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:
1;e"3x"
__F?iRrCM 一、实现方法
eU[f6OGqC f{} zqCK 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:
@Lp;p$G` ?0ezr[`. #pragma data_seg("shareddata")
Aqc
Cb[1r HHOOK hHook =NULL; //钩子句柄
fmDn1N-bG UINT nHookCount =0; //挂接的程序数目
lur$?_gt static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码
m'L7K K-Y) static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
'aq9]D_k static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
$r>\y (W static int KeyCount =0;
lphELPh static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
\0{g~cU4 #pragma data_seg()
6m=FWw3y 6:(R/9!P 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。
\[nvdvJv |=dmxfj@ 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:
d]kP@flOV -G!W6$Y BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR
c
h_1- cKey,UCHAR cMask)
li U=&wM> {
k|ol+
9Z BOOL bAdded=FALSE;
cz2guUu for(int index=0;index<MAX_KEY;index++){
,b&-o?.{ if(hCallWnd[index]==0){
I3{koI hCallWnd[index]=hWnd;
1l8kuwH HotKey[index]=cKey;
dG}.T_l HotKeyMask[index]=cMask;
e:h(, bAdded=TRUE;
POnI&y] KeyCount++;
R%(ww break;
Hy?+p{{G }
Sxj _gn }
86]})H return bAdded;
VcLB0T7m\ }
01/? //删除热键
fn!(cE|`E BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
17itC9U {
@,Re<%\ BOOL bRemoved=FALSE;
N@o Ng}D&: for(int index=0;index<MAX_KEY;index++){
7]i=eD8 if(hCallWnd[index]==hWnd){
dzK]F/L] if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
j:JM v hCallWnd[index]=NULL;
vlHE\%{ HotKey[index]=0;
4f}:)M$5 HotKeyMask[index]=0;
d )}@0Q bRemoved=TRUE;
*=6,}rX"I KeyCount--;
\z/_vzz4 break;
34@f(^d+^ }
bZ/4O*B }
Cb{n4xKW6 }
;}=4z^^5 return bRemoved;
f9Vxtd }
af:wg]g U%Igj:%?;` S.!0~KR:U DLL中的钩子函数如下:
q,<AW> uv:DO6 { LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
3\=iB&Gf| {
c]pO'6] BOOL bProcessed=FALSE;
BFCF+hU^6R if(HC_ACTION==nCode)
_?5$ST@5 {
%(EUZu2 if((lParam&0xc0000000)==0xc0000000){// 有键松开
i$Rlb5RU switch(wParam)
SO}$96 {
;w^-3 U7: case VK_MENU:
@IB+@RmL MaskBits&=~ALTBIT;
q}nL'KQ,n break;
Ww{|:>j case VK_CONTROL:
L5"|RI} MaskBits&=~CTRLBIT;
2EHeQ|# break;
oic}Go case VK_SHIFT:
p|W <xFk MaskBits&=~SHIFTBIT;
D92#&,KD break;
l c<&f default: //judge the key and send message
N|pyp*8Z break;
UF
g N@ }
}]qx " for(int index=0;index<MAX_KEY;index++){
5`ma#_zk|f if(hCallWnd[index]==NULL)
xJ;DkPh continue;
d/Sx+1
"{T if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
W|go*+`W% {
GM5s~, SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
Ly0U')D: bProcessed=TRUE;
A.mIqu,: }
[M^ur%H }
bt$+l[U^J }
/K#t$O4 else if((lParam&0xc000ffff)==1){ //有键按下
aYjFRH` switch(wParam)
U9om}WKO {
vFKt=o$ g case VK_MENU:
.kBZ(`K MaskBits|=ALTBIT;
F-=W7 D:[c break;
IT`r&;5 case VK_CONTROL:
9$9Pv%F:j MaskBits|=CTRLBIT;
nUAs:Q break;
c'9-SY1'~ case VK_SHIFT:
N"i'[!H% MaskBits|=SHIFTBIT;
@ =RH_NB break;
=5JTVF default: //judge the key and send message
Jy,Dcl break;
G1Qc\mp }
IZ2c<B5& for(int index=0;index<MAX_KEY;index++){
R+c
{Pl if(hCallWnd[index]==NULL)
6j]pJ]F6 continue;
ty8\@l if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
>5i(U_`l {
c8o$WyO SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
}tH$/-qnJE bProcessed=TRUE;
+OUYQM mM }
[WOLUb }
%N"9'g> }
a\wpJ|3{=T if(!bProcessed){ //一般按键事件,为监视键盘的程序留出余地
u1?1x for(int index=0;index<MAX_KEY;index++){
Ib)>M`J if(hCallWnd[index]==NULL)
Ha~g8R& continue;
9s5PJj "u if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
-3M6[`/ SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
H8>u: //lParam的意义可看MSDN中WM_KEYDOWN部分
oQrkd: }
T~nm Eap }
,j4 ;:F }
-Oo7]8 return CallNextHookEx( hHook, nCode, wParam, lParam );
\78w1Rkl }
