Added another reorder type to just swap two views without looping through all views between.

.gitignore

@@ -22,6 +22,9 @@ gen/
 build/
 *.iml
 
+# Gradle 
+.gradle/
+
 dynamicgrid/proguard-project.txt
 
 dynamicgrid/build.xml

dynamicgrid/src/org/askerov/dynamicgrid/BaseDynamicGridAdapter.java

@@ -15,6 +15,7 @@ public abstract class BaseDynamicGridAdapter extends AbstractDynamicGridAdapter
 
     private ArrayList<Object> mItems = new ArrayList<Object>();
     private int mColumnCount;
+    private int mReorderType = DynamicGridView.REORDER_TYPE_SNAKE;
 
     protected BaseDynamicGridAdapter(Context context, int columnCount) {
         this.mContext = context;
@@ -39,6 +40,10 @@ public void set(List<?> items) {
         notifyDataSetChanged();
     }
 
+    public void setReorderType(int reorderType) {
+        this.mReorderType = reorderType;
+    }
+
     public void clear() {
         clearStableIdMap();
         mItems.clear();
@@ -94,7 +99,11 @@ public void setColumnCount(int columnCount) {
     @Override
     public void reorderItems(int originalPosition, int newPosition) {
         if (newPosition < getCount()) {
-            DynamicGridUtils.reorder(mItems, originalPosition, newPosition);
+            if(mReorderType == DynamicGridView.REORDER_TYPE_SNAKE) {
+                DynamicGridUtils.reorder(mItems, originalPosition, newPosition);
+            } else if(mReorderType == DynamicGridView.REORDER_TYPE_SWAP) {
+                DynamicGridUtils.swap(mItems, originalPosition, newPosition);
+            }
             notifyDataSetChanged();
         }
     }
@@ -104,6 +113,12 @@ public boolean canReorder(int position) {
         return true;
     }
 
+    @Override
+    public int getReorderType()
+    {
+        return mReorderType;
+    }
+
     public List<Object> getItems() {
         return mItems;
     }

dynamicgrid/src/org/askerov/dynamicgrid/DynamicGridAdapterInterface.java

@@ -30,4 +30,9 @@ public interface DynamicGridAdapterInterface {
      */
     boolean canReorder(int position);
 
+    /**
+     * Determines reorder type.
+     */
+    int getReorderType();
+
 }

dynamicgrid/src/org/askerov/dynamicgrid/DynamicGridView.java

@@ -1,6 +1,11 @@
 package org.askerov.dynamicgrid;
 
-import android.animation.*;
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.AnimatorSet;
+import android.animation.ObjectAnimator;
+import android.animation.TypeEvaluator;
+import android.animation.ValueAnimator;
 import android.annotation.TargetApi;
 import android.content.Context;
 import android.graphics.Bitmap;
@@ -21,14 +26,20 @@
 import android.widget.GridView;
 import android.widget.ListAdapter;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Stack;
 
 /**
  * Author: alex askerov
  * Date: 9/6/13
  * Time: 12:31 PM
  */
 public class DynamicGridView extends GridView {
+    public final static int REORDER_TYPE_SNAKE = 1;
+    public final static int REORDER_TYPE_SWAP = 2;
     private static final int INVALID_ID = -1;
 
     private static final int MOVE_DURATION = 300;
@@ -855,7 +866,7 @@ public boolean onPreDraw() {
                 mTotalOffsetY += mDeltaY;
                 mTotalOffsetX += mDeltaX;
 
-                animateReorder(mOriginalPosition, mTargetPosition);
+                animateSnakeReorder(mOriginalPosition, mTargetPosition);
 
                 assert mMobileView != null;
                 mMobileView.setVisibility(View.VISIBLE);
@@ -913,50 +924,38 @@ private long getId(int position) {
 
