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:
aiE\r/k8s
oaILh 一、实现方法
r[GH#vF;7 VUHf-bKl 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:
yxf#@Je" Lg#(?tMp,' #pragma data_seg("shareddata")
f:~$x HHOOK hHook =NULL; //钩子句柄
Cp>y<C" UINT nHookCount =0; //挂接的程序数目
7(^F@,,@ static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
^\J-LU|"B static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
BTG_c_?]e static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
1Qz@ static int KeyCount =0;
mDD96y static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
[EZ=t k #pragma data_seg()
-XwS?*O -O-?hsV)y 关于共享段,有几点重要的说明:一是必须在链接选项里指定该段为共享:一种方法是在project->settings->link->object/library中加上/section:shareddata,rws;第二种方法是在def文件的sections里加上一句shareddata read write shared;第三种指定共享段的方法在程序里加上一句#pragma comment(linker,"section:shareddata,rws")。二是所有的变量必须初始化,否则链接程序会把它放到普通数据段。三是如果不初始化变量,需要在段外用"__declspec(allocate("shareddata")) 变量类型 变量名"的方式定义。
?gvu
E1 2*Pk1vrI DLL中的两个输出函数分别用来添加/删除热键,函数代码如下:
MpJ<. |h @qx$b~% BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
D+~*nc ~
g cKey,UCHAR cMask)
[*0M$4 {
'#,C5*` BOOL bAdded=FALSE;
bs16G3-p for(int index=0;index<MAX_KEY;index++){
'Yc^9;C( if(hCallWnd[index]==0){
hH%fWB2( hCallWnd[index]=hWnd;
p1HbD`ST HotKey[index]=cKey;
F8Mf,jnPs HotKeyMask[index]=cMask;
#qD[dC$[t bAdded=TRUE;
FS!)KxC/- KeyCount++;
gm!sLZ!X break;
8.I3%u }
3=} P l, }
{{gt>"D, return bAdded;
('\sUZ+5 }
|R!ozlL{} //删除热键
k9:|CEP BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
49}WJC7
) {
lB_X mI1t BOOL bRemoved=FALSE;
~82 {Y
_{/ for(int index=0;index<MAX_KEY;index++){
T3 4Z#PFwe if(hCallWnd[index]==hWnd){
*n[B Bz if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
7^LCP* hCallWnd[index]=NULL;
CQrP%}`r HotKey[index]=0;
*W>, 98 HotKeyMask[index]=0;
Q1|zX@, bRemoved=TRUE;
PDCb(5 KeyCount--;
Ze#DFe$ break;
7-}5
W }
EIyFGCw|U }
Y"yrc0'&T }
u&UmI-} return bRemoved;
^=1u2YdVw }
LEOa=(mN\ nLv~)IQ}: fk>{ DLL中的钩子函数如下:
;c DMcKKIA 2efdJ&eIV LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
BF;}9QebmS {
/;1O9HJa BOOL bProcessed=FALSE;
Hz==,NR-W if(HC_ACTION==nCode)
#:/27 {
,&o^}TFkg if((lParam&0xc0000000)==0xc0000000){// 有键松开
_G'A]O/BZD switch(wParam)
x#zj0vI-8 {
A,=>
|&* case VK_MENU:
1\Pjz
Lj MaskBits&=~ALTBIT;
u^CL }t* break;
- _6`0 case VK_CONTROL:
F[!%,-* MaskBits&=~CTRLBIT;
tm2lxt break;
V`W '] case VK_SHIFT:
o)7Ot\:E MaskBits&=~SHIFTBIT;
`YE=B{q break;
U,61 3G default: //judge the key and send message
y;<suGl break;
#d/T7c# }
1,Mm+_)B for(int index=0;index<MAX_KEY;index++){
{&B_b|g*fW if(hCallWnd[index]==NULL)
84WcaH continue;
>D}|'.& if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
[6_.Y*}N {
KRcB_( SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
BT_XqO bProcessed=TRUE;
{2D|,yH= }
X# ud5h }
v>Kh5H5e~ }
-38"S;M8 else if((lParam&0xc000ffff)==1){ //有键按下
o^*: switch(wParam)
.>.GQUr {
#=33TvprR2 case VK_MENU:
G +41D MaskBits|=ALTBIT;
O"\_%=X9 break;
bGK*1FlH case VK_CONTROL:
k<+Sj
