ch23.htm

好书《C++ Builder高级编程技术》

{

  Width = 25;

  Height = 25;

  Color = clBlue;

  
FHierarchy = new TListHierarchy();

}



void __fastcall TCustomPallet::Paint(void)

{

  Canvas->Brush->Color = Color;

  Canvas->Rectangle(0, 0, ClientWidth, ClientHeight);

}



__fastcall TDataPallet::TDataPallet(TComponent *AOwner)

: 
TCustomPallet(AOwner)

{

  OnDragOver = PalletDragOver;

  OnDragDrop = PalletDragDrop;

}



void __fastcall TDataPallet::PalletDragOver(TObject *Sender,

  TObject *Source, int X, int Y, TDragState State, bool &Accept)

{

  Accept = 
dynamic_cast<TWidget *>(Source);

}



void __fastcall TDataPallet::PalletDragDrop(TObject *Sender,

  TObject *Source, int X, int Y)

{

  if (WidgetsTable == NULL)

    ShowMessage("No table assigned to the WidgetsTable property");

  
else

  {

    if (dynamic_cast<TWidget *>(Source))

    {

      TWidget *W = (TWidget *)(Source);

      AnsiString S = "Enter number of " + W->Name;

      AnsiString NumWidgets;

      

      if (InputQuery("Widget Number 
Dialog", S, NumWidgets))

      {

        EnterWidgets(NumWidgets.ToInt(), W);

      }

    }

  }

}



void TDataPallet::EnterWidgets(int Total, TWidget* W)

{

  int i;



  for (i = 0; i < Total; i++)

  {

    
FWidgetsTable->Insert();

    FWidgetsTable->FieldByName("Name")->AsString = W->Name;

    FWidgetsTable->FieldByName("Created")->AsString = W->TimeCreated;

    
FWidgetsTable->FieldByName("Description")->AsString = W->Description;

    FWidgetsTable->FieldByName("Cost")->AsCurrency = W->Cost;

    FWidgetsTable->FieldByName("PalletNumber")->AsInteger = 
PalletNumber;

    FWidgetsTable->Post();

  }

}



void __fastcall TDataPallet::QueryPallet(TQuery *Query)

{

  AnsiString S = "Select * from Widgets where PalletNumber = " +

    AnsiString(PalletNumber);

  Query->SQL->Clear();

  
Query->SQL->Add(S);

  Query->Open();

}



float __fastcall TDataPallet::QueryPalletSum(TQuery *Query)

{

  AnsiString S = "Select Sum(Cost) from Widgets where PalletNumber = " +

    AnsiString(PalletNumber);

  
Query->SQL->Clear();

  Query->SQL->Add(S);

  Query->Open();

  return Query->Fields[0]->AsFloat;

}



namespace Widgets

{

  void __fastcall RegisterShort()

  {

    TComponentClass classes[4] = {__classid(TWidget),

       
__classid(TPentium), __classid(TPentiumPro),

       __classid(TPallet) };

    RegisterClasses(classes, 3);

  }



  void __fastcall Register()

  {

    TComponentClass classes[5] = {__classid(TWidget),

       __classid(TPentium), 
__classid(TPentiumPro),

       __classid(TPallet), __classid(TDataPallet) };

    RegisterComponents("Unleash", classes, 4);

  }

}



</FONT></PRE>
<P><A NAME="Heading18"></A><FONT COLOR="#000077"><B>Listing 23.6. The final take
on the 
header for the MyObject unit.</B></FONT></P>
<PRE><FONT COLOR="#0066FF">///////////////////////////////////////

// MyObject.h

// Learning how to use objects

// Copyright (c) 1997 by Charlie Calvert

//



#ifndef MyObjectH

#define MyObjectH




#include &lt;conio.h&gt;

#include &lt;vcl\stdctrls.hpp&gt;



class TMyObject :public TObject

{

protected:

  virtual void PrintString(AnsiString S);

public:

  TMyObject() : TObject()  {}

  void ShowHierarchy(TObject *AnObject);

};



class 
TListHierarchy: public TMyObject

{

private:

  TStringList *FList;

protected:

  virtual void PrintString(AnsiString S)

    { FList-&gt;Add(S); }

public:

  TListHierarchy() { FList = new TStringList(); }

  __fastcall virtual ~TListHierarchy() { 
delete FList; }

  TStringList *GetHierarchy(TObject *AnObject)

    { FList-&gt;Clear(); ShowHierarchy(AnObject); return FList; } 

};



class __declspec(delphiclass) TVCLHierarchy;



class THierarchy: public TMyObject

{

  friend TVCLHierarchy;

  
int FTextColor;

  int FBackColor;

protected:

  virtual __fastcall void SetTextColor(int Color)

