Refactor custom views

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

@@ -22,52 +22,93 @@ import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.Paint.Align;
 import android.graphics.Rect;
-import android.support.v4.view.MotionEventCompat;
-import android.view.MotionEvent;
-import android.view.View;
 
 import org.isoron.helpers.ColorHelper;
 import org.isoron.helpers.DateHelper;
-import org.isoron.uhabits.R;
 import org.isoron.uhabits.models.Habit;
 
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.GregorianCalendar;
 
-public class HabitHistoryView extends View
+public class HabitHistoryView extends ScrollableDataView
 {
 
     private Habit habit;
-    private int[] checks;
+    private int[] checkmarks;
-
-    private Context context;
     private Paint pSquareBg, pSquareFg, pTextHeader;
+    private int squareSpacing;
 
-    private int squareSize, squareSpacing;
+    private float squareTextOffset;
-    private int nColumns, offsetWeeks;
+    private float headerTextOffset;
-
-    private int colorPrimary, colorPrimaryBrighter, grey;
-    private Float prevX, prevY;
 
     private String wdays[];
+    private SimpleDateFormat dfMonth;
+    private SimpleDateFormat dfYear;
+
+    private Calendar baseDate;
+    private int nDays;
+    private int todayWeekday;
+    private int colors[];
 
-    public HabitHistoryView(Context context, Habit habit, int squareSize)
+    public HabitHistoryView(Context context, Habit habit, int baseSize)
     {
         super(context);
         this.habit = habit;
-        this.context = context;
-        this.squareSize = squareSize;
 
-        colorPrimary = habit.color;
+        setDimensions(baseSize);
-        colorPrimaryBrighter = ColorHelper.mixColors(colorPrimary, Color.WHITE, 0.5f);
+        createPaints();
-        grey = Color.rgb(230, 230, 230);
+        createColors();
+
+        wdays = DateHelper.getShortDayNames();
+        dfMonth = new SimpleDateFormat("MMM");
+        dfYear = new SimpleDateFormat("yyyy");
+    }
+
+    private void updateDate()
+    {
+        baseDate = new GregorianCalendar();
+        baseDate.add(Calendar.DAY_OF_YEAR, -(dataOffset - 1) * 7);
+
+        nDays = nColumns * 7;
+        todayWeekday = new GregorianCalendar().get(Calendar.DAY_OF_WEEK) % 7;
+
+        baseDate.add(Calendar.DAY_OF_YEAR, -nDays);
+        baseDate.add(Calendar.DAY_OF_YEAR, -todayWeekday);
+    }
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh)
+    {
+        super.onSizeChanged(w, h, oldw, oldh);
+        updateDate();
+    }
+
+    private void createColors()
+    {
+        int primaryColor = habit.color;
+        int primaryColorBright = ColorHelper.mixColors(primaryColor, Color.WHITE, 0.5f);
+        int grey = Color.rgb(230, 230, 230);
+
+        colors = new int[3];
+        colors[0] = grey;
+        colors[1] = primaryColorBright;
+        colors[2] = primaryColor;
+    }
+
+    private void setDimensions(int baseSize)
+    {
+        columnWidth = baseSize;
+        columnHeight = 8 * baseSize;
         squareSpacing = 2;
+    }
 
+    private void createPaints()
+    {
         pTextHeader = new Paint();
         pTextHeader.setColor(Color.LTGRAY);
         pTextHeader.setTextAlign(Align.LEFT);
-        pTextHeader.setTextSize(squareSize * 0.5f);
+        pTextHeader.setTextSize(columnWidth * 0.5f);
         pTextHeader.setAntiAlias(true);
 
         pSquareBg = new Paint();
@@ -76,179 +117,123 @@ public class HabitHistoryView extends View
         pSquareFg = new Paint();
         pSquareFg.setColor(Color.WHITE);
         pSquareFg.setAntiAlias(true);
-        pSquareFg.setTextSize(squareSize * 0.5f);
+        pSquareFg.setTextSize(columnWidth * 0.5f);
         pSquareFg.setTextAlign(Align.CENTER);
 
-        wdays = DateHelper.getShortDayNames();
+        squareTextOffset = pSquareFg.getFontSpacing() * 0.4f;
+        headerTextOffset = pTextHeader.getFontSpacing() * 0.3f;
     }
 
