Mega Code Archive
How to Draw a Radio Button for a TListBox Item in Delphi
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Title: How to Draw a Radio Button for a TListBox Item in Delphi
Delphi's TListBox VCL component displays a collection of items in a scrollable list. The MultiSelect property determines if a user can select more than one item. When MultiSelect is set to false (default state) a ListBox acts as a TRadioButton list container (similar to TRadioGroup).
Here's how to draw a radio button for each of the items in a List Box (meaningful only if MultiSelect is false) :
Note: Drop a TListBox on a Form, add several strings to its Items property:
procedure TRadioListBoxForm.FormCreate(Sender: TObject) ;
begin
//or use Object Inspector to assign the
//OnDrawItem event handler,
//Style and ItemHeight properties...
ListBox1.Style := lbOwnerDrawFixed;
ListBox1.ItemHeight := 20;
ListBox1.OnDrawItem := ListBox_DrawItem;
end;
procedure TRadioListBoxForm.ListBox_DrawItem(
Control: TWinControl;
Index: Integer;
Rect: TRect;
State: TOwnerDrawState) ;
const
IsSelected : array[Boolean] of Integer = (DFCS_BUTTONRADIO, DFCS_BUTTONRADIO or DFCS_CHECKED) ;
var
optionButtonRect: TRect;
listBox : TListBox;
begin
listBox := Control as TListBox;
with listBox.Canvas do
begin
FillRect(rect) ;
optionButtonRect.Left := rect.Left + 1;
optionButtonRect.Right := Rect.Left + 13;
optionButtonRect.Bottom := Rect.Bottom;
optionButtonRect.Top := Rect.Top;
DrawFrameControl(Handle, optionButtonRect, DFC_BUTTON, IsSelected[odSelected in State]) ;
TextOut(15, rect.Top + 3, listBox.Items[Index]) ;
end;
end;
Note: the Style property sets ListBox1 owner drawing to true. The OnDrawItem is used to draw a radio button for each of the items.
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