    { FTextColor = Color; textcolor(FTextColor); }

  virtual __fastcall void SetBackColor(int Color)

    { FBackColor = Color; 
textbackground(FBackColor); }

public:

  THierarchy() : TMyObject() {}

  virtual void PrintString(AnsiString S);

  virtual void ClrScr();

  __property int TextColor={read=FTextColor,write=SetTextColor};

  __property int 
BackColor={read=FBackColor,write=SetBackColor};

};



class TVCLHierarchy : public THierarchy

{

  TMemo *FMemo;

protected:

  virtual __fastcall void SetTextColor(int Color)

    { FTextColor = Color; FMemo-&gt;Font-&gt;Color = TColor(FTextColor); 
}

  virtual __fastcall void SetBackColor(int Color);



public:

  TVCLHierarchy(TMemo *AMemo): THierarchy() { FMemo = AMemo; }

  virtual void PrintString(AnsiString S)

    { FMemo-&gt;Lines-&gt;Add(S); }

  virtual void ClrScr() { 
FMemo-&gt;Clear(); }

};



#endif



</FONT></PRE>
<P><A NAME="Heading19"></A><FONT COLOR="#000077"><B>Listing 23.7. The final take
on the main source file for the MyObject unit.</B></FONT></P>
<PRE><FONT 
COLOR="#0066FF">///////////////////////////////////////

// MyObject.cpp

// Learning how to use objects

// Copyright (c) 1997 by Charlie Calvert

//

#include &lt;vcl\vcl.h&gt;

#include &lt;conio.h&gt;

#pragma hdrstop

#include 
&quot;myobject.h&quot;



void TMyObject::PrintString(AnsiString S)

{

  printf(&quot;%s\n&quot;, S.c_str());

}



void TMyObject::ShowHierarchy(TObject *AnObject)

{

  TClass AClass;



  AnsiString AClassName = 
AnsiString(AnObject-&gt;ClassName()).c_str();

  PrintString(AClassName);



  AClass = AnObject-&gt;ClassParent();

  while (True)

  {

    AClassName = AnsiString(AClass-&gt;ClassName());

    PrintString(AClassName);

    if (AClassName == 
&quot;TObject&quot;)

      break;

    AClass = AClass-&gt;ClassParent();

  }

}



void THierarchy::PrintString(AnsiString S)

{

  char Temp[250];



  sprintf(Temp, &quot;%s\n\r&quot;, S.c_str());

  cputs(Temp);

}



void THierarchy::ClrScr()


{

  clrscr();

}



void __fastcall TVCLHierarchy::SetBackColor(int Color)

{

  FBackColor = Color;

  FMemo-&gt;Color = TColor(FBackColor);

}



</FONT></PRE>
<P><A NAME="Heading20"></A><FONT COLOR="#000077"><B>Listing 23.8. The header file
for 
the programs data module.</B></FONT></P>
<PRE><FONT COLOR="#0066FF">///////////////////////////////////////

// DMod1.h

// Warehouse example: learning about objects

// Copyright (c) 1997 by Charlie Calvert

//

#ifndef DMod1H

#define DMod1H


#include &lt;vcl\Classes.hpp&gt;

#include &lt;vcl\Controls.hpp&gt;

#include &lt;vcl\StdCtrls.hpp&gt;

#include &lt;vcl\Forms.hpp&gt;

#include &lt;vcl\DBTables.hpp&gt;

#include &lt;vcl\DB.hpp&gt;



class TDMod : public TDataModule

{

__published:

  
TTable *WidgetsTable;

  TDataSource *WidgetsTableSource;

  TQuery *WidgetsQuery;

  TDataSource *WidgetsQuerySource;

  void __fastcall DModCreate(TObject *Sender);

private:

public:

  virtual __fastcall TDMod(TComponent* Owner);

  void 
__fastcall SumByProduct();

  void __fastcall ReportByPallet();

};



extern TDMod *DMod;



#endif



</FONT></PRE>
<P><A NAME="Heading21"></A><FONT COLOR="#000077"><B>Listing 23.9. The main source
file for the data module.</B></FONT></P>
<PRE><FONT 
COLOR="#0066FF">///////////////////////////////////////

// DMod1.cpp

// Warehouse example: learning about objects

// Copyright (c) 1997 by Charlie Calvert

//

#include &lt;vcl\vcl.h&gt;

#pragma hdrstop

#include &quot;DMod1.h&quot;

#pragma 
resource &quot;*.dfm&quot;

TDMod *DMod;