Functions Graph

[wally]

Hi there, I would like to design a plotter, where the user enters min x / max x and min y and max y accordingly, and then presses plot button to see the points on the graph. I have managed setting the labels, buttons, combobox; all these entries are settled using the gridbay layout on the left.

Now on the right I have implemented the x and y coordinates which resizes accordingly in any size of the main frame window. How do I rescale the coordinates as well along the x and y coordinates when the main frame window is resized?

Thanks

[Horcrux7]

There are 2 possible options. First you can calculate all painting coordinates with a factor for and factor for y. Alternate you calculated only the factors and set a transformation on the Graphics.

[wally]

Can you please provide me a sample code, cause I tried many times and still cannot do it... thanks

[Horcrux7]

I does not know what you expected. It is like how I have described in text.

Dimension realSize = size();
float factorX = realSite.width/virtualWidth;
float factorY = realSite.heigth/virtualHeight;
Graphics gr = g.createGraphics();
gr.setScale( factorX, factorY );
...

[wally]

The following code is what I have done so far,

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;

import javax.swing.JPanel;

public class GraphPanel extends JPanel {

	private double minX;

	@Override
	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		Graphics2D g2D = (Graphics2D) g;

		this.setBackground(Color.lightGray); // sets GraphPanel background
		// color;

		// Set graph panel width and height to resize accordingly;
		int graphWidth = getWidth();
		int graphHeight = getHeight();

		// Drawed the x and y coordinates;
		g.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2); // x
		g.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight()); // y

		AffineTransform oldtransform = g2D.getTransform();
		g2D.scale(1.0, -1.0);
		g.translate(graphWidth / 2, graphHeight / 2); // shift to cartesian

	int noOfPoints= 10000;
	int maxX = 0;
	int xRange= (int) (minX + maxX);
		
		double x = this.minX;
	double increment = xRange/(1.0*noOfPoints);
	
	 // calculate all the points.
    for (int i=0; i < noOfPoints; i++){
    	int xPoint = x;
    	Object xPoints = null;
		Object yPoint = calculateY(xPoints);
    	x += increment;
               // draw xPoint, yPoint here
    	g.fillRect(x,x,1,1);
	
	

		}
		// restore old coordinate system.
		g2D.setTransform(oldtransform);
	}

	private Object calculateY(Object xPoints) {
		// TODO Auto-generated method stub
		return null;
	}
}

Moderator Edit: Code tags added

[Horcrux7]

Seems ok. For calculateY you need to know the range of your points, the virtual size. Currently xPoint and yPoint are ever null.

[j2me64]

after // calculate all the points you should define the xPoint as double and when you call fillRect cast the x as int.