Swing: How to reduce the response time of MouseInputAdapter?

Swing: How to reduce the response time of MouseInputAdapter? - java

I've made a tool which could allow user to draw on screenshot.Here is my code:
package GUI.Views;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
public class Canvas extends JPanel {
public static int radius = 5;
public class DrawPointListener extends MouseInputAdapter{
private void draw(Point p, int radius){
Graphics2D g2 = (Graphics2D)getGraphics();
int x = (int)p.getX() - radius/2;
int y = (int)p.getY() - radius/2;
g2.fillOval(x, y, radius, radius);
}
#Override
public void mousePressed(MouseEvent e) {
draw(e.getPoint(), radius);
}
#Override
public void mouseDragged(MouseEvent e) {
draw(e.getPoint(), radius);
}
}
private BufferedImage screenShot;
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.drawImage(this.screenShot, 0, 0, null);
}
public Canvas() {
this.setVisible(true);
this.screenShot = getScreenShot();
this.setCursor(new Cursor(Cursor.CROSSHAIR_CURSOR));
DrawPointListener drawListener = new DrawPointListener();
this.addMouseListener(drawListener);
this.addMouseMotionListener(drawListener);
}
private BufferedImage getScreenShot() {
try {
return new Robot().createScreenCapture(new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()));
} catch (AWTException e) {
System.out.println("Error");
return null;
}
}
public static void main(String[] args) {
JFrame f = new JFrame();
Canvas canvas = new Canvas();
f.setUndecorated(true);
f.add(canvas);
f.setExtendedState(JFrame.MAXIMIZED_BOTH);
f.setVisible(true);
}
}
Code worked fine when you try to "draw" on the screen slowly, but when you move your mouse quickly, you would see those points are not consecutive, like this:
I think that because there is a time interval of Listener.How could I improve it?

You can't change the time interval of the listener. You are NOT guaranteed to generate an event for every pixel.
So instead of drawing a single point, you need to draw a line between the current and previous point.
Something like:
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;
class DrawingPanel extends JPanel
{
private ArrayList<ArrayList<Point>> previous = new ArrayList<ArrayList<Point>>();
private ArrayList<Point> current = new ArrayList<Point>();
private BasicStroke basicStroke;
public DrawingPanel(int strokeSize)
{
basicStroke = new BasicStroke(strokeSize, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
MouseAdapter ma = new MouseAdapter()
{
#Override
public void mousePressed(MouseEvent e)
{
current.add( new Point(e.getX(), e.getY()) );
}
#Override
public void mouseDragged(MouseEvent e)
{
current.add( new Point(e.getX(), e.getY()) );
repaint();
}
#Override
public void mouseReleased(MouseEvent e)
{
if (current.size() > 1)
{
previous.add( current );
}
current = new ArrayList<Point>();
}
};
addMouseMotionListener( ma );
addMouseListener( ma );
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setStroke( basicStroke );
// Paint lines from previous drags
for (int i = 0; i < previous.size(); i++)
{
drawLines(g, previous.get(i));
}
// Paint line from current drag
drawLines(g, current);
}
private void drawLines(Graphics g, ArrayList<Point> points)
{
for (int i = 0; i < points.size() - 1; i++)
{
int x = (int) points.get(i).getX();
int y = (int) points.get(i).getY();
int x2 = (int) points.get(i + 1).getX();
int y2 = (int) points.get(i + 1).getY();
g.drawLine(x, y, x2, y2);
}
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("Drawing Panel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new DrawingPanel(15));
frame.setSize(400, 400);
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args) throws Exception
{
EventQueue.invokeLater( () -> createAndShowGUI() );
/*
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
*/
}
}

