How-to-add-a-built-in-editor-to-a-TListBox


            Title: How to add a built - in editor to a TListBox
Question: When using a TListBox and when a user can or must modify an item of the list usually you must add another TEdit control to get the value of the selected item and after the user has set the value he wants you have to update the item by code.
Well here is a solution for you to implement an editor that appears on the item you want to edit and lets you edit the item and by pressing enter you can save the value of the item.
Answer:
{*******************************************************}
{ }
{ GT Delphi Components }
{ ListBox Inplace Editor Demo }
{ }
{ Copyright (c) GT Delphi Components }
{ http://www.gtdelphicomponents.gr }
{ }
{ }
{*******************************************************}
unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls;
type
 TForm1 = class(TForm)
 ListBox1: TListBox;
 Button1: TButton;
 chkBoxAllowEdit: TCheckBox;
 procedure ListBox1Click(Sender: TObject);
 procedure Button1Click(Sender: TObject);
 private
 { Private declarations }
 protected
 FListBoxEditor : TEdit;
 procedure DisplayEditor(AListBox : TListBox);
 procedure InternalOnExit(Sender : TObject);
 procedure InternalOnKeyPress(Sender : TObject;var Key: Char);
 public
 { Public declarations }
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
{-----------------------------------------------------------------------------}
procedure TForm1.ListBox1Click(Sender: TObject);
begin
 //If we allow editing
 if chkBoxAllowEdit.Checked then
 begin
 DisplayEditor(TListBox(Sender));
 end;
end;
{-----------------------------------------------------------------------------}
procedure TForm1.DisplayEditor(AListBox: TListBox);
begin
 //Checking if really an item is selected
 if AListBox.ItemIndex =0 then
 begin
 //If the editor is not created we are creating it for the first time
 if not Assigned(FListBoxEditor) then
 begin
 FListBoxEditor := TEdit.Create(Self);
 FListBoxEditor.Parent := AListBox;
 FListBoxEditor.OnExit := InternalOnExit;
 FListBoxEditor.OnKeyPress := InternalOnKeyPress;
 end;
 //Setting The Color
 FListBoxEditor.Color := clSkyBlue;
 //This is crusial it places the editor exactly at the selected item
 FListBoxEditor.BoundsRect := AListBox.ItemRect(AListBox.ItemIndex);
 //Get the text of the item
 FListBoxEditor.Text := AListBox.Items[AListBox.ItemIndex];
 //Show the editor;
 FListBoxEditor.Visible := True;
 end;
end;
{-----------------------------------------------------------------------------}
procedure TForm1.InternalOnExit(Sender: TObject);
begin
 //TEdit(Sender).Visible := False;
end;
{-----------------------------------------------------------------------------}
procedure TForm1.InternalOnKeyPress(Sender: TObject; var Key: Char);
begin
 //if the Enter key is pressed
 if key = #13 then
 begin
 //Set the new text for the selected item
 ListBox1.Items[ListBox1.ItemIndex] := TEdit(Sender).Text;
 //hide the editor
 TEdit(Sender).Visible := False;
 //Set focus to the listbox
 ListBox1.SetFocus;
 ListBox1.ItemIndex :=ListBox1.ItemIndex;
 chkBoxAllowEdit.Checked := False;
 end;
end;
{-----------------------------------------------------------------------------}
procedure TForm1.Button1Click(Sender: TObject);
begin
 Close;
end;
{-----------------------------------------------------------------------------}
end.
VCL Delphi
