export index from jni and use for fastscrolling. Works, but is a bit slow still.

xwords4/android/XWords4/jni/xwjni.c

@@ -1266,8 +1266,12 @@ Java_org_eehouse_android_xw4_jni_XwJNI_server_1sendChat
 typedef struct _DictIterData {
     JNIEnv* env;
     JNIUtilCtxt* jniutil;
+    VTableMgr* vtMgr;
     DictionaryCtxt* dict;
     DictWord word;
+    XWStreamCtxt* prefixStream;
+    DictIndex* indices;
+    XP_U16 nIndices;
 #ifdef MEM_DEBUG
     MemPoolCtx* mpool;
 #endif
@@ -1287,6 +1291,7 @@ Java_org_eehouse_android_xw4_jni_XwJNI_dict_1iter_1init
     DictionaryCtxt* dict = makeDict( MPPARM(mpool) env, jniutil, NULL,
                                      jDictBytes, jpath, NULL );
     if ( !!dict ) {
+        data->vtMgr = make_vtablemgr( MPPARM_NOCOMMA(mpool) );
         data->jniutil = jniutil;
         data->dict = dict;
 #ifdef MEM_DEBUG
@@ -1313,6 +1318,13 @@ Java_org_eehouse_android_xw4_jni_XwJNI_dict_1iter_1destroy
     if ( NULL != data ) {
         dict_destroy( data->dict );
         destroyJNIUtil( &data->jniutil );
+        if ( NULL != data->prefixStream ) {
+            stream_destroy( data->prefixStream );
+        }
+        if ( !!data->indices ) {
+            XP_FREE( data->mpool, data->indices );
+        }
+        vtmgr_destroy( MPPARM(data->mpool) data->vtMgr );
 #ifdef MEM_DEBUG
         MemPoolCtx* mpool = data->mpool;
 #endif
@@ -1332,10 +1344,57 @@ Java_org_eehouse_android_xw4_jni_XwJNI_dict_1iter_1wordCount
     if ( NULL != data ) {
         result = data->word.wordCount;
     }
-    LOG_RETURNF( "%d", result );
     return result;
 }
 
+JNIEXPORT void JNICALL
+Java_org_eehouse_android_xw4_jni_XwJNI_dict_1iter_1makeIndex
+( JNIEnv* env, jclass C, jint closure )
+{
+    DictIterData* data = (DictIterData*)closure;
+    if ( NULL != data ) {
+        XP_U16 depth = 2;
+        DictIndex indices[depth*32*32];
+        XWStreamCtxt* stream = mem_stream_make( MPPARM(data->mpool) data->vtMgr,
+                                                NULL, 0, NULL );
+        XP_U16 nIndices = dict_makeIndex( data->dict, depth, indices, VSIZE(indices),
+                                          stream );
+        
+        data->indices = XP_MALLOC( data->mpool, nIndices * sizeof(*data->indices) );
+        XP_MEMCPY( data->indices, indices, nIndices * sizeof(*data->indices) );
+        data->nIndices = nIndices;
+        data->prefixStream = stream;
+    }
+}
+
+JNIEXPORT jstring JNICALL
+Java_org_eehouse_android_xw4_jni_XwJNI_dict_1iter_1getPrefixes
+( JNIEnv* env, jclass C, jint closure )
+{
+    jstring result = NULL;
+    DictIterData* data = (DictIterData*)closure;
+    if ( NULL != data && NULL != data->prefixStream ) {
+        result = streamToJString( MPPARM(data->mpool) env, data->prefixStream );
+        (*env)->DeleteLocalRef( env, result );
+    }
+    return result;
+}
+
+JNIEXPORT jintArray JNICALL
+Java_org_eehouse_android_xw4_jni_XwJNI_dict_1iter_1getIndices
+( JNIEnv* env, jclass C , jint closure )
+{
+    jintArray jindices = NULL;
+    DictIterData* data = (DictIterData*)closure;
+    if ( NULL != data ) {
+        XP_ASSERT( !!data->indices );
+        XP_ASSERT( sizeof(jint) == sizeof(data->indices[0]) );
+        jindices = makeIntArray( env, data->nIndices, data->indices );
+        (*env)->DeleteLocalRef( env, jindices );
+    }
+    return jindices;
+}
+
 JNIEXPORT jstring JNICALL
 Java_org_eehouse_android_xw4_jni_XwJNI_dict_1iter_1nthWord
 ( JNIEnv* env, jclass C, jint closure, jint nn)

