Fix a few issues with header scrolling

app/src/main/java/org/isoron/uhabits/activities/common/views/ScrollableChart.java

@@ -33,7 +33,9 @@ public abstract class ScrollableChart extends View
 
     private int dataOffset;
 
-    private int scrollerBucketSize;
+    private int scrollerBucketSize = 1;
+
+    private int direction = 1;
 
     private GestureDetector detector;
 
@@ -43,10 +45,7 @@ public abstract class ScrollableChart extends View
 
     private ScrollController scrollController;
 
-    public void setScrollController(ScrollController scrollController)
-    {
-        this.scrollController = scrollController;
-    }
+    private int maxDataOffset = 10000;
 
     public ScrollableChart(Context context)
     {
@@ -79,19 +78,6 @@ public abstract class ScrollableChart extends View
         }
     }
 
-    private void updateDataOffset()
-    {
-        int newDataOffset =
-            Math.max(0, scroller.getCurrX() / scrollerBucketSize);
-
-        if(newDataOffset != dataOffset)
-        {
-            dataOffset = newDataOffset;
-            scrollController.onDataOffsetChanged(dataOffset);
-            postInvalidate();
-        }
-    }
-
     @Override
     public boolean onDown(MotionEvent e)
     {
@@ -105,19 +91,44 @@ public abstract class ScrollableChart extends View
                            float velocityY)
     {
         scroller.fling(scroller.getCurrX(), scroller.getCurrY(),
-            (int) velocityX / 2, 0, 0, 100000, 0, 0);
+            direction * ((int) velocityX) / 2, 0, 0, getMaxX(), 0, 0);
         invalidate();
 
         scrollAnimator.setDuration(scroller.getDuration());
         scrollAnimator.start();
-
         return false;
     }
 
+    private int getMaxX()
+    {
+        return maxDataOffset * scrollerBucketSize;
+    }
+
     @Override
-    public void onLongPress(MotionEvent e)
+    public void onRestoreInstanceState(Parcelable state)
     {
+        BundleSavedState bss = (BundleSavedState) state;
+        int x = bss.bundle.getInt("x");
+        int y = bss.bundle.getInt("y");
+        direction = bss.bundle.getInt("direction");
+        dataOffset = bss.bundle.getInt("dataOffset");
+        maxDataOffset = bss.bundle.getInt("maxDataOffset");
+        scroller.startScroll(0, 0, x, y, 0);
+        scroller.computeScrollOffset();
+        super.onRestoreInstanceState(bss.getSuperState());
+    }
 
+    @Override
+    public Parcelable onSaveInstanceState()
+    {
+        Parcelable superState = super.onSaveInstanceState();
+        Bundle bundle = new Bundle();
+        bundle.putInt("x", scroller.getCurrX());
+        bundle.putInt("y", scroller.getCurrY());
+        bundle.putInt("dataOffset", dataOffset);
+        bundle.putInt("direction", direction);
+        bundle.putInt("maxDataOffset", maxDataOffset);
+        return new BundleSavedState(superState, bundle);
     }
 
     @Override
@@ -131,11 +142,14 @@ public abstract class ScrollableChart extends View
             if (parent != null) parent.requestDisallowInterceptTouchEvent(true);
         }
 
-        scroller.startScroll(scroller.getCurrX(), scroller.getCurrY(),
-            (int) -dx, (int) dy, 0);
+
+        dx = - direction * dx;
+        dx = Math.min(dx, getMaxX() - scroller.getCurrX());
+        scroller.startScroll(scroller.getCurrX(), scroller.getCurrY(), (int) dx,
+            (int) dy, 0);
+
         scroller.computeScrollOffset();
         updateDataOffset();
-
         return true;
     }
 
@@ -157,32 +171,35 @@ public abstract class ScrollableChart extends View
         return detector.onTouchEvent(event);
     }
 
-    public void setScrollerBucketSize(int scrollerBucketSize)
+    public void setDirection(int direction)
     {
-        this.scrollerBucketSize = scrollerBucketSize;
+        if (direction != 1 && direction != -1)
+            throw new IllegalArgumentException();
+        this.direction = direction;
     }
 
     @Override
-    public void onRestoreInstanceState(Parcelable state)
+    public void onLongPress(MotionEvent e)
     {
-        BundleSavedState bss = (BundleSavedState) state;
-        int x = bss.bundle.getInt("x");
-        int y = bss.bundle.getInt("y");
-        dataOffset = bss.bundle.getInt("dataOffset");
-        scroller.startScroll(0, 0, x, y, 0);
-        scroller.computeScrollOffset();
-        super.onRestoreInstanceState(bss.getSuperState());
+
     }
 
-    @Override
-    public Parcelable onSaveInstanceState()
+    public void setMaxDataOffset(int maxDataOffset)
     {
-        Parcelable superState = super.onSaveInstanceState();
-        Bundle bundle = new Bundle();
-        bundle.putInt("x", scroller.getCurrX());
-        bundle.putInt("y", scroller.getCurrY());
-        bundle.putInt("dataOffset", dataOffset);
-        return new BundleSavedState(superState, bundle);
+        this.maxDataOffset = maxDataOffset;
+        this.dataOffset = Math.min(dataOffset, maxDataOffset);
+        scrollController.onDataOffsetChanged(this.dataOffset);
+        postInvalidate();
+    }
+
+    public void setScrollController(ScrollController scrollController)
+    {
+        this.scrollController = scrollController;
+    }
+
+    public void setScrollerBucketSize(int scrollerBucketSize)
+    {
+        this.scrollerBucketSize = scrollerBucketSize;
     }
 
     private void init(Context context)
@@ -194,6 +211,20 @@ public abstract class ScrollableChart extends View
         scrollController = new ScrollController() {};
     }
 
