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    <p>The issue here is three-fold:</p> <ol> <li>There needs to be a way to display a background image.</li> <li>One must be able to find the point at which the mouse was clicked.</li> <li>There must be a way to draw the point on the panel.</li> </ol> <p>One way to accomplish the above points would be to subclass a <a href="http://java.sun.com/javase/6/docs/api/javax/swing/JPanel.html" rel="noreferrer"><code>JPanel</code></a> and provide those functionalities.</p> <p><strong>1. Display a background image in a panel.</strong></p> <p>Firstly, as a <code>JPanel</code> does not have a way of displaying a background image by default, there must be a way to hold an image in the <code>JPanel</code>, and then draw that on the panel itself, which can be performed via the <a href="http://java.sun.com/javase/6/docs/api/javax/swing/JComponent.html#paintComponent(java.awt.Graphics)" rel="noreferrer"><code>paintComponent</code></a> method.</p> <p>One way to accomplish this is to have a field in the class which holds on to an <code>Image</code> to draw:</p> <pre><code>class MyPanel extends JPanel { // Background image. Initialize appropriately. Image backgroundImage; public void paintComponent(Graphics g) { super.paintComponent(g); // Draw background image each time the panel is repainted. g.drawImage(backgroundImage, 0, 0, null); } } </code></pre> <p>The <a href="http://java.sun.com/javase/6/docs/api/java/awt/Graphics.html" rel="noreferrer"><code>Graphics</code></a> object in <code>paintComponent</code> is associated with the <code>MyPanel</code> and can be used to perform graphics operations.</p> <p><strong>2. Finding the point at which the mouse was clicked.</strong></p> <p>Secondly, in order to retrieve the point at which the mouse was clicked, one could assign a <a href="http://java.sun.com/javase/6/docs/api/java/awt/event/MouseListener.html" rel="noreferrer"><code>MouseListener</code></a> to the <code>MyPanel</code>. In the following example, an anonymous inner class extending the <a href="http://java.sun.com/javase/6/docs/api/java/awt/event/MouseAdapter.html" rel="noreferrer"><code>MouseAdapter</code></a> is used to minimize writing extra code:</p> <pre><code>class MyPanel extends JPanel { // Background image. Initialize appropriately. Image backgroundImage; public MyPanel() { // Add a MouseListener which processes mouse clicks. this.addMouseListener(new MouseAdapter() { public void mouseClicked(MouseEvent e) { // Process mouse-click. } }) } // paintComponents method here. } </code></pre> <p>Processing that needs to be performed when the mouse is clicked can be included in the <code>mouseClicked</code> method.</p> <p><strong>3. How to draw a point on the panel.</strong></p> <p>Thirdly, in order to find one point at which the mouse was clicked, one can obtain it from the <a href="http://java.sun.com/javase/6/docs/api/java/awt/event/MouseEvent.html" rel="noreferrer"><code>MouseEvent</code></a> object that was passed in from the <a href="http://java.sun.com/javase/6/docs/api/java/awt/event/MouseAdapter.html#mouseClicked(java.awt.event.MouseEvent)" rel="noreferrer"><code>mouseClicked</code></a> method:</p> <pre><code>class MyPanel extends JPanel { // Background image. Initialize appropriately. Image backgroundImage; Point pointClicked; public MyPanel() { // Add a MouseListener which processes mouse clicks. this.addMouseListener(new MouseAdapter() { public void mouseClicked(MouseEvent e) { // Retrieve the point at which the mouse was clicked. pointClicked = e.getPoint(); // Repaint the panel. this.repaint(); } }) } public void paintComponent(Graphics g) { super.paintComponent(g); // Draw background image each time the panel is repainted. g.drawImage(backgroundImage, 0, 0, null); // Draw a little square at where the mouse was clicked. g.fillRect(pointClicked.x, pointClicked.y, 1, 1); } } </code></pre> <p>Although the above code is not tested, it should be a starting point.</p> <p>For example, if multiple points needs to be drawing, perhaps having a <code>List&lt;Point&gt;</code> to hold the points, and drawing each <a href="http://java.sun.com/javase/6/docs/api/java/awt/Point.html" rel="noreferrer"><code>Point</code></a> in the <code>paintComponents</code> method could be done.</p> <p>If additional processing needs to be performed when the mouse is clicked, additional code can be added to the <code>mouseClicked</code> method.</p> <p>Additional resources:</p> <ul> <li><a href="http://java.sun.com/docs/books/tutorial/uiswing/painting/" rel="noreferrer">Lesson: Performing Custom Painting</a></li> <li><a href="http://java.sun.com/products/jfc/tsc/articles/painting/" rel="noreferrer">Painting in AWT and Swing</a></li> <li><a href="http://java.sun.com/docs/books/tutorial/uiswing/events/mouselistener.html" rel="noreferrer">How to Write a Mouse Listener</a></li> </ul> <p><em>Thank you to zedoo for pointing out in the comments that making a call to <code>super.paintComponent</code> should be performed when overriding the <code>paintComponent</code> method.</em></p>
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