Related

Swing JPanel - Drawn graphics duplicate instead of moving

For some reason, my KeyListener works just fine and fires off the Booleans to make down and up true and false and the y value changes according to those Booleans exactly how I want it to. My problem is that for some reason, the red rectangle appears to grow in size rather than move, and I'm pretty sure that it's because the previous frame is not cleared. I tried to use super.paintComponent(g); to clear the frame but this accomplishes nothing. Here's the code:
JFrame:
import java.awt.*;
import javax.swing.*;
public class H extends JFrame
{
public H()
{
super("Atlas Blade");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
pack();
P p = new P();
Insets frameInsets = getInsets();
int frameWidth = p.getWidth() +
(frameInsets.left + frameInsets.right);
int frameHeight = p.getHeight() + (
frameInsets.top + frameInsets.bottom);
setPreferredSize(new Dimension(frameWidth, frameHeight));
setLayout(null);
add(p);
pack();
setVisible(true);
}
}
JPanel:
import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import java.awt.image.*;
public class P extends JPanel implements KeyListener, Runnable
{
private long updateCount=0;
private long paintCount=0;
private int updatesPerSecond = 50;
private boolean aLeft,aRight,aDown,aUp=false;
private boolean up,down,left,right=false;
int x = 20;
int y=20;
Hb box = new Hb(x,y);
Rectangle rect = new Rectangle(0,300,300,50);
BufferedImage buffer;
public P()
{
super();
setSize(600,350);
//setSize(50,50);
buffer = new BufferedImage (600,350,BufferedImage.TYPE_4BYTE_ABGR);
addKeyListener(this);
Thread jim = new Thread(this);
jim.start();
}
public void run()
{
int waitToUpdate = 1000/updatesPerSecond;
long startTime = System.nanoTime();
while(true)
{
boolean shouldRepaint = false;
long currentTime = System.nanoTime();
long updatesNeeded = (((currentTime-startTime) / 1000000))/ waitToUpdate;
for(long x = updateCount; x< updatesNeeded; x++)
{
updateGame();
shouldRepaint=true;
updateCount++;
}
if(shouldRepaint)
{
paintCount++;
repaint();
}
try
{
Thread.sleep(5);
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics bg = buffer.getGraphics();
bg.setColor(Color.BLACK);
bg.drawRect(0,300,300,50);
bg.setColor(Color.RED);
bg.fillRect(x,y,35,35);
g.drawImage(buffer,0,0,null);
}
public void updateGame()
{
box.updateHitbox(x,y);
if(down)
{
if(!box.center.intersects(rect))
{
y++;
//y=y+40;
}
}
else if(up)
{
if(!box.center.intersects(rect))
{
y--;
}
}
}
public void keyPressed(KeyEvent e)
{
int code = e.getKeyCode();
if(code==KeyEvent.VK_A)
{
left=true;
right=false;
aLeft=true;
aRight=false;
aDown=false;
aUp=false;
}
if(code==KeyEvent.VK_D)
{
left=false;
right=true;
aLeft=false;
aRight=true;
aDown=false;
aUp=false;
}
if(code==KeyEvent.VK_S)
{
System.out.println(y);
down=true;
up=false;
aLeft=false;
aRight=false;
aDown=true;
aUp=false;
}
if(code==KeyEvent.VK_W)
{
down=false;
up=true;
aLeft=false;
aRight=false;
aDown=false;
aUp=true;
}
repaint();
}
public void keyTyped(KeyEvent e)
{
}
public void keyReleased(KeyEvent e)
{
int code = e.getKeyCode();
if(code==e.VK_A)
{
left=false;
aLeft=false;
}
if(code==e.VK_D)
{
right=false;
aRight=false;
}
if(code==e.VK_S)
{
down=false;
aDown=false;
}
if(code==e.VK_W)
{
up=false;
aUp=false;
}
}
public void addNotify()
{
// call super so the method still does what it was built to do
super.addNotify();
// requests focus so that key inputs are sent to this screen
requestFocus();
}
}
And the Hb class:
import java.awt.Rectangle;
public class Hb
{
public Rectangle center,left,right,up,down;
public Hb(int x, int y)
{
center = new Rectangle(x,y,50,50);
left = new Rectangle(x-1,y+1,1,48);
right = new Rectangle(x+50,y+1,1,48);
up = new Rectangle(x+1,y-1,48,1);
down = new Rectangle(x+1,y+50,48,1);
}
public void updateHitbox(int x, int y)
{
center = new Rectangle(x,y,50,50);
left = new Rectangle(x-1,y+1,1,48);
right = new Rectangle(x+50,y+1,1,48);
up = new Rectangle(x+1,y-1,48,1);
down = new Rectangle(x+1,y+50,48,1);
}
}

Your problem is that you're doing all your drawing in the BufferedImage, and that doesn't allow erasure of "dirty" pixels. Instead, only draw in the BufferedImage that which should be a static and unchanging part of the image, usually the background. The foreground image that moves should be painted directly in paintComponent using the Graphcis object given to the method by the JVM.
public P() {
super();
setSize(600, 350); // not recommended
buffer = new BufferedImage(600, 350, BufferedImage.TYPE_4BYTE_ABGR);
Graphics bg = buffer.getGraphics();
bg.setColor(Color.BLACK);
bg.drawRect(0, 300, 300, 50);
bg.dispose();
// ....
}
and
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(buffer, 0, 0, null);
g.setColor(Color.RED);
g.fillRect(x, y, 35, 35);
}

How to draw a continuous curve of repeated ovals on speedy mouse cursor dragging?

