Develop Reference

Swing: How to reduce the response time of MouseInputAdapter?

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();
}
});
*/
}
}

Draw shapes on scrollable JPanel

I'm trying to draw rectangles on fairly large images in order to get the pixel coordinates of objects within the image. I am able to display the image and make it scrollable, or display the image and be able to draw rectangles on top of it....but not both.
It's obvious that I'm drawing the image on top of the canvas that I'm trying to draw the rectangles on, but I can't for the life of me figure out how to make it all coexist.
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;
public class DrawRect extends JPanel {
int x, y, x2, y2;
private static final long serialVersionUID = 1L;
private BufferedImage image;
private JPanel canvas;
public static void main(String[] args) {
JPanel p = new DrawRect();
JFrame f = new JFrame();
f.setContentPane(p);
f.setSize(400, 300);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
DrawRect() {
x = y = x2 = y2 = 0; //
MyMouseListener listener = new MyMouseListener();
addMouseListener(listener);
addMouseMotionListener(listener);
try {
this.image = ImageIO.read(new URL("https://previews.123rf.com/images/victoroancea/victoroancea1201/victoroancea120100059/12055848-tv-color-test-pattern-test-card-for-pal-and-ntsc.jpg"));
}catch(IOException ex) {
Logger.getLogger(DrawRect.class.getName()).log(Level.SEVERE, null, ex);
}
this.canvas = new JPanel() {
private static final long serialVersionUID = 1L;
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, null);
}
};
canvas.setPreferredSize(new Dimension(image.getWidth(), image.getHeight()));
JScrollPane sp = new JScrollPane(canvas);
setLayout(new BorderLayout());
add(sp, BorderLayout.CENTER);
}
public void setStartPoint(int x, int y) {
this.x = x;
this.y = y;
}
public void setEndPoint(int x, int y) {
x2 = (x);
y2 = (y);
}
public void drawRect(Graphics g, int x, int y, int x2, int y2) {
int px = Math.min(x,x2);
int py = Math.min(y,y2);
int pw=Math.abs(x-x2);
int ph=Math.abs(y-y2);
g.drawRect(px, py, pw, ph);
}
class MyMouseListener extends MouseAdapter {
public void mousePressed(MouseEvent e) {
setStartPoint(e.getX(), e.getY());
}
public void mouseDragged(MouseEvent e) {
setEndPoint(e.getX(), e.getY());
repaint();
}
public void mouseReleased(MouseEvent e) {
setEndPoint(e.getX(), e.getY());
repaint();
}
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.RED);
drawRect(g, x, y, x2, y2);
}
}

