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:
UpCkB}OhR1
Ln&CB!u 一、实现方法
a
#Pr)H Z^ }4bR] 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:
x_.}C% @y{
f>nm #pragma data_seg("shareddata")
ue"e><c6: HHOOK hHook =NULL; //钩子句柄
:N
]H"u9X UINT nHookCount =0; //挂接的程序数目
Hrj@I?4 static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
[HSN*LXe static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
_XUDPC(*qz static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
zc%HBZ3p static int KeyCount =0;
BZAF;j static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
-)Y[t Z^*` #pragma data_seg()
m$bDWxm#e &=hkB9
; 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'xWRSDO s!\Gi5b 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:
]m"6a-,` XT~]pOE;D BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
5WU?Km cKey,UCHAR cMask)
f&L8<ASFo {
qBXIR} BOOL bAdded=FALSE;
,S\AUUt% for(int index=0;index<MAX_KEY;index++){
DyPb]Udb: if(hCallWnd[index]==0){
{^*D5 hCallWnd[index]=hWnd;
Q804_F
F# HotKey[index]=cKey;
xzOM\Nq?O HotKeyMask[index]=cMask;
8PwPI%Pb bAdded=TRUE;
B5H=# KeyCount++;
~U`|+
5 break;
8c0ugM }
<;':'sW }
V( SRw return bAdded;
o
C#W }
B*T;DE //删除热键
eCXw8 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
$SPA'63AC {
X UcM~U- BOOL bRemoved=FALSE;
w]=c^@t_ for(int index=0;index<MAX_KEY;index++){
=y WHm if(hCallWnd[index]==hWnd){
vN3uLz'< if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
8$y5) ~Q hCallWnd[index]=NULL;
V"R ,omh HotKey[index]=0;
R?H[{AX HotKeyMask[index]=0;
cy!;;bB bRemoved=TRUE;
t6a$ZN; KeyCount--;
`} :~,E break;
O t1:z:Pl }
(=/}i' }
vDp|9VY? }
MgUjB~)Y return bRemoved;
#>\%7b59> }
1QJB4|5R# 9Jj:d)E>o cSWn4-B@l DLL中的钩子函数如下:
+EE(d/f _omz74 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
?-D'xqc {
;iTZzmB BOOL bProcessed=FALSE;
fMZzR|_18 if(HC_ACTION==nCode)
eL{6;.C {
kli)6R< if((lParam&0xc0000000)==0xc0000000){// 有键松开
dId&tTMmC switch(wParam)
;LE9w^>^V {
4+'d">+| case VK_MENU:
tB==v{t MaskBits&=~ALTBIT;
wTkcR^ break;
>^ijj`{d case VK_CONTROL:
qjI.Sr70 MaskBits&=~CTRLBIT;
7o4B1YD break;
FCA]zR1 case VK_SHIFT:
?Q G?F9? MaskBits&=~SHIFTBIT;
*#g[
jl4 break;
c&;Xjy default: //judge the key and send message
N@G~+GCxL break;
\+Pk"M }
/j:fc?yv for(int index=0;index<MAX_KEY;index++){
gO,2:, if(hCallWnd[index]==NULL)
lz88//@gZ continue;
*J|]E( if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
J'#R9NO< {
bo04y)Iz SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
.:V4> bProcessed=TRUE;
do&0m[x% }
c3q @]|aI }
Xw_6SR9C }
v!77dj 6I else if((lParam&0xc000ffff)==1){ //有键按下
nHTb~t5Ke switch(wParam)
>P[BwL] {
<Pg<F[eDM case VK_MENU:
=?s0.(; MaskBits|=ALTBIT;
6*tbil_G+ break;
tX7TP( case VK_CONTROL:
$mLiEsJ MaskBits|=CTRLBIT;
WuUT>omH break;
C3GI?|b case VK_SHIFT:
3JcI}w MaskBits|=SHIFTBIT;
?Y|*EH break;
!p$k<?WX c default: //judge the key and send message
VaLl$w break;
<Z^qBM }
SlojB ^% for(int index=0;index<MAX_KEY;index++){
7R5!(g
if(hCallWnd[index]==NULL)
kV:C=MLI continue;
|?Bb{Es if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
C8bv%9 {
to"[r SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
n,.t~ bProcessed=TRUE;
\r7gubD }
EaXDY< }
6>Ca O }
KM jnY2 if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
bk{.9nz 2 for(int index=0;index<MAX_KEY;index++){
%2t#>}If! if(hCallWnd[index]==NULL)
K}1eQS&$a continue;
F\(7B# if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
*, RxOz2= SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
l<YCX[%E //lParam的意义可看MSDN中WM_KEYDOWN部分
#RWH k }
-y5Zc?e }
Zk#?.z} }
Th(F^W9 return CallNextHookEx( hHook, nCode, wParam, lParam );
