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OnClose

EiN — Tue, 06 Jan 2009 08:26:00 GMT

Occurs when the form closes.

enum TCloseAction { caNone, caHide, caFree, caMinimize };
typedef void __fastcall (__closure *TCloseEvent)(System::TObject* Sender, TCloseAction &Action);
__property TCloseEvent OnClose = {read=FOnClose, write=FOnClose, stored=IsForm};

Description

Use OnClose to perform special processing when the form closes. The OnClose event specifies which event handler to call when a form is about to close. The handler specified by OnClose might, for example, test to make sure all fields in a data-entry form have valid contents before allowing the form to close.

A form is closed by the Close method or when the user chooses Close from the form's system menu.

The TCloseEvent type points to a method that handles the closing of a form. The value of the Action parameter determines if the form actually closes. These are the possible values of Action:

Value    Meaning

caNone    The form is not allowed to close, so nothing happens.
caHide    The form is not closed, but just hidden. Your application can still access a hidden form.
caFree    The form is closed and all allocated memory for the form is freed.
caMinimize    The form is minimized, rather than closed. This is the default action for MDI child forms.

If a form is an MDI child form, and its BorderIcons property is biMinimize, then the default Action is caMinimize. If a MDI child form does not have these settings, the default Action is caNone, meaning that nothing happens when the user attempts to close the form.

If a form is an SDI child form, Action defaults to caHide.

To close the form and free it in an OnClose event, set Action to caFree.

Note:    When the application shuts down, the main form receives an OnClose event, but any child forms do not receive the OnClose event.

EiN 2009-01-06 16:26 发表评论

��观构�g

EiN — Fri, 02 Jan 2009 14:21:00 GMT

摘自BCB的例�?��看��有点迷�p?�q�越觉得niubility.像观察者又肯定不是,实在是牛...

Main.cpp:

//----------------------------------------------------------------------------
//Borland C++Builder
//Copyright (c) 1987, 1998-2002 Borland International Inc. All Rights Reserved.
//----------------------------------------------------------------------------
//-------------------------------------------------------------------------
//    minicomp.cpp - uses the TCounter example component
//-------------------------------------------------------------------------
#include "minicomp.h"
#include <stdio.h>
#include <stdlib.h>
#include <condefs.h>
//-------------------------------------------------------------------------
USEUNIT("counter.cpp");
//---------------------------------------------------------------------------
main()
{
  TExample example;

  return 0;
}
//-------------------------------------------------------------------------
TExample::TExample()
{
  TCounter Counter(7);
  int i;
  //把控件Counter的接口FMultiple和外部实现MultipleReached�q�接�?/span>
  Counter.OnMultiple = MultipleReached;

  for (i=0; i < 100; i++)
    Counter.Increment();
}
//-------------------------------------------------------------------------
void TExample::MultipleReached(TCounter *Sender)
{
  printf("Multiple=%d reached with val=%d\n", Sender->Multiple, Sender->Val);
}
//-------------------------------------------------------------------------

minicomp.h:

//-------------------------------------------------------------------------
//    minicomp.h - uses the TCounter example component
//-------------------------------------------------------------------------
#include "counter.h"
//-------------------------------------------------------------------------
class TExample
{
private:
  void MultipleReached(TCounter *Sender);
public:
  TExample();
};
//-------------------------------------------------------------------------

counter.h:

//-------------------------------------------------------------------------
//    counter.h. - example of a small, non-visual counter component
//-------------------------------------------------------------------------
class TCounter;         // forward

typedef void (__closure *TCounterEvent)(TCounter *Sender);
//-------------------------------------------------------------------------
class TCounter
{
private:
  TCounterEvent FOnMultiple; //�q�就是个函数接口
  int FVal;
  int FMultiple;
public:
  __property int Val = {read=FVal, write=FVal};
  __property int Multiple = {read=FMultiple};
  __property TCounterEvent OnMultiple = {read=FOnMultiple, write=FOnMultiple};
  void Clear();
  void Increment();
  TCounter(int Multiple);
};
//-------------------------------------------------------------------------

counter.cpp:

//-------------------------------------------------------------------------
//    counter.cpp - example of a small, non-visual counter component
//-------------------------------------------------------------------------
#include "counter.h"
//-------------------------------------------------------------------------
TCounter::TCounter(int Multiple)
{
  FMultiple = Multiple;
}
//-------------------------------------------------------------------------
void TCounter::Clear()
{
  FVal = 0;
}
//-------------------------------------------------------------------------
void TCounter::Increment()
{
  //�q�句执行旉��是外部来调用�?此时OnMultiple已经和外面那个函数接口连接上�?br>  //也就是调用的其实是外面进来的那个函数,把this传出�?让外部那个函数操�?br>  //TExample::MultipleReached(this)
  if (((++FVal) % FMultiple) == 0)
      OnMultiple(this);
}
//-------------------------------------------------------------------------

