Datetimepicker : Account for RTL locales when formulating Day labels

Doing a simple substring for the first character to generate a single
character day label doesn't work for right-to-left(RTL) and chinese
languages.

Change-Id: Ic7d2a7880179326530830d8deee0f668dde335c8

2 files changed, 42 insertions, 3 deletions

diff --git a/src/com/android/datetimepicker/Utils.java b/src/com/android/datetimepicker/Utils.java
index 4a3110c..0b57f7c 100644
--- a/src/com/android/datetimepicker/Utils.java
+++ b/src/com/android/datetimepicker/Utils.java
@@ -25,6 +25,7 @@ import android.text.format.Time;
 import android.view.View;
 
 import java.util.Calendar;
+import java.util.Locale;
 
 /**
  * Utility helper functions for time and date pickers.
@@ -137,4 +138,20 @@ public class Utils {
 
         return pulseAnimator;
     }
+
+    /**
+     * Determines if the device's current default locale uses right-to-left written script
+     */
+    public static boolean isRtl() {
+        return isRtl(Locale.getDefault());
+    }
+
+    /**
+     * Determines if a particular locale uses right-to-left written script
+     */
+    public static boolean isRtl(Locale locale) {
+        final int directionality = Character.getDirectionality(locale.getDisplayName().charAt(0));
+        return directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT ||
+                directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC;
+    }
 }
diff --git a/src/com/android/datetimepicker/date/MonthView.java b/src/com/android/datetimepicker/date/MonthView.java
index a0f7671..43978b8 100644
--- a/src/com/android/datetimepicker/date/MonthView.java
+++ b/src/com/android/datetimepicker/date/MonthView.java
@@ -552,14 +552,17 @@ public abstract class MonthView extends View {
         int y = getMonthHeaderSize() - (mMonthDayLabelTextSize / 2);
         int dayWidthHalf = (mWidth - mEdgePadding * 2) / (mNumDays * 2);
 
+        boolean isRtl = Utils.isRtl();          // current locale's written script direction
         for (int i = 0; i < mNumDays; i++) {
             int calendarDay = (i + mWeekStart) % mNumDays;
             int x = (2 * i + 1) * dayWidthHalf + mEdgePadding;
 
             mDayLabelCalendar.set(Calendar.DAY_OF_WEEK, calendarDay);
-            String label = mDayLabelCalendar.getDisplayName(Calendar.DAY_OF_WEEK, Calendar.SHORT,
-                            Locale.getDefault()).toUpperCase(Locale.getDefault());
-            canvas.drawText(label.substring(0, 1), x, y, mMonthDayLabelPaint);
+            String dayDisplayName = mDayLabelCalendar.getDisplayName(Calendar.DAY_OF_WEEK,
+                    Calendar.SHORT, Locale.getDefault()).toUpperCase(Locale.getDefault());
+
+            String dayLabel = generateDayLabel(dayDisplayName, isRtl);
+            canvas.drawText(dayLabel, x, y, mMonthDayLabelPaint);
         }
     }
 
@@ -905,4 +908,23 @@ public abstract class MonthView extends View {
     public interface OnDayClickListener {
         public void onDayClick(MonthView view, CalendarDay day);
     }
+
+    /**
+     * Formats a given Day's display name into a single character label
+     *
+     * @param input display name of the day (Saturday, Monday .. etc)
+     * @param isRtl true if the input's written script is right-to-left
+     * @return
+     */
+    private String generateDayLabel(String input, boolean isRtl) {
+        Locale locale = Locale.getDefault();
+        // 'special-case'-ing Chinese languages as their Day labels are written right-to-left
+        if (isRtl || locale.equals(Locale.SIMPLIFIED_CHINESE) ||
+                locale.equals(Locale.TRADITIONAL_CHINESE) ||
+                locale.equals(new Locale("zh", "HK"))) {
+            return input.substring(input.length()-1);
+        } else {
+            return input.substring(0,1);
+        }
+    }
 }