[*|QA9 }
[5O` ps=+wg?] 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:
%zA$+eT &6}] v: BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
h`HdM58CQ BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
E+|r
h-M 7 %*`yd.L0W 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
}j /r jtFet{ LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
*2tG07kI {
m"RE[dQ if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
Y^P'slY{% {
Wy.Xx-3W //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
^vH3 -A;* SaveBmp();
#m<<]L(o8W return FALSE;
8NS1* \z }
^S'tMT_ …… //其它处理及默认处理
6
SosVE>Z }
zu-1|XX Rf.b_Y@O Jxy94y* 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
G B&+EZ <DjFMTCN 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
d3| oKP6 >HH49cCo 二、编程步骤
Q4JvFy0' rtM!|apr 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
{Z=m5Dy} Qy+&N*k> 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
6W abw: Sn lKPd 3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;
A+Xk=k5< k)a-odNrb 4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;
+Eh^j3W \dz@hJl: 5、 添加代码,编译运行程序。
VY9|8g/ i@C$O.m( 三、程序代码
79 svlq=
01nbR+e ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
bf3Njma% #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
02~+$R]L #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
S^Z[w|1 #if _MSC_VER > 1000
Vp'Zm: #pragma once
9w=GB?/ #endif // _MSC_VER > 1000
?T(>!m #ifndef __AFXWIN_H__
URodvyD #error include 'stdafx.h' before including this file for PCH
PmGW\E[ni #endif
H-sJt: #include "resource.h" // main symbols
Q6 G-`&5 class CHookApp : public CWinApp
wf<=rW' {
O,kzU,zOs public:
exqFwmhh CHookApp();
L.uX // Overrides
'xUyGj: // ClassWizard generated virtual function overrides
SJtQK-%wK> //{{AFX_VIRTUAL(CHookApp)
\P;%fN public:
>_Dq )n;% virtual BOOL InitInstance();
{/C
\GxH+ virtual int ExitInstance();
RN1q/H| //}}AFX_VIRTUAL
V #0F2GV<, //{{AFX_MSG(CHookApp)
GN4'LU // NOTE - the ClassWizard will add and remove member functions here.
&;%z1b>F // DO NOT EDIT what you see in these blocks of generated code !
ERO'{nT& //}}AFX_MSG
1XAXokxj DECLARE_MESSAGE_MAP()
cViEvS r };
=7JvS~s LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
|=^p`CT BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
+P?!yH,n BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
P,x'1`k~ BOOL InitHotkey();
?v-( :OF BOOL UnInit();
;/
iBP2 #endif
,m-z D hE41$9?TJ //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
,&$+{3 #include "stdafx.h"
BULf@8~( #include "hook.h"
L7*,v5 #include <windowsx.h>
v`"z
#ifdef _DEBUG
8,Jjv* #define new DEBUG_NEW
qn VxP& #undef THIS_FILE
o~#cpU4{o static char THIS_FILE[] = __FILE__;
`.dX@< #endif
P8N`t&r"7 #define MAX_KEY 100
TBN0u k #define CTRLBIT 0x04
|gvx^)ro #define ALTBIT 0x02
RKu'WD?sdH #define SHIFTBIT 0x01
G x;U 3iV #pragma data_seg("shareddata")
jN\} l|;q HHOOK hHook =NULL;
~C1lbn b UINT nHookCount =0;
PuvC
MD static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
^ lrq`1k static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
poZ04Uxo> static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
WoVPp*zlX static int KeyCount =0;
eI8rnp(Ia static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
uD=i-IHT #pragma data_seg()
_g|zDi^ HINSTANCE hins;
]Ek6EuaK void VerifyWindow();
h0}=C_.^ BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
g.wp
}fz //{{AFX_MSG_MAP(CHookApp)
O)y|G%O // NOTE - the ClassWizard will add and remove mapping macros here.
#k%$A}9 // DO NOT EDIT what you see in these blocks of generated code!
