Need help to adjust a Zoom system in Graphics2D – Java

This is my 1st question here. I’m trying to build a White Page adjustable by zoom. It’s inside a JScrollPane, so the size of the JScrollPane’s ScrollBars are adjustable in the Dimension of that JPanel.

I want to adjust the size of those ScrollBars as the Size of the page (variables width and height in the code) + 2 borderSize, so the full size is equal the Page + margin of a borderSize around it. It works if zoom = 1.0.

If zoom < 1.0, the scroll bar is smaller than the Page and cut a piece of it. If zoom > 1 the Dimension size is way bigger than the page, leaving a huger border on its right and down corners, bigger than the borderSize.

How do I do this?

PS: I’m started learning java by myself, in the Quarantine last year, never had a teacher, just the internet, so any critics or suggestions, please, tell me.

Here’s the JPanel’s code:

package test;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowStateListener;
import java.awt.geom.AffineTransform;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SpringLayout;
import javax.swing.JSlider;
import javax.swing.JScrollPane;
import javax.swing.JLabel;

public class Main2 {
private MyPanel mp = new MyPanel();
private JFrame frame;
private JSlider zoomSlider = new JSlider();
private JLabel zoomLabel = new JLabel("Zoom: XXX");

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Main2 window = new Main2();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}


public Main2() {
    initialize();
}


private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 619, 403);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    SpringLayout springLayout = new SpringLayout();
    frame.getContentPane().setLayout(springLayout);
    
    
    springLayout.putConstraint(SpringLayout.SOUTH, zoomSlider, 40, SpringLayout.NORTH, frame.getContentPane());
    springLayout.putConstraint(SpringLayout.EAST, zoomSlider, -115, SpringLayout.EAST, frame.getContentPane());
    zoomSlider.setValue(100);
    zoomSlider.setSnapToTicks(true);
    zoomSlider.setPaintTicks(true);
    zoomSlider.setMaximum(200);
    zoomSlider.setMinorTickSpacing(5);
    zoomSlider.setMinimum(5);
    springLayout.putConstraint(SpringLayout.NORTH, zoomSlider, 0, SpringLayout.NORTH, frame.getContentPane());
    springLayout.putConstraint(SpringLayout.WEST, zoomSlider, 0, SpringLayout.WEST, frame.getContentPane());
    frame.getContentPane().add(zoomSlider);
    
    JScrollPane scrollPane = new JScrollPane(mp);
    springLayout.putConstraint(SpringLayout.NORTH, scrollPane, 10, SpringLayout.SOUTH, zoomSlider);
    springLayout.putConstraint(SpringLayout.WEST, scrollPane, 10, SpringLayout.WEST, frame.getContentPane());
    springLayout.putConstraint(SpringLayout.SOUTH, scrollPane, -10, SpringLayout.SOUTH, frame.getContentPane());
    springLayout.putConstraint(SpringLayout.EAST, scrollPane, -10, SpringLayout.EAST, frame.getContentPane());
    frame.getContentPane().add(scrollPane);
    
    
    springLayout.putConstraint(SpringLayout.NORTH, zoomLabel, 10, SpringLayout.NORTH, frame.getContentPane());
    springLayout.putConstraint(SpringLayout.WEST, zoomLabel, 6, SpringLayout.EAST, zoomSlider);
    frame.getContentPane().add(zoomLabel);
    
    
    frame.addWindowStateListener(new WindowStateListener() {

        @Override
        public void windowStateChanged(WindowEvent arg0) {
            // TODO Auto-generated method stub
            mp.draw();
        }
        
    });
    
    
    zoomSlider.addMouseListener(new MouseListener() {

        @Override
        public void mouseClicked(MouseEvent arg0) {
            // TODO Auto-generated method stub
            int temp = (zoomSlider.getValue())-zoomSlider.getValue()%5;
            setZoom(temp);
            
            mp.draw();
            
        }

        @Override
        public void mouseEntered(MouseEvent arg0) {
            // TODO Auto-generated method stub
            
        }

        @Override
        public void mouseExited(MouseEvent arg0) {
            // TODO Auto-generated method stub
            
        }

        @Override
        public void mousePressed(MouseEvent arg0) {
            // TODO Auto-generated method stub
    
        }

        @Override
        public void mouseReleased(MouseEvent arg0) {
            int temp = (zoomSlider.getValue())-zoomSlider.getValue()%5;
            setZoom(temp);
            
            
            mp.draw();
        
            
        }
        
        
        
    });
    
    mp.addMouseWheelListener(new MouseWheelListener() {
        @Override
        public void mouseWheelMoved(MouseWheelEvent e) {
            if (e.getPreciseWheelRotation() < 0) {
                
                setZoom(zoomSlider.getValue()- 5);
           
            } else {
                setZoom(zoomSlider.getValue()+ 5);
            }
        // zoom += e.getPreciseWheelRotation();
            if (mp.getZoom()*100 < 10) {
                setZoom(10);
            }
            mp.draw();
        }
        });
    
