Fixed bug when rendering scrolling view (need to set the clip properly

before scrolling); added encloses pathable mode which is like follows
pathable except that the pathable is not tracked with the center of the
screen but instead their bounds are kept inside the visible area.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@1506 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/media/VirtualMediaPanel.java

@@ -1,5 +1,5 @@
 //
-// $Id: VirtualMediaPanel.java,v 1.5 2002/06/20 00:58:36 mdb Exp $
+// $Id: VirtualMediaPanel.java,v 1.6 2002/06/20 07:49:44 mdb Exp $
 
 package com.threerings.media;
 
@@ -58,12 +58,36 @@ public class VirtualMediaPanel extends MediaPanel
      * the pathable always remains in the center of the view. The virtual
      * coordinates will be adjusted after every tick to center the view on
      * the sprite.
+     *
+     * @param pable the pathable to follow.
      */
     public void setFollowsPathable (Pathable pable)
     {
+        _fmode = CENTER_ON_PATHABLE;
         _fpath = pable;
     }
 
+    /**
+     * Instructs the view to scroll to ensure that the specified pathable
+     * is always inside the visible bounds of the view.
+     */
+    public void setEnclosesPathable (Pathable pable)
+    {
+        _fmode = ENCLOSE_PATHABLE;
+        _fpath = pable;
+    }
+
+    /**
+     * Clears out the pathable that was being enclosed or followed due to
+     * a previous call to {@link #setFollowsPathable} or {@link
+     * #setEnclosesPathable}.
+     */
+    public void clearPathable ()
+    {
+        _fpath = null;
+        _fmode = -1;
+    }
+
     /**
      * Configures a region of interest which will be displayed in the
      * center of the viewport in situations where the media panel's actual
@@ -125,11 +149,9 @@ public class VirtualMediaPanel extends MediaPanel
 
         int width = getWidth(), height = getHeight();
 
-        // if we're following a pathable, adjust our view coordinates such
-        // that the pathable is at the center of the view
-        if (_fpath != null) {
-            setViewLocation(_fpath.getX() - width/2, _fpath.getY() - height/2);
-        }
+        // adjusts our view location to track any pathable we might be
+        // tracking
+        trackPathable();
 
         // if we have a new target location, we'll need to generate dirty
         // regions for the area exposed by the scrolling
@@ -166,6 +188,51 @@ public class VirtualMediaPanel extends MediaPanel
         }
     }
 
+    /**
+     * Implements the standard pathable tracking support. Derived classes
+     * may wish to override this if they desire custom tracking
+     * functionality.
+     */
+    protected void trackPathable ()
+    {
+        // if we're tracking a pathable, adjust our view coordinates
+        if (_fpath == null) {
+            return;
+        }
+
+        int width = getWidth(), height = getHeight();
+        int nx = _tx, ny = _ty;
+
+        // figure out where to move
+        switch (_fmode) {
+        case CENTER_ON_PATHABLE:
+            nx = _fpath.getX() - width/2;
+            ny = _fpath.getY() - height/2;
+            break;
+
+        case ENCLOSE_PATHABLE:
+            Rectangle bounds = _fpath.getBounds();
+            if (nx > bounds.x) {
+                nx = bounds.x;
+            } else if (nx + width < bounds.x + bounds.width) {
+                nx = bounds.x + bounds.width - width;
+            }
+            if (ny > bounds.y) {
+                ny = bounds.y;
+            } else if (ny + height < bounds.y + bounds.height) {
+                ny = bounds.y + bounds.height - height;
+            }
+            break;
+
+        default:
+            Log.warning("Eh? Set to invalid pathable mode " +
+                        "[mode=" + _fmode + "].");
+            break;
+        }
+
+        setViewLocation(nx, ny);
+    }
+
     // documentation inherited
     protected void paint (Graphics2D gfx, Rectangle[] dirty)
     {
@@ -175,6 +242,11 @@ public class VirtualMediaPanel extends MediaPanel
             int cx = (_dx > 0) ? _dx : 0;
             int cy = (_dy > 0) ? _dy : 0;
 
+            // set the clip to the bounds of the component (we can't
+            // assume the clip is anything sensible upon entry to paint()
+            // because the frame manager expects us to set our own clip)
+            gfx.setClip(0, 0, width, height);
+
             // on windows, attempting to call copyArea() on a translated
             // graphics context results in boochness; so we have to
             // untranslate the graphics context, do our copyArea() and
@@ -229,10 +301,22 @@ public class VirtualMediaPanel extends MediaPanel
     /** A region of interest which we'll try to keep visible. */
     protected Rectangle _interest;
 
+    /** The mode we're using when following a pathable. */
+    protected int _fmode = -1;
+
     /** The pathable being followed. */
     protected Pathable _fpath;
 
     /** We need to know our absolute coordinates in order to work around
      * the Windows copyArea() bug. */
     protected Rectangle _abounds = new Rectangle();
+
+    /** The code for the pathable following mode wherein we keep the view
+     * centered on the pathable's location. */
+    protected static final int CENTER_ON_PATHABLE = 0;
+
+    /** The code for the pathable following mode wherein we ensure that
+     * the marked pathable is always kept within the visible bounds of the
+     * view. */
+    protected static final int ENCLOSE_PATHABLE = 1;
 }