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POJava Scratch Card demo
 

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  1. POJava Scratch Card demo
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    <p>Building a lottery scratch-card app in Java. Have allot of it done, just need help with the scratching functionality. </p> <p>Basically the program works like this:</p> <ol> <li>create image for the background (right now its just a white background, but later would obviously be an scratchcard image with lotto symbols)</li> <li>create the card_surface which is just a green layer than should reveal the image behind when scratched.</li> <li>onMouseDragged() I used a stroke to draw a line from current mouse co-ordinates to newer mouse-cordinates. I have tried setting the Alphacomposite on this stroke thinking it would reveal the image underneath. Unfortunately not though.</li> </ol> <p>Appreciate any help...</p> <pre><code> import java.awt.BorderLayout; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.RenderingHints; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.MouseMotionAdapter; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.ImageIcon; import java.awt.Stroke; import java.awt.BasicStroke; import java.awt.AlphaComposite; public class Main { public static void main(String[] args) { JFrame frame = new JFrame(); final DrawPad drawPad = new DrawPad(); frame.add(drawPad, BorderLayout.CENTER); JButton clearButton = new JButton("New Scratch-Card"); clearButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { drawPad.clear(); } }); frame.add(clearButton, BorderLayout.SOUTH); frame.setSize(500, 300); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } } class DrawPad extends JComponent { Image image; Image card_surface; Graphics2D graphics2D; int currentX, currentY, oldX, oldY; public DrawPad() { final Stroke stroke = new BasicStroke (17.0F, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL); //image = new ImageIcon("iPhone-4-Pattern-Wallpaper-07.jpg").getImage(); setDoubleBuffered(false); addMouseListener(new MouseAdapter() { public void mousePressed(MouseEvent e) { oldX = e.getX(); oldY = e.getY(); } }); addMouseMotionListener(new MouseMotionAdapter() { public void mouseDragged(MouseEvent e) { currentX = e.getX(); currentY = e.getY(); if (graphics2D != null){ graphics2D.setStroke(stroke); graphics2D.setPaint(Color.GRAY); graphics2D.setComposite(makeComposite(0.5F)); graphics2D.drawLine(oldX, oldY, currentX, currentY); repaint(); oldX = currentX; oldY = currentY; } } }); } private AlphaComposite makeComposite(float alpha) { int type = AlphaComposite.SRC_OVER; return(AlphaComposite.getInstance(type, alpha)); } public void clear() { image=null; card_surface=null; repaint(); } public void paintComponent(Graphics g) { if (image == null) { image = createImage(getSize().width, getSize().height); graphics2D = (Graphics2D) image.getGraphics(); graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); graphics2D.setPaint(Color.white); graphics2D.fillRect(0, 0, getSize().width, getSize().height); graphics2D.setPaint(Color.black); repaint(); } if (card_surface == null) { card_surface = createImage(getSize().width, getSize().height); graphics2D = (Graphics2D) card_surface.getGraphics(); graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); graphics2D.setPaint(Color.green); graphics2D.fillRect(0, 0, getSize().width, getSize().height); repaint(); } g.drawImage(image, 0, 0, null); g.drawImage(card_surface, 0, 0, null); } } </code></pre>
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    1. USaubreybourke
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    1. COYou need to tell us what your problem is. Just telling what you want to do isn't too much help actually. Tell us what doesn't work, which (if any) exceptions you get etc.
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      1. USMagnus Winter
    2. COI don't know where to go from here. I tried using an Alphacomposite stroke to unmask the image underneath. I also looked into clipping the image underneath. The code compile and runs, so no exceptions. I guess I dont really know the best way to do it, so maybe someone could suggest something?
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