Dynamic Component Allocation

Comments

• luckyboy

  March 2007

  [b][red]This message was edited by luckyboy at 2007-3-16 7:43:12[/red][/b][hr]
  : [code]
  : void __fastcall TForm1::FormCreate(TObject *Sender)
  : {
  : TComboBox *cbStdName = new TComboBox(this);
  : cbStdName->Top = 115;
  : cbStdName->Left = 195;
  : cbStdName->Width = 65;
  : cbStdName->Height = 13;
  : cbStdName->Visible = true;
  : }
  : [/code]
  :
  : When i run this code it show an empty Form, Where is my ComboBox?
  :
  : M-Nasim
  :
  
  Hy Guys, here is the answer
  [code]
  void __fastcall TForm1::Button1Click(TObject *Sender)
  {
  TComboBox *cb = new TComboBox(this); //1
  cb->Left = 15;
  cb->Top = 15;
  GroupBox1->InsertControl(cb); //2
  }
  [/code]
  Explanation
  //1 to make a pointer to a combobox and make his "Owner" our form
  //2 to insert this combobox into your groupbox i.e to make the groupbox is the parent (not owner) of this combobox
  obviously i create this groupbox at design time.
  
  can you create this parent at runtime ?!
  of course, just make its parent our form
  
  Mohammad Nasim
  
  
  
• bilderbikkel

  March 2007

  BLIMEY! GREAT TRICK! THANKS!
  Are you okay if I add this to the CodePedia?
  See ya,
  bilderbikkel
  
  
• luckyboy

  March 2007

  [b][red]This message was edited by luckyboy at 2007-3-16 9:7:18[/red][/b][hr]
  : BLIMEY! GREAT TRICK! THANKS!
  : Are you okay if I add this to the CodePedia?
  : See ya,
  : bilderbikkel
  :
  :
  sure, do it even if you don't mention my name, and for any trick you see valuable
  i will be proud if you make that, i like codepedia, it is very useful
  
  
• bilderbikkel

  March 2007

  That's how they programmed Minesweeper, creating 100 TButtons dynamically :-) !
  
  I put it at http://www.codepedia.com/1/CppVclComponentCreateDynamic
  
  Thanks and see you later,
  bilderbikkel
  
  
• luckyboy

  March 2007

  : That's how they programmed Minesweeper, creating 100 TButtons dynamically :-) !
  
  yeah, really i didn't think how they programmed MineSweeper
  it will be so sad if you put them on the form then hide them from the scene. thanx for this example
  
• luckyboy

  March 2007

  : : That's how they programmed Minesweeper, creating 100 TButtons dynamically :-) !
  :
  :
  I agree, but how they could handle each button's click-event ?..!
  remember that, it gives the user the ability to create his own minesweeper size, so no previously known number of buttons to handle each one click-event.
  u used :-) to mention minesweeper, let me use :-( it is not that easy.
  
  Mohammad Nasim
  
• bilderbikkel

  March 2007

  : I agree, but how they could handle each button's click-event ?..!
  Easy, assign an OnClick Event handler to each Button.
  
  In this example, I create 10x10 TButtons in the TForm's constructor. To each Button I assign DynamicButtonClick as the Event handler. Every Button can be identified as each on has its own Tag.
  
  [code]
  __fastcall TForm1::TForm1(TComponent* Owner)
  : TForm(Owner)
  {
  const int maxx = 10;
  const int maxy = 10;
  for (int i=0, y=0; y!=maxy; ++y)
  {
  for (int x=0; x!=maxx; ++x, ++i)
  {
  TButton * myButton = new TButton(this);
  myButton->Left = x * 20;
  myButton->Top = y * 20;
  myButton->Tag = i;
  myButton->Height = 20;
  myButton->Width = 20;
  myButton->OnClick = DynamicButtonClick;
  this->InsertControl(myButton);
  }
  }
  
  }
  //---------------------------------------------------------------------------
  void __fastcall TForm1::DynamicButtonClick(TObject *Sender)
  {
  TWinControl * control = dynamic_cast(Sender);
  ShowMessage(control->Tag);
  }
  //---------------------------------------------------------------------------
  [/code]
  
  See ya later,
  bilderbikkel
  
  
• luckyboy

  March 2007

  [b][red]This message was edited by luckyboy at 2007-3-18 13:3:50[/red][/b][hr]
  : : I agree, but how they could handle each button's click-event ?..!
  : Easy, assign an OnClick Event handler to each Button.
  :
  : In this example, I create 10x10 TButtons in the TForm's constructor. To each Button I assign DynamicButtonClick as the Event handler. Every Button can be identified as each on has its own Tag.
  
  Thanx man
  Mohammad Nasim
  
  
• bilderbikkel

  March 2007

  : Thanx man
  Thank you! This has been the first time I learned something from a forum *cool smiley*.
  
  See ya,
  bilderbikkel
  
  
• luckyboy

  March 2007

  : : Thanx man
  : Thank you! This has been the first time I learned something from a forum *cool smiley*.
  :
  : See ya,
  : bilderbikkel
  :
  :
  hahaha
  but we all here leearn from you
  Mohammad Nasim
  
• Ingvar

  April 2007

  Hi M-Nasim
  I have another solution to your problem.
  Ingvar
  
  : [code]
  : void __fastcall TForm1::FormCreate(TObject *Sender)
  : {
  : TComboBox *cbStdName = new TComboBox(this);
  : cbStdName->Parent = this; <---- insert this line telling where to place it.
  : cbStdName->Top = 115;
  : cbStdName->Left = 195;
  : cbStdName->Width = 65;
  : cbStdName->Height = 13;
  : cbStdName->Visible = true;
  : }
  : [/code]
  :
  
  
• luckyboy

  April 2007

  : Hi M-Nasim
  : I have another solution to your problem.
  : Ingvar
  
  great solution
  and borland suggests to use this coding style to move component from container (groupbox1) to another (groupbox2) ... see help.
  this implicitly removes the component from the first container.
  
  thanx for suggestion,
  and sorry for late answer, i was very busy last days
  M-Nasim
  
• Slimo

  July 2007

  I try to assigne event like this and it always wrote me error undefined symbol DynamicButtonClick and void __fastcall TForm1::DynamicButtonClick(TObject *Sender) is not member of 'Tform1'
  
  what's wrong?
  
• TaylorQi

  September 2007

  Hi all
  
  [code]cbStdName->Parent = this; <---- insert this line telling where to place it.[/code]
  
  I always use this solution because it is good-looking.:)