Select first day of week according to the current locale

app/src/main/java/org/isoron/uhabits/helpers/DateHelper.java

@@ -25,9 +25,12 @@ import android.text.format.DateFormat;
 import org.isoron.uhabits.R;
 
 import java.text.SimpleDateFormat;
+import java.util.Calendar;
 import java.util.Date;
 import java.util.GregorianCalendar;
+import java.util.HashMap;
 import java.util.Locale;
+import java.util.Map;
 import java.util.TimeZone;
 
 public class DateHelper
@@ -155,23 +158,122 @@ public class DateHelper
     }
 
 
+    /**
+     * Throughout the code, it is assumed that the weekdays are numbered
+     * from 0 (Saturday) to 6 (Friday).
+     *
+     * see https://github.com/iSoron/uhabits/issues/74
+     *
+     * In the Java Calendar they are numbered from 1 (Sunday) to 7 (Saturday)
+     *
+     * <table>
+     * <thead>
+     * <tr><th>day</th><th>dayNumber</th><th>wdaysIndex</th></tr>
+     * <thead>
+     * <tbody>
+     * <tr><td>Su</td><td>1</td><td>1</td></tr>
+     * <tr><td>Mo</td><td>2</td><td>2</td></tr>
+     * <tr><td>Tu</td><td>3</td><td>3</td></tr>
+     * <tr><td>We</td><td>4</td><td>4</td></tr>
+     * <tr><td>Th</td><td>5</td><td>5</td></tr>
+     * <tr><td>Fr</td><td>6</td><td>6</td></tr>
+     * <tr><td>Sa</td><td>7</td><td>0</td></tr>
+     * </tbody>
+     * </table>
+     *
+     * So we have {@code wdaysIndex = dayNumber % 7}
+     *
+     * @return weekday number in the internal interpretation
+     *
+     * @see #getWeekday(long)
+     * @see java.util.Calendar#SUNDAY
+     *
+     */
+    public static int weekDayNumber2wdays(int number)
+    {
+        return number % 7;
+    }
+
     public static String[] getDayNames(int format)
     {
         String[] wdays = new String[7];
 
-        GregorianCalendar day = new GregorianCalendar();
-        day.set(GregorianCalendar.DAY_OF_WEEK, 0);
+        Calendar day = new GregorianCalendar();
+        // we start with Saturday
+        day.set(GregorianCalendar.DAY_OF_WEEK, Calendar.SATURDAY);
 
-        for (int i = 0; i < 7; i++)
+        for (int i = 0; i < wdays.length; i++)
         {
             wdays[i] = day.getDisplayName(GregorianCalendar.DAY_OF_WEEK, format,
                     Locale.getDefault());
+            // advance in time by one day
             day.add(GregorianCalendar.DAY_OF_MONTH, 1);
         }
 
         return wdays;
     }
 
+
+    /**
+     *
+     * @return array with weekday names starting according to locale settings,
+     * e.g. [Mo,Di,Mi,Do,Fr,Sa,So] in Europe
+     *
+     */
+    public static String[] getLocaleDayNames(int format)
+    {
+        String[] days = new String[7];
+
+        Calendar calendar = new GregorianCalendar();
+        calendar.set(GregorianCalendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek());
+        for (int i = 0; i < days.length; i++)
+        {
+            days[i] = calendar.getDisplayName(GregorianCalendar.DAY_OF_WEEK, format,
+                    Locale.getDefault());
+            // advance in time by one day
+            calendar.add(GregorianCalendar.DAY_OF_MONTH, 1);
+        }
+
+        return days;
+    }
+
+    /**
+     *
+     * @return array with week days numbers starting according to locale settings,
+     * e.g. [2,3,4,5,6,7,1] in Europe
+     *
+     * @see java.util.Calendar#SUNDAY
+     *
+     */
+    public static Integer[] getLocaleWeekdayList()
+    {
+        Integer[] dayNumbers = new Integer[7];
+        // a dummy calendar
+        Calendar calendar = new GregorianCalendar();
+        // set staring day according to locale
+        calendar.set(GregorianCalendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek());
+        for (int i = 0; i < dayNumbers.length; i++) {
+            dayNumbers[i] = calendar.get(GregorianCalendar.DAY_OF_WEEK);
+            // advance in time by one day
+            calendar.add(GregorianCalendar.DAY_OF_MONTH, 1);
+        }
+        return dayNumbers;
+    }
+
+    /**
+     * here we create the mapping of week days numbers into the "wdays"-indices
+     *
+     * @see DateHelper#getDayNames(int)
+     */
+    public static Map<Integer, Integer> getWeekdayMap()
+    {
+        Map<Integer, Integer> number2wdays = new HashMap<>();
+        for (Integer number : getLocaleWeekdayList()) {
+            number2wdays.put(number, number % 7);
+        }
+        return number2wdays;
+    }
+
     public static String formatWeekdayList(Context context, boolean weekday[])
     {
         String shortDayNames[] = getShortDayNames();

app/src/main/java/org/isoron/uhabits/views/HabitFrequencyView.java

@@ -35,6 +35,7 @@ import java.util.Calendar;
 import java.util.Date;
 import java.util.GregorianCalendar;
 import java.util.HashMap;
+import java.util.Map;
 import java.util.Random;
 
 public class HabitFrequencyView extends ScrollableDataView implements HabitDataView
@@ -62,7 +63,6 @@ public class HabitFrequencyView extends ScrollableDataView implements HabitDataV
     private boolean isBackgroundTransparent;
 
     private HashMap<Long, Integer[]> frequency;
-    private String wdays[];
 
     public HabitFrequencyView(Context context)
     {
@@ -89,8 +89,6 @@ public class HabitFrequencyView extends ScrollableDataView implements HabitDataV
         createPaints();
         createColors();
 
