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:
^-_*@e*JE
P C_! 一、实现方法
"l56?@- x `N *:,8j 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:
\vAjg eBrNhE-[G] #pragma data_seg("shareddata")
D*%am|QL HHOOK hHook =NULL; //钩子句柄
eWcqf/4?" UINT nHookCount =0; //挂接的程序数目
b#
N"}-\^ static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
jmID@37t static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
Sf*)Z3f static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
]nhh|q9r{ static int KeyCount =0;
NUFz'MPv static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
dH^6K0J #pragma data_seg()
by@KdQow ST*h{:u&A 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。
);gY8UL^ }csA|cC 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:
W[8Kia-OD a;HAuy`M x BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
E5&Z={ cKey,UCHAR cMask)
:(n<c {
I}4
PB+yu BOOL bAdded=FALSE;
=Z^5'h~ for(int index=0;index<MAX_KEY;index++){
Y@+Rb if(hCallWnd[index]==0){
;5 j|B|v hCallWnd[index]=hWnd;
j>\c >U HotKey[index]=cKey;
pLB2! + HotKeyMask[index]=cMask;
UCLM*`M bAdded=TRUE;
1INX#qTZ KeyCount++;
,Xn2xOP break;
n%&L&G }
Zhq_ pus"a }
~rb0G*R> return bAdded;
P8d }
?F"o+]i+^ //删除热键
G(&[1V % x BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
QH/py {
TpKAdrY BOOL bRemoved=FALSE;
3f7zW3F for(int index=0;index<MAX_KEY;index++){
=?RI`}vw_H if(hCallWnd[index]==hWnd){
&h334N|4{ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
hQn?qJy%W hCallWnd[index]=NULL;
rVz.Ws# HotKey[index]=0;
ED&nrd1P HotKeyMask[index]=0;
u\*9\G bRemoved=TRUE;
RQ,#TbAe KeyCount--;
Je6[q break;
2Vx4"fHP#N }
A[Mke }
~:a1ELqVw }
Z1
D return bRemoved;
u"v7shRp: }
G^c,i5}w v
Y[s#*+ I=0c\ U} DLL中的钩子函数如下:
\OwF!~& Unk/uk LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
@{y'_fw {
*7!MG BOOL bProcessed=FALSE;
Xh@K89`uX if(HC_ACTION==nCode)
QQl.5'PP {
@nktD. if((lParam&0xc0000000)==0xc0000000){// 有键松开
*g(d}C! switch(wParam)
s@\3|e5g {
cbJgeif case VK_MENU:
`|'w]rj:"+ MaskBits&=~ALTBIT;
#J[g
r_ break;
C`.YOkpj case VK_CONTROL:
Vq'7gJj' MaskBits&=~CTRLBIT;
t1']q" break;
]Ur/DRNS case VK_SHIFT:
[b++bCH3 MaskBits&=~SHIFTBIT;
l]]NVBA]) break;
fs!dI default: //judge the key and send message
l~r;Grd/5 break;
FOiwA.:0 }
qOo4T@t3 for(int index=0;index<MAX_KEY;index++){
ea3w if(hCallWnd[index]==NULL)
:U?g']`Z## continue;
Qte5E}V` if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
=g#PP@X]D! {
]rG=\>U3~ SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
7hk)I`o65 bProcessed=TRUE;
|bnd92fvks }
:5k* kx#y }
=3bk=vy }
!l'nX else if((lParam&0xc000ffff)==1){ //有键按下
|;gx;qp4cN switch(wParam)
8~'cP? {
Ng#psN case VK_MENU:
`^)`J MaskBits|=ALTBIT;
lx`?n<-X break;
|J&\/8Q case VK_CONTROL:
-nb U5o MaskBits|=CTRLBIT;
' @!&{N break;
G@7^M} case VK_SHIFT:
mY 1l2 MaskBits|=SHIFTBIT;
TNu %_
34 break;
yq~ default: //judge the key and send message
?{J1&;j* break;
+Br<;sW }
eb_.@.a for(int index=0;index<MAX_KEY;index++){
.}dLqw if(hCallWnd[index]==NULL)
/uw@o9`~2- continue;
j7P49{ if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
~^F]t$rz {
yX
rI SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
D2ggFxqe bProcessed=TRUE;
Q7+WV`& }
KMhrw s{&B }
7ZUN;mr }
0F$|`v"0 if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
nDrRK for(int index=0;index<MAX_KEY;index++){
RZz?_1' if(hCallWnd[index]==NULL)
iA[T'+.Y continue;
fG 2)r if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
oiyvKMHz7 SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
#(]D]f[@ //lParam的意义可看MSDN中WM_KEYDOWN部分
?1\5X<|, }
k5RzW4zq; }
(
fFrX_K] }