}&Eb {' ))M; .b.D 抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
Pkr0|bs* 1|za>N6[yu BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
WQ\H2go BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
DR."C+ >*TFM[((Y) 为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:
vW\#2[j[ DA[s k7 LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
?i.]|#{Z {
'RIlyH~Yf if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
DU6AlNx {
|%F[.9Dp //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
U]!D=+ SaveBmp();
t83n` LC return FALSE;
#+2|ZfCn% }
r^uo7?gZ^ …… //其它处理及默认处理
{DPobyvwFk }
u`l1
zMk ^cYm.EHI ~E2xIhV 将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。
giy4< [u_-x3` 最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。
v3(W4G` bg\~" 二、编程步骤
Kt,ENbF Fe(qf>E 1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";
5feCA ,v7 SwESDo) 2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;
0K-jF5i$` l$%mZl 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;
GS^U6Xef _rQM[{Bkg 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;
u!([m;
x| w5I
+5/I 5、 添加代码,编译运行程序。
)'{:4MX NX?J 三、程序代码
U>^u!1X N?d4Pu1m ///////////////////////////////////// Hook.h : main header file for the HOOK DLL
s=lkK/ [ #if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
$]/a/!d #define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
Z3K~C_0Cnu #if _MSC_VER > 1000
.bh>_ W_h #pragma once
+tz^ &( #endif // _MSC_VER > 1000
0&1!9-(d #ifndef __AFXWIN_H__
W
s!N%%g #error include 'stdafx.h' before including this file for PCH
X<4h"W6 #endif
gi;#?gps #include "resource.h" // main symbols
j HT2|VGb* class CHookApp : public CWinApp
neGCMKtzlJ {
$ctY#:;pV{ public:
VWoxi$3v CHookApp();
IrU}%ZVV // Overrides
x\vb@!BZ // ClassWizard generated virtual function overrides
W&[}-E8<Y //{{AFX_VIRTUAL(CHookApp)
{`0GAW)q public:
Y-%S,91O virtual BOOL InitInstance();
2}P<}-?6 virtual int ExitInstance();
'l$<DcBj //}}AFX_VIRTUAL
YadY?o./ //{{AFX_MSG(CHookApp)
\2!v~&S // NOTE - the ClassWizard will add and remove member functions here.
P=K+!3ZXo // DO NOT EDIT what you see in these blocks of generated code !
A*ImruV //}}AFX_MSG
=N-,.{` DECLARE_MESSAGE_MAP()
Dm':D };
SSANt?\Z< LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);
g)+45w*+5 BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
|Ew\Tgo/2 BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
}hOExTz BOOL InitHotkey();
O>^0} BOOL UnInit();
pb~&gliW #endif
c43"o N
3)OH6w" //////////////////////////////////////// Hook.cpp : Defines the initialization routines for the DLL.
pA9:1*+;; #include "stdafx.h"
pQaP9Y{OK #include "hook.h"
i)V-q9\ #include <windowsx.h>
]9?_m@Ihx #ifdef _DEBUG
^F<[5e)M #define new DEBUG_NEW
ZFy>Z:&S, #undef THIS_FILE
1!RD
kZwe static char THIS_FILE[] = __FILE__;
|9)Q =( #endif
'vO+,- #define MAX_KEY 100
hia_CuY# #define CTRLBIT 0x04
;b:Ct < #define ALTBIT 0x02
QKYGeT7&Y' #define SHIFTBIT 0x01
9k_3=KS3N #pragma data_seg("shareddata")
tk5Bb`a HHOOK hHook =NULL;
h 5Y3
v UINT nHookCount =0;
OiAi{ 71 static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
w$*t.Q* static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
=R)9_D6I static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
y
1fl=i static int KeyCount =0;
zV {[0s static UCHAR MaskBits =0; //00000 Ctrl Alt Shift
)B@veso{ #pragma data_seg()
2RDos# HINSTANCE hins;
IAbK]kA void VerifyWindow();
#`5 M(
o BEGIN_MESSAGE_MAP(CHookApp, CWinApp)
\[&~.B //{{AFX_MSG_MAP(CHookApp)
,[IN9W // NOTE - the ClassWizard will add and remove mapping macros here.
SE+K"faKQ // DO NOT EDIT what you see in these blocks of generated code!