This code is for drawing on a JPanel. In the paintComponent(Graphics) I am trying to draw curves via repeated Graphics2D#fillOval(x, y, with, height).
The app is working OK, and when I drag the mouse cursor slowly; it draws a continuous curve as I need. But when I speed up dragging the mouse cursor, the result is separated dots and not a continuous curve.
So how to make it draw a continuous curve even if I speed up dragging?
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
public class Painter extends JPanel {
int x, y;
ArrayList<Point> points;
public Painter() {
setBackground(Color.white);
points = new ArrayList<>();
MouseHandler listener = new MouseHandler();
this.addMouseMotionListener(listener);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
private class MouseHandler extends MouseAdapter implements MouseMotionListener {
#Override
public void mouseDragged(MouseEvent e) {
Point point = new Point(e.getX(), e.getY());
points.add(point);
repaint();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (Point point : points) {
g2d.fillOval(point.x, point.y, 15, 15);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame f = new JFrame();
f.setContentPane(new Painter());
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
});
}
}

As mentioned in comment to your previous similar question:
Don't draw discrete ovals in your paintComponent method.
Instead connect the points hold in the List in the paintComponent by drawing lines between adjacent points.
If you need to make the line thicker, change the Stroke property of the Graphics2D object, using one that has a wider thickness.
Be careful with Strokes however since often you don't want the property change to propagate down the paint chain. This means that sometimes you will want to copy the Graphics object and set the Stroke on the new Graphics object and paint with that, then dispose of it.
The simplest way to create a Stroke is to use the BasicStroke class, e.g., new BasicStroke(6f) will get you a nice thick curve.
For example:
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
public class Painter2 extends JPanel {
private static final float STROKE_WIDTH = 15f;
private static final Stroke STROKE = new BasicStroke(STROKE_WIDTH, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
int x, y;
ArrayList<Point> points;
public Painter2() {
setBackground(Color.white);
points = new ArrayList<>();
MouseHandler listener = new MouseHandler();
this.addMouseMotionListener(listener);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
private class MouseHandler extends MouseAdapter implements MouseMotionListener {
#Override
public void mouseDragged(MouseEvent e) {
Point point = new Point(e.getX(), e.getY());
points.add(point);
repaint();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setStroke(STROKE);
for (int i = 1; i < points.size(); i++) {
int x1 = points.get(i - 1).x;
int y1 = points.get(i - 1).y;
int x2 = points.get(i).x;
int y2 = points.get(i).y;
g2d.drawLine(x1, y1, x2, y2);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame f = new JFrame();
f.setContentPane(new Painter2());
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
});
}
}
Or better still:
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
#SuppressWarnings("serial")
public class Painter2 extends JPanel {
private static final float STROKE_WIDTH = 15f;
private static final Stroke STROKE = new BasicStroke(STROKE_WIDTH, BasicStroke.CAP_ROUND,
BasicStroke.JOIN_ROUND);
private static final Color CURVES_COLOR = Color.BLUE;
private static final Color TEMP_CURVE_COLOR = Color.PINK;
private List<List<Point>> curvesList = new ArrayList<>();
private List<Point> tempCurve = null;
public Painter2() {
setBackground(Color.white);
MouseHandler listener = new MouseHandler();
addMouseListener(listener);
addMouseMotionListener(listener);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
private class MouseHandler extends MouseAdapter implements MouseMotionListener {
#Override
public void mousePressed(MouseEvent e) {
tempCurve = new ArrayList<>();
tempCurve.add(e.getPoint());
repaint();
}
#Override
public void mouseDragged(MouseEvent e) {
tempCurve.add(e.getPoint());
repaint();
}
#Override
public void mouseReleased(MouseEvent e) {
tempCurve.add(e.getPoint());
curvesList.add(tempCurve);
tempCurve = null;
repaint();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g.create();
g2.setStroke(STROKE);
g2.setColor(CURVES_COLOR);
for (List<Point> curve : curvesList) {
drawCurve(g2, curve);
}
if (tempCurve != null) {
g2.setColor(TEMP_CURVE_COLOR);
drawCurve(g2, tempCurve);
}
g2.dispose();
}
private void drawCurve(Graphics2D g2, List<Point> ptList) {
for (int i = 1; i < ptList.size(); i++) {
int x1 = ptList.get(i - 1).x;
int y1 = ptList.get(i - 1).y;
int x2 = ptList.get(i).x;
int y2 = ptList.get(i).y;
g2.drawLine(x1, y1, x2, y2);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame f = new JFrame();
f.setContentPane(new Painter2());
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
});
}
}

