Code walkthrough

• TChangeColorCommand::HandleCanDo is overridden to return True only if a tile is currently selected.
• TTilesSelection provides an additional function, ContainsTile, that takes the index of a tile and tells you whether it is currently selected.
• TTilesView provides a helper function, GetTilesSelection, to access the current selection.
• TTilesView functions that interact with selections are modified to access the current selection through the document component's GUI bundle:
  • DrawContents
  • DrawTile
  • MouseDown
  • HandleAfterConnectionToViewRoot

  // Copyright (C) 1995 Taligent, Inc. All rights reserved.
  const TTilesSelection *
  TTilesView::GetTilesSelection () const
  {
      // Gets the current selection via the GUI bundle.
      const TModelSelection* modelSelection = GetCurrentModelSelection();
  
      // Casts the model selection to a TTilesSelection.
      if (modelSelection) {
          TTilesSelection* tilesSelection;
          DynamicCastTo(tilesSelection, modelSelection);
          return tilesSelection;
      }
      else {
          return 0;
      }
  }

  // Copyright (C) 1995 Taligent, Inc. All rights reserved.
  void
  TTilesView::DrawContents(TGrafPort& port) const
  {
      const TModelPointerTo<TTilesModel> model(GetModelReference());
      
      TGArea area;
      GetBounds(area);
      TGrafBundle whitebg (new TColorPaint(TRGBColor(.9,1,1)), TGrafBundle::kFill);
      port.Draw (area, whitebg);
  
      // Gets a pointer to the current selection. If there is none, this will be zero.
      const TTilesSelection* currentSelection = GetTilesSelection();
      bool inCurrentSelection = FALSE;
  
      int numTiles = model->GetNumTiles();
      for (int i = 0; i < numTiles; i++) {
          const TTile* tile = model->GetTileForReading(i);
          
          // Determines if each tile is selected and passes it to DrawTile.
          // DrawTile highlights selected tiles.
          if (currentSelection && currentSelection->ContainsTile(i)) {
              inCurrentSelection = TRUE;
          }
          else {
              inCurrentSelection = FALSE;
          }
          
          DrawTile(port, tile, inCurrentSelection);
      }
  }

  // Copyright (C) 1995 Taligent, Inc. All rights reserved.
  // Takes an argument indicating whether the tile to draw is selected.
  void 
  TTilesView::DrawTile (TGrafPort& port, const TTile* tile, bool inCurrentSelection) const
  {
      TGrafBundle* bundle = new TGrafBundle(new TColorPaint(tile->GetColor()), 
              new TColorPaint(TColorPaint::GetBlack()),
              // If the tile is selected, draws a frame around it. Otherwise, it just uses a fill color.
               inCurrentSelection ? TGrafBundle::kFillAndFrame : TGrafBundle::kFill);
              bundle->AdoptFramePen(new TSolidPen(3.0, TPen::kOutsetFrame));
      
      MGraphic* tileGraphic = ::CopyPointer(fTilesGraphics[tile->GetType()]);
      
      tileGraphic->ScaleBy(tile->GetSize());
      tileGraphic->TranslateBy(tile->GetPosition());
      
      tileGraphic->AdoptBundle(bundle);
      
      tileGraphic->Draw(port);
      delete tileGraphic;
  }

  // Copyright (C) 1995 Taligent, Inc. All rights reserved.
  bool
  TTilesView::MouseDown (TMouseDownEvent& mouseDownEvent)
  {
      TRGBColor newColor;
      TileIndex whichTile;
      TGPoint mousePoint = mouseDownEvent.GetEventPosition();
  
      const TModelPointerTo<TTilesModel> model(GetModelReference());
      
      for (whichTile = model->GetNumTiles() - 1; whichTile >= 0; whichTile--) {
          if (model->GetTileForReading(whichTile)->ContainsPoint(mousePoint)) {
              break;
          }
      }
      
      // If a tile was clicked on, selects that tile. Otherwise, creates an empty selection. The 
      // selection is passed to the GUI bundle as the current selection.
      TTilesSelection* selection = (TTilesSelection*) model->CreateSelection ();
      if (whichTile >= 0) {
          selection->SelectTile (whichTile);
          AdoptCurrentModelSelection (selection);
      }
      else {
          selection->DeselectAll();
          AdoptCurrentModelSelection(selection);
      }
      
      return TRUE;
  }

  // Copyright (C) 1995 Taligent, Inc. All rights reserved.
  void
  TTilesView::HandleAfterConnectionToViewRoot()
  {
      TDocumentComponentView::HandleAfterConnectionToViewRoot ();
      BuildTilesGraphicsMapToModel();
      SetAllocatedArea (TGArea(TGRect(TGPoint(0,0), TGPoint(200, 100))));
      SetCoordinateView(TViewHandle(*this));
      
      // Gets read-only access to the model.
      const TModelPointerTo<TTilesModel> model(GetModelReference());
      
      // Creates an empty selection on the model and passes it to the GUI
      // bundle as the current selection.
      TTilesSelection* selection = (TTilesSelection*) model->CreateSelection();
      selection->DeselectAll();
      
      AdoptCurrentModelSelection(selection);
  }