create scroll bars inside JScrollPane

[noobplus]

my (J)Panel consists of the (J)ScrollPane
my (J)ScrollPane consists of a (J)Panel

public classname extends JPanel
{
   public void paintComponent(Graphics g)
    {
      //my panel with a graph which really really needs a scroll bar to view the full graph
    }
   public static void main(String[] args)
      {
           JScrollPane scrollpane=new JScrollPane();
           scrollpane.setViewPortView(classname);  //my panel is inside the scrollpane
           JFrame frame = new JFrame("title");
           frame.add(scrollpane);                          //my scrollpane is inside the frame
           frame.setVisible(true);
      }
}

the codings ran, and the (J)Panel was inside the (J)ScrollPane which was inside thje (J)Frame,
and there were no scrollbars. hence it showed only a beginning part of the image, and the rest was hidden to the right side of the monitor.
How do we add scrollbars?

thx
dhilip

[Fubarable]

The scrollbars will automatically appear if the component held by the view port is larger than the viewport. For more specific help, you'll need to post some code.

[noobplus]

The scrollbars will automatically appear if the component held by the view port is larger than the viewport. For more specific help, you'll need to post some code.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.MouseWheelListener;
import java.awt.font.FontRenderContext;
import java.awt.font.LineMetrics;
import java.awt.geom.Line2D;
import java.io.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;



public class ReadPlat extends JPanel
{
	/**
	 * 
	 */
	private static final long serialVersionUID = 4157203125948260492L;
	final int PAD = 20;
	double[] xArray ;
	double[] yArray ;
	int Size;
	
//////////////////////////////////////////////////////////////////////////////////////////
	public void paintComponent(Graphics g)
	{
	    

		Graphics2D g2 = (Graphics2D)g;
		g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
		
		int w = getWidth();
        int h = getHeight();
        // Draw ordinate.
        g2.draw(new Line2D.Double(PAD, PAD, PAD, h-PAD));
        
        // Draw abscissa.
        g2.draw(new Line2D.Double(PAD, h-PAD, w-PAD, h-PAD));
        
        // Draw labels.
        Font font = g2.getFont();
        FontRenderContext frc = g2.getFontRenderContext();
        LineMetrics lm = font.getLineMetrics("0", frc);
        float sh = lm.getAscent() + lm.getDescent();
        // Ordinate label.
        String s = "amplitude";
        float sy = PAD + ((h - 2*PAD) - s.length()*sh)/2 + lm.getAscent();
        for(int i = 0; i < s.length(); i++) {
            String letter = String.valueOf(s.charAt(i));
            float sw = (float)font.getStringBounds(letter, frc).getWidth();
            float sx = (PAD - sw)/2;
            g2.drawString(letter, sx, sy);
            sy += sh;
        }
        s = "time";
        sy = h - PAD + (PAD - sh)/2 + lm.getAscent();
        float sw = (float)font.getStringBounds(s, frc).getWidth();
        float sx = (w - sw)/2;
        g2.drawString(s, sx, sy);
        
        double xInc = (double)(w - 2*PAD)/(this.yArray.length-1);
        double scale = (double)(h - 2*PAD)/getMax();
        
        for(int i=PAD;i<w-PAD;i=i+50)
        {
        	g2.drawString(/*Integer.toString*/Double.toString(/*i-20*/this.xArray[i]), i, h-PAD+10);
        }
                
        g2.setPaint(Color.green.darker());
        for(int i = 0; i < this.yArray.length-1; i++) {
            double x1 = PAD + i/**xInc*/;
            double y1 = h - PAD - scale*((this.yArray[i]));
            double x2 = PAD + (i+1)/**xInc*/;
            double y2 = h - PAD - scale*this.yArray[i+1];
            g2.draw(new Line2D.Double(x1, 2*y1, x2, 2*y2));
            
        }
        
        // Mark data points.
        g2.setPaint(Color.red);
     
        

	}
//////////////////////////////////////////////////////////////////////////////////////////
	
	private double getMax() {
	       double max = -Integer.MAX_VALUE;
	        for(int i = 0; i < this.yArray.length; i++) {
	            if(this.yArray[i] > max)
	                max = this.yArray[i];
	        }
	        return max;
	    }
	
	public ReadPlat(int size)
	{
		this.Size=size;
		xArray= new double[this.Size];
		yArray= new double[this.Size];
	}
	
	public void setData(int i,double x,double y)
	{
		if(i>this.Size)
			return;
		xArray[i]=x;
		yArray[i]=y;
	}
	
	public static void main(String[] args) throws Exception
	{   
		ReadPlat ReadPlatInstance;
		String filename;
		FileReader file_in;
		BufferedReader in;	
		String input_line;
		String[]input_split;
		int TotalLineCount=0;
		
		filename = args[0];
		file_in = new FileReader(filename);
	    in 		= new BufferedReader(file_in);
	    
	    input_line ="Starting";
	    
