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:
''H;/&nDX
zg$NrI& 一、实现方法
<Yn-sH GDYFhH7H 热键管理DLL实际上是一个键盘钩子,由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便,本实例把它做成了一个标准的管理库来为其它的程序通过热键服务,它有两个输出函数:AddHotkey()和DeleteHotkey(),程序只需要调用这两个函数就可以了,如果编译之后不用改变热键,则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中,定义如下:
5xhYOwQBo R5=M{ #pragma data_seg("shareddata")
6"yIk4u: HHOOK hHook =NULL; //钩子句柄
Y2$xlqQd" UINT nHookCount =0; //挂接的程序数目
$S/EIN c static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
Y2}m/7aF static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
7 )*q@ static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
#|K5ma static int KeyCount =0;
xE-
_Fv9 static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
xM?tdQ~VHY #pragma data_seg()
;]>a7o t8.^Y TI 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。
C(n_*8{ cUr5x8<W). 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:
_ ( $U\FW `5SQ4 BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
HL%|DCo cKey,UCHAR cMask)
,L\>mGw {
up2wkc8 BOOL bAdded=FALSE;
|!L0X@> for(int index=0;index<MAX_KEY;index++){
o]<J&<WM if(hCallWnd[index]==0){
Dlg9PyQ hCallWnd[index]=hWnd;
jD?*sd HotKey[index]=cKey;
dH)\zCt HotKeyMask[index]=cMask;
eC`G0.op bAdded=TRUE;
k,61Va KeyCount++;
6*:U1{Gl) break;
$:D\yZ, }
> ,x``- }
lJt?0;gn return bAdded;
814cCrr,o }
Bi7&yS5V //删除热键
5=Il2 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
7`tJ/xtMy; {
EzU3'x BOOL bRemoved=FALSE;
[JKLlR for(int index=0;index<MAX_KEY;index++){
@PV3G
KJ if(hCallWnd[index]==hWnd){
Mp06A.j[ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
^e--4B9| hCallWnd[index]=NULL;
%[on.Q'1]2 HotKey[index]=0;
'#>(JN5\ HotKeyMask[index]=0;
_Uhl4Mh bRemoved=TRUE;
rC6@
] KeyCount--;
L,sFwOWY break;
!-4VGt&c, }
o
@nsv&i }
x{S2 }
,zh_-2^X return bRemoved;
T:g%b @ }
hbm#H7Y d(C5i8d e6Kyu* DLL中的钩子函数如下:
QObHW[:F (3&P8ZGNR LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
x5b .^75p$ {
; jrmr`l= BOOL bProcessed=FALSE;
n&8SB'-r if(HC_ACTION==nCode)
!:a^f2^= {
W!JEl|] if((lParam&0xc0000000)==0xc0000000){// 有键松开
~YXkAS: switch(wParam)
9>=S@hVMd {
bT`et*] case VK_MENU:
^GNL:D%6d MaskBits&=~ALTBIT;
36}&{A break;
V0xO:7G^ case VK_CONTROL:
,,;vG6^a MaskBits&=~CTRLBIT;
NG?g( break;
T>w;M?`9K case VK_SHIFT:
04:QEC"9mj MaskBits&=~SHIFTBIT;
uG(XbDZZ1W break;
=d/$B!t{ default: //judge the key and send message
P?Kg7m W break;
XO}SPf- }
!UHX?<3r for(int index=0;index<MAX_KEY;index++){
TP mb]j if(hCallWnd[index]==NULL)
3g5D[>J' continue;
A}i>ys if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
Y^eF( {
5YLc4z* SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
qfF2S bProcessed=TRUE;
lqvP
Dz }
[<X ~m }
s?PB ]Tr }
=z\/xzAwX else if((lParam&0xc000ffff)==1){ //有键按下
eE@7AM switch(wParam)
j|LO g {
%$=2tfR case VK_MENU:
fni7HBV? MaskBits|=ALTBIT;
szp.\CMz break;
sU/vXweky" case VK_CONTROL:
W&7( MaskBits|=CTRLBIT;
goc; .~? break;
eQ<GNvm case VK_SHIFT:
fYlqaO4[ MaskBits|=SHIFTBIT;
+@~e9ZG%a break;
S2EV[K8# default: //judge the key and send message
o0TB>DX$` break;
-_bDbYL }
m`n#Q#6 for(int index=0;index<MAX_KEY;index++){
;f
/2u if(hCallWnd[index]==NULL)
r`e6B!p continue;
?=b#H6vs if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
)NO,G {
J7@Q;gcl: SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
d3NER} f4V bProcessed=TRUE;
%2'Y@AX` }
zpg512\y }
{FR+a** }
9Dd`x7$a if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
TWdhl9Ot for(int index=0;index<MAX_KEY;index++){
Tn?D~?a*O if(hCallWnd[index]==NULL)
Z9i~>k continue;
a\KM^jrCD if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
cCcJOhk|d SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
