Retain display (and display history) on configuration change.

This works surprisingly well: there must be a grue hiding in the
darkness waiting to eat me. :-)

1 files changed, 31 insertions, 7 deletions

diff --git a/src/org/madore/android/unicodeMap/UnicodeMapActivity.java b/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
index 9f8194f..687493e 100644
--- a/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
+++ b/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
@@ -136,7 +136,7 @@ public final class UnicodeMapActivity extends ListActivity {
 	dispHistory.add(new DisplayAndPosition(curDisp, position, yOffset));
     }
 
-    protected void doDisplay(Display disp) {
+    protected void doDisplay(Display disp, boolean isNew) {
 	curDisp = disp;
 	List<UnicodeDisplayable> list;
 	UnicodeArrayAdapter adapter;
@@ -168,7 +168,7 @@ public final class UnicodeMapActivity extends ListActivity {
 		list.remove(list.size()-1);
 	    adapter = new UnicodeArrayAdapter(this, list);
 	    setListAdapter(adapter);
-	    if ( overflowed ) {
+	    if ( overflowed && isNew ) {
 		String str = getResources().getString(R.string.list_too_long);
 		Toast.makeText(UnicodeMapActivity.this,
 			       String.format(str, limit),
@@ -195,7 +195,7 @@ public final class UnicodeMapActivity extends ListActivity {
 	    else if ( it instanceof UnicodeCharacter.Range ) {
 		Display newDisp = new RangeDisplay((UnicodeCharacter.Range)it);
 		saveDisplay(view, position);
-		doDisplay(newDisp);
+		doDisplay(newDisp, true);
 	    } else
 		throw new AssertionError("unknown UnicodeDisplayable");
 	}
@@ -262,7 +262,19 @@ public final class UnicodeMapActivity extends ListActivity {
 	final boolean needPopulate = db.needPopulate();
 	if ( needPopulate )
 	    launchPopulation();
-	doDisplay(new RootDisplay());
+	lv = getListView();
+	Object testament = getLastNonConfigurationInstance();
+	if ( testament != null ) {
+	    @SuppressWarnings("unchecked")
+	    List<DisplayAndPosition> oldDispHistory = (List<DisplayAndPosition>)testament;
+	    dispHistory.clear();
+	    dispHistory.addAll(oldDispHistory);
+	    assert(dispHistory.size() > 0);
+	    DisplayAndPosition saved = dispHistory.remove(dispHistory.size()-1);
+	    doDisplay(saved.getDisp(), false);
+	    lv.setSelectionFromTop(saved.getSelPosition(), saved.getYOffset());
+	} else
+	    doDisplay(new RootDisplay(), true);
 	final ClipboardManager cmgr
 	    = (ClipboardManager)getSystemService(Context.CLIPBOARD_SERVICE);
 	final Button btn = (Button) findViewById(R.id.copyButton);
@@ -275,20 +287,32 @@ public final class UnicodeMapActivity extends ListActivity {
 				   Toast.LENGTH_SHORT).show();
 		}
 	    });
-	lv = getListView();
 	lv.setTextFilterEnabled(true);
 	MapItemClickListener listener = new MapItemClickListener();
 	lv.setOnItemClickListener(listener);
 	lv.setOnItemLongClickListener(listener);
     }
 
+    @Override
+    public void onDestroy() {
+	db.close();
+	db = null;
+	super.onDestroy();
+    }
+
+    @Override
+    public Object onRetainNonConfigurationInstance() {
+	saveDisplay();
+	return dispHistory;
+    }
+
     final static int searchLimit = 1000;
 
     protected void doSearch(String s) {
 	Display newDisp = new SearchDisplay(getResources().getString(R.string.search_results),
 					    s, searchLimit);
 	saveDisplay();
-	doDisplay(newDisp);
+	doDisplay(newDisp, true);
     }
 
     protected void querySearch() {
@@ -347,7 +371,7 @@ public final class UnicodeMapActivity extends ListActivity {
     public boolean onKeyDown(int keyCode, KeyEvent event) {
 	if ( ( keyCode == KeyEvent.KEYCODE_BACK ) && dispHistory.size() > 0 ) {
 	    DisplayAndPosition saved = dispHistory.remove(dispHistory.size()-1);
-	    doDisplay(saved.getDisp());
+	    doDisplay(saved.getDisp(), false);
 	    lv.setSelectionFromTop(saved.getSelPosition(), saved.getYOffset());
 	    return true;
 	} else if ( keyCode == KeyEvent.KEYCODE_SEARCH ) {