Your image-drawing JPanel must be the same JPanel that draws the rectangle and that has the MouseAdapter added to it. For instance:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Image;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
#SuppressWarnings("serial")
public class DrawRect2 extends JPanel {
public static final String IMG_PATH = "https://previews.123rf.com/images/victoroancea"
+ "/victoroancea1201/victoroancea120100059"
+ "/12055848-tv-color-test-pattern-test-card-for-pal-and-ntsc.jpg";
private static final int PREF_W = 600;
private static final int PREF_H = PREF_W;
private DrawingPanel drawingPanel;
public DrawRect2(Image img) {
drawingPanel = new DrawingPanel(img);
JScrollPane scrollPane = new JScrollPane(drawingPanel);
MyMouse myMouse = new MyMouse();
drawingPanel.addMouseListener(myMouse);
drawingPanel.addMouseMotionListener(myMouse);
setLayout(new BorderLayout());
add(scrollPane);
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
Image img = null;
try {
URL url = new URL(IMG_PATH);
img = ImageIO.read(url);
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
DrawRect2 mainPanel = new DrawRect2(img);
JFrame frame = new JFrame("DrawRect2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class DrawingPanel extends JPanel {
private Image img;
private Rectangle rectangle;
public DrawingPanel(Image img) {
this.img = img;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, this);
}
if (rectangle != null) {
Graphics2D g2 = (Graphics2D) g.create();
g2.setXORMode(Color.WHITE);
g2.draw(rectangle);
g2.dispose(); // since we created this object
}
}
#Override
public Dimension getPreferredSize() {
Dimension superSize = super.getPreferredSize();
if (img == null) {
return super.getPreferredSize();
} else {
int w = img.getWidth(this);
int h = img.getHeight(this);
return new Dimension(w, h);
}
}
public void setRectangle(Rectangle rectangle) {
this.rectangle = rectangle;
}
}
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
public class MyMouse extends MouseAdapter {
private Point p1;
#Override
public void mousePressed(MouseEvent e) {
p1 = e.getPoint();
}
#Override
public void mouseDragged(MouseEvent e) {
if (p1 != null) {
createRect(e);
}
}
private void createRect(MouseEvent e) {
Point p2 = e.getPoint();
int x = Math.min(p1.x, p2.x);
int y = Math.min(p1.y, p2.y);
int width = Math.abs(p1.x - p2.x);
int height = Math.abs(p1.y - p2.y);
Rectangle r = new Rectangle(x, y, width, height);
((DrawingPanel) e.getSource()).setRectangle(r);
((DrawingPanel) e.getSource()).repaint();
}
#Override
public void mouseReleased(MouseEvent e) {
if (p1 != null) {
createRect(e);
}
p1 = null;
}
}
So in this paintComponent method, I draw both the image and the Rectangle, using Graphics2D XOR mode to help show the lines regardless of the background color:
#SuppressWarnings("serial")
public class DrawingPanel extends JPanel {
private Image img;
private Rectangle rectangle;
public DrawingPanel(Image img) {
this.img = img;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, this);
}
if (rectangle != null) {
Graphics2D g2 = (Graphics2D) g.create();
g2.setXORMode(Color.WHITE);
g2.draw(rectangle);
g2.dispose(); // since we created this object
}
}
I also have this method:
public void setRectangle(Rectangle rectangle) {
this.rectangle = rectangle;
}
To allow the MouseListener/Adapter to pass in the Rectangle into this JPanel.
Rectangle r = new Rectangle(x, y, width, height);
((DrawingPanel) e.getSource()).setRectangle(r);
((DrawingPanel) e.getSource()).repaint();

JLabel goes out of alignment (aka funky) when overlaying a rectangle on it

I have a GUI I am making for the popular software ImageMagick in Java SWING.
Now, I am implementing the Crop feature into it and was trying to implement a drawable box to denote the region to be cropped.
The issue is that although I have gotten the rectangle to draw on the JLabel, the JLabel itself starts to move around once I finish painting the graphics on it.
As an example, here is a screenshot of the app before and after the selection is made.
Here is the code for the MouseReleased() event listener
private void input_showerMouseReleased(java.awt.event.MouseEvent evt) {
end_x = evt.getX();
end_y = evt.getY();
paint(input_shower.getGraphics());
input_shower.revalidate();
}
Here is the code for the paint() method
public void paint(Graphics g) {
super.paintComponents(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.red);
g2.setStroke(new BasicStroke(5));
Rectangle2D.Double rectangle = new Rectangle2D.Double(start_x, start_y, (end_x - start_x), (end_y - start_y));
g2.draw(rectangle);
}
Are there any ideas as to why this is happening and any possible solutions?

This is dangerous code:
private void input_showerMouseReleased(java.awt.event.MouseEvent evt) {
end_x = evt.getX();
end_y = evt.getY();
paint(input_shower.getGraphics());
input_shower.revalidate();
}
since you're painting directly to a component with a Graphics object that was not given to you by the JVM. Just don't do this, and instead paint passively.
Instead use end_x and end_y in your listened to jcomponent's paintComponent method and draw with that.
e.g.,
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class PaintComponentCorrect extends JPanel {
public static final String BULL_FIGHT = "https://duke.kenai.com/misc/Bullfight.jpg";
private static final Color RECT_COLOR = new Color(150, 150, 255);
private int startX;
private int startY;
private int endX;
private int endY;
private BufferedImage img;
public PaintComponentCorrect() throws IOException {
URL url = new URL(BULL_FIGHT);
img = ImageIO.read(url);
MyMouseAdapt myMouseAdapt = new MyMouseAdapt();
addMouseListener(myMouseAdapt);
addMouseMotionListener(myMouseAdapt);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, null);
}
g.setColor(RECT_COLOR);
int x = Math.min(startX, endX);
int y = Math.min(startY, endY);
int width = Math.abs(startX - endX);
int height = Math.abs(startY - endY);
g.drawRect(x, y, width, height);
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet() || img == null) {
return super.getPreferredSize();
}
return new Dimension(img.getWidth(), img.getHeight());
}
private class MyMouseAdapt extends MouseAdapter {
private BufferedImage subImg;
#Override
public void mousePressed(MouseEvent e) {
if (e.getButton() != MouseEvent.BUTTON1) {
return;
}
startX = e.getX();
startY = e.getY();
endX = startX;
endY = startY;
repaint();
}
#Override
public void mouseReleased(MouseEvent e) {
if (e.getButton() != MouseEvent.BUTTON1) {
return;
}
endX = e.getX();
endY = e.getY();
repaint();
int x = Math.min(startX, endX);
int y = Math.min(startY, endY);
int w = Math.abs(startX - endX);
int h = Math.abs(startY - endY);
subImg = img.getSubimage(x, y, w, h);
ImageIcon icon = new ImageIcon(subImg);
JOptionPane.showMessageDialog(PaintComponentCorrect.this, icon);
}
#Override
public void mouseDragged(MouseEvent e) {
endX = e.getX();
endY = e.getY();
repaint();
}
}
private static void createAndShowGui() {
PaintComponentCorrect mainPanel = null;
try {
mainPanel = new PaintComponentCorrect();
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
JFrame frame = new JFrame("PaintComponent Correct");
frame.setDefaultCloseOperation(JFrame.DISPOSE_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();
}
});
}
}

