uistatenav.pas

类似IE的前进、后退、历史记录 功能 (VCL组件) delphi语言编写

{
   组件：界面历史导航组件
   作者：程龙华
   创建日期：2005-10-9
}
unit UIStateNav;

interface

uses
  SysUtils, Classes,Controls;

type
  TUIStateData=record
        NavigationID:integer;
        DetailID:integer;
        TagString:string;
        Tag:integer;
  end;
  TPUIStateData=^ TUIStateData ;

  TUIStateNotifyEvent=procedure (Sender:TObject;aUIState:TPUIStateData) of object;
  TUIStateNav = class(TComponent)
  private
    FUIToNav: TWincontrol;
    function GetHistory(index: integer): TUIStateData;
    function getHistoryCount: integer;
  protected
    { Private declarations }
    FNavigating:boolean;
    FHistory:TList;
    FIndex:integer;
    FUI:TWincontrol;
    FCapacity:integer;
    FActive:boolean;

    FOnSaveUIState:TUIStateNotifyEvent;
    FOnRetrieveUIState:TUIStateNotifyEvent;
    { Protected declarations }
  public
    { Public declarations }
    property HistoryCount:integer read getHistoryCount;
    property History[index:integer]:TUIStateData read GetHistory;
    procedure UpdateUIStateByData(aUIStateData:TPUIStateData);

    procedure RecordUIState;
    procedure UpdateUIState;
    property Index:integer read FIndex write FIndex;

    procedure Forward;
    procedure Backward;
    constructor Create(AOwner: TComponent);override;
    destructor Destroy;override;
  published
    { Published declarations }
    property UIToNav:TWincontrol read FUIToNav write FUIToNav;
    property Active:Boolean read FActive write FActive;
    property Capacity:Integer read FCapacity write FCapacity default 100;
    property OnSaveUIState:TUIStateNotifyEvent read FOnSaveUIState write FOnSaveUIState;
    property OnRetrieveUIState:TUIStateNotifyEvent read FOnRetrieveUIState write FOnRetrieveUIState;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Samples', [TUIStateNav]);
end;

{ TUIStateNav }

procedure TUIStateNav.Backward;
begin
  if FIndex>0 then
  begin
     FNavigating:=true;
     FIndex:=FIndex-1;
     UpdateUIState;
     FNavigating:=false;
  end;
end;

constructor TUIStateNav.Create(AOwner: TComponent);
begin
  inherited;
  Findex:=-1;
  FHistory:=TList.Create;
  FCapacity:=100;
end;

destructor TUIStateNav.Destroy;
var
  i:integer;
  aP:TPUIStateData;
begin
  for i:=0 to FHistory.Count-1 do
  begin
    aP:=FHistory[i];
    Dispose(aP);
  end;
  FHistory.Free;
  inherited;
end;


procedure TUIStateNav.Forward;
begin
  if FIndex < (FHistory.Count-1) then
  begin
     FNavigating:=true;
     FIndex:=FIndex+1;
     UpdateUIState;
     FNavigating:=false;
  end;
end;

function TUIStateNav.GetHistory(index: integer): TUIStateData;
var
  aP:TPUIStateData;
begin
  aP:=FHistory[index];
  Result:=aP^;
end;

function TUIStateNav.getHistoryCount: integer;
begin
  result:=FHistory.Count;
end;

procedure TUIStateNav.RecordUIState;
var
  aP:TPUIStateData;
begin
  if not FNavigating then
  begin
    if assigned(FOnSaveUIState) then
    begin
      new(aP);
      FOnSaveUIState(self,aP);
      if FHistory.Count>(FCapacity-1)then
         FHistory.Delete(0);
      FIndex:=FHistory.Add(aP);
    end;
  end;
  FNavigating:=false;
end;



procedure TUIStateNav.UpdateUIState;
var
  aP:TPUIStateData;
begin
  FNavigating:=true;
  if (FIndex>=0) and (Findex<FHistory.Count) then
  begin
    aP:=FHistory[FIndex];
    UpdateUIStateByData(aP);
  end;
  FNavigating:=true;
end;

procedure TUIStateNav.UpdateUIStateByData(aUIStateData: TPUIStateData);
begin
  FNavigating:=true;
  if assigned(FOnRetrieveUIState) then
      FOnRetrieveUIState(self,aUIStateData);
end;

end.