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Change Listbox color with OnEnter and OnExit

Posted on 2004-08-12
17
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Last Modified: 2011-04-14
Hi
   I would like to change the Listbox color when you click on it and another color once another control has focus.
Listbox has focus, color = red.
Listbox has no focus, color = white.
I tryed:

procedure TForm1.ListBox1Enter(Sender: TObject);
begin
  ListBox1.Color := clBlue;
end;

procedure TForm1.ListBox1Exit(Sender: TObject);
begin
  ListBox1.Color := clWindow;
end;

But once the listbox has a few lines the color doesn't changed properly.

Thanks
Chris.
0
Comment
Question by:ChrisLM
  • 8
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  • 2
17 Comments
 
LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    Edit1: TEdit;
    procedure ListBox1DrawItem(Control: TWinControl; Index: Integer;
      Rect: TRect; State: TOwnerDrawState);
    procedure ListBox1Enter(Sender: TObject);
    procedure ListBox1Exit(Sender: TObject);
  private
    ListBoxColor  : TColor;
  public
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.ListBox1DrawItem(Control: TWinControl; Index: Integer;
  Rect: TRect; State: TOwnerDrawState);
begin
  with ListBox1.Canvas do
    begin
      Brush.Color := ListBoxColor;
      FillRect(Rect);
      TextOut(Rect.Left + 2, Rect.Top + 2, ListBox1.Items[index]);
    end;
end;

procedure TForm1.ListBox1Enter(Sender: TObject);
begin
  ListBoxColor := clRed;
  ListBox1.Invalidate;
end;

procedure TForm1.ListBox1Exit(Sender: TObject);
begin
  ListBoxColor := clWhite;
  ListBox1.Invalidate;
end;

end.
0
 
LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
in addition to the above, you will have to draw the whole rectangle of the ListBox somewhere in OnDrawItem

  with FullRect do
    begin
      Left   := 0;
      Top    := 0;
      Right  := Width;
      Bottom := Height;
    end;
  FillRect(FullRect);

  and after that draw the items
0
 

Author Comment

by:ChrisLM
Comment Utility
Thanks for your input.

Can you send the code for the whole form, with the additional piece of code added, as I tryed what your last two comments said, but I cannot get it too work,

Thanks
Chris
0
 
LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
Aaaa, yes, not I understand what I forgot (in order to draw the ListBox, you have to set it's style to lbOwnerDrawFixed). I set this in Design time, but it can be done in OnCreate

procedure TForm1.FormCreate(Sender: TObject);
begin
  ListBox1.Style := lbOwnerDrawFixed;
end;
0
 

Author Comment

by:ChrisLM
Comment Utility
That helped a little, but 1 slight problem.

The items are not being displayed, so I must be doing something wrong with the OnDrawItem procedure. I have this:
var
  FullRect: TRect;
begin
with ListBox1.Canvas do
    begin
      Brush.Color := ListBoxColor;
      FillRect(Rect);
      TextOut(Rect.Left + 2, Rect.Top + 2, ListBox1.Items[index]);
end;
with FullRect do
    begin
      Left   := 0;
      Top    := 0;
      Right  := Width;
      Bottom := Height;
    end;
  Listbox1.Canvas.FillRect(FullRect);
end;
0
 
LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
 There are 2 problems here:

  1) You draw the item and the FullRect, which hides the items.

  2) My suggestion with the FullRect was NOT good, because OnDrawItem is called for all items. And if you draw FullRect for the second item, it Hides the first one, which was already drawn.