public void paint(Graphics g) {
super.paintComponents(g);
Custom painting is done by overriding the paintComponent() method.
You then invoke super.paintComponent(), not "paintComponents" with an "s"
For example check out Custom Painting Approaches. The code isn't designed to do what you want, but it does show how to draw a Rectangle on a component using the above suggestion.

Select, Copy and Paste Images

What I want my app to do:
1 - Select an area of Image and get the coordinates. This code below should do this:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;
public class ScreenCaptureRectangle {
Rectangle captureRect;
ScreenCaptureRectangle(final BufferedImage screen) {
final BufferedImage screenCopy = new BufferedImage(
screen.getWidth(),
screen.getHeight(),
screen.getType());
final JLabel screenLabel = new JLabel(new ImageIcon(screenCopy));
JScrollPane screenScroll = new JScrollPane(screenLabel);
screenScroll.setPreferredSize(new Dimension(
(int)(screen.getWidth()/3),
(int)(screen.getHeight()/3)));
JPanel panel = new JPanel(new BorderLayout());
panel.add(screenScroll, BorderLayout.CENTER);
final JLabel selectionLabel = new JLabel(
"Drag a rectangle in the screen shot!");
panel.add(selectionLabel, BorderLayout.SOUTH);
repaint(screen, screenCopy);
screenLabel.repaint();
screenLabel.addMouseMotionListener(new MouseMotionAdapter() {
Point start = new Point();
#Override
public void mouseMoved(MouseEvent me) {
start = me.getPoint();
repaint(screen, screenCopy);
selectionLabel.setText("Start Point: " + start);
screenLabel.repaint();
}
#Override
public void mouseDragged(MouseEvent me) {
Point end = me.getPoint();
captureRect = new Rectangle(start,
new Dimension(end.x-start.x, end.y-start.y));
repaint(screen, screenCopy);
screenLabel.repaint();
selectionLabel.setText("Rectangle: " + captureRect);
}
});
JOptionPane.showMessageDialog(null, panel);
System.out.println("Rectangle of interest: " + captureRect);
}
public void repaint(BufferedImage orig, BufferedImage copy) {
Graphics2D g = copy.createGraphics();
g.drawImage(orig,0,0, null);
if (captureRect!=null) {
g.setColor(Color.RED);
g.draw(captureRect);
g.setColor(new Color(255,255,255,150));
g.fill(captureRect);
}
g.dispose();
}
public static void main(String[] args) throws Exception {
Robot robot = new Robot();
final Dimension screenSize = Toolkit.getDefaultToolkit().
getScreenSize();
final BufferedImage screen = robot.createScreenCapture(
new Rectangle(screenSize));
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new ScreenCaptureRectangle(screen);
}
});
}
}
2 - get the coordinates and use it on getSubimage method.
double w = captureRect.getWidth();
double h = captureRect.getHeight();
double x = captureRect.getX();
double y = captureRect.getY();
int W = (int) w;
int H = (int) h;
int X = (int) x;
int Y = (int) y;
BufferedImage selectImg = screen.getSubimage(x, y, w, h);
3 - this code create a new image file and copy the imageselected.
BufferedImage img = new BufferedImage ( 5000, 5000, BufferedImage.TYPE_INT_RGB );
img.createGraphics().drawImage(selectImg, 0, 0, null);
File final_image = new File("C:/Final.jpg");
ImageIO.write(img, "jpeg", final_image);
The idea of app is:
- Select an area of the image.
- Copy that image and paste in other file. ( when I pressed any button )
- The program will continue run until I press another button.
- Every image that I copy the program will paste it beside the last one.
I think I am near to the solution. Can any one help me to "connect the parts" ?

