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我的新博客在 http://www.codediscuss.com

flyingxu — Tue, 02 Oct 2007 06:23:00 GMT

http://www.codediscuss.com 是我的博客的新地址。还是以VC++�~�程��Z��Q�有mfc�Q�英语，�q�有点点shareware的内宏V�?br>

flyingxu 2007-10-02 14:23 发表评论

关于IServiceProvider的一��很好的文章

flyingxu — Thu, 04 Jan 2007 16:14:00 GMT

关于几个HTML文档接口的��用探�?
http://www.vckbase.com/vckbase/vckbase10/vc/nonctrls/atlcomocx_02/1002005.htm

我觉得讲的很清楚�Q�呵�?img src ="http://www.shnenglu.com/flyingxu/aggbug/17275.html" width = "1" height = "1" />

flyingxu 2007-01-05 00:14 发表评论

thinking in c++ 习题�{�案

flyingxu — Tue, 08 Aug 2006 16:19:00 GMT

�q�个�{�案本来是作者卖��q��Q�我忘了是从那个�|�站下蝲的了�Q�估计不全�?br>现在有�h要，��放上来�?/p>

http://www.shnenglu.com/Files/flyingxu/ThinkinginCppExercise.rar

(未验证，可能不全�Q�或者根本就不是�{�案)

flyingxu 2006-08-09 00:19 发表评论

Memory leak in CWinThread?

flyingxu — Wed, 26 Jul 2006 11:11:00 GMT

�c�M��的问题见http://www.experts-exchange.com/Programming/Programming_Languages/MFC/Q_20084406.html

下面的代码，当用AfxBeginThread开始一个线�E�时�Q�实际上是有内存泄漏�?/p>

for (ii = 0 ; ii < 1000 ; ii ++ )
{
  CWinThread * pWinThread;
  pWinThread = AfxBeginThread(ThreadLBProc, NULL);
  ::Sleep( 500 );
}

UINT ThreadLBProc(LPVOID pParam)
{
   return 0 ;
}

VC输出的典型提�C�Zؓ�Q?br />Detected memory leaks!
Dumping objects ->
thrdcore.cpp(166) : {782} client block at 0x00425300, subtype 0, 112 bytes long.
实际上，只要看到�?font style="BACKGROUND-COLOR: #ffff00">thrdcore.cpp(166) 的内存泄漏，基本��是同一个原因，和上面的代码一栗��?br />解决�Ҏ��Q?br />step 1)
在线�E�函��C��Q�记得写AfxEndThread();(与AfxBeginThread对应�Q�其他的开始线�E�的函数�Q�有相应的函�?
step 2)
�?:WaitForSingleObject()��保�U�程��d��退�?br />
step 2是比较容易忽略的�Q�用sleep函数只能侥幸的保证线�E�退出，但不能确保�?img src ="http://www.shnenglu.com/flyingxu/aggbug/10557.html" width = "1" height = "1" />

flyingxu 2006-07-26 19:11 发表评论

flyingxu — Thu, 13 Jul 2006 10:29:00 GMT

用VC调试�E�序�Q�只要按下F12�Q�程序就出错了，出错的代码还很奇怪，再PeekMessage中，但是只出现在调试�Q�按F5�Q�，不出现在全速运行（Ctrl+F5�Q�，release版本也没有问�?br />�|�上的解�{?
http://support.microsoft.com/kb/q130667/ F12居然��是�q�么定义的，ft

所以，在定义程序功能的时候，��尽量不要用到F12 �Q�哈

flyingxu 2006-07-13 18:29 发表评论

Is MSDN wrong? or I made a mistake? about static member function

flyingxu — Tue, 11 Jul 2006 11:14:00 GMT

我在ms的group上问了个问题http://msdn.microsoft.com/newsgroups/default.aspx?dg=microsoft.public.vc.mfc&tid=402a414c-a125-45bd-9cf4-c1819db7e3e4�Q?br />

in http://msdn2.microsoft.com/en-us/library/480b7kf7.aspx, it says that
pGdiObject->DeleteTempMap(); // Causes compiler error
But I'm confused for a static member can be called by the object or a pointer.
Is there anything wrong of my understanding?

回答的�h到蛮多，讨论的也很热烈，但都没有直接回答我的问题�Q�我的问题是�Q�对于静态函敎ͼ�
pGdiObject->DeleteTempMap(); // Causes compiler error�Q?br />到底对不对？如果不对�Q�就是msdn错了�Q�不�q�总觉得比较奇怪，msdn不该��L��错的

flyingxu 2006-07-11 19:14 发表评论

[zz]MFC�q�回的��时对象指针成�?

flyingxu — Mon, 10 Jul 2006 15:18:00 GMT

csdn上难得的好文章，怕不争气的csdn�|�站�q�几天又找不到这��文章了�Q�我得先转一下，保存一下：
http://community.csdn.net/Expert/FAQ/FAQ_Index.asp?id=193097