	    
	    //Reading total lines 
	    while((input_line=in.readLine())!=null)
	    {	
	    	//input_line =in.readLine();
	    	TotalLineCount++;
	    }
	    System.out.println(TotalLineCount);
	    ReadPlatInstance = new  ReadPlat(TotalLineCount);
	    
	    //Closing the File and reopening
	    TotalLineCount=0;
	    input_line ="ReStarting";
	    in.close();
	    file_in.close();
	    file_in = new FileReader(filename);
	    in 		= new BufferedReader(file_in);	    
	    while((input_line=in.readLine())!=null)
	    {	
	    	 System.out.println("---------------");
	    	 System.out.println("Line No:"+TotalLineCount);
	    	
	    	
	    	
	    	input_line=input_line.replaceAll("\"","");
	    	input_split = input_line.split(" ");    	   	
	    	
	    	 System.out.println("Input Line:"+input_line);
	    	 System.out.print(input_split.length);
	    	 System.out.print("x"+input_split[0]);
	    	 System.out.print("y"+input_split[2]);
	    	ReadPlatInstance.setData(TotalLineCount, Double.valueOf(input_split[0].trim()).doubleValue(),Double.valueOf(input_split[2].trim()).doubleValue()   )	;    	
	    	System.out.println("\n"+"instant x "+ReadPlatInstance.xArray[TotalLineCount] + "\t instant y" + ReadPlatInstance.yArray[TotalLineCount]);
	    	TotalLineCount++;
	    	
	    }	
	    
	    
	  
	    
	      
	    JFrame f=new JFrame("ReadPlatInstance");//////
	    JScrollPane spp=new JScrollPane();
	    spp.setViewportView(ReadPlatInstance);
	    spp.setVisible(true);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(spp);
        f.pack();
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
	    in.close();
	    file_in.close();
        
	    
	    
	    
	    
	    
	}
	
}

this is my code,
this is my input file added to the argument for my class (ReadPlat) input.txt
the original file has 63375 lines, but i couldn't upload it in this forum, hence, I've deleted so many lines and this file has only 849 lines, and scrollbar doesn't appear yet.

thx
dhilip

[Fubarable]

You need to give your ReadPlat class an override for the getPreferredSize method. Then you also need to set the preferredSize of your JScrollPane's viewport (making sure that the two heights match. Do not set the size of the JFrame but rather let pack() take care of its size.

Also the logic in your paintComponent is wrong as you change how many data points are displayed depending on the size of the JPanel. Don't do that.

[noobplus]

You need to give your ReadPlat class an override for the getPreferredSize method.

thx, I've added the line

ReadPlatInstance.setPreferredSize(new Dimension(TotalLineCount,718));//TotalLineCount is the size of the array of y-axis values

(after initializing the JFrame),

Then you also need to set the preferredSize of your JScrollPane's viewport (making sure that the two heights match. Do not set the size of the JFrame but rather let pack() take care of its size.

spp.setPreferredSize(new Dimension(1357,718));

and yay the scroll bar has appeared!!! and the graph was alright.

but when I scroll the scrollbar, the incoming graph gets drawn below, and appears as kind of the lines are overlapped,

Also the logic in your paintComponent is wrong as you change how many data points are displayed depending on the size of the JPanel. Don't do that.

that's what I can't get in mind.. I've removed "xInc" so it got dependency-free(depending on the size of the panel), and got that error while scrolling

regards
dhilip

[noobplus]

I'll go with this question..
where do we create the actionListener and which listener? because I need the scrollPane get refreshed or repainted every scrolling action

regards
dhilip

[noobplus]

hi again,

is it possible to get rid of the error by using repaint() ? I tried that in vain anyway, but
is there any other way?
or listener is needed?

thanks
dhilip

[DarrylBurke]

Cross posted
why does my viewport gets accumulated? (Swing / AWT / SWT / JFace forum at JavaRanch)

db

[noobplus]

Cross posted

db

Hi,
they asked me to add "super.paintComponent();" at the beginning of the overriding. and it works good , and I thought there are different moderators there, glad to meet you on that forum, anyways

regards
dhilip

[Fubarable]

... and I thought there are different moderators there,

What does this have to do with anything?

[noobplus]

What does this have to do with anything?

i mean, different mods, but this is my fav forums

regards
dhilip