-        wdays = DateHelper.getShortDayNames();
-
         dfMonth = DateHelper.getDateFormat("MMM");
         dfYear = DateHelper.getDateFormat("yyyy");
 
@@ -230,11 +228,13 @@ public class HabitFrequencyView extends ScrollableDataView implements HabitDataV
         float rowHeight = rect.height() / 8.0f;
         prevRect.set(rect);
 
-        for (int i = 0; i < 7; i++)
+        Integer[] localeWeekdayList = DateHelper.getLocaleWeekdayList();
+        for (int j = 0; j < localeWeekdayList.length; j++)
         {
             rect.set(0, 0, baseSize, baseSize);
-            rect.offset(prevRect.left, prevRect.top + columnWidth * i);
+            rect.offset(prevRect.left, prevRect.top + columnWidth * j);
 
+            int i = DateHelper.weekDayNumber2wdays(localeWeekdayList[j]);
             if(values != null)
                 drawMarker(canvas, rect, values[i]);
 
@@ -272,9 +272,8 @@ public class HabitFrequencyView extends ScrollableDataView implements HabitDataV
         pText.setColor(textColor);
         pGrid.setColor(dimmedTextColor);
 
-        for (int i = 0; i < nRows; i++)
-        {
-            canvas.drawText(wdays[i], rGrid.right - columnWidth,
+        for (String day : DateHelper.getLocaleDayNames(Calendar.SHORT)) {
+            canvas.drawText(day, rGrid.right - columnWidth,
                     rGrid.top + rowHeight / 2 + 0.25f * em, pText);
 
             pGrid.setStrokeWidth(1f);

app/src/main/java/org/isoron/uhabits/views/HabitHistoryView.java

@@ -40,6 +40,7 @@ import org.isoron.uhabits.tasks.ToggleRepetitionTask;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.GregorianCalendar;
+import java.util.Map;
 import java.util.Random;
 
 public class HabitHistoryView extends ScrollableDataView implements HabitDataView,
@@ -57,13 +58,13 @@ public class HabitHistoryView extends ScrollableDataView implements HabitDataVie
     private float columnHeight;
     private int nColumns;
 
-    private String wdays[];
     private SimpleDateFormat dfMonth;
     private SimpleDateFormat dfYear;
 
     private Calendar baseDate;
     private int nDays;
-    private int todayWeekday;
+    /** 0-based-position of today in the column */
+    private int todayPositionInColumn;
     private int colors[];
     private RectF baseLocation;
     private int primaryColor;
@@ -98,7 +99,6 @@ public class HabitHistoryView extends ScrollableDataView implements HabitDataVie
         isEditable = false;
         checkmarks = new int[0];
         primaryColor = ColorHelper.palette[7];
-        wdays = DateHelper.getShortDayNames();
         dfMonth = DateHelper.getDateFormat("MMM");
         dfYear = DateHelper.getDateFormat("yyyy");
 
@@ -111,10 +111,11 @@ public class HabitHistoryView extends ScrollableDataView implements HabitDataVie
         baseDate.add(Calendar.DAY_OF_YEAR, -(getDataOffset() - 1) * 7);
 
         nDays = (nColumns - 1) * 7;
-        todayWeekday = DateHelper.getStartOfTodayCalendar().get(Calendar.DAY_OF_WEEK) % 7;
+        int realWeekday = DateHelper.getStartOfTodayCalendar().get(Calendar.DAY_OF_WEEK);
+        todayPositionInColumn = (7 + realWeekday - baseDate.getFirstDayOfWeek()) % 7;
 
         baseDate.add(Calendar.DAY_OF_YEAR, -nDays);
-        baseDate.add(Calendar.DAY_OF_YEAR, -todayWeekday);
+        baseDate.add(Calendar.DAY_OF_YEAR, -todayPositionInColumn);
     }
 
     @Override
@@ -155,7 +156,7 @@ public class HabitHistoryView extends ScrollableDataView implements HabitDataVie
     {
         float width = 0;
 
-        for(String w : wdays)
+        for(String w : DateHelper.getLocaleDayNames(Calendar.SHORT))
             width = Math.max(width, pSquareFg.measureText(w));
 
         return width;
@@ -274,9 +275,9 @@ public class HabitHistoryView extends ScrollableDataView implements HabitDataVie
 
         for (int j = 0; j < 7; j++)
         {
-            if (!(column == nColumns - 2 && getDataOffset() == 0 && j > todayWeekday))
+            if (!(column == nColumns - 2 && getDataOffset() == 0 && j > todayPositionInColumn))
             {
-                int checkmarkOffset = getDataOffset() * 7 + nDays - 7 * (column + 1) + todayWeekday - j;
+                int checkmarkOffset = getDataOffset() * 7 + nDays - 7 * (column + 1) + todayPositionInColumn - j;
                 drawSquare(canvas, location, date, checkmarkOffset);
             }
 
@@ -298,10 +299,10 @@ public class HabitHistoryView extends ScrollableDataView implements HabitDataVie
 
     private void drawAxis(Canvas canvas, RectF location)
     {
-        for (int i = 0; i < 7; i++)
+        for (String day : DateHelper.getLocaleDayNames(Calendar.SHORT))
         {
             location.offset(0, columnWidth);
-            canvas.drawText(wdays[i], location.left + headerTextOffset,
+            canvas.drawText(day, location.left + headerTextOffset,
                     location.bottom - headerTextOffset, pTextHeader);
         }
     }