xwords4/android/XWords4/src/org/eehouse/android/xw4/DictBrowseActivity.java

@@ -23,12 +23,14 @@ package org.eehouse.android.xw4;
 import android.content.Intent;
 import android.database.DataSetObserver;
 import android.os.Bundle;
+import android.text.TextUtils;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.BaseAdapter;
 import android.widget.ListAdapter;
 import android.widget.SectionIndexer;
 import android.widget.TextView;
+import java.util.Arrays;
 
 import junit.framework.Assert;
 
@@ -51,6 +53,9 @@ public class DictBrowseActivity extends XWListActivity {
     private class DictListAdapter extends BaseAdapter
         implements SectionIndexer {
 
+        private String[] m_prefixes;
+        private int[] m_indices;
+
         public Object getItem( int position ) 
         {
             TextView text = new TextView( DictBrowseActivity.this );
@@ -76,21 +81,36 @@ public class DictBrowseActivity extends XWListActivity {
         // SectionIndexer
         public int getPositionForSection( int section )
         {
-            Utils.logf( "DictBrowseActivity: getPositionForSection" );
+            return m_indices[section];
-            return 0;
         }
         
         public int getSectionForPosition( int position )
         {
-            Utils.logf( "DictBrowseActivity: getSectionForPosition" );
+            int section = Arrays.binarySearch( m_indices, position );
-            return 0;
+            if ( section < 0 ) {
+                section *= -1;
+            }
+            if ( section >= m_indices.length ) {
+                section = m_indices.length - 1;
+            }
+            // for ( section = 0; section < m_indices.length - 1; ++section ) {
+            //     if ( position <= m_indices[section] ) {
+            //         break;
+            //     }
+            // }
+            // Utils.logf( "DictBrowseActivity: getSectionForPosition" );
+            return section;
         }
         
         public Object[] getSections() 
         {
-            Utils.logf( "DictBrowseActivity: getSections" );
+            String prefs = XwJNI.dict_iter_getPrefixes( m_dictClosure );
-            String[] sections = { "AA", "BB", "CC", "DD", "EE" };
+            m_prefixes = TextUtils.split( prefs, "\n" );
-            return sections;
+            m_indices = XwJNI.dict_iter_getIndices( m_dictClosure );
+            Utils.logf( "len(m_indices): %d; len(m_prefixes): %d",
+                        m_indices.length, m_prefixes.length );
+            Assert.assertTrue( m_indices.length == m_prefixes.length );
+            return m_prefixes;
         }
     }
 
@@ -108,6 +128,7 @@ public class DictBrowseActivity extends XWListActivity {
         DictUtils.DictPairs pairs = DictUtils.openDicts( this, names );
         m_dictClosure = XwJNI.dict_iter_init( pairs.m_bytes[0], pairs.m_paths[0],
                                               JNIUtilsImpl.get() );
+        XwJNI.dict_iter_makeIndex( m_dictClosure );
 
         setContentView( R.layout.dict_browser );
         setListAdapter( new DictListAdapter() );

xwords4/android/XWords4/src/org/eehouse/android/xw4/jni/XwJNI.java

@@ -241,4 +241,7 @@ public class XwJNI {
     public static native void dict_iter_destroy( int closure );
     public static native int dict_iter_wordCount( int closure );
     public static native String dict_iter_nthWord( int closure, int nn );
+    public static native void dict_iter_makeIndex( int closure );
+    public static native String dict_iter_getPrefixes( int closure );
+    public static native int[] dict_iter_getIndices( int closure );
 }