jvqcontextprovider.pas

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        end
        else
          ParentList := Self;
        GetProvider.Changing(pcrAdd, ParentList);
      end;
    pcrContextDelete:
      begin
        { Source is the IJvDataContext that is about to be destroyed. }
        CtxItem := Find(IJvDataContext(Source), True);
        GetProvider.Changing(pcrDelete, CtxItem);
      end;
    pcrContextUpdate:
      begin
        { Source is the IJvDataContext that is about to be changed. }
        CtxItem := Find(IJvDataContext(Source), True);
        GetProvider.Changing(pcrUpdateItem, CtxItem);
      end;
  end;
end;

procedure TContextRootItems.DataProviderChanged(ADataProvider: IJvDataProvider;
  AReason: TDataProviderChangeReason; Source: IUnknown);
var
  CtxItem: IJvDataItem;
  ParentList: IJvDataItems;
begin
  case AReason of
    pcrContextAdd:
      begin
        { Source contains the IJvDataContext that was just added. }
        CtxItem := Find(IJvDataContext(Source), True);
        GetProvider.Changed(pcrAdd, CtxItem);
      end;
    pcrContextDelete:
      begin
        { Source is the IJvDataContext from which the item was just removed or nil if the removed
          context was at the root. }
        if Source <> nil then
        begin
          CtxItem := Find(IJvDataContext(Source), True);
          if CtxItem <> nil then
          begin
            if not Supports(CtxItem, IJvDataItems, ParentList) then
              ParentList := Self;
          end
          else
            ParentList := Self;
        end
        else
          ParentList := Self;
        GetProvider.Changed(pcrDelete, ParentList);
      end;
    pcrContextUpdate:
      begin
        { Source is the IJvDataContext that has changed. }
        CtxItem := Find(IJvDataContext(Source), True);
        GetProvider.Changed(pcrUpdateItem, CtxItem);
      end;
  end;
end;

function TContextRootItems.GetContexts: IJvDataContexts;
var
  ParentCtx: IJvDataContext;
begin
  if GetParent <> nil then
  begin
    if Supports(GetParent, IJvDataContext, ParentCtx) then
      Supports(ParentCtx, IJvDataContexts, Result);
  end
  else
    Supports(ClientProvider, IJvDataContexts, Result);
end;

//=== { TContextItem } =======================================================

constructor TContextItem.CreateCtx(AOwner: IJvDataItems; AContext: IJvDataContext);
begin
  Create(AOwner);
  FContext := AContext;
end;

function TContextItem.GetContext: IJvDataContext;
begin
  Result := FContext;
end;

function TContextItem.GetCaption: string;
begin
  if Context <> nil then
    Result := Context.Name
  else
    Result := RsContextItemEmptyCaption;
end;

procedure TContextItem.SetCaption(const Value: string);
var
  CtxMan: IJvDataContextManager;
begin
  if Context <> nil then
  begin
    if Supports(Context, IJvDataContextManager, CtxMan) then
    begin
      if Context.Name <> Value then
      begin
        GetItems.GetProvider.Changing(pcrUpdateItem, Self as IJvDataItem);
        CtxMan.SetName(Value);
        GetItems.GetProvider.Changed(pcrUpdateItem, Self as IJvDataItem);
      end;
    end;
  end
  else
    raise EJVCLException.CreateRes(@RsENoContextAssigned);
end;

function TContextItem.Editable: Boolean;
begin
  Result := True;
end;

procedure TContextItem.InitID;
var
  S: string;
  Ctx: IJvDataContext;
begin
  S := GetContext.Name;
  Ctx := GetContext.Contexts.Ancestor;
  while Ctx <> nil do
  begin
    S := Ctx.Name + '\' + S;
    Ctx := Ctx.Contexts.Ancestor;
  end;
  SetID('CTX:' + S);
end;

function TContextItem.IsDeletable: Boolean;
begin
  if GetContext <> nil then
    Result := GetContext.IsDeletable
  else
    Result := True;
end;

//=== { TContextItemsManager } ===============================================

function TContextItemsManager.GetContexts: IJvDataContexts;
var
  ICI: IJvDataContextItems;
begin
  if Supports(Items, IJvDataContextItems, ICI) then
    Result := ICI.GetContexts
  else
    Result := nil;
end;

function TContextItemsManager.Add(Item: IJvDataItem): IJvDataItem;
var
  Contexts: IJvDataContexts;
  Mngr: IJvDataContextsManager;
  CtxItem: IJvDataContextItem;
begin
  Contexts := GetContexts;
  if (Contexts <> nil) and Supports(Contexts, IJvDataContextsManager, Mngr) then
  begin
    if Supports(Item, IJvDataContextItem, CtxItem) then
      Result := Item
    else
      raise EJVCLException.CreateRes(@RsENoContextItem);
  end;
end;

function TContextItemsManager.New: IJvDataItem;
var
  Contexts: IJvDataContexts;
  Mngr: IJvDataContextsManager;
begin
  Contexts := GetContexts;
  if (Contexts <> nil) and Supports(Contexts, IJvDataContextsManager, Mngr) then
    Result := Add(TContextItem.CreateCtx(Items, Mngr.New));
end;

