We Keep Coding

How can I fix this NullPointerException when trying to render on a JPanel with Graphics2D? [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 6 years ago.
I've been trying to make a shop for my game.
This has been unsuccessful.
I've tried drawComponent, didn't work.
No errors, code executed, but didn't work.
Now i'm trying to do:
private void render() {
Graphics2D g = (Graphics2D) graphics.getGraphics();
/////////////////////
g.drawImage(img, 0, 0, WIDTH, HEIGHT, null);
/////////////////////
g.dispose();
Graphics2D g2d = (Graphics2D) getGraphics();
g2d.drawImage(img, 0, 0, null);
g2d.dispose();
}
Now i get a NullPointerException on g2d.
I've tried everything.
`Exception in thread "game" java.lang.NullPointerException
at com.johnythecarrot.game.Shop$DrawPane.access$2(Shop.java:123)
at com.johnythecarrot.game.Shop.render(Shop.java:154)
at com.johnythecarrot.game.Game.render(Game.java:75)
at com.johnythecarrot.game.Game.run(Game.java:112)
at java.lang.Thread.run(Unknown Source)`
My goals are to be able to have clickable buttons.
It DID work. But i had to restart almost everytime. Because mostly of the time to code wasn't even executed. So i tried to fix it. Now it's all messed up.
This is the code to it.
(DoubleInt is a part of my library it's nothing more than just x and y. )
public class Shop {
public BuildWindow window;
public static JWindow w;
private int WIDTH = 860, HEIGHT = 440;
private BufferedImage graphics = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
public DrawPane drawPane;
public Shop() {
//window = new BuildWindow().setSize(new DoubleInt(100, 100)).at(wi, he).setTitle("Shop").setOpacity(1).setDragable(false).showEmpty(true);
w = new JWindow();
w.setOpacity(1);
w.setSize(WIDTH, HEIGHT);
w.setLocation(800, 800);
w.setVisible(false);
w.setAlwaysOnTop(true);
//graphics = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
}
private void createShop() {
/***Graphics2D g = (Graphics2D) graphics.getGraphics();
g.setColor(Color.blue);
g.drawString("hey", WIDTH-50, HEIGHT-50);
g.fillRect(0, 0, WIDTH, HEIGHT);*/
}
public class DrawPane extends JPanel {
int width = WIDTH;
int height = HEIGHT;
private ArrayList<Shape> buttons;
private Shape btn1 = new Rectangle2D.Double(20, 60, width/2, height-20);
private Shape btnClose = new Rectangle2D.Double(width-25, 5, 20, 20);
Point wCoords;
Point mCoords;
public DrawPane() {
buttons = new ArrayList<>();
buttons.add(btn1);
buttons.add(btnClose);
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
super.mouseClicked(e);
for(Shape s : buttons) {
if(s.contains(e.getPoint())) {
System.out.println("Clicked " + s.getBounds());
if(s == btnClose) {
w.dispose();
}
}
}
}
#Override
public void mousePressed(MouseEvent e) {
mCoords = e.getPoint();
}
#Override
public void mouseReleased(MouseEvent arg0) {
mCoords = null;
}
});
addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent e) {
wCoords = e.getLocationOnScreen();
w.setLocation(wCoords.x - mCoords.x, wCoords.y - mCoords.y);
}
});
}
void repaintThis() {
repaint();
}
BufferedImage img = loadImageFrom.LoadImageFrom(Shop.class, "bar.png");
Graphics gb;
/**
* super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g.setColor(Color.red);
//g.fillRect(0, 0, width, 50);
g.drawImage(img, 0, 0, width, 50, null);
g.setColor(Color.WHITE);
g.drawString("SHOP", 15, 30);
g.drawString("X", width-20, 20);
for(Shape b : buttons) {
g2d.draw(b);
}
System.out.println("Built");
gb = g;
*/
private void render() {
Graphics2D g = (Graphics2D) graphics.getGraphics();
/////////////////////
g.drawImage(img, 0, 0, WIDTH, HEIGHT, null);
/////////////////////
g.dispose();
Graphics2D g2d = (Graphics2D) getGraphics();
g2d.drawImage(img, 0, 0, null);
g2d.dispose();
}
public void Build() {
Graphics g = gb;
Graphics2D g2d = (Graphics2D) g;
g.setColor(Color.red);
//g.fillRect(0, 0, width, 50);
g.drawImage(img, 0, 0, width, 50, null);
g.setColor(Color.WHITE);
g.drawString("SHOP", 15, 30);
g.drawString("X", width-20, 20);
for(Shape b : buttons) {
g2d.draw(b);
}
System.out.println("Built");
}
}
public void render(Graphics2D g) {
drawPane.render();
}
public void addDrawPane() {
drawPane = new DrawPane();
w.add(drawPane);
}
}
If you need access to more code, just ask me.