Q :	MFC�q�回的��时对象指针成�?
主要解答�?	QunKangLi	提交�?	QunKangLi
感谢:	oldforest、yu_hl、QunKangLi
审核�?	happyparrot	�C�֌�对应贴子:	查看
A :
msdn在介�l�GetDlgItem的时候，明确指出�Q? The returned pointer may be temporary and should not be stored for later use. 如果真是�q�样那我不惨了！在我的一个��Y件中�Q�因为常常要使切换按钮的可用与不可用以及改变按钮文字�Q�所以我用DetDlgItem把它们存了�v来，用的时候直接到数组里面取，�q�样的话�q�个软�g不是犯了一个重大的错误了？可是用这么久也没出错�? 另外�Q�它也是说可能是临时的，那一定在某种情况下不是��时的�Q�高手能不能解释一下这个问题？ --------------------------------------------------------------- // Most Windows objects are represented with a HANDLE, including // the most important ones, HWND, HDC, HPEN, HFONT etc. // We want C++ objects to wrap these handle based objects whenever we can. // Since Windows objects can be created outside of C++ (eg: calling // ::CreateWindow will return an HWND with no C++ wrapper) we must // support a reasonably uniform mapping from permanent handles // (i.e. the ones allocated in C++) and temporary handles (i.e. // the ones allocated in C, but passed through a C++ interface. // We keep two dictionaries for this purpose. The permanent dictionary // stores those C++ objects that have been explicitly created by // the developer. The C++ constructor for the wrapper class will // insert the mapping into the permanent dictionary and the C++ // destructor will remove it and possibly free up the associated // Windows object. // When a handle passes through a C++ interface that doesn't exist in // the permanent dictionary, we allocate a temporary wrapping object // and store that mapping into the temporary dictionary. // At idle time the temporary wrapping objects are flushed (since you better // not be holding onto something you didn't create). // 在CWinThread::OnIdle里调用AfxUnlockTempMaps�Q�AfxUnlockTempMaps会释放temporary maps. 所以不要保留GetDlgItem�{�返回的临时指针�Q�可以直接保存HWND objects�Q�然后CWnd::FromHandle获取临时指针来用�? --------------------------------------------------------------- 临时包装对象会在�I�闲旉��删除.在同一函数中多�ơ��用是没用问题�?不同函数中��用先前保存下来的指针��有可能出错,特别是对话框初��化时候存下来的指�? 在MFC层次上的函数使用CWnd对象,而本地Windows代码(API)使用句柄.�?当Windows�pȝ��调用一个窗口过�E�时��传递一个HWND参数,而MFC本��n的消息机制��用CWnd�c?��Z��更好更高效的实现,MFC需要与Windows�pȝ��合作,��句柄与CWnd对象�q�行兌��---它用CHandleMap完成兌��. CHandleMap有两个CMapPtrToPtr的成员变�?m_permanentMap(�怹�映射�?�E�序�q�行�q�程中对�?句柄之间的关�p?,m_temporaryMap(临时映射�?在消息存在的�q�程中才存在).�怹�表保存显式创建的CWnd对象,当对象创建时��在�怹�目录下插入一个条�?在CWnd::OnNcDestrory时删除对应条�?但是Windows有时会传入某些不是由开发�h员显式创建的�H�口的句�?此时MFC会分配一个��时对象来包装�q�个句柄�q�将它们的映��保存到临时映射表中,�q�些临时对象会在�I�闲旉��被删除�ƈ�U�走相应的��时映��表条目.�c�M��的MFC对象与Windows句柄的映��表�? m_pmapHWND: �H�口句柄与CWnd对象 m_pampHMENU: 菜单句柄与CMenu对象 m_pmapHDC: 讑֤�环境句柄与CDC对象 m_pmapHGDIOBJ: GDI句柄与CGDI对象 m_mapHIMAGELIST: 囑փ�链表句柄到CImageList对象当给定句�?如HWND�?MFC��单调用CWnd* PASCAL CWnd::FromHandle(HWND hWnd), 此函数内部��用CHandleMap::FromHandle(hWnd)获取相关联的CWnd对象.在CHandleMap::FromHandle(h)内部(源代码在WinHand.cpp),先��用CObject* pObject = LookupPermanent(h); if (pObject != NULL)return pObject; ��查永久表;如永久表中不存在,使用pObject = LookupTemporary(h)) != NULL��查��时表,都不存在�?使用pTemp = = m_pClass->CreateObject();if (pTemp == NULL)AfxThrowMemoryException();m_temporaryMap.SetAt((LPVOID)h, pTemp);创徏临时对象�q�将其插入到临时表中�?同时�q�回该��时对�? void CHandleMap::RemoveHandle(HANDLE h)的注释说明��时对象将在空闲时由OnIdel释放: // remove only from permanent map -- temporary objects are removed // at idle in CHandleMap::DeleteTemp, always! 如果想不自动释放临时对象,使用void AFXAPI AfxLockTempMaps()/BOOL AFXAPI AfxUnlockTempMaps(BOOL bDeleteTemps)�q�行锁定.