Boolean not keeping value

I have an application where the user draws lines. There is a JButton btnClear which, when the user clicks, must clear the drawings, so that the user can draw anew. I use an ActionListener on btnClear to know when it is clicked. I set a boolean Clear so that the correct IF statement is executed in paintComponent(). However, the boolean Clear keeps a False value in paintComponent() although I set it to True just before repaint(). Why is it so?
Note: I tried setting the frame's background to red just for to test the boolean in paintComponent().
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Line2D;
import javax.swing.*;
public class Clipping extends JPanel implements MouseListener, ActionListener
{
static JFrame frame;
static JComboBox cboDraw;
static JButton btnClear;
static JButton btnClip;
double x1, y1, x2, y2;
boolean FirstPoint;
boolean Clear = false;
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
CreateFrame();
}
});
}
private static void CreateFrame()
{
frame = new JFrame("Clipping");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Clipping());
frame.setSize(500,500);
frame.setVisible(true);
}
public Clipping()
{
setLayout(new BorderLayout());
JToolBar toolbar = new JToolBar(JToolBar.VERTICAL);
PopulateToolBar(toolbar);
add(toolbar, BorderLayout.WEST);
addMouseListener(this);
cboDraw.addMouseListener(this);
btnClip.addActionListener(this);
btnClear.addActionListener(this);
}
private static void PopulateToolBar(JToolBar toolbar)
{
String[] cboList = {"Line", "Polygon"};
cboDraw = new JComboBox(cboList);
cboDraw.setMaximumSize(new Dimension(70,30));
btnClip = new JButton("Set clip area");
btnClear = new JButton("Clear");
toolbar.add(cboDraw);
toolbar.addSeparator();
toolbar.add(btnClip);
toolbar.addSeparator();
toolbar.add(btnClear);
cboDraw.setAlignmentX(Component.CENTER_ALIGNMENT);
btnClip.setAlignmentX(Component.CENTER_ALIGNMENT);
btnClear.setAlignmentX(Component.CENTER_ALIGNMENT);
toolbar.setMargin(new Insets(10,10,10,10));
toolbar.setFloatable(false);
toolbar.setBackground(Color.black);
}
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
if (cboDraw.getSelectedIndex() == 0) //draw line
{
g2.draw(new Line2D.Double(x1, y1, x2, y2));
}
else if (Clear == true)
{
frame.setBackground(Color.red); //ONLY FOR TESTING PURPOSE
}
}
public void mousePressed(MouseEvent e)
{
if (e.getSource() != cboDraw) //to prevent line coordinates from being saved when selecting from combobox
{
if (cboDraw.getSelectedIndex() == 0) //user wants to draw line
{
if (FirstPoint == false) //first coordinates
{
x1 = e.getX();
y1 = e.getY();
FirstPoint = true;
}
else //second coordinates
{
x2 = e.getX();
y2 = e.getY();
repaint();
FirstPoint = false;
}
}
}
}
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == btnClear)
{
Clear = true;
repaint();
Clear = false;
}
}
public void mouseClicked(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
}

You should just do setBackground(Color.red); to call it on your JPanel instead of the JFrame

I think your actionPerformed and mousePressed are both executed at the same time. In mousePressed your if condition inside mousePressed is satisfied also if btnClear() is the source. So repaint method is called anyway, and you see no changes.