Start by taking a look at:
How to Write a Mouse Listener
How to Use Buttons, Check Boxes, and Radio Buttons
How to Write an Action Listeners
Performing Custom Painting
Writing/Saving an Image
You need to take the concepts you have and rework them into a coherent workable solution. That is, provide functionality between the areas you need (selecting a region and saving the file) so that they work cleanly together...
The following example takes a screenshot, allows you to select an area, click save and the file will be saved. The example checks to see how many files are already in the current directory and increments the count by 1 so you are not overwriting the existing files...
import java.awt.AWTException;
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.Point;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ScreenImage {
public static void main(String[] args) {
new ScreenImage();
}
public ScreenImage() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
try {
Robot robot = new Robot();
final Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
final BufferedImage screen = robot.createScreenCapture(new Rectangle(screenSize));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane(screen));
frame.setSize(400, 400);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (AWTException exp) {
exp.printStackTrace();
}
}
});
}
public class TestPane extends JPanel {
private BufferedImage master;
public TestPane(BufferedImage image) {
this.master = image;
setLayout(new BorderLayout());
final ImagePane imagePane = new ImagePane(image);
add(new JScrollPane(imagePane));
JButton btnSave = new JButton("Save");
add(btnSave, BorderLayout.SOUTH);
btnSave.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
try {
BufferedImage img = imagePane.getSubImage();
master = append(master, img);
File save = new File("Capture.png");
ImageIO.write(master, "png", save);
imagePane.clearSelection();
JOptionPane.showMessageDialog(TestPane.this, save.getName() + " was saved", "Saved", JOptionPane.INFORMATION_MESSAGE);
} catch (IOException ex) {
ex.printStackTrace();
JOptionPane.showMessageDialog(TestPane.this, "Failed to save capture", "Error", JOptionPane.ERROR_MESSAGE);
}
}
public BufferedImage append(BufferedImage master, BufferedImage sub) {
// Create a new image which can hold both background and the
// new image...
BufferedImage newImage = new BufferedImage(
master.getWidth() + sub.getWidth(),
Math.max(master.getHeight(), sub.getHeight()),
BufferedImage.TYPE_INT_ARGB);
// Get new image's Graphics context
Graphics2D g2d = newImage.createGraphics();
// Draw the old background
g2d.drawImage(master, 0, 0, null);
// Position and paint the new sub image...
int y = (newImage.getHeight() - sub.getHeight()) / 2;
g2d.drawImage(sub, master.getWidth(), y, null);
g2d.dispose();
return newImage;
}
});
}
}
public class ImagePane extends JPanel {
private BufferedImage background;
private Rectangle selection;
public ImagePane(BufferedImage img) {
background = img;
MouseAdapter ma = new MouseAdapter() {
private Point clickPoint;
#Override
public void mousePressed(MouseEvent e) {
clickPoint = e.getPoint();
}
#Override
public void mouseDragged(MouseEvent e) {
Point dragPoint = e.getPoint();
int x = Math.min(clickPoint.x, dragPoint.x);
int y = Math.min(clickPoint.y, dragPoint.y);
int width = Math.abs(clickPoint.x - dragPoint.x);
int height = Math.abs(clickPoint.y - dragPoint.y);
selection = new Rectangle(x, y, width, height);
repaint();
}
};
addMouseListener(ma);
addMouseMotionListener(ma);
}
public void clearSelection() {
selection = null;
repaint();
}
public BufferedImage getSubImage() {
BufferedImage img = null;
if (selection != null) {
img = background.getSubimage(selection.x, selection.y, selection.width, selection.height);
}
return img;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(background.getWidth(), background.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - background.getWidth()) / 2;
int y = (getHeight() - background.getHeight()) / 2;
g2d.drawImage(background, x, y, this);
if (selection != null) {
Color stroke = UIManager.getColor("List.selectionBackground");
Color fill = new Color(stroke.getRed(), stroke.getGreen(), stroke.getBlue(), 128);
g2d.setColor(fill);
g2d.fill(selection);
g2d.setColor(stroke);
g2d.draw(selection);
}
g2d.dispose();
}
}
}
So apart from rendering the selection the hardest part would be generating the resulting image...
Basically, this done by creating a new BufferedImage and painting the old image and the new, sub, image together.
public BufferedImage append(BufferedImage master, BufferedImage sub) {
// Create a new image which can hold both background and the
// new image...
BufferedImage newImage = new BufferedImage(
master.getWidth() + sub.getWidth(),
Math.max(master.getHeight(), sub.getHeight()),
BufferedImage.TYPE_INT_ARGB);
// Get new image's Graphics context
Graphics2D g2d = newImage.createGraphics();
// Draw the old background
g2d.drawImage(master, 0, 0, null);
// Position and paint the new sub image...
int y = (newImage.getHeight() - sub.getHeight()) / 2;
g2d.drawImage(sub, master.getWidth(), y, null);
g2d.dispose();
return newImage;
}
The example replaces the previous (master) image with the one created here, so it will constantly be appending new images to the end of it...