    AdjustmentListener adj = new AdjustmentListener() {

        @Override
        public void adjustmentValueChanged(AdjustmentEvent e) {
            setZoom(zoomSlider.getValue());
            mp.draw();
            
        }
        
    };
    scrollPane.getVerticalScrollBar().addAdjustmentListener(adj);
    scrollPane.getHorizontalScrollBar().addAdjustmentListener(adj);
    
    
}
public void setZoom(int n) {
    mp.setZoom(n);
    zoomSlider.setValue(n);
    zoomLabel.setText("Zoom: "+mp.getZoom()+"x");
    
}
}
class MyPanel extends JPanel{

private static final long serialVersionUID = -716735372803790424L;

int borderSize=28;
int zoom=100;
int height = 3565;
int width = 2537;
int widthz, heightz; 

public MyPanel() {
setBackground(Color.DARK_GRAY);
}

@Override
public Dimension getPreferredSize() {
int a, b;
String temp;
Float x, y;
x=(getZoom()*width); //Size of the page adjusted by zoom
y=(getZoom()*height);

temp = x.toString(); 
String temp1[] = temp.split("\."); // converted to string to convert it to int
a = Integer.valueOf(temp1[0])+2*borderSize; //that value + 2 BorderSize
temp = y.toString();
String temp2[] = temp.split("\.");
b = Integer.valueOf(temp2[0])+2*borderSize;

return new Dimension (a,b);
}

@Override
public void paintComponent (Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d = putZoom(g2d);
g2d.setColor(Color.WHITE);
g2d.fillRect(this.getX(),this.getY(), width, height);
g2d.setColor(Color.BLACK);
g2d.drawRect(this.getX()+borderSize,this.getY()+borderSize,width-2*borderSize,height-2*borderSize);
g2d.dispose();

}

public Graphics2D putZoom(Graphics2D g) {

AffineTransform at = new AffineTransform();
at.translate(borderSize,borderSize); // put the page a borderSize from the upper-left corner
at.scale(getZoom(),getZoom()); //adjust the page as zoom 

Graphics2D g2d = g;
g2d.setTransform(at);
return g2d;
}

public void draw() { //this method is to update the draw from the main
repaint();

}

public Float getZoom() {
return Float.valueOf(zoom)/100;
}
public void setZoom(int zom) { //this method is to update Zoom from the main

zoom=zom;
String zoomheight []= (String.valueOf(getZoom()*height)).split("\.");
heightz = Integer.valueOf(zoomheight[0]);
String zoomwidth []= (String.valueOf(getZoom()*width)).split("\.");
widthz = Integer.valueOf(zoomwidth[0]);

}

public int getZoomInt() {
return this.zoom;
}

}

Zoom(values from 0.1 to 2.0).

How can i improve this? Also, i have no idea how to update the JScrollPane’s scrollbars together with the zoom.Thanks for the help.

UPDATE: i’ve created a minimal reproducible exemple.

Answer

I’ve finally did it. Started by not using transformation for scaling it, but making a new draw with the size zoomed, adapting all sizes in the method setSizes(), and adjusting the Dimension by those sizes. (Just changed this class)

class MyPanel extends JPanel{

private static final long serialVersionUID = -716735372803790424L;

int borderSize=28;
int zoom=100;
int height = 3565;
int width = 2537;
int widthz, heightz;
int maxHeight, maxWidth; //max size of draw
int maxAreaHeight, maxAreaWidth; //max size of area

public MyPanel() {
    setBackground(Color.DARK_GRAY);
}

@Override
public Dimension getPreferredSize() {
    setSizes();
    return new Dimension (maxAreaWidth,maxAreaHeight);
}

@Override
public void paintComponent (Graphics g) {
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D) g.create();
    g2d= createBase(g2d);

}

public void draw() { //this method is to update the draw from the main
    repaint();

}

public Float getZoom() {return Float.valueOf(zoom)/100;}
public void setZoom(int zom) {zoom=zom;}
public int getZoomInt() {return this.zoom;}

public void setSizes () {
    widthz= width*getZoomInt()/100;
    heightz=height*getZoomInt()/100;
    maxHeight = heightz+2*borderSize;
    maxWidth = widthz +2*borderSize;
    maxAreaHeight = this.getY()+maxHeight;
    maxAreaWidth = this.getX()+maxWidth;

    if (this.getSize() != new Dimension(maxAreaWidth, maxAreaHeight)) {
        this.setSize(maxAreaWidth, maxAreaHeight);
    }
}
public Graphics2D createBase(Graphics2D g2d) {
    Graphics2D g = g2d;
    setSizes();

    g.setColor(Color.WHITE);
    g.fillRect(this.getX()+borderSize,this.getY()+borderSize, widthz, heightz);
    g.setColor(Color.BLACK);
    g.drawRect(this.getX()+borderSize+borderSize*zoom/100,this.getY()+borderSize+borderSize*zoom/100,widthz-2*borderSize*zoom/100,heightz-2*borderSize*zoom/100);


    return g;
}

}

Thanks for all the help.

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