g. l.!
~t1i 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。
}_x oT9HUr NeP1 # 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。
-)GfSk
.X9^ A,9 二、编程步骤
AS;{{^mM( 5+J/Qm8{bb 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";
7[\B{N9&W 6(=:j"w0 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
<j'#mUzd s+11) ~ 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;
B HYEd}M ^C{a' 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;
fA^ O zb (u?U 5、 添加代码,编译运行程序。
vPi+8) t30V_`eQ 三、程序代码
?{V[bm 2},}R'aR ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
$- L)>" #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
W~4|Z=f #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
f &|SGD* #if _MSC_VER > 1000
JC-L80- #pragma once
)mU)7@! #endif // _MSC_VER > 1000
)yk
LUse+ #ifndef __AFXWIN_H__
ZO~N|s6B^ #error include 'stdafx.h' before including this file for PCH
h)rHf3: #endif
C-7.Sa
#include "resource.h" // main symbols
q0<g#jK class CHookApp : public CWinApp
%rsW:nl {
;Baf&xK public:
-3Ffk: CHookApp();
sXUM,h8$!+ // Overrides
S=Zjdbd // ClassWizard generated virtual function overrides
L2N/DB'{ //{{AFX_VIRTUAL(CHookApp)
_Z%C{~,7)x public:
Jad'8}0J virtual BOOL InitInstance();
"o1/gV virtual int ExitInstance();
lUrchLoDt //}}AFX_VIRTUAL
I4$a#; //{{AFX_MSG(CHookApp)
I'!KWpYJT // NOTE - the ClassWizard will add and remove member functions here.
O/-xkzR* // DO NOT EDIT what you see in these blocks of generated code !
k$zDofdfp //}}AFX_MSG
)wC>Hq[mhW DECLARE_MESSAGE_MAP()
uZNR]+Yu@ };
,J[sg7vcv LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
=3@^TW(j BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
czj[U|eB}= BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
0-@waK BOOL InitHotkey();
eI@O9<.& BOOL UnInit();
:Q%&:[2 #endif
{W-PYHZ; =I?p(MqW //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
,}NG@JID #include "stdafx.h"
tW,<Pe #include "hook.h"
rh+OgKi #include <windowsx.h>
Z/64E^ #ifdef _DEBUG
E\QSU88^ #define new DEBUG_NEW
pDu~84!]) #undef THIS_FILE
_PuMZjGL static char THIS_FILE[] = __FILE__;
1vobfZ-w9 #endif
+q3W t| #define MAX_KEY 100
;m\E9ple #define CTRLBIT 0x04
L-fAT'!' #define ALTBIT 0x02
f6DPah# #define SHIFTBIT 0x01
': HV9]k #pragma data_seg("shareddata")
>
vgqf>)kk HHOOK hHook =NULL;
4kx#=MLt UINT nHookCount =0;
PoC24#vS static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
Blu^\:?#z- static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
iJ~pX\FKO static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
ieObo foD static int KeyCount =0;
&We'omq static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
pt<84CP #pragma data_seg()
.[~E}O HINSTANCE hins;
{D7!'Rq, void VerifyWindow();
:qI myaGQ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
0evG //{{AFX_MSG_MAP(CHookApp)
)]v vp{ // NOTE - the ClassWizard will add and remove mapping macros here.
q+SDJ?v // DO NOT EDIT what you see in these blocks of generated code!
