TListview component in Delphi

Using TListview component in Delphi.

TListview

TListView component is used to hold multiple items of various type. We can use TListview component to show Items in different view like items in Windows Explorer. When you want to show information in table-like manner, you might want to consider using TListView in vsReport style.

The items in the list view can have one or more of the following appearance features:

- A caption or detail text (for example, using the Item.Text bindable member of TListView)

- An associated image (for example, using the Item.Bitmap bindable member of TListView)

Defining Columns

After changing the style to vsReport we need to define columns of our "table". In design time we use Columns Editor like shown below.

    or   

In runtime, you can add column using code like below.

var

  vNewColumn: TListColumn;

  ..

begin

  ...

  vNewColumn := ListView1.Columns.Add;

  vNewColumn.Caption := 'Items';

  vNewColumn.Width := 100;

  ...

  vNewColumn := ListView1.Columns.Add;

  vNewColumn.Caption := 'SubItem1';

  vNewColumn.Width := 100;

  ...

  vNewColumn := ListView1.Columns.Add;

  vNewColumn.Caption := 'SubItem2';

  vNewColumn.Width := 100;  

end;

To delete n-th column:

  ListView1.Columns.Delete(n);

Adding Items and Subitems to a Listview

Each item correspond with one row. The items are of TListItem class. In this case we are interested in its Caption and SubItems property. TListItem's Caption will be displayed in the first column. Subsequent columns content came from strings contained in SubItems property.   

Here is a code example that shows how to add items to a TListView:

// To achieve the best performance use BeginUpdate and EndUpdate.  

var

  LItem: TListViewItem;

  I: Integer;

begin

  ListView1.BeginUpdate;

  try

    for I := 1 to 10 do

    begin

      LItem := ListView1.Items.Add;

      LItem.Caption := 'Item '+IntToStr(I);

      LItem.SubItems.Add('SubItem 1');

      LItem.SubItems.Add('SubItem 2);

    end;

  finally

    ListView1.EndUpdate;

  end;

end;

To delete n-th item:

    ListView1.Items.Delete(N);

Some of interesting stuffs we can do with Listview component.

Setting colors of Listview Items as per User setting...

Changing color of Listview row as per Odd/Even row.

procedure TForm1.Listview1AdvancedCustomDrawItem(   Sender: TCustomListView;   Item: TListItem;   State: TCustomDrawState;   Stage: TCustomDrawStage;   var DefaultDraw: Boolean) ;

begin

  if Item=nil then Exit;

  with Sender.Canvas do

  begin

if Odd(Sender.ItemIndex ) then

begin

      Brush.Color := clNavy;

      Font.Color := clWhite;

    end

    else 

begin

      csUnknown : Brush.Color := clSilver;

      Font.Color := clWindowText;

    end;

  end;

end;

Displaying hints for Listview items and subitems when that is too wide for its column the text gets truncated to fit.

Listview control helpfully displays a hint containing the full text when you hover the mouse over the item only. Usually that is a default behavior of Listview. But how can we show hints when we move mouse over Subitems then following are some tricks.

The list view control displays the info tip if it has the LVS_EX_INFOTIP extended style flag set. To inhibit the tips we need to remove the flag. Here is a little routine to do the job:

uses

  CommCtrl;

.....

procedure TForm1.RemoveDefaultInfoTips(const LV: TListView);

begin

  ListView_SetExtendedListViewStyle(

    LV.Handle,

    ListView_GetExtendedListViewStyle(LV.Handle) and not LVS_EX_INFOTIP

  );

end;

Note* that this method has no effect when the list view style is vsIcon: the tool tip is still displayed. To use the routine just call it from somewhere convenient, say a form's OnCreate event handler, as pass it a reference to the list view control where you want to disabled the hints, e.g.:

procedure TForm1.FormCreate(Sender: TObject);

begin
  RemoveDefaultInfoTips(ListView1);
end;

Implement Listview.onmousemove event to show formated hint as per our requirement.
procedure TForm1.ListView1MouseMove(Sender: TObject;
  Shift: TShiftState; X, Y: Integer);
var
  ptPos: TPoint;
  lvItem : TListItem;
  lvHitInfo: TLVHitTestInfo;
  sHint: string;
begin
  if ListView1.ViewStyle=vsReport then
  begin
    ptPos := ListView1.ScreenToClient(Mouse.CursorPos) ;
    lvItem := ListView1.GetItemAt(ptPos.X, ptPos.Y) ;
    if assigned(lvItem) then
    begin
      ListView1.Hint := '';
      Application.CancelHint;
    end
    else     // To show multiline hint for Listview subitems //
    begin
      FillChar(lvHitInfo, SizeOf(lvHitInfo), 0) ;
      lvHitInfo.pt := ptPos;
      if -1 <> ListView1.Perform(LVM_SUBITEMHITTEST, 0, LParam(@lvHitInfo)) then
      begin
        sHint:=Trim(ListView1.Items[lvHitInfo.iItem].SubItems[lvHitInfo.iSubItem-1]);
        ListView1.Hint := WrapText(sHint, 60);
        Application.ActivateHint(Mouse.CursorPos) ;
      end
      else
      begin
        ListView1.Hint := '';
        Application.CancelHint;
      end;
    end;
  end;
end;