PageManager.java

package org.tgdb.frame;
import java.io.Serializable;

public class PageManager implements Serializable {
   
    private int start;
    private int delta;
    private int max;
    private int viewed;
    private int page = 1;
    
    private boolean last;
    
    
    /** Creates a new instance of PageManager */
    public PageManager() {
        start = 1;
        delta = 60;
        max = -1;
    }

    /**
     * Returns the number of what to display
     * @return The start number
     */
    public int getStart() {
        start = (page - 1)*delta + 1;
        if(start > max) {
            setFirst();
        }
        return start;
    }
    
    /**
     * Sets the number of what to display
     * @return The start number
     */
    public void setStart(int start) {
        this.start = start;
        
        if(start + delta - 1 < max) {
            last = false;
        } else {
            last = true;
        }
    }

    /**
     * Returns the value of how much to jump when browsing pages
     * @return The value of how many objects to jump when browsing pages
     */
    public int getDelta() {
        return delta;
    }

    /**
     * Sets the value of how many objects to jump when browsing pages
     * @param delta The value stating how many objects to jump when browsing pages
     */
    public void setDelta(int delta) {
        this.delta = delta;
    }

    /**
     * Returns the maximum number of objects to display
     * @return The maximum number of objects, i.e. the size of the collection
     */
    public int getMax() {
        return max;
    }

    /**
     * Sets the maximum number of objects to display
     * @param max The maximum number of objects to display
     */
    public void setMax(int max) {
        this.max = max;
        
        if (last) {
            int from = max % delta;
            //start = max - from + 1;
            if(from != 0) {
                start = max - from + 1;
            } else {
                start = max - delta + 1;
            }
        }
    }
    
    /**
     * Returns the stop value, i.e. the max index to use in the collection of objects to display
     * @return The stop value
     */
    public int getStop() {
        return start+delta-1;
    }
    
    /**
     * Sets the next interval to display
     */
    public void setNext() {
        if(start + delta - 1 < max) {
            start += delta;
            page++;
            if(start + delta - 1 < max) {
                last = false;
            } else {
                last = true;
            }
        }
    }
    
    public void setCurrentPage(int pagenum){
        this.page = pagenum;
        start = (pagenum - 1)*delta + 1;
        if(start + delta - 1 < max) {
            last = false;
        } else {
            last = true;
        }
    }
    
    /**
     * Sets the previous interval to display
     */
    public void setPrev() {
        if (start-delta>0) {
            page--;
            start -= delta;
            last = false;
        }
    }
    
    /**
     * Sets the first interval to display
     */
    public void setFirst() {
        start = 1;
        page = 1;
        last = false;
    }
    
    /**
     * Sets the last interval to display
     */
    public void setLast() {
        /*
        if (max==-1)
            throw new ApplicationException("Last button unsupported if setMax is not called. ");
          */
        //page = max/delta;
        int from = max % delta;
        if(from != 0){
            start = max - from + 1;
            page = (max/delta)+1;
        }
        else{
            start = max - delta + 1;
            page = max/delta;
        }
        
        last = true;
        
    }
    
    /**
     * Returns if the current interval is the last to display
     * @return If the interval is the last to display
     */
    public boolean isLast() {
        return last;
    }
    
    public int getViewed() {
        if (last){
           return max-start+1;
        }else{
            if(start==1 && max < delta){
                return max;
            }else{
                return delta; 
            }
        }
    }
    
    public int getPages(){
        int numpages = max/delta;
        if(max-(delta*numpages)>0) {
            numpages += 1;
        }
        return numpages;
    }
}