Remember position in list when returning.

Phew!  Finding how to do this was far from obvious!

1 files changed, 21 insertions, 9 deletions

diff --git a/src/org/madore/android/unicodeMap/UnicodeMapActivity.java b/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
index def8537..c352b58 100644
--- a/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
+++ b/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
@@ -22,8 +22,12 @@ public final class UnicodeMapActivity extends ListActivity {
     protected final List<UnicodeDisplayable> rootList
 	= new ArrayList<UnicodeDisplayable>(200);
 
-    protected final List<List<UnicodeDisplayable>> stack
-	= new ArrayList<List<UnicodeDisplayable>>(10);
+    protected final List<UnicodeArrayAdapter> stack
+	= new ArrayList<UnicodeArrayAdapter>(10);
+    protected final List<Integer> positionStack
+	= new ArrayList<Integer>(10);
+    protected final List<Integer> positionYStack
+	= new ArrayList<Integer>(10);
 
     protected void launchPopulation() {
 	final ProgressDialog progress = new ProgressDialog(this);
@@ -64,8 +68,10 @@ public final class UnicodeMapActivity extends ListActivity {
 	    launchPopulation();
 	for ( UnicodeCharacter.Range rng : UnicodeCharacter.Range.values() )
 	    rootList.add(rng);
-	stack.add(rootList);
-	setListAdapter(new UnicodeArrayAdapter(this, rootList));
+	UnicodeArrayAdapter rootAdapter
+	    = new UnicodeArrayAdapter(this, rootList);
+	stack.add(rootAdapter);
+	setListAdapter(rootAdapter);
 	final ClipboardManager cmgr
 	    = (ClipboardManager)getSystemService(Context.CLIPBOARD_SERVICE);
 	final Button btn = (Button) findViewById(R.id.button);
@@ -94,8 +100,13 @@ public final class UnicodeMapActivity extends ListActivity {
 			    = new ArrayList<UnicodeDisplayable>(db.countRange(from,to));
 			for ( UnicodeCharacter ch : db.getRange(from,to) )
 			    list.add(ch);
-			stack.add(list);
-			setListAdapter(new UnicodeArrayAdapter(UnicodeMapActivity.this, list));
+			UnicodeArrayAdapter adapter
+			    = new UnicodeArrayAdapter(UnicodeMapActivity.this,
+						      list);
+			stack.add(adapter);
+			positionStack.add(position);
+			positionYStack.add(view.getTop());
+			setListAdapter(adapter);
 		    } else
 			throw new AssertionError("unknown UnicodeDisplayable");
 		}
@@ -105,10 +116,11 @@ public final class UnicodeMapActivity extends ListActivity {
     @Override
     public boolean onKeyDown(int keyCode, KeyEvent event) {
 	if ( ( keyCode == KeyEvent.KEYCODE_BACK) && stack.size() > 1 ) {
+	    final ListView lv = getListView();
 	    stack.remove(stack.size()-1);
-	    List<UnicodeDisplayable> list
-		= stack.get(stack.size()-1);
-	    setListAdapter(new UnicodeArrayAdapter(UnicodeMapActivity.this, list));
+	    setListAdapter(stack.get(stack.size()-1));
+	    lv.setSelectionFromTop(positionStack.remove(positionStack.size()-1),
+				   positionYStack.remove(positionYStack.size()-1));
 	    return true;
 	}
 	return super.onKeyDown(keyCode, event);