KBXdr5 2" //}}AFX_MSG_MAP
H>M0GL END_MESSAGE_MAP()
$)kIYM& ~fr1O`8 CHookApp::CHookApp()
c!s{QWd% {
#B54p@.} // TODO: add construction code here,
.Yo#vV // Place all significant initialization in InitInstance
*#~3\{ }
S0\:1B W/fM0=! CHookApp theApp;
P[^!Uq[0n7 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
R9{6$djq\: {
jo+T!CUM' BOOL bProcessed=FALSE;
jMg Ni@ if(HC_ACTION==nCode)
+>{{91mN {
KWM.b"WnXr if((lParam&0xc0000000)==0xc0000000){// Key up
F7a\Luae switch(wParam)
*S*;rLH9c {
Rg+V;C
C~ case VK_MENU:
$YFn$.70\ MaskBits&=~ALTBIT;
5'.j+{" break;
AuSL?kZ4|Y case VK_CONTROL:
9].!mpR MaskBits&=~CTRLBIT;
tXwnK[~x break;
)4 "G1R`3 case VK_SHIFT:
Ws'3*HAce MaskBits&=~SHIFTBIT;
pZF`+642 break;
.DIHd/wA default: //judge the key and send message
e>X&[\T break;
=f?| f }
yG{'hx6H for(int index=0;index<MAX_KEY;index++){
{'EQ%H$q if(hCallWnd[index]==NULL)
vxY7/ _] continue;
|G!-FmIK if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
kznmA`#jn {
Ez+.tbEA, SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
pv;}Sv$
]- bProcessed=TRUE;
V] <J^m8 }
|-=^5q5 }
+Z#lf }
Q(>89*b& else if((lParam&0xc000ffff)==1){ //Key down
szGp<xv_p switch(wParam)
-"#;U`.oh7 {
9^x'x@6 case VK_MENU:
e%u1O-* MaskBits|=ALTBIT;
QzCu$ [ break;
[C.Pzo case VK_CONTROL:
h1q ?kA MaskBits|=CTRLBIT;
vrLI`3n] break;
aU4v-9@U8 case VK_SHIFT:
,FlF.pt MaskBits|=SHIFTBIT;
oX8e} break;
cEhwv0f!qS default: //judge the key and send message
ix [aS break;
$
nx&(V }
m?`U;R[ for(int index=0;index<MAX_KEY;index++)
"at*G>+ {
ag+$qU if(hCallWnd[index]==NULL)
+W
x/zo continue;
[f!sBJ! if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Mnn\y Tblp {
UMuRB>ey SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
aq@/sMn bProcessed=TRUE;
MDM/~Qpj_ }
z
GhJ }
3){ /u$iH. }
+vY8HQ|v if(!bProcessed){
82O#Fe q for(int index=0;index<MAX_KEY;index++){
KU|dw^Y k if(hCallWnd[index]==NULL)
FFQ=<(Ki continue;
(&npr96f if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
_3i.o$GO SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
Lf`LFPKb }
16Ym*kWIps }
?BtWM4Id8 }
;4tmnC>OnA return CallNextHookEx( hHook, nCode, wParam, lParam );
8FYcUvxfT }
TY6
D.ikA KjFNb;mM BOOL InitHotkey()
Y??8P {
;j|T#-. if(hHook!=NULL){
WP{!|d& nHookCount++;
k<x
% return TRUE;
Lx6C fR }
>U?HXu/TJr else
j5QS/3 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
YaI8hj@} if(hHook!=NULL)
G$FNofQx nHookCount++;
MDI[TNYG return (hHook!=NULL);
;[9WB<t }
7v\K,P8 BOOL UnInit()
z'FD{xdf {
"9mJ$us if(nHookCount>1){
ZtG5vdf nHookCount--;
^wDZg` return TRUE;
OY$P8y3MY }
<7Igd6u BOOL unhooked = UnhookWindowsHookEx(hHook);
BCN<l +u if(unhooked==TRUE){
~Mu=,OT nHookCount=0;
CtItzp hHook=NULL;
$7
1(g$6# }
Hp`Mp)1s return unhooked;
Q?]307g7 }
Id-?her>B Ip_S8
;; BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
`}uOlC]I {
s+m,ASj BOOL bAdded=FALSE;
[;O 6)W for(int index=0;index<MAX_KEY;index++){
haj\Dm if(hCallWnd[index]==0){
v"x{oD$R hCallWnd[index]=hWnd;
I[b@U<\ HotKey[index]=cKey;
-?)` OHc^ HotKeyMask[index]=cMask;
0>PO4WFVJ bAdded=TRUE;
zQsu~8PX KeyCount++;
6uWzv~!*D break;
%) A-zzj }
cQj{[Wt4 }
bqBgq return bAdded;
ZUE?19GA }
8GC(?#Kb .^]=h#[e BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Id->F0x0 {
e*[M*u BOOL bRemoved=FALSE;
[ Tv!Pc for(int index=0;index<MAX_KEY;index++){
etbB;!6 if(hCallWnd[index]==hWnd){
~i&Lc7Xl if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
F,B, D^WD hCallWnd[index]=NULL;
ep]tio_ HotKey[index]=0;
t-#Y6U}b+ HotKeyMask[index]=0;
==d@0` bRemoved=TRUE;
G(piq4D KeyCount--;
y~jKytq^@ break;
/W !A^ }
T?=[6 }
vF45tw }
1EW-%GQO return bRemoved;
e<