procedure TContextItemsManager.Clear;
var
  Contexts: IJvDataContexts;
  Mngr: IJvDataContextsManager;
begin
  Contexts := GetContexts;
  if (Contexts <> nil) and Supports(Contexts, IJvDataContextsManager, Mngr) then
    Mngr.Clear;
end;

procedure TContextItemsManager.Delete(Index: Integer);
var
  Item: IJvDataItem;
begin
  Item := Items.GetItem(Index);
  if Item <> nil then
    Remove(Item);
end;

procedure TContextItemsManager.Remove(var Item: IJvDataItem);
var
  Contexts: IJvDataContexts;
  Mngr: IJvDataContextsManager;
  CtxItem: IJvDataContextItem;
  Ctx: IJvDataContext;
begin
  Contexts := GetContexts;
  if (Contexts <> nil) and Supports(Contexts, IJvDataContextsManager, Mngr) then
  begin
    if Supports(Item, IJvDataContextItem, CtxItem) then
    begin
      Ctx := CtxItem.GetContext;
      Item := nil;
      CtxItem := nil;
      Mngr.Delete(Ctx);
    end;
  end;
end;

//=== { TJvContextProvider } =================================================

function TJvContextProvider.GetProviderIntf: IJvDataProvider;
begin
  Result := TContextRootItems(DataItemsImpl).ClientProvider;
end;

procedure TJvContextProvider.SetProviderIntf(Value: IJvDataProvider);
begin
  if Value <> ProviderIntf then
    TContextRootItems(DataItemsImpl).ClientProvider := Value;
end;

function TJvContextProvider.GetProviderComp: TComponent;
var
  ICR: IInterfaceComponentReference;
begin
  if Supports(ProviderIntf, IInterfaceComponentReference, ICR) then
    Result := ICR.GetComponent
  else
    Result := nil;
end;

procedure TJvContextProvider.SetProviderComp(Value: TComponent);
var
  PI: IJvDataProvider;
  ICR: IInterfaceComponentReference;
begin
  if (Value = nil) or Supports(Value, IJvDataProvider, PI) then
  begin
    if (Value = nil) or Supports(Value, IInterfaceComponentReference, ICR) then
      ProviderIntf := PI
    else
      raise EJVCLException.CreateRes(@RsENotSupportedIInterfaceComponentReference);
  end
  else
    raise EJVCLException.CreateRes(@RsENotSupportedIJvDataProvider);
end;

class function TJvContextProvider.ItemsClass: TJvDataItemsClass;
begin
  Result := TContextRootItems;
end;

function TJvContextProvider.ConsumerClasses: TClassArray;
begin
  Result := inherited ConsumerClasses;
  AddToArray(Result, TJvContextProviderServerNotify);
end;

//=== { TJvContextProviderServerNotify } =====================================

procedure TJvContextProviderServerNotify.ItemSelected(Value: IJvDataItem);
var
  CtxItem: IJvDataContextItem;
  Ctx: IJvDataContext;
  I: Integer;
  ConCtx: IJvDataConsumerContext;
begin
  // First we allow the default behavior to take place
  inherited ItemSelected(Value);
  // Now we find out which context is selected and update the linked client consumers accordingly.
  if Supports(Value, IJvDataContextItem, CtxItem) then
    Ctx := CtxItem.GetContext
  else
    Ctx := nil;
  for I := 0 to Clients.Count - 1 do
    if Supports(Clients[I], IJvDataConsumerContext, ConCtx) then
      ConCtx.SetContext(Ctx);
end;

function TJvContextProviderServerNotify.IsValidClient(Client: IJvDataConsumerClientNotify): Boolean;
var
  ClientProv: IJvDataProvider;
  ConsumerProv: IJvDataConsumerProvider;
begin
  { Only allow client consumers who's Provider points to the ClientProvider of the context
    provider this consumer is linked to. }
  ClientProv := (ConsumerImpl.ProviderIntf as IJvDataContextProvider).ClientProvider;
  Result := Supports(Client, IJvDataConsumerProvider, ConsumerProv) and
    (ConsumerProv.GetProvider = ClientProv);
end;

{$IFDEF UNITVERSIONING}
const
  UnitVersioning: TUnitVersionInfo = (
    RCSfile: '$RCSfile: JvQContextProvider.pas,v $';
    Revision: '$Revision: 1.14 $';
    Date: '$Date: 2004/09/07 23:11:16 $';
    LogPath: 'JVCL\run'
  );
{$ENDIF UNITVERSIONING}

initialization
  {$IFDEF UNITVERSIONING}
  RegisterUnitVersion(HInstance, UnitVersioning);
  {$ENDIF UNITVERSIONING}

  RegisterClasses([TJvContextProviderServerNotify]);
  

{$IFDEF UNITVERSIONING}
finalization
  UnregisterUnitVersion(HInstance);
{$ENDIF UNITVERSIONING}

end.