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Java paint issue

Ok, I searched and searched for searches, and that made me mad. (note that it started as a code from the University).

Any help would be appreciated by weight! Since I seem to have a mental block when it comes to java graphics: (.

The problem is marking the image, but I am having problems with half the lost image for various reasons, if I do not move around the frame and then return. Similarly, if I try to remove the “tags” that are written in BufferedImage, I need to navigate through the Jframe to see the result.

Finally, when a JOptionPane appears to request a label name, it does this when closing:

receiving image for publication https://docs.google.com/document/d/1I5rFH23a75IHB6twTu1dPRwmRt-By1sIUvDvI6FE_OY/edit

package hci; import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; /** * Deals with the label tools */ public class LabelToolGUI extends JPanel implements ActionListener { JButton newButton = new JButton("New"); JButton deleteButton = new JButton("Delete"); JButton editButton = new JButton("Edit"); JButton undoButton = new JButton("Undo"); JComboBox labelsBox = new JComboBox(); String saveIcon = "./images/icons/save.jpg"; String deleteIcon = "./images/icons/delete.jpg"; String openIcon = "./images/icons/open.jpg"; String newIcon = "./images/icons/new.jpg"; String helpIcon = "./images/icons/help.jpg"; String labelsIcon = "./images/icons/help.jpg"; String fname = ""; String fnameURL = ""; public LabelToolGUI() { super(); newButton.addActionListener(this); deleteButton.addActionListener(this); editButton.addActionListener(this); undoButton.addActionListener(this); setLayout(new BorderLayout()); setBorder(BorderFactory.createTitledBorder("Label tools")); add(newButton, BorderLayout.WEST); add(deleteButton, BorderLayout.EAST); add(editButton, BorderLayout.CENTER); add(labelsBox, BorderLayout.NORTH); add(undoButton, BorderLayout.SOUTH); } @Override public void actionPerformed(ActionEvent e) { Object src = e.getSource(); if(src == newButton) { String labelName = JOptionPane.showInputDialog("Please input a value"); ImageLabeller.addNewPolygon(labelName); labelsBox.addItem(labelName); } else if(src == deleteButton) { String toDelete = labelsBox.getSelectedItem().toString(); System.out.println("Deleting " + toDelete); labelsBox.removeItem(labelsBox.getSelectedItem()); ImageLabeller.removeLabel(toDelete); } else if(src == undoButton) { ImageLabeller.undo(); ImageLabeller.imagePanel.repaint(); } } } 
 package hci; import javax.swing.*; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; /** * Main class of the program - handles display of the main window * @author Michal * */ public class ImageLabeller extends JFrame implements ActionListener { /** * some java stuff to get rid of warnings */ private static final long serialVersionUID = 1L; /** * main window panel */ JPanel appPanel = null; /** * toolbox - put all buttons and stuff here! */ JPanel toolboxPanel = null; /** * image panel - displays image and editing area */ static ImagePanel imagePanel = null; /** * handles New Object button action */ public static void addNewPolygon(String labelName) { imagePanel.addNewPolygon(labelName); } public static void removeLabel(String labelName) { LabelHandler.deleteLabel(labelName); } /** * Removes last point added to the label. */ public static void undo() { imagePanel.currentLabel.removeLast(); } /*@Override public void paint(Graphics g) { super.paint(g); imagePanel.paint(g); //update image panel } */ /** * sets up application window * @param imageFilename image to be loaded for editing * @throws Exception */ public void setupGUI(String imageFilename) throws Exception { this.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent event) { //here we exit the program (maybe we should ask if the user really wants to do it?) //maybe we also want to store the polygons somewhere? and read them next time System.out.println("Bye bye!"); System.exit(0); } }); //setup main window panel appPanel = new JPanel(); this.setLayout(new BoxLayout(appPanel, BoxLayout.X_AXIS)); this.setContentPane(appPanel); //Create and set up the image panel. imagePanel = new ImagePanel(imageFilename); imagePanel.setOpaque(true); //content panes must be opaque appPanel.add(imagePanel); //add toolbox to window appPanel.add(new LabelToolGUI()); //display all the stuff this.pack(); this.setVisible(true); } /** * Runs the program * @param argv path to an image */ public static void main(String argv[]) { try { //create a window and display the image ImageLabeller window = new ImageLabeller(); window.setupGUI(argv[0]); } catch (Exception e) { System.err.println("Image: " + argv[0]); e.printStackTrace(); } } @Override public void actionPerformed(ActionEvent e) { System.out.println("Action clicked"); imagePanel.paint(imagePanel.getGraphics()); } } 