+    private void updateDataOffset()
+    {
+        int newDataOffset = scroller.getCurrX() / scrollerBucketSize;
+        newDataOffset = Math.max(0, newDataOffset);
+        newDataOffset = Math.min(maxDataOffset, newDataOffset);
+
+        if (newDataOffset != dataOffset)
+        {
+            dataOffset = newDataOffset;
+            scrollController.onDataOffsetChanged(dataOffset);
+            postInvalidate();
+        }
+    }
+
     public interface ScrollController
     {
         default void onDataOffsetChanged(int newDataOffset) {}

app/src/main/java/org/isoron/uhabits/activities/habits/list/ListHabitsRootView.java

@@ -164,6 +164,7 @@ public class ListHabitsRootView extends BaseRootView
     {
         int count = getCheckmarkCount();
         header.setButtonCount(count);
+        header.setMaxDataOffset(Math.max(MAX_CHECKMARK_COUNT - count, 0));
         listView.setCheckmarkCount(count);
         super.onSizeChanged(w, h, oldw, oldh);
     }

app/src/main/java/org/isoron/uhabits/activities/habits/list/views/HeaderView.java

@@ -34,8 +34,6 @@ import org.isoron.uhabits.utils.*;
 
 import java.util.*;
 
-import static org.isoron.uhabits.utils.InterfaceUtils.*;
-
 public class HeaderView extends ScrollableChart
     implements Preferences.Listener, MidnightTimer.MidnightListener
 {
@@ -52,6 +50,8 @@ public class HeaderView extends ScrollableChart
 
     private RectF rect;
 
+    private int maxDataOffset;
+
     public HeaderView(Context context, AttributeSet attrs)
     {
         super(context, attrs);
@@ -61,18 +61,6 @@ public class HeaderView extends ScrollableChart
             setButtonCount(5);
         }
 
-        StyledResources res = new StyledResources(context);
-        setScrollerBucketSize((int) dpToPixels(context, 42));
-        paint = new TextPaint();
-        paint.setColor(Color.BLACK);
-        paint.setAntiAlias(true);
-        paint.setTextSize(getResources().getDimension(R.dimen.tinyTextSize));
-        paint.setTextAlign(Paint.Align.CENTER);
-        paint.setTypeface(Typeface.DEFAULT_BOLD);
-        paint.setColor(res.getColor(R.attr.mediumContrastTextColor));
-
-        rect = new RectF();
-
         Context appContext = context.getApplicationContext();
         if (appContext instanceof HabitsApplication)
         {
@@ -85,6 +73,21 @@ public class HeaderView extends ScrollableChart
             ListHabitsActivity activity = (ListHabitsActivity) context;
             midnightTimer = activity.getListHabitsComponent().getMidnightTimer();
         }
+
+        Resources res = context.getResources();
+        setScrollerBucketSize((int) res.getDimension(R.dimen.checkmarkWidth));
+        setDirection(shouldReverseCheckmarks() ? 1 : -1);
+
+        StyledResources sr = new StyledResources(context);
+        paint = new TextPaint();
+        paint.setColor(Color.BLACK);
+        paint.setAntiAlias(true);
+        paint.setTextSize(getResources().getDimension(R.dimen.tinyTextSize));
+        paint.setTextAlign(Paint.Align.CENTER);
+        paint.setTypeface(Typeface.DEFAULT_BOLD);
+        paint.setColor(sr.getColor(R.attr.mediumContrastTextColor));
+
+        rect = new RectF();
     }
 
     @Override
@@ -96,6 +99,7 @@ public class HeaderView extends ScrollableChart
     @Override
     public void onCheckmarkOrderChanged()
     {
+        setDirection(shouldReverseCheckmarks() ? 1 : -1);
         postInvalidate();
     }
 
@@ -137,24 +141,26 @@ public class HeaderView extends ScrollableChart
         super.onDraw(canvas);
 
         GregorianCalendar day = DateUtils.getStartOfTodayCalendar();
-
         Resources res = getContext().getResources();
         float width = res.getDimension(R.dimen.checkmarkWidth);
         float height = res.getDimension(R.dimen.checkmarkHeight);
-        rect.set(0, 0, width, height);
-        rect.offset(canvas.getWidth(), 0);
+        boolean reverse = shouldReverseCheckmarks();
 
         day.add(GregorianCalendar.DAY_OF_MONTH, -getDataOffset());
         float em = paint.measureText("m");
 
         for (int i = 0; i < buttonCount; i++)
         {
-            rect.offset(-width, 0);
+            rect.set(0, 0, width, height);
+            rect.offset(canvas.getWidth(), 0);
+            if(reverse) rect.offset(- (i + 1) * width, 0);
+            else rect.offset((i - buttonCount) * width, 0);
+
             String text = DateUtils.formatHeaderDate(day).toUpperCase();
             String[] lines = text.split("\n");
 
-            int y1 = (int)(rect.centerY() - 0.5 * em);
-            int y2 = (int)(rect.centerY() + em);
+            int y1 = (int)(rect.centerY() - 0.25 * em);
+            int y2 = (int)(rect.centerY() + 1.25 * em);
 
             canvas.drawText(lines[0], rect.centerX(), y1, paint);
             canvas.drawText(lines[1], rect.centerX(), y2, paint);