h$ MaskBits|=CTRLBIT;
d
ePk}Sn break;
Yg,b
;H case VK_SHIFT:
j u"?b2f MaskBits|=SHIFTBIT;
/4c`[ break;
4Y2I'~' default: //judge the key and send message
T6=|)UTe1 break;
V+@ }dJS }
5y\35kT' for(int index=0;index<MAX_KEY;index++){
7Hgn/b[?b if(hCallWnd[index]==NULL)
<*dcl2xS continue;
6-TYOUm if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
1IS1P)4_0 {
Dykh|" SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
f5b|,JJ bProcessed=TRUE;
I9>vm] }
&0%Zb~ts }
dzAumWoh }
SG|AJ9 if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
\ERxr
for(int index=0;index<MAX_KEY;index++){
?<
teHFj if(hCallWnd[index]==NULL)
]sL.+.P continue;
/#(IV_Eol if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
k}&wy SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
Ka-o$o[^u` //lParam的意义可看MSDN中WM_KEYDOWN部分
K\XQE50 }
F~
\ONO5 }
]y=U"g }
?Fny_{&^H return CallNextHookEx( hHook, nCode, wParam, lParam );
9lR6:}L7 }
V;"2=)X V:J|shRo 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:
'q |"+; c$2kR: BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
z~3ubta8(@ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
Ax;?~v4Z ]w _&%mB 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
I]+
zG N0kCdJv LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
)j~{P {
W)/f5[L if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
8~R.iqLoX {
p#]9^oA //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
knG:6tQ SaveBmp();
O TlqJ return FALSE;
1+N'cB!y }
i7r)9^y …… //其它处理及默认处理
8Nyz{T[ }
'iZwM>l\ R3lZ|rxv: JQ0Z%;" 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
LTo!DUi` stUv! 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
hLgX0QV [m
h>N$ 二、编程步骤
`^hA &/1 Oy=0Hsh@x 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";
iJOG"gI& f>C+ l( 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
a6./;OC Ib{l$# 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;
__QnzEF 8~-TN1H 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;
3))R91I Ua
6O~,\ 5、 添加代码,编译运行程序。
;7?oJH; H,w8+vZ4\ 三、程序代码
z[QDJMt> &ZC{ _t ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
Ji9o0Y R #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
$fD%18 #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
L%5y@b{AR #if _MSC_VER > 1000
nKr'cb #pragma once
.u#Hg'o P #endif // _MSC_VER > 1000
wUr(i * #ifndef __AFXWIN_H__
wdBBx\FP #error include 'stdafx.h' before including this file for PCH
2ns,q0I
A #endif
?zutU w/m #include "resource.h" // main symbols
V
)oXJL class CHookApp : public CWinApp
),B/NZ/- {
>TCit1yD public:
>"<s7$g CHookApp();
RS}_cm0 // Overrides
UV}:3c6 ZX // ClassWizard generated virtual function overrides
YQd($ //{{AFX_VIRTUAL(CHookApp)
6IT6EkiT public:
zNKB'hsK virtual BOOL InitInstance();
T$2A2gb` virtual int ExitInstance();
4C_1wk(' //}}AFX_VIRTUAL
YB4
ZI //{{AFX_MSG(CHookApp)
%u&Vt"6m= // NOTE - the ClassWizard will add and remove member functions here.
*#}=>, v // DO NOT EDIT what you see in these blocks of generated code !
