Documentation of 'org.opengis.go.display.canvas.Canvas' Java class
Canvas
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org.opengis.go.display.canvas

Interface Canvas

  • All Known Subinterfaces:
    Map2D, WebCanvas, WebMap2D

    public interface Canvas
    Canvas defines a common abstraction for implementations that manage the display and user manipulation of Graphic instances. A Canvas with an XY (Cartesian) display field should support the following properties:
    • pixelWidth
    • pixelHeight
    • center
    • width
    • scale
    • envelope

    • Method Detail

      • dispose

        void dispose()
        Method that may be called when a Canvas is no longer needed. Implementations may use this method to release resources or to return the object to an object pool. It is an error to reference a Canvas after its dispose method has been called.

      • disposeEventManagers

        void disposeEventManagers()
        Method that may be called when the EventManagers of a Canvas are no longer needed. Implementations may use this method to release resources or to return the object to an object pool. It is an error to reference any EventManager s of a Canvas after this method has been called.

      • getUID

        java.lang.String getUID()
        Returns the unique identifier of this Canvas, which is assigned by the implementation. The UID is immutable and may be used to retrieve a particular Canvas from the GraphicFactory.
        Returns:
        the UID of this Canvas.

      • setTitle

        void setTitle(java.lang.String title)
        Sets the title of this Canvas. The title of a Canvas may or may not be displayed on the titlebar of an application's window.
        Parameters:
        title - the new title for this Canvas.

      • getTitle

        java.lang.String getTitle()
        Returns the title assigned to this Canvas.
        Returns:
        the title of this Canvas.

      • getFactory

        DisplayFactory getFactory()
        Returns the DisplayFactory associated with this Canvas.
        Returns:
        the DisplayFactory.

      • getState

        CanvasState getState()
        Returns a copy of the current state of this Canvas. The object returned will implement CanvasState or one of its subinterfaces, depending on the type of Canvas.

      • isVisible

        boolean isVisible(DirectPosition coordinate)
        Returns true if the given coordinate is visible on this Canvas.

      • add

        Graphic add(Graphic graphic)
        Adds the given Graphic to this Canvas. Implementations should respect the zOrder retrieved by calling Graphic.getGraphicStyle().getZOrderHint(). When two added Graphics have the same zOrder, the most recently added one should be on top.
        Parameters:
        graphic - the Graphic to add.

      • addAsEditable

        Graphic addAsEditable(Graphic graphic)
        Adds the given Graphic to this Canvas, immediately placing the Graphic in an editing/drawing mode, as defined by the Canvas implementation. A Graphic added as editable may or may not be visible when it is added, as it may wait for user input to define the Graphic's values through mouse gestures or key input.
        Parameters:
        graphic - the Graphic to add as editable.

      • remove

        void remove(Graphic graphic)
        Removes the given Graphic from this Canvas.
        Parameters:
        graphic - the Graphic to remove.

      • findEventManager

        EventManager findEventManager(java.lang.Class eventManagerClass)
        Returns the EventManager subinterface, based on the class type.

        Note: While the class implementing Canvas may additionally implement EventManager subinterface(s). While this design is simple, it limits the Canvas object to the input mechanisms supported by to those particular EventManager subinterface(s), and thus is discouraged.

        If the class implementing Canvas does not implement the particular EventManager subinterface, then this method can look up the EventManager via an implementation-specific mechanism. Otherwise, if the class implementing Canvas does implement the particular EventManager subinterface, this method can return the this reference.

        Parameters:
        eventManagerClass - the class type of the EventManager subinterface.
        Returns:
        a class that implements the requested EventManager subinterface, or null if there is no implementing class.

      • addEventManager

        void addEventManager(EventManager eventManager)
        Adds the EventManager subinterface if it not currently in the Canvas's collection of EventManagers.
        Parameters:
        eventManager - the EventManager type to be added to the Canvas's collection.

      • getTopGraphicAt

        Graphic getTopGraphicAt(DirectPosition directPosition)
        Returns the top-most Graphic that occupies given DirectPosition. The top-most Graphic will have the highest zOrder.
        Parameters:
        directPosition - the DirectPosition at which to look for Graphics.
        Returns:
        the top-most Graphic at the given DirectPosition.

      • getGraphicsAt

        Graphic[] getGraphicsAt(DirectPosition directPosition)
        Returns the Graphics that occupy the given DirectPosition. The order is implementation-specific.
        Parameters:
        directPosition - the DirectPosition at which to look for Graphics.
        Returns:
        the array of Graphics at the given DirectPosition.