j9.%(* //lParam的意义可看MSDN中WM_KEYDOWN部分
iYGa4@/uM }
[X kWPx` }
B?ipo,2~{ }
ps*iE=D return CallNextHookEx( hHook, nCode, wParam, lParam );
umt(e:3f5 }
BwVq:)P/R vd/ BO 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:
8L[\(~Zf czK}F/Sg ` BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
7A{Z1[7 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
f;!L\$yKy HBA|NV3. 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
sn+ kFvk}S n!U1cB{ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
6n
H'NNS:J {
w I[Hoi
V if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Nhtc^DX {
c_Iq!MH //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
~;uU{TT SaveBmp();
B^.:dn
return FALSE;
.g_^! t }
lYU?j|n …… //其它处理及默认处理
df/7u}>9 }
zUWeOR'X nLR %
@!hf! 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
>RrG&Wv59 zrwzI+4 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
zuF]E+ lU`t~|>r+ 二、编程步骤
uJa.]J~L= <&HHo>rl 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
]+>Kl>@ 0CI\Yd= 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
xu@xP5GB^ WA5.qw 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
#-l+cu{ rj/nn)vv; 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
#;h>
x ]2_=(N\Kt 5、 添加代码,编译运行程序。
Q)5V3Q]@^ TXqtE("BDl 三、程序代码
!E^\)=E)P XE#$|Z ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
ycf)*0k #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
2B+qS'OT #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
T%E/k#
)q #if _MSC_VER > 1000
H%{k.#O #pragma once
:bkmm,%O #endif // _MSC_VER > 1000
7_J0[C!G #ifndef __AFXWIN_H__
}/jWa|)f #error include 'stdafx.h' before including this file for PCH
mNJCV8 < #endif
6UU<:KH #include "resource.h" // main symbols
0JW
=RW class CHookApp : public CWinApp
}4?z<. V {
j%gle%_ public:
hb1eEn CHookApp();
n^<J@uC // Overrides
fM"&=X // ClassWizard generated virtual function overrides
bpa'`sf //{{AFX_VIRTUAL(CHookApp)
6cOlY=
bn public:
m14'u GC virtual BOOL InitInstance();
[{zfI`6 virtual int ExitInstance();
BY@l:y4 //}}AFX_VIRTUAL
Yi <1z:\ //{{AFX_MSG(CHookApp)
(UZ].+)s // NOTE - the ClassWizard will add and remove member functions here.
Sx1OY0)s // DO NOT EDIT what you see in these blocks of generated code !
EIF //}}AFX_MSG
\/-4 jF: DECLARE_MESSAGE_MAP()
&,* ILz };
1JV-X G6 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
*DQa6,b BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
/)sP<WPQ6 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
+]Ev BOOL InitHotkey();
s%G%s,d BOOL UnInit();
&d]@$4u$; #endif
wJu9. z}Um$'. = //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
A.(e=;0bu #include "stdafx.h"
p[}~Z|( #include "hook.h"
Ao\Im(? #include <windowsx.h>
8EU/}Ym #ifdef _DEBUG
,x?Jrcx~'C #define new DEBUG_NEW
< Yc)F.: #undef THIS_FILE
-8v:eyc static char THIS_FILE[] = __FILE__;
{:=]J4] #endif
D58RHgY[ #define MAX_KEY 100
6_K7!?YG7 #define CTRLBIT 0x04
yi2F#o 'K #define ALTBIT 0x02
3CPSyF #define SHIFTBIT 0x01
E@-5L9eJ\ #pragma data_seg("shareddata")
gw$?&[wY HHOOK hHook =NULL;
arvKJmD UINT nHookCount =0;
}/Qj8l. static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
>u]9(o7I static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
szXqJG8| static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
I A$= static int KeyCount =0;
h)s&Nqg1B static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
w%(D4ldp #pragma data_seg()
k7]4TIUD* HINSTANCE hins;
<@c@`K void VerifyWindow();
g!Ui|]BI9 BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
# hw;aQ //{{AFX_MSG_MAP(CHookApp)
|W}D_2 // NOTE - the ClassWizard will add and remove mapping macros here.