:0Nd4hA //}}AFX_MSG_MAP
\M/XM6:UG4 END_MESSAGE_MAP()
TL(L[ B[^mWVp6L CHookApp::CHookApp()
O&93QN0 {
T`46\KkN // TODO: add construction code here,
,D-VC{lj // Place all significant initialization in InitInstance
V)\|I8" }
ANh5-8y m?hC!n> CHookApp theApp;
=)C}u6 LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
(
q^umw {
W`], BOOL bProcessed=FALSE;
XA{tVh if(HC_ACTION==nCode)
hQrO8T?2 {
K"1xtpy if((lParam&0xc0000000)==0xc0000000){// Key up
hqVx%4s*J
switch(wParam)
Sg1$/+ {
.L%_#A case VK_MENU:
^ MkT"> MaskBits&=~ALTBIT;
6.|f iQs] break;
vyT$IdV2 case VK_CONTROL:
CqDMq ! MaskBits&=~CTRLBIT;
Nko;I?Fn break;
8}m]XO case VK_SHIFT:
GE=#8-@g~p MaskBits&=~SHIFTBIT;
Y'kD_T`f, break;
+ oyW_!( default: //judge the key and send message
D.|h0gU break;
$H ^hK0?' }
li\hH d5 for(int index=0;index<MAX_KEY;index++){
& v=2u,]T if(hCallWnd[index]==NULL)
|r5|IA continue;
Vin d\yvM if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
G8"L#[~ {
|{HtY SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
)RlaVAtM bProcessed=TRUE;
C\UD0r'p? }
mfLS</A }
UT$G?D";M }
tsq]QTA* else if((lParam&0xc000ffff)==1){ //Key down
^<xpp.eY switch(wParam)
\}t(g}7T {
GOHRBV case VK_MENU:
JI5?,
)-St MaskBits|=ALTBIT;
^lB'7#7 break;
XXacWdh \ case VK_CONTROL:
#X7fs5$& MaskBits|=CTRLBIT;
&ZFsK c# break;
2#5SI case VK_SHIFT:
<R}(UK MaskBits|=SHIFTBIT;
[|V<e+>T/ break;
+2`RvQN default: //judge the key and send message
0Ep%&>@ break;
t)XNS!6#]? }
?f[#O&# for(int index=0;index<MAX_KEY;index++)
j&)+qTV {
[-_u{j if(hCallWnd[index]==NULL)
ro7\}O:I continue;
oUR'gc : if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
(Ac
'}O {
ZVE q{x1Zc SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
]1rr$f9 bProcessed=TRUE;
$zq`hI!1 }
9)s=%dL }
MsCY5g }
IX;u +B if(!bProcessed){
C/ow{MxA for(int index=0;index<MAX_KEY;index++){
9f;\fe if(hCallWnd[index]==NULL)
~:Dr]kt continue;
Q u2W if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
QNzI SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
=dUeQ?>t= }
Ix !O&_6s }
Ra[{K@ }
sCSrwsbhv return CallNextHookEx( hHook, nCode, wParam, lParam );
U,Nf&g }
8 vK
Z; gO4`e(W BOOL InitHotkey()
Z1u{.^~ ^z {
)Ve?1?s '8 if(hHook!=NULL){
py9(z`} nHookCount++;
zCj]mH`es' return TRUE;
%7pT\8E5 }
{,|*99V else
c&IIqT@Gb0 hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
>V@-tT"^: if(hHook!=NULL)
XJDp%B nHookCount++;
[Hy0j* return (hHook!=NULL);
u!?.vx<qy }
5E?{>1 BOOL UnInit()
GUE3| {
yb56nd if(nHookCount>1){
$S|bD$e nHookCount--;
B@G'6 ? return TRUE;
bcC;i~9 }
V9NE kS BOOL unhooked = UnhookWindowsHookEx(hHook);
&,2XrXiFu if(unhooked==TRUE){
6<.Ma7)lA nHookCount=0;
Hq"i0Xm hHook=NULL;
O8TAc]B }
^k]OQc7q' return unhooked;
wqJ^tA! }
3|-)]^1O NMM0'tY~ BOOL __declspec(dllexport) __stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
rq Dre`m {
DG}t! BOOL bAdded=FALSE;
>`Gys8T for(int index=0;index<MAX_KEY;index++){
3iJ4VL7 if(hCallWnd[index]==0){
".onev^( hCallWnd[index]=hWnd;
a,U[$c HotKey[index]=cKey;
\ $}^u5Y HotKeyMask[index]=cMask;
|7 ]v&?y bAdded=TRUE;
BV"7Wp; KeyCount++;
+DaPXZ5. break;
l4u_Z:<w }
rePJ4i [y }
{<o_6 z`$ return bAdded;
yNi/JM }
p)RASIB \-$wY%7 BOOL __declspec(dllexport) __stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)
s6%% /| {
?<bByxa BOOL bRemoved=FALSE;
"detDB
for(int index=0;index<MAX_KEY;index++){
4,!#E0 if(hCallWnd[index]==hWnd){
Hly2{hokq if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
DX l3 hCallWnd[index]=NULL;
<XiHQ
B! HotKey[index]=0;
e82SG8#] HotKeyMask[index]=0;
thIuK V{CO bRemoved=TRUE;
,<0R'R KeyCount--;
Vb az#I break;
kL\
FY }
?%dsY\ }
ET;YAa* }
Xd@ - return bRemoved;
<0g.<n, }
FY+0r67] @{3$H^ void VerifyWindow()
!f[LFQD {
FJomUVR . for(int i=0;i<MAX_KEY;i++){
rg64f'+Eug if(hCallWnd
!=NULL){ 8+5#FC7
if(!IsWindow(hCallWnd)){ 9`VgD<?v
hCallWnd=NULL; Fy37I/#)r&
HotKey=0; c1B<