-    @Override
+    protected void fetchData()
-    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
-    {
-        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
-        setMeasuredDimension(getMeasuredWidth(), 8 * squareSize);
-    }
-
-    @Override
-    protected void onSizeChanged(int w, int h, int oldw, int oldh)
-    {
-        nColumns = (w / squareSize) - 1;
-        fetchReps();
-    }
-
-    private void fetchReps()
     {
         Calendar currentDate = new GregorianCalendar();
-        currentDate.add(Calendar.DAY_OF_YEAR, -offsetWeeks * 7);
+        currentDate.add(Calendar.DAY_OF_YEAR, -dataOffset * 7);
         int dayOfWeek = currentDate.get(Calendar.DAY_OF_WEEK) % 7;
 
         long dateTo = DateHelper.getStartOfToday();
         for (int i = 0; i < 7 - dayOfWeek; i++)
             dateTo += DateHelper.millisecondsInOneDay;
 
-        for (int i = 0; i < offsetWeeks * 7; i++)
+        for (int i = 0; i < dataOffset * 7; i++)
             dateTo -= DateHelper.millisecondsInOneDay;
 
         long dateFrom = dateTo;
         for (int i = 0; i < nColumns * 7; i++)
             dateFrom -= DateHelper.millisecondsInOneDay;
 
-        checks = habit.getCheckmarks(dateFrom, dateTo);
+        checkmarks = habit.getCheckmarks(dateFrom, dateTo);
+        updateDate();
     }
 
+    private String previousMonth;
+    private String previousYear;
+    private boolean justPrintedYear;
+
     @Override
     protected void onDraw(Canvas canvas)
     {
         super.onDraw(canvas);
 
-        Rect square = new Rect(0, 0, squareSize - squareSpacing, squareSize - squareSpacing);
+        Rect location = new Rect(0, 0, columnWidth - squareSpacing, columnWidth - squareSpacing);
 
-        Calendar currentDate = new GregorianCalendar();
+        previousMonth = "";
-        currentDate.add(Calendar.DAY_OF_YEAR, -(offsetWeeks - 1) * 7);
+        previousYear = "";
-
+        justPrintedYear = false;
-        int nDays = nColumns * 7;
-        int todayWeekday = new GregorianCalendar().get(Calendar.DAY_OF_WEEK) % 7;
-
-        currentDate.add(Calendar.DAY_OF_YEAR, -nDays);
-        currentDate.add(Calendar.DAY_OF_YEAR, -todayWeekday);
 
-        SimpleDateFormat dfMonth = new SimpleDateFormat("MMM");
+        GregorianCalendar currentDate = (GregorianCalendar) baseDate.clone();
-        SimpleDateFormat dfYear = new SimpleDateFormat("yyyy");
 
-        String previousMonth = "";
+        for (int column = 0; column < nColumns - 1; column++)
-        String previousYear = "";
+        {
+            drawColumn(canvas, location, currentDate, column);
+            location.offset(columnWidth, -columnHeight);
+        }
 
-        int colors[] = {grey, colorPrimaryBrighter, colorPrimary};
+        drawAxis(canvas, location);
-        String markers[] =
+    }
-                {context.getString(R.string.fa_times), context.getString(R.string.fa_check),
-                        context.getString(R.string.fa_check)};
 
-        float squareTextOffset = pSquareFg.getFontSpacing() * 0.4f;
+    private void drawColumn(Canvas canvas, Rect location, GregorianCalendar date, int column)
-        float headerTextOffset = pTextHeader.getFontSpacing() * 0.3f;
+    {
-        boolean justPrintedYear = false;
+        drawColumnHeader(canvas, location, date);
+        location.offset(0, columnWidth);
 
-        int k = nDays;
+        for (int j = 0; j < 7; j++)
-        for (int i = 0; i < nColumns; i++)
         {
-            String month = dfMonth.format(currentDate.getTime());
+            if (!(column == nColumns - 2 && dataOffset == 0 && j > todayWeekday))
-            String year = dfYear.format(currentDate.getTime());
-
-            if (!month.equals(previousMonth))
             {
-                int offset = 0;
+                int checkmarkOffset = nDays - 7 * column - j;
-                if (justPrintedYear) offset += squareSize;
+                drawSquare(canvas, location, date, checkmarkOffset);
-
-                canvas.drawText(month, square.left + offset, square.bottom - headerTextOffset,
-                        pTextHeader);
-                previousMonth = month;
-                justPrintedYear = false;
-            }
-            else if (!year.equals(previousYear))
-            {
-                canvas.drawText(year, square.left, square.bottom - headerTextOffset, pTextHeader);
-                previousYear = year;
-                justPrintedYear = true;
-            }
-            else
-            {
-                justPrintedYear = false;
             }
 