  Wait few minutes, I am trying something...
0
 
LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    Button1: TButton;
    Edit1: TEdit;
    procedure ListBox1DrawItem(Control: TWinControl; Index: Integer;
      Rect: TRect; State: TOwnerDrawState);
    procedure ListBox1Enter(Sender: TObject);
    procedure ListBox1Exit(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    ListBoxColor  : TColor;
  public
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.ListBox1DrawItem(Control: TWinControl; Index: Integer;
  Rect: TRect; State: TOwnerDrawState);
begin
  with ListBox1.Canvas do
    begin
      Brush.Color := ListBoxColor;
      FillRect(Rect);
      Font.Color := clBlack;
      TextOut(Rect.Left + 2, Rect.Top + 2, ListBox1.Items[index]);
    end;
end;

procedure TForm1.ListBox1Enter(Sender: TObject);
begin
  ListBoxColor := clRed;
  ListBox1.Refresh;
end;

procedure TForm1.ListBox1Exit(Sender: TObject);
begin
  ListBoxColor := clWhite;
  ListBox1.Refresh;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ListBox1.Style := lbOwnerDrawFixed;
end;

end.
0
 

Author Comment

by:ChrisLM
Comment Utility
Appreciate your help mate.

Your example paints the items properly, but doesn't paint the rest of the listbox?

Thanks.
0
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LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
Yes, I notices that problem. But the ONLY solution I found here is to set the ListBox height in a proper way - to display exact number of items and you will not have additional space.

I couldn't solve this problems, because as I told you in problem 2) - if you draw the background for item 2 - you will erase item 1...
0
 

Author Comment

by:ChrisLM
Comment Utility
Thanks for the help buddy.

I don't know what to do know since the question wasn't answered.
I would still like to give you a few points for your troubles though and then close the question.

Any ideas on how to give you some points??
0
 
LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
You can if you open a new question "Points for Ivanov_G" and refer to this question.

But this is not the case here. The problems comes to be solved. But sometimes, due to some limitation we can not proceed in the way we won't, so we have to think for another alternative.
0
 

Author Comment

by:ChrisLM
Comment Utility
"due to some limitation we can not proceed in the way we won't, so we have to think for another alternative."

Are you saying to leave it open to wait for a solution or due to limitations this problem cannot be solved?
0
 
LVL 12

Expert Comment

by:Ivanov_G
Comment Utility
No, I don't say it can not be solved. Each problem have its solution.

But now because of not so good written VCL there is a bug. And we are trying to override it. I've done the same this you want, but with TEdit-s and there is works file. This is what I mean.
0
 

Author Comment

by:ChrisLM
Comment Utility
ok thanks.
I posted a comment "Points for Ivanov_G" for some points to you.

I will leave the solution open for a few days to see if anyone else can come up with something.

Thanks.
0
 
LVL 3

Accepted Solution

by:
Tyrsis earned 500 total points
Comment Utility
This method worked for me, give it a try:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
    TForm1 = class(TForm)
        Button1: TButton;
        Edit1: TEdit;
        ListBox1: TListBox;
        procedure ListBox1Enter(Sender: TObject);
        procedure ListBox1Exit(Sender: TObject);
        procedure Button1Click(Sender: TObject);
    private
    public

    end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.ListBox1Enter(Sender: TObject);
var
    Rect : TRect;
begin
    ListBox1.Color := clRed;

    Rect := ListBox1.ClientRect;
    ListBox1.Canvas.Brush.Color := ListBox1.Color;
    ListBox1.Canvas.FillRect(Rect);

    ListBox1.Invalidate;
end;

procedure TForm1.ListBox1Exit(Sender: TObject);
var
    Rect : TRect;
begin
    ListBox1.Color := clWhite;

    Rect := ListBox1.ClientRect;
    ListBox1.Canvas.Brush.Color := ListBox1.Color;
    ListBox1.Canvas.FillRect(Rect);

    ListBox1.Invalidate;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
    ListBox1.Items.Add(Edit1.Text);
end;

end.
0
 
LVL 3

Expert Comment

by:Tyrsis
Comment Utility
Also, note to the above code sample.  You don't need to set ownerdraw or anything.  Just use lbStandard.  

Tyrsis
0
 

Author Comment

by:ChrisLM
Comment Utility
Thanks Tyrsis.

That was exactly what I needed and worked perfectly. Points are yours.

Chris.
0

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