simpletool.java

geotools的源码

package uk.ac.leeds.ccg.geotools;

import uk.ac.leeds.ccg.geotools.*;
import java.awt.*;
/**
 * An abstract implemtation of the Tool interface.
 * This class provides some base functionality that might be useful to a wide range of tools
 * and extending it would make the life of a tool developer much easier.<br>
 * Essentialy this call splits the update(reason) method into seperate calls, defalt versions of
 * which are provided.<br>
 * The class also provides some simple rubber band tools that can be used by extending classes automaticaly.
 * In order to make a concrete extention of this class all that is needed is a getCursor and a getRubberBandShape method
 * although such a tool would not actualy do anything.
 *
 * @author James Macgill JM
 * @since 0.7.7.2 07 June 2000
 */
public abstract class SimpleTool implements uk.ac.leeds.ccg.geotools.Tool
{
    /**
     * All tools only operate on one viewer at a time.  This variable holds a reference to
     * that viewer.
     */
    protected Viewer context;
    /**
     * A reference to a Graphics object onto which tools can place tempory graphics.
     */
    Graphics toolGraphics;
    /**
     * Tracks at all times, the mouse status for the viewer this tool is attached to.
     * Provides information on mouse movments and drag regions in screen, geographic and projected space.
     */
    protected MouseStatus mouse;
    
    /**
     * RubberBandShape constant
     */
    public static final int NONE=-1,CIRCLE=1,RECTANGLE=2,LINE=3;
    
    /**
     * Locks the rubber bands to boxes and circles instead of ellipes and rectangles.
     */
    protected boolean lockAspect = false;
    
    public void setLockAspect(boolean flag){
        lockAspect = flag;
    }
    
    public boolean isLockAspect(){
        return lockAspect;
    }
    
    /**
     * Retun one of the above constants to specify which rubber band should be
     * automaticaly displayed during mouse drag events.
     * @return int A value from above representing a circle, rectangle or line (or none)
     */
    public abstract int getRubberBandShape();
    
    /**
     * called by the viewer which has recived this tool in order to set that viewer
     * as the context for this tool.
     * <br>It also initalizes the mouse status object. Once set up mouse provides useful features for
     * querying user acctions.  e.g. mouse.getScreenDragBox() mouse.getMapDragBox();
     * @param v The viewer to which this tool should now be attached.
     */
    public void setContext(Viewer v)
    {
        context = v;
        mouse = context.getMouseStatus();
    }

    /**
     * Called by the viewer to which the tool is attached (context)
     * The tool uses this to update its display and behavior based on the reason code passed in
     * and current mouse status.
     *
     * The method rebradcasts the reason code to seperate methods:<p>
     * clear()<br>
     * drag()<br>
     * release()<br>
     * click()<br>
     *
     * @author James Macgill JM
     * @since 0.7.7.2 07 June 2000
     * 
     * @param g A Graphics object that cen be used for transient tool graphics. It is pre set to XORMode.
     * @param reason An int that references the reason why this method has been called.
     */
    public void update(Graphics g,int reason)
    {
        toolGraphics = g;
        switch(reason){
            case CLEAR:
                clear();
                break;
            case M_DRAG:
                drag();
                break;
            case M_RELEASE:
                release();
                break;
            case M_CLICK:
                clear();
                click();
                break;
        }
    }
    
    /**
     * A default implemention of the percistent paint method.
     * most tools will NOT need to overide this method and can instead use the
     * toolGraphics object set up in the update method.
     *
     * @author James Macgill JM
     * @since 0.7.7.2 07 June 2000
     * @param g A Graphics object that references the viewers static buffer.
     */
    public void paint(Graphics g){
        //do nothing
    }
    
    /**
     * Called by update when the reason code is DRAG.
     * Provides automatic suport for drawing a 'rubber band' of the shape specified by getRubberBandShape().
     * @author James Macgill JM
     * @since 0.7.7.2 07 june 2000
     */
    public void drag(){
        if(!mouse.isDragStart()){
            clear();
        }
        drawRubberBand(context.getMouseStatus().getScreenDragBox());
    }
    
    /**
     * Called when update is called with reason code CLICK.
     * This default implementation does nothing, overide to add behavior.
     * @author James Macgill
     * @since 0.7.7.2 07 June 2000
     */
    public void click(){
        //do nothing
    }
    
    /**
     * Called when update is called with reason code RELEASE.
     * This default implementaion calls clear() to remove any rubberBand marks, overide to add behavior but try to call clean
     * @author James Macgill
     * @since 0.7.7.2 07 June 2000
     */
    public void release(){
        clear();
        //do nothing
    }
    
    /**
     * Called when update is called with reason code CLEAR whenever the old rubber band needs to be removed.
     *
     * @author James Macgill
     * @since 0.7.7.2 07 June 2000
     */
    public void clear(){
        drawRubberBand(context.getMouseStatus().getOldScreenDragBox());
    }
    
    /**
     * Uses XOR painting (preset in the toolGraphics) to draw a removable shape to the screen.
     * @author James Macgill
     * @since 0.7.7.2 07 June 2000
     * @param box A Rectangle defining the start and finish points of the rubber band to draw.
     */
    public void drawRubberBand(Rectangle box){
         toolGraphics.setColor(Color.red);
         toolGraphics.setXORMode(Color.blue);
         int x,y,width,height;
         x = box.x;
         y = box.y;
         if(lockAspect){
             width = height = Math.max(box.width,box.height);
         }
         else{
             width = box.width;
             height = box.height;
         }
         switch(getRubberBandShape()){
            case RECTANGLE:
                toolGraphics.drawRect(x,y,width,height);
                break;
            case CIRCLE:
                toolGraphics.drawOval(x-width,y-height,width*2,height*2);
                break;
            case LINE:
                toolGraphics.drawLine(x,y,width,height);
                break;
         }
         toolGraphics.setPaintMode();       
    }
}