Author: Tomas Rutkauskas

How do I get CheckBoxes when using a TListView with OwnerData set to true and using 
an OnData event method?

Answer:

1   { ... }
2   const
3     W_64: Word = 64; {Width of thumbnail in ICON view mode}
4     H_64: Word = 64; {Height of thumbnail size}
5     CheckWidth: Word = 14; {Width of check mark box}
6     CheckHeight: Word = 14; {Height of checkmark}
7     CheckBiasTop: Word = 2; {This aligns the checkbox to be in centered}
8     CheckBiasLeft: Word = 3; {In the row of the list item display}
9   
10  procedure DrawCheckMark(const ListViewX: TListView; Item: TListItem; Checked:
11    Boolean);
12  var
13    TP1, TP2: TPoint;
14    XBias, YBias: Integer;
15    OldColor: TColor;
16    BiasTop, BiasLeft: Integer;
17    Rect1: TRect;
18  begin
19    GetCheckBias(XBias, YBias, BiasTop, BiasLeft, ListViewX);
20    OldColor := ListViewX.Canvas.Pen.Color;
21    TP1 := Item.GetPosition;
22    if Checked then
23      ListViewX.Canvas.Brush.Color := clBlack;
24    Rect1.Left := Item.Left - CheckWidth - BiasLeft + 1 + XBias;
25    Rect1.Top := Tp1.Y + BiasTop + 1 + YBias;
26    Rect1.Right := Item.Left - BiasLeft - 1 + XBias;
27    Rect1.Bottom := Tp1.Y + BiasTop + CheckHeight - 1 + YBias;
28    ListViewX.Canvas.FillRect(Rect1);
29    if Checked then
30      ListViewX.Canvas.Brush.Color := clBlue
31    else
32      ListViewX.Canvas.Brush.Color := clBlack;
33    ListViewX.Canvas.FrameRect(Rect1);
34    ListViewX.Canvas.FrameRect(Rect(Rect1.Left - 1, Rect1.Top - 1,
35      Rect1.Right + 1, Rect1.Bottom + 1));
36    if Checked then
37    begin
38      ListViewX.Canvas.Pen.Color := clLime;
39      TP2.X := Item.Left - BiasLeft - 2 + XBias;
40      TP2.Y := Tp1.Y + BiasTop + 2 + YBias;
41      ListViewX.Canvas.PenPos := TP2;
42      ListViewX.Canvas.LineTo(Item.Left - BiasLeft - (CheckWidth div 2) +
43        XBias, Tp1.Y + BiasTop + (CheckHeight - 2) + YBias);
44      ListViewX.Canvas.LineTo(Item.Left - BiasLeft - (CheckWidth - 2) + XBias,
45        Tp1.Y + BiasTop + (CheckHeight div 2) + YBias);
46      TP2.X := Item.Left - BiasLeft - 2 - 1 + XBias;
47      TP2.Y := Tp1.Y + BiasTop + 2 + YBias;
48      ListViewX.Canvas.PenPos := TP2;
49      ListViewX.Canvas.LineTo(Item.Left - BiasLeft - (CheckWidth div 2) - 1 + XBias,
50        Tp1.Y + BiasTop + (CheckHeight - 2) + YBias);
51      ListViewX.Canvas.LineTo(Item.Left - BiasLeft - (CheckWidth - 2) - 1 + XBias,
52        Tp1.Y + BiasTop + (CheckHeight div 2) + YBias);
53    end;
54    ListViewX.Canvas.Brush.Color := ListViewX.Color;
55    ListViewX.Canvas.Pen.Color := OldColor;
56  end;
57  
58  procedure GetCheckBias(var XBias, YBias, BiasTop, BiasLeft: Integer;
59    const ListView: TListView);
60  begin
61    XBias := 0;
62    YBias := 0;
63    if ListView.ViewStyle = vsICON then
64    begin
65      YBias := H_64 - CheckHeight;
66      XBias := 0;
67    end;
68    BiasTop := CheckBiasTop;
69    BiasLeft := CheckBiasLeft;
70    if ListView.ViewStyle <> vsReport then
71    begin
72      BiasTop := 0;
73      BiasLeft := 0;
74    end;
75  end;
76  
77  //In the OnCustomDrawItem event you would do something like this:
78  
79  DrawCheckMark(FileListMenu.ListView1, Item, Item.Checked);