You should override the paintComponent method like this:
public class DrawPane extends JPanel {
// all your variables and other things
#Override
paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
// Your code goes here, use the g2d
}
}
then if you need to repaint your component, simply call repaint() on it.

Change Color BufferImage

I want to change the color of my BufferdImage.
When I do it like in this post: BufferedImage draw white when I say red it works only in my method which constructs my JFrame with all the components.
But when I want to use it in an ActionEvent in my Controller class, it does nothing, but the rest of the ActionEvent works, like for example change text in text field.
Methods in the JPanel class:
public void testImage(){
System.out.println("Methode suc. called");
Graphics g = image.getGraphics();
tempC = Color.GREEN;
g.setColor(tempC);
g.fillRect(150, 300, 100, 100);
tempC = Color.CYAN;
g.setColor(tempC);
g.fillOval(0, 0, 100, 100);
g.dispose();
if(image == null){System.out.println("Image is null");}
}
public void clearImage(){
Graphics g = image.getGraphics();
tempC = Color.WHITE;
g.setColor(tempC);
g.fillRect(0, 0, darstellungsBreite, darstellungsHoehe);
g.dispose();
}
The ActionListener:
public void actionPerformed(ActionEvent arg0) {
if(arg0.getActionCommand().equals(view.ACTION_CLEAR))
{
//Clear Graphics
view.drawArea.clearImage();
//view.useClear();
}

Shape over an image?? (Java)

I am trying to code a board game in Java.
I have the board which is an image and the pawns which are shapes (for example a rectangle). I want the board to be the background in the JFrame and the pawns to be over the board. I have tried multiple times but either the board covers the shape or only the shape appears. I could join the shape with the image..and create a new image but this is not what i want. Any ideas?
public class Board extends JPanel {
#Override
public void paintComponent(Graphics g) {
try {
BufferedImage img = ImageIO.read(new File("C:\\Users\\i\\Desktop\\j.png"));
Graphics2D g2 = (Graphics2D) g;
super.paintComponent(g);
g.drawImage(img, 0, 0, null);
}catch (IOException ex) {
Logger.getLogger(Board.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
And my other class
public class GameGUI extends javax.swing.JFrame {
public GameGUI() {
Board b=new Board();
setContentPane(b);
setSize(600,600);
setTitle("gui");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
}
The class for the player
public class Player extends JPanel{
int xPos = 100, yPos = 100, vwidth = 100, vheight = 100;
Rectangle r = new Rectangle(xPos, yPos, vwidth, vheight);
public Player(){ .....}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
super.paintComponent(g);
g.setColor(Color.black);
if (fill) {
g.fillRect((int) r.getX(), (int) r.getY(), (int) r.getWidth(), (int) r.getHeight());
}
g2.draw(r);
}
}

Painting different non-rectangle polygons on semi-transparent JPanel causes ugly edges