|gk*{3~y return CallNextHookEx( hHook, nCode, wParam, lParam );
OS[
s Qo5 }
?qQ{]_q1&. f}c;s 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:
?O25k!7 LW=qX%o{ BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
=9&2udV1 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
nDkG}JkB! (Q{JI~P 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:
e{8C0= NZGO8u LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
gc4o
|x {
R&uPoY,f if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
7] y3<t {
/qQx~doK //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
ihkZs3} SaveBmp();
Gb^63.} return FALSE;
g!0
j1 }
h),;j`PrC …… //其它处理及默认处理
xbiprhdv }
?"b __(3 >Iij,J5i v8-szW). 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。
UB@(r86d 8i6iynR 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。
c<1$zQY! t_/qd9Jv 二、编程步骤
o9sQ!gptw GVT 6cR 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
3r%v@8)!b 9No6\{[M
2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
6F^/k,(k4 l"8g9z 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
Wi$?k{C )F9IzR-&m 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;
Qe~C}j% j Hq+/\ 5、 添加代码,编译运行程序。
I85wP}c( oX6Cd:c- 三、程序代码
$bp'b<jx D u<P^CE ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
~Dg:siw #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
?3DL .U{ #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
:/->m6C`0 #if _MSC_VER > 1000
!UzE&CirV #pragma once
,vR>hyM #endif // _MSC_VER > 1000
v0'z''KM! #ifndef __AFXWIN_H__
:{w3l O #error include 'stdafx.h' before including this file for PCH
0o/;cBH
#endif
z7fX!'3V #include "resource.h" // main symbols
+^:uPW^U class CHookApp : public CWinApp
ufR|V-BWx {
IlEU6Rs
public:
e,XT(KY CHookApp();
n_sV>$f-u // Overrides
41R~.? // ClassWizard generated virtual function overrides
c%<81Y= //{{AFX_VIRTUAL(CHookApp)
o5],c9R9b public:
~,W|i virtual BOOL InitInstance();
''2:ZX X virtual int ExitInstance();
6@Q; LV+ //}}AFX_VIRTUAL
zRh)q,Dt //{{AFX_MSG(CHookApp)
$zz4A~
// NOTE - the ClassWizard will add and remove member functions here.
5P*jGOg . // DO NOT EDIT what you see in these blocks of generated code !
319 4] //}}AFX_MSG
; <- f DECLARE_MESSAGE_MAP()
3meZ]u };
P'}EZ' LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
89[/UxM) BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
8f,",NCgc BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
oKRI2ni$j9 BOOL InitHotkey();
k8Dk;N BOOL UnInit();
QKk7"2t| #endif
b#709VHm |$8N*7UD //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
"+Ks# #include "stdafx.h"
1%@i4 #include "hook.h"
,*$Y[UT #include <windowsx.h>
J?p|Vy|9 #ifdef _DEBUG
({4?RtYm #define new DEBUG_NEW
s]vsD77& #undef THIS_FILE
k]4CN static char THIS_FILE[] = __FILE__;
z'Bvjul #endif
|}l/6WHB #define MAX_KEY 100
`[=/f=Q} #define CTRLBIT 0x04
1\TkI=N3 #define ALTBIT 0x02
B
\V;{: #define SHIFTBIT 0x01
.Sm 8t$ #pragma data_seg("shareddata")
z#5qI',L HHOOK hHook =NULL;
rl"yE= UINT nHookCount =0;
x!4<ff. static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
2Z(?pJyDM static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
$SLyI$<gP static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
Nj;(QhYZ static int KeyCount =0;
m=`V static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
j1JdG<n #pragma data_seg()
\KEmfCx'n HINSTANCE hins;
2%l(qfN9 void VerifyWindow();
SM}&
@cJ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
H2_6m5[&, //{{AFX_MSG_MAP(CHookApp)
&sq q+&ao // NOTE - the ClassWizard will add and remove mapping macros here.
c:DV8'fT // DO NOT EDIT what you see in these blocks of generated code!
