MVVM Framework für Delphi

[Sir Rufo]

Hier mal ein Beispiel zu einem simplen aber sehr effektiven Beispiel was man bei .net findet
http://www.codeproject.com/Articles/...ying-Recursion

Ein TreeView-Walker ... da hätte man auch selber mal drauf kommen können und hier der Delphi-Code dazu, der dem quasi 1:1 dem entspricht und auch so verwendet werden kann (der hier ist für FMX):

Delphi-Quellcode:

  TProcessNodeEventArgs = class( TEventArgs )
  private
    FNode: TTreeViewItem;
    FProcessDescendants: Boolean;
    FProcessSiblings: Boolean;
    FStopProcessing: Boolean;
  public
    constructor Create( ANode: TTreeViewItem );
    property Node: TTreeViewItem read FNode;
    property ProcessDescendants: Boolean read FProcessDescendants write FProcessDescendants;
    property ProcessSiblings: Boolean read FProcessSiblings write FProcessSiblings;
    property StopProcessing: Boolean read FStopProcessing write FStopProcessing;
  end;

  IProcessNodeEvent = IEvent<TProcessNodeEventArgs>;
  ProcessNodeEvent = Event<TProcessNodeEventArgs>;

  TTreeViewWalker = class( TComponent )
  private
    FTreeView: TTreeView;
    FStopProcessing: Boolean;
    FProcessNode: ProcessNodeEvent;
    function GetProcessNode: IProcessNodeEvent;
    function WalkNodes( ANode: TTreeViewItem ): Boolean;
  public
    constructor Create( ATreeView: TTreeView ); reintroduce;
    procedure ProcessTree;
    property ProcessNode: IProcessNodeEvent read GetProcessNode;
  end;

{ TProcessNodeEventArgs }

constructor TProcessNodeEventArgs.Create( ANode: TTreeViewItem );
begin
  inherited Create;
  FNode := ANode;
  FProcessDescendants := True;
  FProcessSiblings := True;
  FStopProcessing := False;
end;

{ TTreeViewWalker }

constructor TTreeViewWalker.Create( ATreeView: TTreeView );
begin
  if not Assigned( ATreeView )
  then
    raise EArgumentNilException.Create( 'ATreeView' );

  inherited Create( ATreeView );
  FTreeView := ATreeView;
end;

function TTreeViewWalker.GetProcessNode: IProcessNodeEvent;
begin
  Result := FProcessNode;
end;

procedure TTreeViewWalker.ProcessTree;
var
  LIdx: Integer;
begin
  FStopProcessing := False;
  for LIdx := 0 to FTreeView.Count - 1 do
    if not WalkNodes( FTreeView.ItemByIndex( LIdx ) ) or FStopProcessing
    then
      Break;
end;

function TTreeViewWalker.WalkNodes( ANode: TTreeViewItem ): Boolean;
var
  LArgs: TProcessNodeEventArgs;
  LIdx: Integer;
begin
  LArgs := TProcessNodeEventArgs.Create( ANode );
  try
    FProcessNode.Invoke( FTreeView, LArgs, False );
    Result := LArgs.ProcessSiblings;
    if LArgs.StopProcessing then
      FStopProcessing := True
    else begin
      if LArgs.ProcessDescendants then
      begin
        for LIdx := 0 to ANode.Count - 1 do
        begin
          if not WalkNodes(ANode.Items[LIdx]) or FStopProcessing then
            Break;
        end;
      end;
    end;
  finally
    LArgs.Free;
  end;
end;