I'm working on a custom menu for a game and a problem occured to me by trying to draw the components.
The idea is, to have either a picture or a video running in the background with a panel on top of it containing some custom menu-items.
The panel which contains the menu-items shall be semi-transparent and thats the problem I guess.
Since it's a bit hard to explain I've build an example wich demonstrates the issue. Redrawing the menu-item on mouseover works without any problems but it appears that the redraw also kinda affects the parts of the panel which should not be drawn since the shape of the actual menu-item doesn't fit the panels rectangle shape. This results in my menu-item having ugly dark edges which should not be there (top-right and bottom-left).
Hope you guys know a solution for that cause I start getting really annoyed. I tried everything I found here or somewhere else in the web, but it appears all the other problems only had to deal with redrawing one shape which does not change.
import java.awt.AlphaComposite;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class TransparentDrawTest extends JPanel implements MouseListener {
private final static Dimension SIZE = new Dimension(400, 50);
private boolean isSelected;
private boolean isClicked;
public static void main(String[] args) {
JFrame testFrame = new JFrame();
testFrame.setSize(500, 100);
testFrame.setResizable(false);
testFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
testFrame.setLocationRelativeTo(null);
testFrame.setBackground(Color.WHITE);
JPanel semiTransPanel = new JPanel();
semiTransPanel.setBackground(new Color(0.0f, 0.0f, 0.0f, 0.6f));
semiTransPanel.setOpaque(true);
semiTransPanel.add(new TransparentDrawTest());
testFrame.add(semiTransPanel);
testFrame.setVisible(true);
}
public TransparentDrawTest() {
this.addMouseListener(this);
this.setSize(SIZE);
this.setMinimumSize(SIZE);
this.setMaximumSize(SIZE);
this.setPreferredSize(SIZE);
this.setOpaque(false);
}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC));
g2d.fillRect(0, 0, 400, 50);
int[] pointsX;
int[] pointsY;
if (this.isSelected) {
pointsX = new int[] { 2, 348, 398, 48 };
pointsY = new int[] { 2, 2, 48, 48 };
}
else {
pointsX = new int[] { 2, 298, 348, 48 };
pointsY = new int[] { 2, 2, 48, 48 };
}
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(5));
g2d.setColor(Color.WHITE);
g2d.drawPolygon(pointsX, pointsY, 4);
if (this.isClicked)
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.75f));
else
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));
g.fillPolygon(pointsX, pointsY, 4);
}
#Override
public void mouseClicked(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
this.isSelected = true;
this.repaint();
}
#Override
public void mouseExited(MouseEvent e) {
this.isSelected = false;
this.repaint();
}
#Override
public void mousePressed(MouseEvent e) {
this.isClicked = true;
this.repaint();
}
#Override
public void mouseReleased(MouseEvent e) {
this.isClicked = false;
this.repaint();
}
}

There are at least two things I can see which will give you trouble...
Firstly, you are changing the alpha composite of the Graphics context, but you are not resting it....
Graphics2D g2d = (Graphics2D) g;
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC));
The Graphics context is a shared resource, all components being painted in the current paint cycle will be given the same instance of Graphics, meaning that any changes you make to it will be passed to the other components being painted.
Instead, you should create a temporary copy of the Graphics context and use that instead...
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC));
//...
// If you create it, you must dispose of it...
g2d.dispose();
Second of all, you are setting the background color of a opaque component to a semi transparent value...
semiTransPanel.setBackground(new Color(0.0f, 0.0f, 0.0f, 0.6f));
The problem is, Swing only treats components and opaque or transparent. By doing this, Swing won't know that it should also update the components below this one. Basically it will think that the component is opaque (because it is) and will not update the components below...
Basically, you will need to do something simular to what you've done with TransparentDrawTest panel, and fake it, for example...
JPanel semiTransPanel = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(0.6f));
g2d.setColor(getBackground());
g2d.fillRect(0, 0, getWidth(), getHeight());
g2d.dispose();
}
};
semiTransPanel.setBackground(new Color(0.0f, 0.0f, 0.0f));
semiTransPanel.setOpaque(false);
I also can't figure out why you are doing this...
g2d.fillRect(0, 0, 400, 50);
In your TransparentDrawTest pane...
You should be calling super.paintComponent(g) first, this is actually what this method does anyway, it clears the Graphics context for painting...amongst other things ;)
Updated with example code...
This is the example code I've been using to test you code with...
Ps: I changed the background color of the semi transparent panel so I can see the difference...
import java.awt.AlphaComposite;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Composite;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TransparentDrawTest extends JPanel implements MouseListener {
private final static Dimension SIZE = new Dimension(400, 50);
private boolean isSelected;
private boolean isClicked;
public static void main(String[] args) {
JFrame testFrame = new JFrame();
testFrame.setSize(500, 100);
testFrame.setResizable(false);
testFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
testFrame.setLocationRelativeTo(null);
testFrame.setBackground(Color.WHITE);
JPanel semiTransPanel = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(getBackground());
g2d.setComposite(AlphaComposite.SrcOver.derive(0.6f));
g2d.fillRect(0, 0, getWidth(), getHeight());
g2d.dispose();
}
};
semiTransPanel.setOpaque(false);
semiTransPanel.setBackground(Color.RED);
semiTransPanel.add(new TransparentDrawTest());
testFrame.add(semiTransPanel);
testFrame.setVisible(true);
}
public TransparentDrawTest() {
this.addMouseListener(this);
this.setSize(SIZE);
this.setMinimumSize(SIZE);
this.setMaximumSize(SIZE);
this.setPreferredSize(SIZE);
this.setOpaque(false);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int[] pointsX;
int[] pointsY;
if (this.isSelected) {
pointsX = new int[]{2, 348, 398, 48};
pointsY = new int[]{2, 2, 48, 48};
} else {
pointsX = new int[]{2, 298, 348, 48};
pointsY = new int[]{2, 2, 48, 48};
}
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(5));
g2d.setColor(Color.WHITE);
Composite comp = g2d.getComposite();
if (this.isClicked) {
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.75f));
} else {
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));
}
g2d.fillPolygon(pointsX, pointsY, 4);
g2d.setComposite(comp);
g2d.drawPolygon(pointsX, pointsY, 4);
g2d.dispose();
}
#Override
public void mouseClicked(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
this.isSelected = true;
this.repaint();
}
#Override
public void mouseExited(MouseEvent e) {
this.isSelected = false;
this.repaint();
}
#Override
public void mousePressed(MouseEvent e) {
this.isClicked = true;
this.repaint();
}
#Override
public void mouseReleased(MouseEvent e) {
this.isClicked = false;
this.repaint();
}
}