+            date.add(Calendar.DAY_OF_MONTH, 1);
+            location.offset(0, columnWidth);
+        }
+    }
 
-            square.offset(0, squareSize);
+    private void drawSquare(Canvas canvas, Rect location, GregorianCalendar date,
-
+                            int checkmarkOffset)
-            for (int j = 0; j < 7; j++)
+    {
-            {
+        if (checkmarkOffset >= checkmarks.length) pSquareBg.setColor(colors[0]);
-                if (!(i == nColumns - 1 && offsetWeeks == 0 && j > todayWeekday))
+        else pSquareBg.setColor(colors[checkmarks[checkmarkOffset]]);
-                {
-                    if (k >= checks.length) pSquareBg.setColor(colors[0]);
-                    else pSquareBg.setColor(colors[checks[k]]);
-
-                    canvas.drawRect(square, pSquareBg);
-                    canvas.drawText(Integer.toString(currentDate.get(Calendar.DAY_OF_MONTH)),
-                            square.centerX(), square.centerY() + squareTextOffset, pSquareFg);
-                }
-
-                currentDate.add(Calendar.DAY_OF_MONTH, 1);
-                square.offset(0, squareSize);
-                k--;
-            }
 
-            square.offset(squareSize, -8 * squareSize);
+        canvas.drawRect(location, pSquareBg);
-        }
+        String text = Integer.toString(date.get(Calendar.DAY_OF_MONTH));
+        canvas.drawText(text, location.centerX(), location.centerY() + squareTextOffset, pSquareFg);
+    }
 
+    private void drawAxis(Canvas canvas, Rect location)
+    {
         for (int i = 0; i < 7; i++)
         {
-            square.offset(0, squareSize);
+            location.offset(0, columnWidth);
-            canvas.drawText(wdays[i], square.left + headerTextOffset,
+            canvas.drawText(wdays[i], location.left + headerTextOffset,
-                    square.bottom - headerTextOffset, pTextHeader);
+                    location.bottom - headerTextOffset, pTextHeader);
         }
     }
 
-    @Override
+    private void drawColumnHeader(Canvas canvas, Rect location, GregorianCalendar date)
-    public boolean onTouchEvent(MotionEvent event)
     {
-        int action = event.getAction();
+        String month = dfMonth.format(date.getTime());
-
+        String year = dfYear.format(date.getTime());
-        int pointerIndex = MotionEventCompat.getActionIndex(event);
-        final float x = MotionEventCompat.getX(event, pointerIndex);
-        final float y = MotionEventCompat.getY(event, pointerIndex);
 
-        if (action == MotionEvent.ACTION_DOWN)
+        if (!month.equals(previousMonth))
         {
-            prevX = x;
+            int offset = 0;
-            prevY = y;
+            if (justPrintedYear) offset += columnWidth;
-        }
 
-        if (action == MotionEvent.ACTION_MOVE)
+            canvas.drawText(month, location.left + offset, location.bottom - headerTextOffset,
+                    pTextHeader);
+            previousMonth = month;
+            justPrintedYear = false;
+        }
+        else if (!year.equals(previousYear))
         {
-            float dx = x - prevX;
+            canvas.drawText(year, location.left, location.bottom - headerTextOffset, pTextHeader);
-            float dy = y - prevY;
+            previousYear = year;
-
+            justPrintedYear = true;
-            if (Math.abs(dy) > Math.abs(dx)) return false;
-            getParent().requestDisallowInterceptTouchEvent(true);
-            if (move(dx))
-            {
-                prevX = x;
-                prevY = y;
-            }
         }
-
+        else
-        return true;
-    }
-
-    private boolean move(float dx)
-    {
-        int newOffsetWeeks = offsetWeeks + (int) (dx / squareSize);
-        newOffsetWeeks = Math.max(0, newOffsetWeeks);
-
-        if (newOffsetWeeks != offsetWeeks)
         {
-            offsetWeeks = newOffsetWeeks;
+            justPrintedYear = false;
-            fetchReps();
-            invalidate();
-            return true;
         }
-        else return false;
     }
 }

