Adapt with ViewHolder Pattern on adapter

Author: bopbi

README.md

@@ -5,4 +5,5 @@ an Android Parallax ListView item, this effect inspired by sound cloud android a
 the scroll detector is using technique from [http://stackoverflow.com/questions/16791100/detect-scroll-up-scroll-down-in-listview](http://stackoverflow.com/questions/16791100/detect-scroll-up-scroll-down-in-listview)
 
 example video:
-[![VIdeo Example](http://img.youtube.com/vi/BbMvH5jAqA8/0.jpg)](http://www.youtube.com/watch?v=BbMvH5jAqA8)
+
+[![Video Example](http://img.youtube.com/vi/BbMvH5jAqA8/0.jpg)](http://www.youtube.com/watch?v=BbMvH5jAqA8)

app/src/main/java/com/arjunalabs/parallaxlistviewitem/app/ImageListAdapter.java

@@ -36,15 +36,33 @@ public long getItemId(int i) {
     }
 
     @Override
-    public View getView(int i, View view, ViewGroup viewGroup) {
-        ImageView imageView = new ImageView(context);
-        imageView.setLayoutParams(new AbsListView.LayoutParams(AbsListView.LayoutParams.MATCH_PARENT, 300));
-        imageView.setAdjustViewBounds(true);
-        imageView.setScaleType(ImageView.ScaleType.MATRIX);
-        Matrix matrix = imageView.getImageMatrix();
+    public View getView(int position, View convertView, ViewGroup viewGroup) {
+        ViewHolder viewHolder;
+        if (convertView == null) {
+            ImageView imageView = new ImageView(context);
+            imageView.setLayoutParams(new AbsListView.LayoutParams(AbsListView.LayoutParams.MATCH_PARENT, 300));
+            imageView.setAdjustViewBounds(true);
+            imageView.setScaleType(ImageView.ScaleType.MATRIX);
+            Matrix matrix = imageView.getImageMatrix();
+            matrix.postTranslate(0, -100);
+            imageView.setImageMatrix(matrix);
+            imageView.setImageResource(R.drawable.lorempixel);
+            viewHolder = new ViewHolder();
+            convertView = imageView;
+            viewHolder.imageView = imageView;
+            convertView.setTag(viewHolder);
+        }
+        viewHolder = (ViewHolder) convertView.getTag();
+        Matrix matrix = viewHolder.imageView.getImageMatrix();
+        matrix.reset();
         matrix.postTranslate(0, -100);
-        imageView.setImageMatrix(matrix);
-        imageView.setImageResource(R.drawable.lorempixel);
-        return imageView;
+        viewHolder.imageView.setImageMatrix(matrix);
+
+        return convertView;
+    }
+
+    static class ViewHolder {
+        ImageView imageView;
     }
+
 }