See Backgrounds With Transparency for the probable problem and a simple solution:
//testFrame.add(semiTransPanel);
testFrame.add( new AlphaContainer(semiTransPanel) );

How to add imagepanel in jpanel inside Jframe?

I'm trying to add an imagepanel which extends JPanel to another JPanel. Which is not working well for me. The paint function of image panel don't get invoked inside Jpanel but works fine in JFrame. Any ideas or help will be appreciated.
import javax.swing.*;
import java.awt.*;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.BufferedImage;
class ImagePanel extends JPanel
{
int g_h=10,g_w=10;
int width=50,height=50;
int cornerradius;
Image castle;
Dimension size;
protected int x1,y1;
Color c1=new Color(255, 0, 0);
Rectangle rec;
boolean b=false;
boolean imboo=false;
boolean roundb= false;
Graphics g= this.getGraphics();
protected int strokeSize = 1;
protected Color shadowColor = Color.BLACK;
boolean shadowed = false;
public ImagePanel()
{
//super();
setOpaque(false);
setLayout(null);
System.out.println("it executed");
}
public ImagePanel(int x, int y)
{
setSize(x, y);
}
public void setSize(int x,int y){
width=x;
height=y;
}
public int getheight(){
return height;
}
public int getwidth(){
return width;
}
public void setImagePanelBounds(
int x, int y, int width, int height){
x1=x;
y1=y;
this.width= width;
this.height= height;
System.out.println("6it executed");
}
public void setroundcorners(boolean b, int i){
roundb=b;
cornerradius=i;
System.out.println("5it executed");
}
public void setImage(String s){
imboo=true;
size = new Dimension();
castle = new ImageIcon(s).getImage();
size.width = castle.getWidth(null);
size.height = castle.getHeight(null);
setPreferredSize(size);
System.out.println("4it executed");
}
public void paint(Graphics gh){
System.out.println("it executed p");
{int x=this.getWidth();
int j=20,a=20;
Graphics2D g2= (Graphics2D)gh.create();
{
g2.setColor(Color.WHITE);
g2.setComposite(AlphaComposite.Src);
g2.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setComposite(AlphaComposite.SrcAtop);
rec= new Rectangle(x1, y1, width, height);
//Start of If-else
if(roundb){
g2.setClip(new RoundRectangle2D.Float(
(int)rec.getX(),(int)rec.getY(),
(int)rec.getWidth(),(int)rec.getHeight(),
cornerradius, cornerradius));
System.out.println("it executed");
}
// End of If-Else
// Image condition Starts
if (imboo){
g2.drawImage(castle, (int)rec.getX(),
(int)rec.getY(), (int)rec.getWidth(),
(int)rec.getHeight(), null);
//g.drawImage(castle, (int)rec.getX(),(int)rec.getY(), null);
}
// Image condition Ends
g2.setColor(Color.BLUE);
}
}
}
public static void main(String[]args)
{
ImagePanel t1=new ImagePanel();
JPanel jp1= new JPanel();
jp1.add(t1);
jp1.setLayout(null);
jp1.setBounds(0, 0, 600, 600);
JFrame jf1= new JFrame("Testing");
t1.setImage("icons/1.png");
//t1.setImage("1.jpg");
t1.setLayout(null);
t1.setroundcorners(true, 10);
//t1.setShadow(true);
t1.add(new JLabel("niak"));
//t1.setShadowDimensions(18, 18, 305, 305, 12);
t1.setImagePanelBounds(20, 20, 100, 100);
// jf1.add(t1);
jf1.setSize(600, 600);
jf1.setDefaultCloseOperation(jf1.EXIT_ON_CLOSE);
jf1.setVisible(true);
//jf1.revalidate();
jf1.setLayout(null);
}
}