You're not calling the super.paintComponent(g) method within your paintComponent method override. Call this first, else, clear won't work.
Note that in your current code, this will not work for you since you're painting incorrectly in that you're not specifying, iterating through and drawing all the lines that need to be drawn within your paintComponent method. The way to solve this is via one of two ways:
Either create a List<Line2D> such as an ArrayList<Line2D>, fill it in your MouseListener/MouseMotionListener code, and then iterate through this List in your paintComponent method, drawing each line. If you do this, then your clear button's action would be to simply clear the List via clear() and call repaint(). No need for a boolean.
Or you could draw your lines onto a BufferedImage, and then draw the BufferedImage in your paintComponent method via the g.drawImage(...) method. If you do this, always check that the image is not null before drawing. Then in your mouse listening code, you'd draw to this image. In your clear button action, you'd create a new BufferedImage, or clear the current BufferedImage.
Also get rid of setBackground(...) calls from within paintComponent as they really shouldn't be in there.
For example of use of an ArrayList of lines:
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.Stroke;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Line2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
#SuppressWarnings("serial")
public class DrawPanelViaArrayList extends JPanel {
private static final int PREF_W = 500;
private static final int PREF_H = PREF_W;
private static final Color LINES_COLOR = Color.black;
private static final Color DRAW_LINE_COLOR = Color.pink;
private static final Stroke STROKE = new BasicStroke(3f);
private List<Line2D> lineList = new ArrayList<>();
private int x1 = 0;
private int y1 = 0;
private int x2 = 0;
private int y2 = 0;
public DrawPanelViaArrayList() {
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseListener(myMouseAdapter);
addMouseMotionListener(myMouseAdapter);
add(new JButton(new ClearAction("Clear")));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
// for smooth graphics
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// first draw the temporary line to show the user
// where he's drawing
if (x1 != x2 && y1 != y2) {
g2.setColor(DRAW_LINE_COLOR);
g2.drawLine(x1, y1, x2, y2);
}
// then draw all the lines held in the linesList.
Stroke oldStroke = g2.getStroke();
g2.setColor(LINES_COLOR);
g2.setStroke(STROKE); // draw thicker lines
for (Line2D line2d : lineList) {
g2.draw(line2d);
}
g2.setStroke(oldStroke); // reset stroke
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
private class MyMouseAdapter extends MouseAdapter {
#Override
public void mousePressed(MouseEvent e) {
x1 = e.getPoint().x;
y1 = e.getPoint().y;
}
#Override
public void mouseReleased(MouseEvent e) {
x2 = e.getPoint().x;
y2 = e.getPoint().y;
Line2D line = new Line2D.Double(x1, y1, x2, y2);
// add line to ArrayList
lineList.add(line);
x1 = x2 = y1 = y2 = 0;
repaint();
}
#Override
public void mouseDragged(MouseEvent e) {
x2 = e.getPoint().x;
y2 = e.getPoint().y;
// draw temporary line
repaint();
}
}
private class ClearAction extends AbstractAction {
public ClearAction(String name) {
super(name);
}
#Override
public void actionPerformed(ActionEvent e) {
lineList.clear();
repaint();
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("Foo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new DrawPanelViaArrayList());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
And what the heck, a BufferedImage version
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.Stroke;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Line2D;
import java.awt.image.BufferedImage;
import javax.swing.*;
#SuppressWarnings("serial")
public class DrawPanelViaBufferedImage extends JPanel {
private static final int PREF_W = 500;
private static final int PREF_H = PREF_W;
private static final Color LINES_COLOR = Color.black;
private static final Color DRAW_LINE_COLOR = Color.pink;
public static final Color CLEAR_COLOR = new Color(0, 0, 0, 0);
public static final Stroke STROKE = new BasicStroke(3f);
private int x1 = 0;
private int y1 = 0;
private int x2 = 0;
private int y2 = 0;
private BufferedImage img = new BufferedImage(PREF_W, PREF_W, BufferedImage.TYPE_INT_ARGB);
public DrawPanelViaBufferedImage() {
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseListener(myMouseAdapter);
addMouseMotionListener(myMouseAdapter);
add(new JButton(new ClearAction("Clear")));
// if the GUI is to be re-sizeable, then consider adding a
// ComponentListener here, and resizing the BufferedImage in it
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
// for smooth graphics
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// first draw the temporary line to show the user
// where he's drawing
if (x1 != x2 && y1 != y2) {
g2.setColor(DRAW_LINE_COLOR);
g2.drawLine(x1, y1, x2, y2);
}
// then draw the BufferedImage if not null
if (img != null) {
g2.drawImage(img, 0, 0, null);
}
}
// size of our GUI
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
private class MyMouseAdapter extends MouseAdapter {
#Override
public void mousePressed(MouseEvent e) {
x1 = e.getPoint().x;
y1 = e.getPoint().y;
}
#Override
public void mouseReleased(MouseEvent e) {
x2 = e.getPoint().x;
y2 = e.getPoint().y;
Line2D line = new Line2D.Double(x1, y1, x2, y2);
// draw to the BufferedImage
Graphics2D g2 = img.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(STROKE);
g2.setColor(LINES_COLOR);
g2.draw(line);
g2.dispose();
x1 = x2 = y1 = y2 = 0;
repaint();
}
#Override
public void mouseDragged(MouseEvent e) {
x2 = e.getPoint().x;
y2 = e.getPoint().y;
repaint();
}
}
private class ClearAction extends AbstractAction {
public ClearAction(String name) {
super(name);
}
#Override
public void actionPerformed(ActionEvent e) {
Graphics2D g2 = img.createGraphics();
g2.setBackground(CLEAR_COLOR);
g2.clearRect(0, 0, getWidth(), getHeight());
g2.dispose();
repaint();
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("Foo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new DrawPanelViaBufferedImage());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