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

@@ -21,9 +21,6 @@ import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.RectF;
-import android.support.v4.view.MotionEventCompat;
-import android.view.MotionEvent;
-import android.view.View;
 
 import org.isoron.helpers.ColorHelper;
 import org.isoron.helpers.DateHelper;
@@ -33,30 +30,23 @@ import org.isoron.uhabits.models.Score;
 import java.text.SimpleDateFormat;
 import java.util.List;
 
-public class HabitScoreView extends View
+public class HabitScoreView extends ScrollableDataView
 {
     public static final int BUCKET_SIZE = 7;
 
     private final Paint pGrid;
     private final float em;
     private Habit habit;
-    private int columnWidth, columnHeight, nColumns;
 
     private Paint pText, pGraph;
-    private int dataOffset;
-
-    private int barHeaderHeight;
 
     private int[] colors;
-    private float prevX;
-    private float prevY;
     private List<Score> scores;
 
     public HabitScoreView(Context context, Habit habit, int columnWidth)
     {
         super(context);
         this.habit = habit;
-        this.columnWidth = columnWidth;
 
         pText = new Paint();
         pText.setColor(Color.LTGRAY);
@@ -75,8 +65,11 @@ public class HabitScoreView extends View
         pGrid.setAntiAlias(true);
         pGrid.setStrokeWidth(columnWidth * 0.05f);
 
+        this.columnWidth = columnWidth;
         columnHeight = 8 * columnWidth;
-        barHeaderHeight = columnWidth;
+        headerHeight = columnWidth;
+        footerHeight = columnWidth;
+
         em = pText.getFontSpacing();
 
         colors = new int[4];
@@ -87,7 +80,7 @@ public class HabitScoreView extends View
         colors[2] = ColorHelper.mixColors(colors[0], colors[3], 0.33f);
     }
 
-    private void fetchScores()
+    protected void fetchData()
     {
 
         long toTimestamp = DateHelper.getStartOfToday();
@@ -102,31 +95,15 @@ public class HabitScoreView extends View
                 BUCKET_SIZE * DateHelper.millisecondsInOneDay, toTimestamp);
     }
 
-    @Override
-    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
-    {
-        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
-        setMeasuredDimension(getMeasuredWidth(), columnHeight + 2 * barHeaderHeight);
-    }
-
-    @Override
-    protected void onSizeChanged(int w, int h, int oldw, int oldh)
-    {
-        super.onSizeChanged(w, h, oldw, oldh);
-        nColumns = w / columnWidth;
-        fetchScores();
-    }
-
     @Override
     protected void onDraw(Canvas canvas)
     {
         super.onDraw(canvas);
 
         float lineHeight = pText.getFontSpacing();
-        float barHeaderOffset = lineHeight * 0.4f;
 
         RectF rGrid = new RectF(0, 0, nColumns * columnWidth, columnHeight);
-        rGrid.offset(0, barHeaderHeight);
+        rGrid.offset(0, headerHeight);
         drawGrid(canvas, rGrid);
 
         SimpleDateFormat dfMonth = new SimpleDateFormat("MMM");
@@ -150,7 +127,7 @@ public class HabitScoreView extends View
 
             RectF r = new RectF(0, 0, columnWidth, columnWidth);
             r.offset(offset * columnWidth,
-                    barHeaderHeight + columnHeight - height - columnWidth / 2);
+                    headerHeight + columnHeight - height - columnWidth / 2);
 
             if (prevR != null)
             {
@@ -163,15 +140,11 @@ public class HabitScoreView extends View
             prevR = r;
 
             r = new RectF(0, 0, columnWidth, columnHeight);
-            r.offset(offset * columnWidth, barHeaderHeight);
+            r.offset(offset * columnWidth, headerHeight);
             if (!month.equals(previousMonth))
-            {
                 canvas.drawText(month, r.centerX(), r.bottom + lineHeight * 1.2f, pText);
-            }
             else
-            {
                 canvas.drawText(day, r.centerX(), r.bottom + lineHeight * 1.2f, pText);
-            }
 
             previousMonth = month;
 
@@ -180,10 +153,6 @@ public class HabitScoreView extends View
 
     private void drawGrid(Canvas canvas, RectF rGrid)
     {
-//        pGrid.setColor(Color.rgb(230, 230, 230));
-//        pGrid.setStyle(Paint.Style.STROKE);
-//        canvas.drawRect(rGrid, pGrid);
-
         int nRows = 5;
         float rowHeight = rGrid.height() / nRows;
 
