Improve ListPopupWindow RTL support

- add Javadoc for new method setLayoutDirection()
- fix one issue where the layout direction would not be set
when the popup was recreated

Change-Id: Ic53a8b0d01dc86e03e9bf5f09195af77404dca39

Author: Fabrice Di Meglio

core/java/android/widget/ListPopupWindow.java

@@ -22,6 +22,7 @@
 import android.graphics.drawable.Drawable;
 import android.os.Handler;
 import android.util.AttributeSet;
+import android.util.LocaleUtil;
 import android.util.Log;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
@@ -31,6 +32,8 @@
 import android.view.ViewGroup;
 import android.view.ViewParent;
 
+import java.util.Locale;
+
 /**
  * A ListPopupWindow anchors itself to a host view and displays a
  * list of choices.
@@ -92,6 +95,8 @@ public class ListPopupWindow {
 
     private boolean mModal;
 
+    private int mLayoutDirection;
+
     /**
      * The provided prompt view should appear above list content.
      * 
@@ -193,6 +198,9 @@ public ListPopupWindow(Context context, AttributeSet attrs, int defStyleAttr, in
         mContext = context;
         mPopup = new PopupWindow(context, attrs, defStyleAttr, defStyleRes);
         mPopup.setInputMethodMode(PopupWindow.INPUT_METHOD_NEEDED);
+        // Set the default layout direction to match the default locale one
+        final Locale locale = mContext.getResources().getConfiguration().locale;
+        mLayoutDirection = LocaleUtil.getLayoutDirectionFromLocale(locale);
     }
 
     /**
@@ -1013,6 +1021,8 @@ public void onNothingSelected(AdapterView<?> parent) {
                 mDropDownList.setOnItemSelectedListener(mItemSelectedListener);
             }
 
+            mDropDownList.setLayoutDirection(mLayoutDirection);
+
             dropDownView = mDropDownList;
 
             View hintView = mPromptView;
@@ -1121,9 +1131,18 @@ public void onNothingSelected(AdapterView<?> parent) {
         return listContent + otherHeights;
     }
 
-    public void setLayoutDirection(int resolvedLayoutDirection) {
+    /**
+     * Set the layout direction for this popup. Should be a resolved direction as the
+     * popup as no capacity to do the resolution on his own.
+     *
+     * @param layoutDirection One of {@link View#LAYOUT_DIRECTION_LTR},
+     *   {@link View#LAYOUT_DIRECTION_RTL},
+     *
+     */
+    public void setLayoutDirection(int layoutDirection) {
+        mLayoutDirection = layoutDirection;
         if (mDropDownList != null) {
-            mDropDownList.setLayoutDirection(resolvedLayoutDirection);
+            mDropDownList.setLayoutDirection(mLayoutDirection);
         }
     }