Implement tooltips in a TListView

Problem/Question/Abstract:

Is there a possibility to get tooltips in a common TListView component under Delphi 4.0? I want to display details if the user moves the mouse over an item and wait a little (same function like the component names in Delphi, if you move your mouse over a component).

Answer:

There is an event handler in Delphi 5, which makes it possible for you to get tooltips for each item of a ListView easily: TListView.OnInfoTip. In Delphi 3 and 4, you have to write your own hint event handler, which you assign to the method OnShowHint of TApplication:

unit Test_u1;
{ ... }

type
  TForm1 = class(TForm)
    ListView1: TListView;
    { ... }
  private
    procedure DisplayHint(var HintStr: string; var CanShow: Boolean; var HintInfo:
      THintInfo);
  end;

  { ... }

implementation

{$R *.DFM}

procedure TForm1.FormCreate(Sender: TObject);
var
  NewItem: TListItem;
begin
  Application.OnShowHint := DisplayHint;
  { ... }
end;

procedure TForm1.DisplayHint;
var
  Item: TListItem;
  Rect: TRect;
begin
  CanShow := true;
  {Trace the item of ListView1, which is found on the mouse position X, Y.
        If the mouse isn't dragged over a item, result will be nil.}
  Item := ListView1.GetItemAt(HintInfo.CursorPos.X, HintInfo.CursorPos.Y);
  if Item <> nil then
  begin
    Rect := Item.DisplayRect(drBounds); {in coordinates of ListView1!}
    HintInfo.HintStr := 'Mouse is over Item ' + Item.Caption;
  end
  else
  begin
    Rect := ActiveControl.ClientRect;
    HintInfo.HintStr := GetShortHint(TControl(ActiveControl).Hint);
  end;
  { Converting into coordinates of screen. }
  Rect.TopLeft := ActiveControl.ClientToScreen(Rect.TopLeft);
  Rect.BottomRight := ActiveControl.ClientToScreen(Rect.BottomRight);
  with HintInfo do
  begin
    HintPos.Y := Rect.Top + GetSystemMetrics(SM_CYCURSOR);
    HintPos.X := Rect.Left + GetSystemMetrics(SM_CXCURSOR);
    HintMaxWidth := TControl(ActiveControl).ClientWidth;
    HintColor := clInfoBk;
    ReshowTimeout := 10;
    HideTimeout := 100;
  end;
end;

end.

BTW: The type THintInfo is used to define the appearance and the function of the HintWindow:

type
  THintWindowClass = class of THintWindow;

  THintInfo = record
    HintControl: TControl;
    HintWindowClass: THintWindowClass;
    HintPos: TPoint;
    HintMaxWidth: Integer;
    HintColor: TColor;
    CursorRect: TRect;
    CursorPos: TPoint;
    ReshowTimeout: Integer;
    HideTimeout: Integer;
    HintStr: string;
    HintData: Pointer;
  end;