Drawing shapes in JPanel over an image

I need to draw shapes (circle or free line) over an image that is shown in a JLabel of a JPanel.
I based my code on the questions How to draw thin line with no gap while dragging the cursor? and Draw a circle using 2 mouse clicks.
The code is bellow. The problem is that when I start drawing the image disappears and only reappears after I stop.
If I comment the line super.paintComponent(g); that doesnt happen but when I draw the circle it maintains a path of the previous positions.
public static void main(String args[]) {
try {
URL url = new URL("http://www.senhoritatours.com/wp-content/uploads/2014/05/Porto-.jpg");
backgroundImage = ImageIO.read(url);
} catch (Exception e) {
e.printStackTrace();
}
loadAnnotation();
loadBackground();
JFrame f;
f = new JFrame();
f.setLayout(new BorderLayout());
f.add(mp);
f.pack();
f.setVisible(true);
}
/* Layer 0:
* Load background picture */
public static void loadBackground() {
JLabel lbImg = new JLabel();
lbImg.setBounds(0, 0, new ImageIcon(backgroundImage).getIconWidth(), new ImageIcon(backgroundImage).getIconHeight());
lbImg.setIcon(new ImageIcon(backgroundImage));
mp = new JPanel(new BorderLayout());
btnCircle.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
if(btnCircle.isEnabled())
{
btnCircle.setEnabled(false);
btnLine.setEnabled(true);
}
}
});
btnLine.setEnabled(true);
btnCircle.setEnabled(false);
btnLine.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
if(btnLine.isEnabled())
{
btnLine.setEnabled(false);
btnCircle.setEnabled(true);
}
}
});
mp.add(btnCircle);
mp.add(btnLine);
mp.add(lbImg);
mp.add(p);
}
/* Layer 1:
* Annotation: Draw on top of background picture anything! */
public static void loadAnnotation() {
p = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setColor(Color.RED);
if (_bufImage == null) {
int w = this.getWidth();
int h = this.getHeight();
_bufImage = new BufferedImage(1024,600, BufferedImage.TRANSLUCENT);
Graphics2D gc = _bufImage.createGraphics();
}
g2.drawImage(_bufImage, null, 0, 0);
if (_state == State.DRAGGING) {
if (!btnLine.isEnabled())
{
g.drawLine(_start.x, _start.y, _end.x , _end.y);
}
}
if (!btnCircle.isEnabled())
{
g.drawOval(x, y, width, height);
}
}
public Dimension getPreferredSize() {
return new Dimension(1024, 600);
}
};
p.setLayout(new OverlayLayout(p));
p.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent me) {
}
#Override
public void mousePressed(MouseEvent me) {
last = me.getPoint();
dragging = isInsideEllipse(last);
if (!dragging) {
x = last.x;
y = last.y;
width = 0;
height = 0;
}
p.repaint();
}
#Override
public void mouseReleased(MouseEvent me) {
//_state = State.IDLE;
last = null;
dragging = false;
_state = State.IDLE;
p.repaint();
}
#Override
public void mouseEntered(MouseEvent me) {
}
#Override
public void mouseExited(MouseEvent me) {
}
});
p.addMouseMotionListener(new MouseMotionListener() {
#Override
public void mouseDragged(MouseEvent me) {
if(!btnLine.isEnabled())
{
_state = State.DRAGGING;
_end = me.getPoint();
if (_state == State.DRAGGING) {
Graphics2D g2 = _bufImage.createGraphics();
g2.setColor(Color.red);
g2.setStroke(new BasicStroke(2));
g2.drawLine(_start.x, _start.y, _end.x, _end.y);
p.repaint();
//
}
_start = _end;
}
else
{
int dx = me.getX() - last.x;
int dy = me.getY() - last.y;
if (dragging) {
x += dx;
y += dy;
} else {
width += dx;
height += dy;
}
last = me.getPoint();
p.repaint();
}
}
#Override
public void mouseMoved(MouseEvent me) {
//System.out.println("move");
_start = me.getPoint();
}
});
}

Either
Display the image in the same paintComponent method that you're doing your drawing in, via Graphics#drawImage(...). You would call this immediately after the super.paintComponent(g) call.
Or do your drawing in the paintComponent(...) method of your JLabel, the one displaying the image.
For example:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class DrawingPanel extends JPanel {
private final static String PATH = "https://upload.wikimedia.org/wikipedia/commons/"
+ "thumb/7/7c/Thomas_Hicks_-_Leopold_Grozelier_-_Presidential_Candidate_"
+ "Abraham_Lincoln_1860_-_cropped_to_lithographic_plate.jpg/"
+ "463px-Thomas_Hicks_-_Leopold_Grozelier_-_Presidential_Candidate_"
+ "Abraham_Lincoln_1860_-_cropped_to_lithographic_plate.jpg";
private static final Color DRAWING_COLOR = new Color(255, 100, 200);
private static final Color FINAL_DRAWING_COLOR = Color.red;
private BufferedImage backgroundImg;
private Point startPt = null;
private Point endPt = null;
private Point currentPt = null;
private int prefW;
private int prefH;
public DrawingPanel() throws IOException {
URL imgUrl = new URL(PATH);
BufferedImage bImg = ImageIO.read(imgUrl);
prefW = bImg.getWidth();
prefH = bImg.getHeight();
backgroundImg = new BufferedImage(prefW, prefH,
BufferedImage.TYPE_INT_ARGB);
Graphics g = backgroundImg.getGraphics();
g.drawImage(bImg, 0, 0, this);
g.dispose();
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseMotionListener(myMouseAdapter);
addMouseListener(myMouseAdapter);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (backgroundImg != null) {
g.drawImage(backgroundImg, 0, 0, this);
}
if (startPt != null && currentPt != null) {
g.setColor(DRAWING_COLOR);
int x = Math.min(startPt.x, currentPt.x);
int y = Math.min(startPt.y, currentPt.y);
int width = Math.abs(startPt.x - currentPt.x);
int height = Math.abs(startPt.y - currentPt.y);
g.drawRect(x, y, width, height);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(prefW, prefH);
}
public void drawToBackground() {
Graphics g = backgroundImg.getGraphics();
g.setColor(FINAL_DRAWING_COLOR);
int x = Math.min(startPt.x, endPt.x);
int y = Math.min(startPt.y, endPt.y);
int width = Math.abs(startPt.x - endPt.x);
int height = Math.abs(startPt.y - endPt.y);
g.drawRect(x, y, width, height);
g.dispose();
startPt = null;
repaint();
}
private class MyMouseAdapter extends MouseAdapter {
#Override
public void mouseDragged(MouseEvent mEvt) {
currentPt = mEvt.getPoint();
DrawingPanel.this.repaint();
}
#Override
public void mouseReleased(MouseEvent mEvt) {
endPt = mEvt.getPoint();
currentPt = null;
drawToBackground();
}
#Override
public void mousePressed(MouseEvent mEvt) {
startPt = mEvt.getPoint();
}
}
private static void createAndShowGui() {
DrawingPanel mainPanel = null;
try {
mainPanel = new DrawingPanel();
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
JFrame frame = new JFrame("Drawing Panel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