You need more listeners for button pressed and released.. some lines in the mouseMoved also better placed in mousePressed.
You would want to update your captureRect when you release the mouse (in mouseReleased method).
Then you just write it to the file. You may adjust other things according to your needs.
And for clarity maybe it's better to add a save button into your UI.
public class ScreenCaptureRectangle {
Rectangle captureRect;
Point start = new Point();
SimpleDateFormat sdf;
ScreenCaptureRectangle(final BufferedImage screen) {
sdf = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
final BufferedImage screenCopy = new BufferedImage(
screen.getWidth(),
screen.getHeight(),
screen.getType());
final JLabel screenLabel = new JLabel(new ImageIcon(screenCopy));
JScrollPane screenScroll = new JScrollPane(screenLabel);
screenScroll.setPreferredSize(new Dimension(
(int) (screen.getWidth() / 3),
(int) (screen.getHeight() / 3)));
JPanel panel = new JPanel(new BorderLayout());
panel.add(screenScroll, BorderLayout.CENTER);
JButton btnSave = new JButton("SAVE");
btnSave.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
double w = captureRect.getWidth();
double h = captureRect.getHeight();
double x = captureRect.getX();
double y = captureRect.getY();
int W = (int) w;
int H = (int) h;
int X = (int) x;
int Y = (int) y;
BufferedImage selectImg = screen.getSubimage(X, Y, W, H);
try {
String fName = generateFileName();
if (fName != null) {
File f = new File(fName);
if (f.createNewFile()) {
ImageIO.write(selectImg, "jpg", f);
}
}
} catch (IOException ex) {
Logger.getLogger(ScreenCaptureRectangle.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
panel.add(btnSave, BorderLayout.AFTER_LAST_LINE);
final JLabel selectionLabel = new JLabel(
"Drag a rectangle in the screen shot!");
panel.add(selectionLabel, BorderLayout.SOUTH);
repaint(screen, screenCopy);
screenLabel.repaint();
screenLabel.addMouseMotionListener(new MouseMotionAdapter() {
#Override
public void mouseDragged(MouseEvent me) {
Point end = me.getPoint();
captureRect = new Rectangle(start,
new Dimension(end.x - start.x, end.y - start.y));
repaint(screen, screenCopy);
screenLabel.repaint();
selectionLabel.setText("Rectangle: " + captureRect);
}
});
screenLabel.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent me) {
start = me.getPoint();
repaint(screen, screenCopy);
selectionLabel.setText("Start Point: " + start);
screenLabel.repaint();
}
#Override
public void mouseReleased(MouseEvent me) {
int endX = me.getX();
int endY = me.getY();
if (endX > start.x && endY > start.y) {
captureRect = new Rectangle(start.x, start.y, endX-start.x, endY-start.y);
System.out.println("Rectangle of interest: " + captureRect);
}
}
});
JOptionPane.showMessageDialog(null, panel);
}
private String generateFileName() {
return new StringBuilder("screencrop_").append(sdf.format(new Date())).append(".jpg").toString();
}
public void repaint(BufferedImage orig, BufferedImage copy) {
Graphics2D g = copy.createGraphics();
g.drawImage(orig, 0, 0, null);
if (captureRect != null) {
g.setColor(Color.RED);
g.draw(captureRect);
g.setColor(new Color(255, 255, 255, 150));
g.fill(captureRect);
}
g.dispose();
}
public static void main(String[] args) throws Exception {
Robot robot = new Robot();
final Dimension screenSize = Toolkit.getDefaultToolkit().
getScreenSize();
final BufferedImage screen = robot.createScreenCapture(
new Rectangle(screenSize));
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new ScreenCaptureRectangle(screen);
}
});
}
}

