GrafEdit - Cursor tool support

Cursor tool support

Although a canvas view can respond to mouse input directly, TCanvasView is designed primarily to respond to higher-level interaction from cursor tools. A cursor tool provides direct manipulation and interactive feedback. The current cursor tool is set any time by calling TTool::SetCurrentTool, which is a static function in the TTool class.

static void TTool::SetCurrentTool( const TTool& );

Whenever the mouse is used over a canvas view, the canvas view delegates mouse event handling to the Cursor Tools framework, which determines when a tool is bound to the device that produced the event and when the tool can begin interaction with the event. The Cursor Tools framework calls a tool handler identified by the application to create either a tool target or a tool interactor. TCanvasView is able to identify itself as the application tool handler because it derives from a mix of TContentView and MToolHandler. TCanvasView implements the following MToolHandler functions:

  virtual MToolTarget* CreateToolTarget( const TTypeDescriptions&, const TGPoint& );
  virtual TToolInteractor* CreateToolInteractor( const TGPoint&, const TToken& hint );
  virtual Boolean SupportsFeedback() const;
  virtual void AdoptFeedbackGraphic(  MGRaphic* adopt, const TGArea& total, 

const TGarea& changed );
  virtual MGraphic* OrphanFeedbackGraphic( Boolean repair );

TCanvasView does not implement the following MToolHandler functions, which must be implemented in all TCanvasView derived classes, such as TStandardCanvasView.

  virtual void AdoptAndDo( TToolCommandBinding* ) = 0;
  virtual void DoBegin*( TToolCommandBinding& ) = 0;
  virtual void DoIncrement( TToolCommandBinding& ) = 0;
  virtual void AdoptAndDoEnd( TToolCommandBinding* ) = 0;

[Contents] [Previous] [Next]

Click the icon to mail questions or corrections about this material to Taligent personnel.

Generated with WebMaker