Graphics in repaint draws random lines

So I'm creating a free hand drawing JPanel, that reacts to mouse movements and draws lines. I got it mostly working except for a bug where it'll randomly draw a straight line between lines. That random straight line isn't intentional, what's drawn on the buffered image is supposed to be strictly what the user draws. These random drawn lines are not done by the user and it's confusing. Below is my code, can anyone take a look? The image included gives you a visual representation of what it is doing.
public class NoteDocument extends JPanel implements MouseListener, MouseMotionListener {
private Frame commands;
private JDesktopPane desktop;
private JInternalFrame colorFrame;
private JPanel colorPanel;
private JColorChooser colorChooser;
private enum State { IDLING, DRAGGING };
private enum ButtonPosition { PRESSED, RELEASED };
private enum Shape { SQUARE, RECTANGLE, CIRCLE, OVAL, LINE };
private State state = State.IDLING;
private ButtonPosition position = ButtonPosition.RELEASED;
private Shape shape = null;
//private ArrayList<Point> points = new ArrayList<Point>();
private ArrayList<Point> pressedPoints = new ArrayList<Point>();
private ArrayList<Point> draggedPoints = new ArrayList<Point>();
private ArrayList<Point> releasedPoints = new ArrayList<Point>();
private BufferedImage bufferedImage = null;
public NoteDocument(Frame commands) {
this.commands = commands;
setBackground(Color.WHITE);
addMouseListener(this);
addMouseMotionListener(this);
createColorChooser();
}
private void createColorChooser() {
for (int i = 0; i < commands.getLayeredPane().getComponentCount(); i++) {
if (commands.getLayeredPane().getComponent(i) instanceof JDesktopPane) {
desktop = (JDesktopPane) commands.getLayeredPane().getComponent(i);
}
}
colorChooser = new JColorChooser();
colorPanel = new JPanel();
colorFrame = new JInternalFrame();
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(colorPanel);
colorPanel.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(colorChooser, javax.swing.GroupLayout.PREFERRED_SIZE, 434, javax.swing.GroupLayout.PREFERRED_SIZE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(colorChooser, javax.swing.GroupLayout.PREFERRED_SIZE, 328, javax.swing.GroupLayout.PREFERRED_SIZE)
);
colorFrame.add(colorPanel);
desktop.add(colorFrame);
colorFrame.pack();
colorFrame.setVisible(true);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
if(bufferedImage == null)
{
int panelHeight = this.getHeight();
int panelWidth = this.getWidth();
bufferedImage = (BufferedImage) this.createImage(panelHeight, panelWidth);
Graphics2D gc = bufferedImage.createGraphics();
gc.setColor(Color.WHITE);
gc.fillRect(0, 0, panelWidth, panelHeight);
g2.drawImage(bufferedImage, null, 0, 0);
}
//draw pressed points
for (int a = 0; a < pressedPoints.size(); a++) {
Point p1 = pressedPoints.get(a);
g.drawLine(p1.x, p1.y, p1.x, p1.y);
}
//draw draggedPoints
for (int b = 0; b < draggedPoints.size() - 2; b++) {
Point p1 = draggedPoints.get(b);
Point p2 = draggedPoints.get(b + 1);
g.drawLine(p1.x, p1.y, p2.x, p2.y);
}
//draw released points
for (int c = 0; c < releasedPoints.size(); c++) {
Point p1 = releasedPoints.get(c);
g.drawLine(p1.x, p1.y, p1.x, p1.y);
}
}
#Override
public void mouseClicked(MouseEvent e) {}
#Override
public void mouseEntered(MouseEvent e) {}
#Override
public void mouseExited(MouseEvent e) {}
#Override
public void mousePressed(MouseEvent e) {
if (e.getButton() == MouseEvent.BUTTON1) {
position = ButtonPosition.PRESSED;
state = State.DRAGGING;
pressedPoints.add(e.getPoint());
this.repaint();
} else if (e.getButton() == MouseEvent.BUTTON2) {
//TODO right click popup
}
}
#Override
public void mouseReleased(MouseEvent e) {
if (state == State.DRAGGING) {
releasedPoints.add(e.getPoint());
position = ButtonPosition.RELEASED;
state = State.IDLING;
this.repaint();
}
}
#Override
public void mouseDragged(MouseEvent e) {
if ((state == State.DRAGGING) && (position == ButtonPosition.PRESSED)) {
draggedPoints.add(e.getPoint());
this.repaint();
} else if ((state == State.IDLING) && (position == ButtonPosition.RELEASED)) {
return;
}
}
#Override
public void mouseMoved(MouseEvent e) {
if ((state == State.DRAGGING) && (position == ButtonPosition.PRESSED)) {
draggedPoints.add(e.getPoint());
this.repaint();
} else if ((state == State.IDLING) && (position == ButtonPosition.RELEASED)) {
return;
}
}
}