0 c]] // DO NOT EDIT what you see in these blocks of generated code!
d+"F(R9 //}}AFX_MSG_MAP
cv. j END_MESSAGE_MAP()
KL"_h`UW 6q,CEm CHookApp::CHookApp()
G/_xn5XDD {
AYDAt5K_ // TODO: add construction code here,
+W8kMuM! // Place all significant initialization in InitInstance
Hm+VGH'H? }
2'Raj'2S4 %g69kizoWi CHookApp theApp;
8Nx fYA LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
0v``4z2Z {
P G
zwS BOOL bProcessed=FALSE;
I:1Pz|$` if(HC_ACTION==nCode)
xpI8QV$# {
gLlA'`! if((lParam&0xc0000000)==0xc0000000){// Key up
n6 wx/: switch(wParam)
y( UWh4?t {
-h=wLYl@0i case VK_MENU:
'@5x=> MaskBits&=~ALTBIT;
.N7&Jy
break;
E+/XKF case VK_CONTROL:
tH:?aP*2 MaskBits&=~CTRLBIT;
|nU%H=Rs/ break;
t{`uN case VK_SHIFT:
Jgy6 !qUn_ MaskBits&=~SHIFTBIT;
B] Koi1B break;
g[;&_gL default: //judge the key and send message
;u<F,o( break;
{MUO25s02 }
4L r,}tA for(int index=0;index<MAX_KEY;index++){
X^i3(N if(hCallWnd[index]==NULL)
.=) *Qx+ continue;
ONUa7 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
}%<cFi & {
-s^cy+jd SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
D;OPsNQ bProcessed=TRUE;
NOf{Xx<#k }
N:EljzvP} }
=6N=5JePB }
ReGT*+UN else if((lParam&0xc000ffff)==1){ //Key down
3@* ~>H switch(wParam)
Iz&d
S?p_ {
@6-3D/= case VK_MENU:
S_s;foT MaskBits|=ALTBIT;
&a6-+r break;
X5= Ki
$+ case VK_CONTROL:
G]dHYxG MaskBits|=CTRLBIT;
e~nh95 break;
I<"UQ\) case VK_SHIFT:
3f:]*U+O MaskBits|=SHIFTBIT;
'1d0
*5+6k break;
Hi U/fi` default: //judge the key and send message
%D7 '7E8. break;
cW?6Iao }
dvglh?7d for(int index=0;index<MAX_KEY;index++)
.tsXQf {
}:*?w>= if(hCallWnd[index]==NULL)
SN`L@/I continue;
nO;ox*Bk+8 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
wkp$/IZKMj {
ES#q/yab5 SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
r MJ4w['J= bProcessed=TRUE;
24fN3 }
~se
;L }
mA#^Pv* }
Djf~8q V! if(!bProcessed){
"V,dH%&j for(int index=0;index<MAX_KEY;index++){
@JOsG-VW~ if(hCallWnd[index]==NULL)
gL1r"&^L continue;
ObataUxQT if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
@?</8;%3W SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
2]r5e; }
S)"vyGv }
i,L"%q)C }
NkQain9 return CallNextHookEx( hHook, nCode, wParam, lParam );
l a_ }
L>N)[;| R^.c BOOL InitHotkey()
/q!_f!<q4x {
EPM(hxCIQ if(hHook!=NULL){
)
urUaE nHookCount++;
:]* =f]. return TRUE;
o+\?E.%%g }
9~ifST\ else
YT@N$kOg_ hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
]ij:>O@{$ if(hHook!=NULL)
uuy0fQQ8ti nHookCount++;
- @KT# return (hHook!=NULL);
j92+kq>Xd }
3 >^B%qg6 BOOL UnInit()
7K!n'dAi6 {
HBw0N? if(nHookCount>1){
/#}%c' nHookCount--;
7/\SN04l return TRUE;
/ $'M }
PG'I7)Bv BOOL unhooked = UnhookWindowsHookEx(hHook);
2 xi@5;! if(unhooked==TRUE){
P[e#j nHookCount=0;
5=!aq\
5 hHook=NULL;
r?`7i' }
u;8bbv4 return unhooked;
U*T :p>& }
Fd._D" {[+Q\<