@@ -220,51 +189,4 @@ public class HabitScoreView extends View
         pGraph.setColor(Color.WHITE);
         canvas.drawOval(rect, pGraph);
     }
-
-    @Override
-    public boolean onTouchEvent(MotionEvent event)
-    {
-        int action = event.getAction();
-
-        int pointerIndex = MotionEventCompat.getActionIndex(event);
-        final float x = MotionEventCompat.getX(event, pointerIndex);
-        final float y = MotionEventCompat.getY(event, pointerIndex);
-
-        if (action == MotionEvent.ACTION_DOWN)
-        {
-            prevX = x;
-            prevY = y;
-        }
-
-        if (action == MotionEvent.ACTION_MOVE)
-        {
-            float dx = x - prevX;
-            float dy = y - prevY;
-
-            if (Math.abs(dy) > Math.abs(dx)) return false;
-            getParent().requestDisallowInterceptTouchEvent(true);
-            if (move(dx))
-            {
-                prevX = x;
-                prevY = y;
-            }
-        }
-
-        return true;
-    }
-
-    private boolean move(float dx)
-    {
-        int newDataOffset = dataOffset + (int) (dx / columnWidth);
-        newDataOffset = Math.max(0, newDataOffset);
-
-        if (newDataOffset != dataOffset)
-        {
-            dataOffset = newDataOffset;
-            fetchScores();
-            invalidate();
-            return true;
-        }
-        else return false;
-    }
 }

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

@@ -21,9 +21,6 @@ import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.Rect;
-import android.support.v4.view.MotionEventCompat;
-import android.view.MotionEvent;
-import android.view.View;
 
 import org.isoron.helpers.ColorHelper;
 import org.isoron.uhabits.models.Habit;
@@ -32,29 +29,43 @@ import org.isoron.uhabits.models.Streak;
 import java.text.SimpleDateFormat;
 import java.util.List;
 
-public class HabitStreakView extends View
+public class HabitStreakView extends ScrollableDataView
 {
     private Habit habit;
-    private int columnWidth, columnHeight, nColumns;
-
     private Paint pText, pBar;
     private List<Streak> streaks;
-    private int dataOffset;
-
     private long maxStreakLength;
-
-    private int barHeaderHeight;
-
     private int[] colors;
-    private float prevX;
-    private float prevY;
 
     public HabitStreakView(Context context, Habit habit, int columnWidth)
     {
         super(context);
         this.habit = habit;
-        this.columnWidth = columnWidth;
 
+        setDimensions(columnWidth);
+        createPaints();
+        createColors();
+    }
+
+    private void setDimensions(int baseSize)
+    {
+        this.columnWidth = baseSize;
+        columnHeight = 8 * baseSize;
+        headerHeight = baseSize;
+        footerHeight = baseSize;
+    }
+
+    private void createColors()
+    {
+        colors = new int[4];
+        colors[0] = Color.rgb(230, 230, 230);
+        colors[3] = habit.color;
+        colors[1] = ColorHelper.mixColors(colors[0], colors[3], 0.66f);
+        colors[2] = ColorHelper.mixColors(colors[0], colors[3], 0.33f);
+    }
+
+    private void createPaints()
+    {
         pText = new Paint();
         pText.setColor(Color.LTGRAY);
         pText.setTextAlign(Paint.Align.CENTER);
@@ -65,21 +76,9 @@ public class HabitStreakView extends View
         pBar.setTextAlign(Paint.Align.CENTER);
         pBar.setTextSize(columnWidth * 0.5f);
         pBar.setAntiAlias(true);
-
-        columnHeight = 8 * columnWidth;
-        barHeaderHeight = columnWidth;
-
-        colors = new int[4];
-
-        colors[0] = Color.rgb(230, 230, 230);
-        colors[3] = habit.color;
-        colors[1] = ColorHelper.mixColors(colors[0], colors[3], 0.66f);
-        colors[2] = ColorHelper.mixColors(colors[0], colors[3], 0.33f);
-
-        fetchStreaks();
     }
 
-    private void fetchStreaks()
+    protected void fetchData()
     {
         streaks = habit.getStreaks();
 
@@ -87,19 +86,6 @@ public class HabitStreakView extends View
             maxStreakLength = Math.max(maxStreakLength, s.length);
     }
 
-    @Override
-    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
-    {
-        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
-        setMeasuredDimension(getMeasuredWidth(), columnHeight + 2 * barHeaderHeight);
-    }
-
-    @Override
-    protected void onSizeChanged(int w, int h, int oldw, int oldh)
-    {
-        super.onSizeChanged(w, h, oldw, oldh);
-        nColumns = w / columnWidth;
-    }
 