EiN 2009-01-02 22:21 发表评论

New Application

EiN — Wed, 31 Dec 2008 15:10:00 GMT

Project1.cpp:

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop
//---------------------------------------------------------------------------
USEFORM("Unit1.cpp", Form1); //调用�q�个vcl模块,详见Unit1.cpp
//---------------------------------------------------------------------------
//�q�里很搞�W?没给参数名重�?不知道这样函数里面能不能用到�q�几个参�?img src="http://www.shnenglu.com/Images/dot.gif">
//不过好像也就没用
WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)
{
    try
    {
         Application->Initialize();
         //The owner of the new form is the Application object
         //__classid�q�回一个指向TForm1的vtable的指�?�q�点�q�要再看看实现过�E?/span>
         Application->CreateForm(__classid(TForm1), &Form1);
         Application->Run();
    }
    catch (Exception &exception)
    {
         Application->ShowException(&exception);
    }
    catch ()
    {
         try
         {
             throw Exception("");
         }
         catch (Exception &exception)
         {
             Application->ShowException(&exception);
         }
    }
    return 0;
}
//---------------------------------------------------------------------------

Unit1.h:

//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
//都只是些声明部分,所以包含在头文仉��?/span>
#include <Classes.hpp> //TPersistent, TComponent
#include <Controls.hpp> //TControl, TWinControl
#include <StdCtrls.hpp> //TButton
#include <Forms.hpp> //TApplication, TForm
//---------------------------------------------------------------------------
/*
TObject(RTTI,垃圾回收�{�最基本�?
    |
    |--TList(stores an array of pointers)
    |
    |--TStream(read and write to some media)
    |   |
    |   |--TFileStream,TStringStream,TWinSocketStrem
    |
    |--TFiler(��d��控�g[objects]属�?比如保存dfm文�g信息,在内存中暂存控�g信息�{?
    |   |
    |   |--TReader
    |   |--TWriter(具体实现Filer功能)
    |
    |--TPersistent(have assignment and streaming capabilities)
        |
        |--TStrings(for objects that represent a list of strings)
        |   |
        |   |--TStringList(具体实现)
        |
        |--TComponent(控�g父类,包括可显�C�和不可昄��)
            |
            |--TApplication(抽象WindowsGUI环境,消息机制当然�q�有针对web的环�?
            |
            |--TControl(可视控�g)
                |
                |--TWinControl(针对Windows的可视控�?
                    |
                    |--TButtonControl(Button的抽�?
                    |   |
                    |   |--TButton(Button的具体实�?
                    |
                    |--TScrollingWinControl(支持滚动条的Windows控�g)
                        |
                        |--TCustomForm
                            |
                            |--TForm
*/
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:    // IDE-managed Components
private:    // User declarations
public:        // User declarations
    __fastcall TForm1(TComponent* Owner); //Owner是创造�?Parent是呈现�?只对于可视控�?
};
//---------------------------------------------------------------------------
/*
把这个vcl(Form1)导出,其他模块使用�q�个头文件时��告诉编译器,�q�个vcl在别处具体定�?br>*/
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

Unit1.cpp:

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop //之前的头文�g可以使用头文件缓存技�?其他包含vcl.h的编译块��q��译一��?/span>

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
/*
�q�里的疑问在�?头文仉��面已�l�有一个extern的指�?�q�里��Z��q�要再次搞出个指�?
注意在Project1.cpp里面有个USEFORM的宏,�q�个宏的具体定义在vcl\sysclass.h文�g�?br>如下:

#ifdef BCBVER1
  #define USEFORM(FileName, FormName) \
    class DELPHICLASS T##FormName;       \
    extern T##FormName *FormName;
#else
  #define USEFORM(FileName, FormName) \
    class DELPHICLASS T##FormName;       \
    extern PACKAGE T##FormName *FormName;
#endif

可以看出�q�里FileName�Ҏ��没用�?所�?既然�l�了cpp也就�l�了.h也就�l�了那个extern指针"
的想法是错误�?cpp文�g�Ҏ��没有�v��C�Q何作�?�q�是完全依赖�q�接旉��extern的存�?br>属性在obj里面��L��.�q�也��是��Z��么cpp里面如果没有下面�q�个指针声明,报错的不是Unit1
而是Project1,因�ؓ是在Project1调用了这么个没有定义个指�?�q�有一点就�?之所以会�q?br>��h��因�ؓ.h是不会编译的,Project1在Unit1.cpp对应的obj里面��L��,当然找不�?所以这�?br>必须要再�ơ写上一�?
*/
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
//---------------------------------------------------------------------------

EiN 2008-12-31 23:10 发表评论

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OnClose

���观构�g

New Application

��观构�g