      • getGraphicsIn

        Graphic[] getGraphicsIn(Envelope bounds)
        Returns the Graphics that occupy the given Envelope. The order is implementation-specific.
        Parameters:
        bounds - the Envelope in which to look for Graphics.
        Returns:
        the array of Graphics in the given Envelope.

      • addCanvasListener

        void addCanvasListener(CanvasListener listener)
        Adds the given listener that will be notified when the state of this Canvas has changed.

      • removeCanvasListener

        void removeCanvasListener(CanvasListener listener)
        Removes the given listener.

      • enableCanvasHandler

        void enableCanvasHandler(CanvasHandler handler)
        Enables the given CanvasHandler, removing the current handler (if any). The new handler's handlerEnabled(CanvasController) method is called, passing in a new, active CanvasController that will allow the programmer to modify the Canvas's properties.

        Implementation suggestion: 

        
 
 public void enableCanvasHandler(CanvasHandler handler) {
      if (handler != activeHandler) {
          if (activeHandler != null) {
              removeCanvasHandler(activeHandler);
          }
          activeHandler = handler;
          activeController = new CanvasController(this);
          activeHandler.handlerEnabled(activeController);
      }
  }

      • removeCanvasHandler

        void removeCanvasHandler(CanvasHandler handler)
        Removes the given CanvasHandler from this Canvas.

      • getActiveCanvasHandler

        CanvasHandler getActiveCanvasHandler()
        Returns the currently active CanvasHandler or null if no handler is active.

      • setImplHint

        void setImplHint(java.lang.String hintName,
                 java.lang.Object hint)
        Sets a rendering hint for implementation or platform specific rendering information.
        Parameters:
        hintName - the name of the hint.
        hint - the rendering hint.

      • getImplHint

        java.lang.Object getImplHint(java.lang.String hintName)
        Returns the rendering hint associated with the hint name.
        Parameters:
        hintName - the name of the hint.
        Returns:
        the rendering hint.

      • getDisplayCoordinateReferenceSystem

        CoordinateReferenceSystem getDisplayCoordinateReferenceSystem()
        Returns the Coordinate Reference System associated with the display of this Canvas. The display Coordinate Reference System corresponds to the geometry of the display device (e.g. video monitor = Cartesian, planetarium = Spherical).
        Returns:
        the display Coordinate Reference System

      • getObjectiveCoordinateReferenceSystem

        CoordinateReferenceSystem getObjectiveCoordinateReferenceSystem()
        Returns the objective Coordinate Reference System (e.g. the projection of a georeferenced Coordinate Reference System) for this Canvas. This is the default objective Coordinate Reference System for this Canvas.
        Returns:
        the objective Coordinate Reference System

      • setObjectiveCoordinateReferenceSystem

        void setObjectiveCoordinateReferenceSystem(CoordinateReferenceSystem crs)
        Sets the objective Coordinate Reference System (e.g. the projection of a georeferenced Coordinate Reference System) for this Canvas. This is the default objective Coordinate Reference System for this Canvas.
        Parameters:
        crs - the objective Coordinate Reference System
        Throws:
        IncompatibleOperationException - when the specified transformation does not apply to either the objective or the display Coordinate Reference Systems.

      • setObjectiveCoordinateReferenceSystem

        void setObjectiveCoordinateReferenceSystem(CoordinateReferenceSystem crs,
                                           MathTransform objectiveToDisplay,
                                           MathTransform displayToObjective)
                                    throws IncompatibleOperationException
        Sets the objective Coordinate Reference System (e.g. the projection of a georeferenced Coordinate Reference System) for this Canvas. This is the default objective Coordinate Reference System for this Canvas.
        Parameters:
        crs - the objective Coordinate Reference System
        objectiveToDisplay - the trasformation that converts between this objective Coordinate Reference System and the Canvas display Coordinate Reference System.
        displayToObjective - the trasformation that converts between the Canvas display Coordinate Reference System and this objective Coordinate Reference System.
        Throws:
        IncompatibleOperationException - when the specified transformation does not apply to either the objective or the display Coordinate Reference Systems.

      • getObjectiveToDisplayTransform

        MathTransform getObjectiveToDisplayTransform()
        Returns the coordinate transformation object for this Canvas. This allows the Canvas to resolve conversions of coordinates between the objective and display Coordinate Reference Systems.
        Returns:
        the coordinate transformation object

      • getDisplayToObjectiveTransform

        MathTransform getDisplayToObjectiveTransform()
        Returns the coordinate transformation object for this Canvas. This allows the Canvas to resolve conversions of coordinates between the display and objective Coordinate Reference Systems.
        Returns:
        the coordinate transformation object
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