D00I!D16 //}}AFX_MSG_MAP
!~+"TI}_%w END_MESSAGE_MAP()
B$R"Ntp BI\ )vr$ CHookApp::CHookApp()
y0!-].5UH {
$#3O:aW // TODO: add construction code here,
C-i9F%.. // Place all significant initialization in InitInstance
0E*q-$P }
)Gf"#TM[ [D!-~]5 CHookApp theApp;
0(!j]w"r3 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
h^yLmRL {
!t. BOOL bProcessed=FALSE;
z+ch-L^K4 if(HC_ACTION==nCode)
LA!2!60R {
;DQ{6( if((lParam&0xc0000000)==0xc0000000){// Key up
`/W6,] switch(wParam)
0GEM3~~D.? {
Q"o* \I case VK_MENU:
!*[Fw1-J MaskBits&=~ALTBIT;
<SK%W= break;
tM&O<6Y case VK_CONTROL:
q1rBSlzN MaskBits&=~CTRLBIT;
/y8=r"'G break;
9|kc$+(+6 case VK_SHIFT:
!V<c:6" MaskBits&=~SHIFTBIT;
\<cs:C\h7 break;
0\qLuF[) default: //judge the key and send message
/INjP~C break;
OV@MT^ }
MHl ffj for(int index=0;index<MAX_KEY;index++){
1!(Og~#( if(hCallWnd[index]==NULL)
|6]2X W continue;
%y7&~me if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
OoW,mmthj> {
(d9G` SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
g 0Rny bProcessed=TRUE;
ld *W\ }
Ge'[AhA }
sBN"eHg }
@u@N&{b5" else if((lParam&0xc000ffff)==1){ //Key down
LS"_-4I} switch(wParam)
o|Q:am'H {
prIPPeMdz case VK_MENU:
35q4](o9" MaskBits|=ALTBIT;
U?@ s`. break;
fGZZ['E case VK_CONTROL:
71S~*"O0f MaskBits|=CTRLBIT;
^bD)Tg5K break;
~__r-z case VK_SHIFT:
hSl6X3W MaskBits|=SHIFTBIT;
2F}D?]A break;
VVd9VGvh default: //judge the key and send message
OON]E3yy break;
0A,u!"4[ }
8;%F-? for(int index=0;index<MAX_KEY;index++)
QPD[uJ(I {
`>HM<Nn-0 if(hCallWnd[index]==NULL)
;h f{B7 continue;
/JqNiqvh if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
*#n#J[ {
bjL8Wpk SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
vtByC u5 bProcessed=TRUE;
MvCB|N"qy }
;bYpMcH }
/h]#}y j }
~ERA if(!bProcessed){
b41f7t= for(int index=0;index<MAX_KEY;index++){
&UFj
U%Z% if(hCallWnd[index]==NULL)
GJr1[ continue;
-X]?ql*%` if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
+A;AX.mr SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
kB!
iEoIBA }
>;sz(F3) }
hifC.guK }
'NAC4to;; return CallNextHookEx( hHook, nCode, wParam, lParam );
J<vVsz+7: }
zObrp af>^<q BOOL InitHotkey()
-"CXBKHb
{
n40&4n if(hHook!=NULL){
it.'.aK4 nHookCount++;
W2w A66MB return TRUE;
;irAq| }
d#U~>wr else
#xoFcjRE hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
Zl\$9Q_ if(hHook!=NULL)
k .#I ;7 nHookCount++;
9Qb6ek return (hHook!=NULL);
)*`cJ_t }
%7v!aJ40 BOOL UnInit()
)JXlPU {
7L4~yazmK if(nHookCount>1){
>(\Z-I&YQ nHookCount--;
L!LhH return TRUE;
VBN=xg} }
eJy}W / BOOL unhooked = UnhookWindowsHookEx(hHook);
DX(!G a if(unhooked==TRUE){
BCI[jfd 7 nHookCount=0;
cna/?V hHook=NULL;
6
=H]p1p~O }
nrM_ay return unhooked;
2uzy]faM }
>9+h2B
d "%6S*dL BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
Q35D7wo'} {
9YvK<i&I BOOL bAdded=FALSE;
z5g4+y, for(int index=0;index<MAX_KEY;index++){
O"ebrv if(hCallWnd[index]==0){
.L8g(F(=: hCallWnd[index]=hWnd;
S7h?tR*u HotKey[index]=cKey;
>* h3u7t HotKeyMask[index]=cMask;
m:)sUC0 bAdded=TRUE;
.H}#,pQ}l KeyCount++;
giHWC%/ break;
!-~sxa280r }
y1bo28 }
NRMEZ\*L return bAdded;
sEHA?UP$<F }
Zo#c[9IaC zI$'D|A BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
oR~s
\Gt {
6^sH3=# BOOL bRemoved=FALSE;
&l~9FE* for(int index=0;index<MAX_KEY;index++){
7qLB 9r if(hCallWnd[index]==hWnd){
$Ned1@%[ if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
sf Zb$T
J hCallWnd[index]=NULL;
M&}_3 HotKey[index]=0;
oIGF=x,e8 HotKeyMask[index]=0;
CE7{>pl bRemoved=TRUE;
@;7Ht Z` KeyCount--;
8<=]4- X@ break;
=\IUBH+C }
$ qTv2)W1{ }
Xu7lV }
4l@aga return bRemoved;
>9,LN;Ic }
|&_(I jJV1 /]TJ void VerifyWindow()
3'!*/UnU {
SedVp cb+ for(int i=0;i<MAX_KEY;i++){
ot,=.%O if(hCallWnd
!=NULL){ B=HEi\55K
if(!IsWindow(hCallWnd)){ \u*[mrX_B:
hCallWnd=NULL; &F.L*M
HotKey=0; T\ [CQO
HotKeyMask=0; 6E$ET5p&