787i4h:71 //}}AFX_MSG_MAP
?r0>HvUf!l END_MESSAGE_MAP()
ylmVmHmc * se),CP!s CHookApp::CHookApp()
UuJ gB) {
Dhft[mvo // TODO: add construction code here,
]VVx2ERs // Place all significant initialization in InitInstance
iA2TvP# }
17rg!'+ <t *3w CHookApp theApp;
yWYsN LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
-z/>W+k {
xG%O^ BOOL bProcessed=FALSE;
c*8k _o, if(HC_ACTION==nCode)
e~G IUwJ {
K>+c2;t; if((lParam&0xc0000000)==0xc0000000){// Key up
En+`ZcA\z switch(wParam)
&>@EfW]( {
m]++
! case VK_MENU:
Xp^71A?> MaskBits&=~ALTBIT;
btf]~YN break;
bmC{d case VK_CONTROL:
l%cE o`U MaskBits&=~CTRLBIT;
A*{V%7hs& break;
M/6q
^* case VK_SHIFT:
`?"[u"* MaskBits&=~SHIFTBIT;
*fDhNmQ ` break;
L{1PCs36c default: //judge the key and send message
:as2fO$? break;
i/DUB<>p6 }
}5gQ dj[Y for(int index=0;index<MAX_KEY;index++){
BfvvJh_ if(hCallWnd[index]==NULL)
p6{8t} continue;
_'r&'s;<z if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
xirZ.wj W {
c+TCC%AJQI SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
d_Y7/_i bProcessed=TRUE;
J16(d+ }
@}e5T/{X}T }
NSh~O!pX }
tjy@sO/Q else if((lParam&0xc000ffff)==1){ //Key down
z!9w Lo^r switch(wParam)
Gy[m4n~Z5 {
nrZZk QNI case VK_MENU:
a/
Z\h{* MaskBits|=ALTBIT;
{Ve_u break;
H|!|fo-Tx case VK_CONTROL:
f,Dj@?3+ MaskBits|=CTRLBIT;
z!\)sL/" break;
LT '2446 case VK_SHIFT:
?F%,d{^ MaskBits|=SHIFTBIT;
#.W<[KZf break;
8<g9 ~L default: //judge the key and send message
G
C3G=DTt break;
tsTCZ);( }
=qTmFszT for(int index=0;index<MAX_KEY;index++)
4}HY= 0Um {
>uDE<MUC if(hCallWnd[index]==NULL)
Bt-2S,c,o continue;
zC\L-i>G if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
!.5,RIf {
4T:@W C SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
I.}E#f/A' bProcessed=TRUE;
eN]9=Y~-K }
LZ*ZXFIg }
64-;| k4F }
w
]$Hr if(!bProcessed){
h>'Mh;+ for(int index=0;index<MAX_KEY;index++){
0W>,RR) if(hCallWnd[index]==NULL)
?,x3*'-( continue;
T|Fl$is if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
8d"Ff SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
0h~7"qUF@ }
L,wEUI }
jG&gd<^ }
niJtgK:H^ return CallNextHookEx( hHook, nCode, wParam, lParam );
iyf vcKO }
3N 5b3F 'e06QMp@ BOOL InitHotkey()
C.;H?So( {
G$$y\e$ if(hHook!=NULL){
4brKAqg. nHookCount++;
pbePxOG return TRUE;
4XXuj }
OB5`a,5dI else
>hmBV7nR hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
%oE3q>S$en if(hHook!=NULL)
S+&Bf ~~D nHookCount++;
#Rcb
iV*M return (hHook!=NULL);
Ves
x$!F# }
5ki<1{aVtZ BOOL UnInit()
KI{B<S3*Z {
]728x["(19 if(nHookCount>1){
6Z3L=j nHookCount--;
u3ns-e return TRUE;
wm/=]*jpK }
h"DxgG BOOL unhooked = UnhookWindowsHookEx(hHook);
&;Jg2f%. if(unhooked==TRUE){
<^8&2wAkJ nHookCount=0;
'9d]
B^)F hHook=NULL;
8C>\!lW" }
(7_}UT@w- return unhooked;
3c.,T }
^9*kZV<K Pwg?a BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
0B?t:XU , {
'6zD`Q BOOL bAdded=FALSE;
B)}.%G* for(int index=0;index<MAX_KEY;index++){
I[v6Y^{q if(hCallWnd[index]==0){
&;]KntxB hCallWnd[index]=hWnd;
z->[:)c HotKey[index]=cKey;
ruQ1Cph HotKeyMask[index]=cMask;
qz<>9n@o bAdded=TRUE;
OkaNVTB KeyCount++;
Gm2q`ki break;
w[X/|O }
qmx4hs8sh }
~dc~<hK return bAdded;
W2F *+M }
#XPY\n^k 7dbGUbT BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
?(d<n {
oi:!YVc BOOL bRemoved=FALSE;
NP^j5|A*" for(int index=0;index<MAX_KEY;index++){
Oq3]ZUVa if(hCallWnd[index]==hWnd){
KJ;;825? if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
`}Z`aK hCallWnd[index]=NULL;
[Y_CRxa\u HotKey[index]=0;
2=/,9ka~ HotKeyMask[index]=0;
$\A=J bRemoved=TRUE;
waI:w, KeyCount--;
'Wz`P#/ break;
+<1MY'>y }
zt|DHVy }
g ONybz6] }
6z keWR return bRemoved;
|`,AAa }
.ZK^kcyA /\0g)B;] void VerifyWindow()
}lP'bu {
he\ pW5p for(int i=0;i<MAX_KEY;i++){
82*nC!P3E if(hCallWnd
!=NULL){ o3OtG#g2
if(!IsWindow(hCallWnd)){ 9O2??N7f
hCallWnd=NULL; _aj,tz
HotKey=0; yT<