Component with transparent background to BufferedImage?

I have a component extends JPanel. It saves itself as bufferedimage on every call of paintComponent method. Component is not completely transparent, only its background. Problem is background is not transparent. I am using setOpaque(false);
Here is my relevant code;
private BufferedImage bufImage = null;
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
// if first time call
if (bufImage == null) {
int w = this.getWidth();
int h = this.getHeight();
bufImage = (BufferedImage)this.createImage(w, h);
}
g2.drawImage(bufImage, null, 0, 0);
// draw sth
g2.draw(sth);
}
--
I also tried
bufImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
instead of
bufImage = (BufferedImage)this.createImage(w, h);
When i do that; background transperancy works but i can only draw with white color. I have no idea what causes that.
Note:
I used that code to check if it is working;
File outputfile = new File("saved.png");
ImageIO.write(bufImage, "png", outputfile);
saved.png had transparent background but drawings were only white.
This is the component, only lets drawing rectangle with mouse;
class PaintPanel extends JPanel implements MouseListener, MouseMotionListener {
private BufferedImage _bufImage = null;
private boolean dragging = false;
private Point _start = null, _end = null;
public PaintPanel() {
setOpaque(false);
this.addMouseListener(this);
this.addMouseMotionListener(this);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
if (_bufImage == null) {
int w = this.getWidth();
int h = this.getHeight();
_bufImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
//_bufImage = (BufferedImage)this.createImage(w, h);
}
g2.drawImage(_bufImage, null, 0, 0);
if (dragging) {
drawCurrentShape(g2);
}
}
private void drawCurrentShape(Graphics2D g2) {
int startx = (int) _start.getX();
int starty = (int) _start.getY();
int stopx = (int) _end.getX();
int stopy = (int) _end.getY();
int width = Math.abs(startx - stopx);
int height = Math.abs(starty - stopy);
int x = startx, y = starty;
if(x > stopx)
x = stopx;
if(y > stopy)
y = stopy;
Rectangle r = new Rectangle(x, y, width, height);
g2.draw(r);
}
public void mousePressed(MouseEvent e) {
dragging = true;
_start = e.getPoint();
_end = _start;
}
public void mouseDragged(MouseEvent e) {
_end = e.getPoint();
this.repaint();
}
public void mouseReleased(MouseEvent e) {
_end = e.getPoint();
if (dragging) {
dragging = false;
drawCurrentShape(_bufImage.createGraphics());
this.repaint();
}
}
public void mouseMoved (MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited (MouseEvent e) {}
public void mouseClicked(MouseEvent e) {}
}

try this:
bufImage = new BufferedImage(w,h,java.awt.image.BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics = bufImage.createGraphics();
this.print(graphics);
graphics.dispose();
The key is to use print()
Edit: I tried the following and transparency works like a charm:
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test2 {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JPanel p = new JPanel();
p.setPreferredSize(new Dimension(400, 400));
p.setOpaque(false);
JButton button = new JButton("Hello world");
p.add(button);
frame.add(p);
frame.pack();
frame.setVisible(true);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
BufferedImage bufImage = new BufferedImage(p.getWidth(), p.getHeight(), java.awt.image.BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics = bufImage.createGraphics();
p.print(graphics);
graphics.dispose();
try {
ImageIO.write(bufImage, "png", new File("d:/tmp/tmp.png"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
}

createImage(w, h) will create a "blank" image with the specified width and height. That being said, what you'll need to do is invoke createGraphics on the BufferedImage instance and draw directly to the returned Graphics object.