Mouse cursor hourglass/normal changer unit

Problem/Question/Abstract:

Howto change the mousecursor into a hourglass/normal.

Answer:

unit waitcursor;
{ WaitCursor  -  Copyright (c) 2001 by E.J.Molendijk

  A mousecursor hourglass/normal changer tool. Supports layered requests.

  WCursor.SetWait     = mouse cursor as Hourglass
  WCursor.SetWaitSQL  = mouse cursor as SQL Hourglass
  WCursor.SetNormal   = mouse cursor as normal

  example:
      WCursor.setWait;
      try
        DoSometingVerySlow;
      finally
        WCursor.setNormal;
      end;
}

interface

type
  TWaitCursor = class
  private
    FCursor: integer;
    FCnt: integer;
  public
    constructor Create;
    destructor Destroy; override;
    procedure SetCursor(Index: integer);
    procedure SetWait;
    procedure SetWaitSQL;
    procedure SetNormal;
  end;

var
  WCursor: TWaitCursor;

implementation

uses Forms, Controls;

constructor TWaitCursor.Create;
begin
  inherited;
  // depth is zero
  FCnt := 0;

  // remember default cursor
  FCursor := Screen.Cursor;
end;

destructor TWaitCursor.Destroy;
begin
  // Reset to default cursor
  Screen.Cursor := FCursor;
  inherited;
end;

procedure TWaitCursor.SetCursor(Index: integer);
begin
  // select cursor
  Screen.Cursor := Index;
end;

procedure TWaitCursor.SetNormal;
begin
  // decrease depth
  if FCnt > 0 then
    Dec(FCnt);

  // if we reach depth 0 we restore default cursor
  if FCnt = 0 then
    SetCursor(FCursor);
end;

procedure TWaitCursor.SetWait;
begin
  // increase depth
  Inc(FCnt);

  // select wait cursor
  SetCursor(crHourglass);
end;

procedure TWaitCursor.SetWaitSQL;
begin
  // increase depth
  Inc(FCnt);

  // select wait cursor
  SetCursor(crSQLWait);
end;

initialization
  WCursor := TWaitCursor.Create;
finalization
  WCursor.Free;
end.