flyingxu 2006-07-10 23:18 发表评论

bug�Q?OnIdle called only while mouse's moving

flyingxu — Sat, 08 Jul 2006 18:03:00 GMT

在mfc的group上有�q�样一个问题：�Q?a >http://msdn.microsoft.com/newsgroups/default.aspx?dg=microsoft.public.vc.mfc&mid=1aa1eddf-7bcf-407b-84fe-234fe0975331&sloc=en-us�Q?br />

I need to update one class data and the view during the idle, I used this
method in the Cdoc:
void CMyAppDoc::OnIdle(){

    theClass->Update();
    POSITION pos = GetFirstViewPosition();
    CView* pView = GetNextView(pos);
    pView->Invalidate(true);
    pView->UpdateWindow();
}

It works only when I move the mouse, what's wrong? Z_Z

�q�个问题的确比较搞，要好好看mfc源码的，下面是我的回�{?br />Nothing is wrong, I can explain it is by design.
Please take a look at the source code of int CWinThread::Run(), in that function, IsIdleMessage() is called, and in IsIdleMessage() WM_PAINT is ignored, which means WM_PAINT will not cause OnIdle to be called, for windows think it's just a WM_PAINT message and will not change the UI.
Your UpdateWindow() only post a WM_PAINT message, the message queue is not empty but it's ignored by IsIdleMessage(), that's why.
But when you move your mouse, the message queue is filled with some WM_MOUSEMOVE and it's not ignored for the position changes. So your OnIdle() is called again.
-
My suggestion is to move your Invalidate & UpdateWindow code to somewhere else.
OnIdle�Q�）的确是个有点复杂的问题，我可能还会写几篇文章 �Q�）
�q�里�Q?a >http://groups.google.com/group/microsoft.public.vc.mfc/browse_thread/thread/14f20aa5ffd6994d/66b6e5949a31bfa2?lnk=st&q=AfxUnlockTempMaps&rnum=40&hl=zh-CN#66b6e5949a31bfa2�Q�有��文章讲的很��C��

flyingxu 2006-07-09 02:03 发表评论

_asm int 3 的一个应用：在程序运行后再进入调试器

flyingxu — Thu, 06 Jul 2006 09:35:00 GMT

调试�E�序的时候，一�?br />1�Q�启动调试器�Q�比如VC
2�Q�在VC中设断点
3�Q�操作程序，使得�E�序�q�行到断点，停下�?br />但是现在我遇��C��个情况，希望调试的情景是�q�样的：双击某个文�g�Q�我的程序启动后�Q�这个时候我想程序停下来�Q�让我在VC中调试它�?br />但是�Q�双��L��件后启动的程序，是个独立的exe�q�行�E�序�Q�肯定不是在VC的运行控制下的，VC中设�|�的断点不�v作用的。怎么办呢�Q?br />�q�个时候可以在惌��E�序停下来的地方增加指��o_asm int 3�Q�debug下编译好。双��L��件后�q�行�q�个exe�Q�在exe�q�行到_asm int 3�Ӟ��׃��中断�Q�而把当前的exe�q�行与一个新的调试器�Q�一个新的VC�q�程�Q�结合�v来。接下来��像一般的调试了�?br />�q�时的调试步骤类��g��Q?br />1�Q�程序运�?br />2�Q�遇到特定条件时�Q�_asm int 3把当前exe与一个新的调试器�Q�比如一个新的VC�q�程�Q�联�p��v�?br />3�Q�在调试器中调试exe

�Q�）

flyingxu 2006-07-06 17:35 发表评论

flyingxu — Fri, 23 Jun 2006 12:56:00 GMT

C�Q�＋�~�程规范中第23条中��_��
If one header file won't work unless the file that includes it also includes another header, that's gauche and puts unnecessary burden on that header file's users.
呵呵�Q�英语有�Ҏ��口，后面丄��例子也都是模板的例子。我倒是遇到�q�一个实际的例子�Q�简化后如下�Q?br />

//a.h
class A
{
int a;
};

//b.h
//注意�Q�b.h�q�没有include a.h
class B
{
A a;
};

用的时候怎么用呢�Q�比如在main.cpp中想用class B

//main.cpp
#include "a.h"
#include "b.h"
//
B b;
//
//do something on b

可以看到�Q�main��Z��使用B�Q�还得包含a.h�Q�这��是上面一�D�英语说的：
如果一个头文�g�Q�b.h�Q�不能工作，除非包含它（b.h�Q�的文�g�Q�也��是main.cpp�Q�也包含另一个头文�g�Q�a.h�Q?..

hehe�Q�当我第一�ơ遇到这�U�情冉|��Q�想了半天也想不明白��Z��么我明明包含了b.h�q�是不能用B�?br />
那么�Q�正��的写法应该是什么呢�Q?br />在类B的作者在设计B的时候，��应该想到用户只需�?include "b.h"��可以��用这个class B。所以，在b.h文�g中，应该写明#include "a.h"�Q�而不是让用户在main.cpp中去include "a.h"

:)

flyingxu 2006-06-23 20:56 发表评论