You will likely want to nest Lists to achieve your goal:
List<List<Point>>
This way, when the mouse is pressed, start an ArrayList, and when released, finish it. Then you can use nested for loops to draw all the curves.
For example (from a previous answer of mine):
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
import javax.swing.border.Border;
import javax.swing.border.TitledBorder;
public class LineDrawEg {
private static void createAndShowGui() {
JPanel mainPanel = new JPanel(new GridLayout(1, 0));
mainPanel.setPreferredSize(new Dimension(800, 400));
MyMouseAdapter mouseAdapter = new MyMouseAdapter();
JPanel[] panels = {new Panel1(), new Panel2()};
for (int i = 0; i < panels.length; i++) {
String title = "Panel " + (i + 1);
Border border = new TitledBorder(title);
panels[i].setBorder(border);
panels[i].addMouseListener(mouseAdapter);
panels[i].addMouseMotionListener(mouseAdapter);
mainPanel.add(panels[i]);
}
JFrame frame = new JFrame("Line Draw Eg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class Panel1 extends JPanel implements Positionable {
private int xPos = 0;
private int yPos = 0;
#Override
protected void paintComponent(Graphics g) {
// super.paintComponent(g);
g.setColor(Color.red);
g.fillOval(xPos, yPos, 5, 5);
}
#Override
public void mouseDragged(Point p) {
xPos = p.x;
yPos = p.y;
repaint();
}
#Override
public void mousePressed(Point p) {
xPos = p.x;
yPos = p.y;
repaint();
}
#Override
public void mouseReleased(Point p) {
xPos = p.x;
yPos = p.y;
repaint();
}
}
class Panel2 extends JPanel implements Positionable {
private List<List<Point>> listOfLists = new ArrayList<List<Point>>();
private List<Point> currentPoints;
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setStroke(new BasicStroke(5f));
if (currentPoints != null && currentPoints.size() > 1) {
g2.setColor(Color.blue);
for (int i = 1; i < currentPoints.size(); i++) {
int x1 = currentPoints.get(i - 1).x;
int y1 = currentPoints.get(i - 1).y;
int x2 = currentPoints.get(i).x;
int y2 = currentPoints.get(i).y;
g2.drawLine(x1, y1, x2, y2);
}
}
g2.setColor(Color.red);
for (List<Point> pointList : listOfLists) {
if (pointList.size() > 1) {
for (int i = 1; i < pointList.size(); i++) {
int x1 = pointList.get(i - 1).x;
int y1 = pointList.get(i - 1).y;
int x2 = pointList.get(i).x;
int y2 = pointList.get(i).y;
g2.drawLine(x1, y1, x2, y2);
}
}
}
}
#Override
public void mousePressed(Point p) {
currentPoints = new ArrayList<Point>();
currentPoints.add(p);
repaint();
}
#Override
public void mouseDragged(Point p) {
currentPoints.add(p);
repaint();
}
#Override
public void mouseReleased(Point p) {
if (currentPoints != null) {
currentPoints.add(p);
listOfLists.add(currentPoints);
}
currentPoints = null;
repaint();
}
}
class MyMouseAdapter extends MouseAdapter {
#Override
public void mouseDragged(MouseEvent mEvt) {
Positionable positionable = (Positionable) mEvt.getSource();
positionable.mouseDragged(mEvt.getPoint());
}
#Override
public void mousePressed(MouseEvent mEvt) {
Positionable positionable = (Positionable) mEvt.getSource();
positionable.mousePressed(mEvt.getPoint());
}
#Override
public void mouseReleased(MouseEvent mEvt) {
Positionable positionable = (Positionable) mEvt.getSource();
positionable.mouseReleased(mEvt.getPoint());
}
}
interface Positionable {
void mouseDragged(Point p);
void mousePressed(Point p);
void mouseReleased(Point p);
}

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Swing: How to reduce the response time of MouseInputAdapter? - java

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