 package hci; import javax.imageio.ImageIO; import javax.swing.JPanel; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.awt.image.BufferedImage; import java.io.File; import java.util.ArrayList; import hci.utils.*; /** * Handles image editing panel * @author Michal * */ public class ImagePanel extends JPanel implements MouseListener { /** * some java stuff to get rid of warnings */ private static final long serialVersionUID = 1L; /** * image to be tagged */ BufferedImage image = null; /** * list of current polygon vertices */ Label currentLabel = null; /** * default constructor, sets up the window properties */ public ImagePanel() { currentLabel = new Label(); this.setVisible(true); Dimension panelSize = new Dimension(800, 600); this.setSize(panelSize); this.setMinimumSize(panelSize); this.setPreferredSize(panelSize); this.setMaximumSize(panelSize); addMouseListener(this); } /** * extended constructor - loads image to be labelled * @param imageName - path to image * @throws Exception if error loading the image */ public ImagePanel(String imageName) throws Exception{ this(); image = ImageIO.read(new File(imageName)); if (image.getWidth() > 800 || image.getHeight() > 600) { int newWidth = image.getWidth() > 800 ? 800 : (image.getWidth() * 600)/image.getHeight(); int newHeight = image.getHeight() > 600 ? 600 : (image.getHeight() * 800)/image.getWidth(); System.out.println("SCALING TO " + newWidth + "x" + newHeight ); Image scaledImage = image.getScaledInstance(newWidth, newHeight, Image.SCALE_FAST); image = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB); image.getGraphics().drawImage(scaledImage, 0, 0, this); } } /** * Displays the image */ public void ShowImage() { Graphics g = this.getGraphics(); if (image != null) { g.drawImage(image, 0, 0, null); } } public void paintComponent(Graphics g) { super.paintComponent(g); //display iamge ShowImage(); //display all the completed polygons for(Label l : LabelHandler.labels) { drawLabel(l); finishPolygon(l); } //display current polygon drawLabel(currentLabel); } /** * displays a polygon without last stroke * @param l label to be displayed */ public void drawLabel(Label l) { Graphics2D g = (Graphics2D)this.getGraphics(); g.setColor(Color.GREEN); for(int i = 0; i < l.size(); i++) { Point currentVertex = l.getPoint(i); if (i != 0) { Point prevVertex = l.getPoint(i - 1); g.drawLine(prevVertex.getX(), prevVertex.getY(), currentVertex.getX(), currentVertex.getY()); } g.fillOval(currentVertex.getX() - 5, currentVertex.getY() - 5, 10, 10); } } /** * displays last stroke of the polygon (arch between the last and first vertices) * @param l label to be finished */ public void finishPolygon(Label l) { //if there are less than 3 vertices than nothing to be completed if (l.size() >= 3) { Point firstVertex = l.getPoint(0); Point lastVertex = l.getPoint(l.size() - 1); Graphics2D g = (Graphics2D)this.getGraphics(); g.setColor(Color.GREEN); g.drawLine(firstVertex.getX(), firstVertex.getY(), lastVertex.getX(), lastVertex.getY()); } } /** * moves current polygon to the list of polygons and makes pace for a new one */ public void addNewPolygon(String labelName) { //finish the current polygon if any if (currentLabel != null ) { finishPolygon(currentLabel); LabelHandler.addLabel(currentLabel); } currentLabel = new Label(labelName); } @Override public void mouseClicked(MouseEvent e) { int x = e.getX(); int y = e.getY(); //check if the cursos withing image area if (x > image.getWidth() || y > image.getHeight()) { //if not do nothing return; } Graphics2D g = (Graphics2D)this.getGraphics(); //if the left button than we will add a vertex to poly if (e.getButton() == MouseEvent.BUTTON1) { g.setColor(Color.GREEN); if (currentLabel.size() != 0) { Point lastVertex = currentLabel.getPoint(currentLabel.size() - 1); g.drawLine(lastVertex.getX(), lastVertex.getY(), x, y); } g.fillOval(x-5,y-5,10,10); currentLabel.addPoint(new Point(x,y)); System.out.println(x + " " + y); } } @Override public void mouseEntered(MouseEvent arg0) { } @Override public void mouseExited(MouseEvent arg0) { } @Override public void mousePressed(MouseEvent arg0) { } @Override public void mouseReleased(MouseEvent arg0) { } }
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2 answers

Do not use getGraphics() for your picture, as this is a temporary buffer that is recycled the next time you redraw. You paint in paintComponent() and call repaint() if necessary.

Also do not call paint() manually (i.e.: imagePanel.paint(imagePanel.getGraphics()); )

For more information, see Performing Custom Painting . Also see Painting in AWT and Swing .

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In ImagePanel.paintComponent replace ShowImage(); on if (image != null) g.drawImage( image, 0, 0, this ); .

The device context g initialized by swinging, you do not need to get another getGraphics() value.

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Source: https://habr.com/ru/post/1441921/

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