     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
     private void animateReorder(final int oldPosition, final int newPosition) {
+        if(getAdapterInterface().getReorderType() == REORDER_TYPE_SNAKE) {
+            animateSnakeReorder(oldPosition, newPosition);
+        } else if(getAdapterInterface().getReorderType() == REORDER_TYPE_SWAP) {
+            animateSwapReorder(oldPosition, newPosition);
+        }
+    }
+
+    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
+    private void animateSnakeReorder(final int oldPosition, final int newPosition) {
         boolean isForward = newPosition > oldPosition;
         List<Animator> resultList = new LinkedList<Animator>();
-        if (isForward) {
-            for (int pos = Math.min(oldPosition, newPosition); pos < Math.max(oldPosition, newPosition); pos++) {
-                View view = getViewForId(getId(pos));
-                if ((pos + 1) % getColumnCount() == 0) {
-                    resultList.add(createTranslationAnimations(view, -view.getWidth() * (getColumnCount() - 1), 0,
-                            view.getHeight(), 0));
-                } else {
-                    resultList.add(createTranslationAnimations(view, view.getWidth(), 0, 0, 0));
-                }
-            }
-        } else {
-            for (int pos = Math.max(oldPosition, newPosition); pos > Math.min(oldPosition, newPosition); pos--) {
-                View view = getViewForId(getId(pos));
-                if ((pos + getColumnCount()) % getColumnCount() == 0) {
-                    resultList.add(createTranslationAnimations(view, view.getWidth() * (getColumnCount() - 1), 0,
-                            -view.getHeight(), 0));
-                } else {
-                    resultList.add(createTranslationAnimations(view, -view.getWidth(), 0, 0, 0));
-                }
-            }
-        }
 
-        AnimatorSet resultSet = new AnimatorSet();
-        resultSet.playTogether(resultList);
-        resultSet.setDuration(MOVE_DURATION);
-        resultSet.setInterpolator(new AccelerateDecelerateInterpolator());
-        resultSet.addListener(new AnimatorListenerAdapter() {
-            @Override
-            public void onAnimationStart(Animator animation) {
-                mReorderAnimation = true;
-                updateEnableState();
-            }
+        for (int pos = Math.min(oldPosition, newPosition); pos < Math.max(oldPosition, newPosition); pos++) {
 
-            @Override
-            public void onAnimationEnd(Animator animation) {
-                mReorderAnimation = false;
-                updateEnableState();
-            }
-        });
-        resultSet.start();
+            int oldViewPosition = isForward ? pos : pos+1;
+            int newViewPosition = isForward ? pos+1 : pos;
+
+            resultList.add(createViewSwapAnimations(oldViewPosition, newViewPosition));
+        }
+
+        startAnimations(resultList);
     }
 
+    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
+    private void animateSwapReorder(final int oldPosition, final int newPosition) {
+
+        List<Animator> resultList = new LinkedList<Animator>();
+
+        resultList.add(createViewSwapAnimations(oldPosition, newPosition));
+
+        startAnimations(resultList);
+    }
 
     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
     private AnimatorSet createTranslationAnimations(View view, float startX, float endX, float startY, float endY) {
@@ -975,6 +974,44 @@ protected void dispatchDraw(Canvas canvas) {
         }
     }
 
+    /**
+     * Basically the old view is set to the new position and
+     * animates it's way from the old position to the new position.
+     * @param oldViewPosition Position of the old view.
+     * @param newViewPosition Position of the new view.
+     * @return
+     */
+    private AnimatorSet createViewSwapAnimations(int oldViewPosition, int newViewPosition) {
+        View viewOld = getViewForId(getId(oldViewPosition));
+        View viewNew = getViewForId(getId(newViewPosition));
+
+        return createTranslationAnimations(viewOld, viewNew.getX()-viewOld.getX(), 0, viewNew.getY()-viewOld.getY(), 0);
+    }
+
+    /**
+     *
+     * @param resultList
+     */
+    private void startAnimations(List<Animator> resultList) {
+        AnimatorSet resultSet = new AnimatorSet();
+        resultSet.playTogether(resultList);
+        resultSet.setDuration(MOVE_DURATION);
+        resultSet.setInterpolator(new AccelerateDecelerateInterpolator());
+        resultSet.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationStart(Animator animation) {
+                mReorderAnimation = true;
+                updateEnableState();
+            }
+
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                mReorderAnimation = false;
+                updateEnableState();
+            }
+        });
+        resultSet.start();
+    }
 
     public interface OnDropListener {
         void onActionDrop();