Basic implementation of an AnimatedView built on top of a JPanel.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@475 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/media/sprite/AnimatedPanel.java

@@ -0,0 +1,109 @@
+//
+// $Id: AnimatedPanel.java,v 1.1 2001/10/17 22:12:20 shaper Exp $
+
+package com.threerings.media.sprite;
+
+import java.awt.*;
+import javax.swing.JComponent;
+import javax.swing.JPanel;
+
+import com.threerings.media.Log;
+
+/**
+ * The animated panel provides a useful extensible implementation of a
+ * Swing {@link JPanel} that implements the {@link AnimatedView}
+ * interface.  Sub-classes should override {@link #render} to draw
+ * their panel-specific contents, and may choose to override {@link
+ * #invalidateRects} to optimize their internal rendering.
+ */
+public class AnimatedPanel extends JPanel implements AnimatedView
+{
+    /**
+     * Constructs an animated panel.
+     */
+    public AnimatedPanel ()
+    {
+	// set our attributes for optimal display performance
+        setDoubleBuffered(false);
+        setOpaque(true);
+    }        
+
+    // documentation inherited
+    public void paintComponent (Graphics g)
+    {
+        // create the offscreens if they don't yet exist
+	if (_offimg == null) {
+	    createOffscreen();
+	}
+
+        // give sub-classes a chance to do their thing
+        render(_offg);
+
+        // Rectangle bounds = getBounds();
+        // Log.info("paintComponent [bounds=" + bounds + "].");
+        // _offg.drawRect(bounds.x, bounds.y, bounds.width-1, bounds.height-1);
+
+        // draw the offscreen to the screen
+	g.drawImage(_offimg, 0, 0, null);
+    }
+
+    /**
+     * Renders the panel to the given graphics object.  Sub-classes
+     * should override this method to paint their panel-specific
+     * contents.
+     */
+    protected void render (Graphics g)
+    {
+        // nothing for now
+    }
+
+    /**
+     * Creates the offscreen image and graphics context to which we
+     * draw the scene for double-buffering purposes.
+     */
+    protected void createOffscreen ()
+    {
+	Rectangle bounds = getBounds();
+	_offimg = createImage(bounds.width, bounds.height);
+	_offg = _offimg.getGraphics();
+    }
+
+    // documentation inherited
+    public void invalidateRects (DirtyRectList rects)
+    {
+        // nothing for now
+    }
+
+    /**
+     * Paints this panel immediately. Since we know that we are always
+     * opaque and not dependent on Swing's double-buffering, we bypass the
+     * antics that <code>JComponent.paintImmediately()</code> performs in
+     * the interest of better performance.
+     */
+    public void paintImmediately ()
+    {
+        Graphics g = null;
+
+        try {
+            Graphics pcg = getGraphics();
+            g = pcg.create();
+            pcg.dispose();
+            paint(g);
+
+        } catch (NullPointerException e) {
+            e.printStackTrace();
+        }
+    }
+
+    // documentation inherited
+    public JComponent getComponent ()
+    {
+	return this;
+    }
+
+    /** The offscreen image used for double-buffering. */
+    protected Image _offimg;
+
+    /** The graphics context for the offscreen image. */
+    protected Graphics _offg;
+}