     @Override
     protected void onDraw(Canvas canvas)
@@ -126,7 +112,7 @@ public class HabitStreakView extends View
 
             int height = (int) (columnHeight * lRelative);
             Rect r = new Rect(0, 0, columnWidth - 2, height);
-            r.offset(offset * columnWidth, barHeaderHeight + columnHeight - height);
+            r.offset(offset * columnWidth, headerHeight + columnHeight - height);
 
             canvas.drawRect(r, pBar);
             canvas.drawText(Long.toString(l), r.centerX(), r.top - barHeaderOffset, pBar);
@@ -137,50 +123,4 @@ public class HabitStreakView extends View
             previousMonth = month;
         }
     }
-
-    @Override
-    public boolean onTouchEvent(MotionEvent event)
-    {
-        int action = event.getAction();
-
-        int pointerIndex = MotionEventCompat.getActionIndex(event);
-        final float x = MotionEventCompat.getX(event, pointerIndex);
-        final float y = MotionEventCompat.getY(event, pointerIndex);
-
-        if (action == MotionEvent.ACTION_DOWN)
-        {
-            prevX = x;
-            prevY = y;
-        }
-
-        if (action == MotionEvent.ACTION_MOVE)
-        {
-            float dx = x - prevX;
-            float dy = y - prevY;
-
-            if (Math.abs(dy) > Math.abs(dx)) return false;
-            getParent().requestDisallowInterceptTouchEvent(true);
-            if (move(dx))
-            {
-                prevX = x;
-                prevY = y;
-            }
-        }
-
-        return true;
-    }
-
-    private boolean move(float dx)
-    {
-        int newDataOffset = dataOffset + (int) (dx / columnWidth);
-        newDataOffset = Math.max(0, Math.min(streaks.size() - nColumns, newDataOffset));
-
-        if (newDataOffset != dataOffset)
-        {
-            dataOffset = newDataOffset;
-            invalidate();
-            return true;
-        }
-        else return false;
-    }
 }

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

@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2016 Alinson Santos Xavier
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied  warranty of MERCHANTABILITY or
+ * FITNESS  FOR  A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You  should  have  received  a  copy  of the GNU General Public License
+ * along  with  this  program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ */
+
+package org.isoron.uhabits.views;
+
+import android.content.Context;
+import android.support.v4.view.MotionEventCompat;
+import android.view.MotionEvent;
+import android.view.View;
+
+public abstract class ScrollableDataView extends View
+{
+
+    protected int dataOffset;
+    protected int nColumns;
+    protected int columnWidth, columnHeight;
+    protected int headerHeight, footerHeight;
+
+    private float prevX, prevY;
+
+    public ScrollableDataView(Context context)
+    {
+        super(context);
+    }
+
+    protected abstract void fetchData();
+
+    protected boolean move(float dx)
+    {
+        int newDataOffset = dataOffset + (int) (dx / columnWidth);
+        newDataOffset = Math.max(0, newDataOffset);
+
+        if (newDataOffset != dataOffset)
+        {
+            dataOffset = newDataOffset;
+            fetchData();
+            invalidate();
+            return true;
+        }
+        else return false;
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event)
+    {
+        int action = event.getAction();
+
+        int pointerIndex = MotionEventCompat.getActionIndex(event);
+        final float x = MotionEventCompat.getX(event, pointerIndex);
+        final float y = MotionEventCompat.getY(event, pointerIndex);
+
+        if (action == MotionEvent.ACTION_DOWN)
+        {
+            prevX = x;
+            prevY = y;
+        }
+
+        if (action == MotionEvent.ACTION_MOVE)
+        {
+            float dx = x - prevX;
+            float dy = y - prevY;
+
+            if (Math.abs(dy) > Math.abs(dx)) return false;
+            getParent().requestDisallowInterceptTouchEvent(true);
+            if (move(dx))
+            {
+                prevX = x;
+                prevY = y;
+            }
+        }
+
+        return true;
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
+    {
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+        setMeasuredDimension(getMeasuredWidth(), columnHeight + headerHeight + footerHeight);
+    }
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh)
+    {
+        super.onSizeChanged(w, h, oldw, oldh);
+        nColumns = w / columnWidth;
+        fetchData();
+    }
+}