_oBx:G6E //}}AFX_MSG
iz/CC V L DECLARE_MESSAGE_MAP()
5ILKYUg, };
ll$mRC LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
w2'z~\dG8 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
<>n|_6'$90 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
T>|
hID BOOL InitHotkey();
sB*dv06b0 BOOL UnInit();
G5t7KI #endif
_/>I-\xWA FN!?o:|( //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
@"fv[=Xb #include "stdafx.h"
zFO0l). #include "hook.h"
!]uB4 #include <windowsx.h>
,{q#U3 #ifdef _DEBUG
0.R3(O #define new DEBUG_NEW
&XCd2 #undef THIS_FILE
PV"\9OIKb. static char THIS_FILE[] = __FILE__;
iN'T^+um= #endif
x2)WiO/As #define MAX_KEY 100
Hn)?
xw]x #define CTRLBIT 0x04
^J7q,tvbJ #define ALTBIT 0x02
a9NuYYr,h #define SHIFTBIT 0x01
<BBzv-?D #pragma data_seg("shareddata")
jmq^98jB HHOOK hHook =NULL;
&glh >9:G UINT nHookCount =0;
$X)|`$#pL# static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
b1IAp >*2l static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
?OnL,y| static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
m)<+?Bv y static int KeyCount =0;
~s'}_5;VY static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
JP\jhkn #pragma data_seg()
dPpQCxf HINSTANCE hins;
>T[Y>] void VerifyWindow();
`fEzE\\!* BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
?F[_5ls|] //{{AFX_MSG_MAP(CHookApp)
JLWm9c+UTG // NOTE - the ClassWizard will add and remove mapping macros here.
zJ8T.+qJ // DO NOT EDIT what you see in these blocks of generated code!
X!z-J> //}}AFX_MSG_MAP
~1*37 w~ END_MESSAGE_MAP()
4>L*7i #M w70@6 CHookApp::CHookApp()
x{w|Hy {
) aMiT // TODO: add construction code here,
{RI^zNgs[ // Place all significant initialization in InitInstance
-;"A\2_y }
S#p_Y^A z0ufLxq CHookApp theApp;
5D7 L)> LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
x@oxIXN {
7#UJ444b~ BOOL bProcessed=FALSE;
C "@>NC_ if(HC_ACTION==nCode)
V!]|u ^4I {
xE--)=<$ if((lParam&0xc0000000)==0xc0000000){// Key up
KV;q}EyG switch(wParam)
_IU5HT}2 {
6j{ynt case VK_MENU:
*zweZG8: MaskBits&=~ALTBIT;
K-Pcew^? break;
.c<U5/ case VK_CONTROL:
Ei]SksV>* MaskBits&=~CTRLBIT;
b g0ix" break;
`/R. 5;$| case VK_SHIFT:
'M? ptu?f MaskBits&=~SHIFTBIT;
hUvA;E(qD break;
;
Gv-$0{P3 default: //judge the key and send message
GGHeC/4 break;
Iy*Q{H3[ }
i}>EGmv m for(int index=0;index<MAX_KEY;index++){
NqKeQezX if(hCallWnd[index]==NULL)
[=cbzmX[ continue;
&*O'qOO<2 if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
GcO:!b*YMp {
oM@%2M_O( SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
u"hr4+/ bProcessed=TRUE;
8_`C&vx }
Txe*$T,( }
"X?Zw$gRud }
@zw&-b:qI else if((lParam&0xc000ffff)==1){ //Key down
N,9~J"z switch(wParam)
_[&.`jTFn {
G){+.X4g3 case VK_MENU:
/\Xe'& MaskBits|=ALTBIT;
fYZd:3VdC break;
!JDuVqW case VK_CONTROL:
.sj/Lw} MaskBits|=CTRLBIT;
3''Kg<k,I break;
j8?! J^TC case VK_SHIFT:
#!TlalV MaskBits|=SHIFTBIT;
h1 "# break;
wS7Vo{#@\ default: //judge the key and send message
-3d`e2^&} break;
FR'Nzi$ }
L5d
YTLY for(int index=0;index<MAX_KEY;index++)
_RzoXn{1e {
"#8^":,4 if(hCallWnd[index]==NULL)
a ge8I$*`@ continue;
I=[0 9o if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
*&_A4) {
l&W:t9o SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
,:-^O# bProcessed=TRUE;
}>,%El/ }
>N`,
3;Z }
c-.F{~ }
"[z/\l8O if(!bProcessed){
Q-G8Fo%#,E for(int index=0;index<MAX_KEY;index++){
N@'l:N'f4 if(hCallWnd[index]==NULL)
'MyJw*%b] continue;
WyQ8}]1b if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
,_7m<(/f SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
X>yE<ni }
D"fjk1 }
k{Y\YG%b
}
$OGMw+$C^ return CallNextHookEx( hHook, nCode, wParam, lParam );
@#o7U }
n@C#,v#^0 1UrkDz?X BOOL InitHotkey()
rfgsas{F {
i6;rh-M?. if(hHook!=NULL){
/
)[\+Nc nHookCount++;
@LU[po1I return TRUE;
e2nZwPH }
? )IH#kL else
^Nav8dma hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
F$:mGyl5_ if(hHook!=NULL)
Q3t%JP>;g nHookCount++;
wc}x
[cS return (hHook!=NULL);
}+[!h=Bx }
Y<@_d BOOL UnInit()
l:#'i`; {
slr>6o%W` if(nHookCount>1){
U&$I!80. nHookCount--;
<A\g*ld return TRUE;
JiA1yt }
>:
@\SU BOOL unhooked = UnhookWindowsHookEx(hHook);
s1%2({wP if(unhooked==TRUE){
[P)](8nR[ nHookCount=0;
G[zy sxd hHook=NULL;
mkBQTQGT }
.rDao]K return unhooked;
C<^S$ }
b3GTsX\2| 6is+\ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
rg%m {
3],(oQq^ BOOL bAdded=FALSE;
FY+@fy for(int index=0;index<MAX_KEY;index++){
ecp0 hG`% if(hCallWnd[index]==0){
K TE*Du hCallWnd[index]=hWnd;
>u
.u#d e HotKey[index]=cKey;
>Bm>/%2 HotKeyMask[index]=cMask;
lL'K1%{+
\ bAdded=TRUE;
$K|2k7 KeyCount++;
AMK3I`=8WO break;
sJg3WN }
TQ {8 ee{ }
f,@~@f
X return bAdded;
4 T/ ~erc }
/cZcfCW AZJ|.mV q BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
]InDcE {
r9-)+R
J BOOL bRemoved=FALSE;
`E>o:tff for(int index=0;index<MAX_KEY;index++){
ydzvjp= if(hCallWnd[index]==hWnd){
cf_X=;yaqy if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
qNkX:|j hCallWnd[index]=NULL;
yW_goS0 HotKey[index]=0;
M|$A)D1 HotKeyMask[index]=0;
D@iS#+22 bRemoved=TRUE;
b0/[+OY KeyCount--;
=D 5!Xq'| break;
Zk gj_ }
].gC9@C:$i }
pl 1CEoe }
+k return bRemoved;
7H[.o~\ }
6SSrkj }U # kmI#W"^ void VerifyWindow()
6<n+p'+n {
ia-&? for(int i=0;i<MAX_KEY;i++){
,=}+.ax if(hCallWnd
!=NULL){ mx^rw*'JGC
if(!IsWindow(hCallWnd)){ F@X8a/;F-
hCallWnd=NULL; YE@!`!`d:
HotKey=0; %U97{y
HotKeyMask=0; Fi+,omB&
KeyCount--; E{}eYU
} gLg\W3TOi
} g aXF3v*j
} p*Hf<)}
} C2J@] &