Let's start with...
Don't use getGraphics. This is not how to perform custom painting. getGraphics may return null and is, at best, a snapshot, which will be discard when the next paint cycle occurs.
JPanel already has getWidth, getHeight and setSize methods, you should never have a need to overridden them. Instead, you should override getPreferredSize and return a size hint back that the parent layout manager can use.
If you create a Graphics context, you should dispose of it. In your paint method, you use gh.create, this is consuming resources and under some systems, until the Graphics context is disposed, it may not actually paint anything.
Don't override paint, instead use paintComponent
DO NOT modify the clip rectangle. Seriously, this is going to cause you more issues then you can imagine.
Don't use null layout managers without EXTREMELY good reason.
JPanel has a setBounds method, while, under normal circumstances, you shouldn't need to use it, since you've thrown away the layout manager, you should use it.
Basically, you've discard all the inner workings of the JPanel that enable the paint system to know that it should actually paint your panel
Updated with example
As an example...
Instead of using the clip, I use a masking technique, and mask the shape I want over the source image. I also buffer the result, which should make it more memory conservative as well as render faster
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
public class ImagePaneExample {
public static void main(String[] args) {
new ImagePaneExample();
}
public ImagePaneExample() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
BufferedImage img = ImageIO.read(new File("C:\\hold\\thumbnails\\2005-09-29-3957.jpeg"));
ImagePane imgPane = new ImagePane();
imgPane.setImage(img);
imgPane.setRounded(true);
imgPane.setBorder(new EmptyBorder(20, 20, 20, 20));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(imgPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (Exception exp) {
exp.printStackTrace();
}
}
});
}
public class ImagePane extends JPanel {
private BufferedImage img;
private BufferedImage renderImg;
private boolean rounded;
public ImagePane() {
}
public void setRounded(boolean value) {
if (value != rounded) {
rounded = value;
renderImg = null;
firePropertyChange("rounded", !rounded, rounded);
repaint();
}
}
public boolean isRounded() {
return rounded;
}
public void setImage(BufferedImage value) {
if (value != img) {
BufferedImage old = img;
img = value;
renderImg = null;
firePropertyChange("image", old, img);
repaint();
}
}
public BufferedImage getImage() {
return img;
}
#Override
public Dimension getPreferredSize() {
Dimension size = img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
Insets insets = getInsets();
size.width += (insets.left + insets.right);
size.height += (insets.top + insets.bottom);
return size;
}
protected void applyQualityRenderHints(Graphics2D g2d) {
g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
}
protected BufferedImage getImageToRender() {
if (renderImg == null) {
BufferedImage source = getImage();
if (source != null) {
if (isRounded()) {
BufferedImage mask = new BufferedImage(source.getWidth(), source.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = mask.createGraphics();
applyQualityRenderHints(g2d);
g2d.setBackground(new Color(255, 255, 255, 0));
g2d.clearRect(0, 0, mask.getWidth(), mask.getHeight());
g2d.setBackground(new Color(255, 255, 255, 255));
g2d.fillRoundRect(0, 0, mask.getWidth(), mask.getHeight(), 40, 40);
g2d.dispose();
BufferedImage comp = new BufferedImage(source.getWidth(), source.getHeight(), BufferedImage.TYPE_INT_ARGB);
g2d = comp.createGraphics();
applyQualityRenderHints(g2d);
g2d.setBackground(new Color(255, 255, 255, 0));
g2d.clearRect(0, 0, source.getWidth(), source.getHeight());
g2d.drawImage(source, 0, 0, this);
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.DST_IN));
g2d.drawImage(mask, 0, 0, this);
g2d.dispose();
renderImg = comp;
} else {
renderImg = source;
}
}
}
return renderImg;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
BufferedImage img = getImageToRender();
System.out.println(img);
if (img != null) {
Insets insets = getInsets();
Graphics2D g2d = (Graphics2D) g.create();
int width = getWidth();
int height = getHeight();
int x = ((width - img.getWidth()) / 2);
int y = ((height - img.getHeight()) / 2);
g2d.drawImage(img, x, y, this);
g2d.dispose();
}
}
}
}
I'd recommend some more reading through Creating a UI with Swing, in particular the section on layout managers, as well as Performing Custom Painting and Painting in AWT and Swing

All you have to do is to set the Layout of your panel jp1 to BorderLayout and add the image panel t1 to BorderLayout.CENTER, like this:
JPanel jp1= new JPanel(new BorderLayout());
jp1.add(t1, BorderLayout.CENTER);