set the graph viewport dynamically

android_app/app/src/main/java/com/health/openscale/core/OpenScale.java

@@ -159,6 +159,10 @@ public class OpenScale {
         return scaleDB.getAllDBEntriesOfMonth(year, month);
     }
 
+    public float getMaxValueOfDBEntries(int year, int month) {
+        return scaleDB.getMaxValueOfDBEntries(year, month);
+    }
+
 	public void startBluetoothServer(String deviceName) {
 		Log.d("OpenScale", "Bluetooth Server started! I am searching for device ...");
 

android_app/app/src/main/java/com/health/openscale/core/ScaleDatabase.java

@@ -146,6 +146,48 @@ public class ScaleDatabase extends SQLiteOpenHelper {
         return numOfMonth;
     }
 
+    public float getMaxValueOfDBEntries(int year, int month) {
+        SQLiteDatabase db = getReadableDatabase();
+
+        Calendar start_cal = Calendar.getInstance();
+        Calendar end_cal = Calendar.getInstance();
+
+        start_cal.set(year, month, 1, 0, 0, 0);
+        end_cal.set(year, month, 1, 0, 0, 0);
+        end_cal.add(Calendar.MONTH, 1);
+
+        String[] projection = {
+                "MAX(" + COLUMN_NAME_WEIGHT + ")",
+                "MAX(" + COLUMN_NAME_FAT + ")",
+                "MAX(" + COLUMN_NAME_WATER + ")",
+                "MAX(" + COLUMN_NAME_MUSCLE + ")"
+        };
+
+        Cursor cursorScaleDB = db.query(
+                TABLE_NAME, 	// The table to query
+                projection, 	// The columns to return
+                COLUMN_NAME_DATE_TIME + " >= ? AND " + COLUMN_NAME_DATE_TIME + " < ? ",            // The columns for the WHERE clause
+                new String[]{formatDateTime.format(start_cal.getTime()), formatDateTime.format(end_cal.getTime())},            // The values for the WHERE clause
+                null, 			// don't group the rows
+                null,			// don't filter by row groups
+                null  		// The sort order
+        );
+
+        cursorScaleDB.moveToFirst();
+
+        float maxValue = -1;
+
+        for (int i=0; i<4; i++)
+        {
+            if (maxValue < cursorScaleDB.getFloat(i))
+            {
+                maxValue =  cursorScaleDB.getFloat(i);
+            }
+        }
+
+        return maxValue;
+    }
+
 
     public ArrayList<ScaleData> getAllDBEntriesOfMonth(int year, int month) {
         SQLiteDatabase db = getReadableDatabase();

android_app/app/src/main/java/com/health/openscale/gui/GraphFragment.java

@@ -117,15 +117,16 @@ public class GraphFragment extends Fragment implements FragmentUpdateListener {
     private void generateLineData(Calendar cal)
     {
         scaleDBEntries = openScale.getAllDataOfMonth(yearCal.get(Calendar.YEAR), cal.get(Calendar.MONTH));
+        float maxValue = openScale.getMaxValueOfDBEntries(yearCal.get(Calendar.YEAR), cal.get(Calendar.MONTH));
 
         SimpleDateFormat day_date = new SimpleDateFormat("dd", Locale.getDefault());
 
         cal.set(Calendar.DAY_OF_MONTH, 1);
-        int max_days = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
+        int maxDays = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
 
         List<AxisValue> axisValues = new ArrayList<AxisValue>();
 
-        for (int i=0; i<max_days; i++) {
+        for (int i=0; i<maxDays; i++) {
             String day_name = day_date.format(cal.getTime());
 
             axisValues.add(new AxisValue(i, day_name.toCharArray()));
@@ -212,7 +213,13 @@ public class GraphFragment extends Fragment implements FragmentUpdateListener {
         chartTop.setLineChartData(lineData);
         chartTop.setViewportCalculationEnabled(false);
 
-        Viewport v = new Viewport(0, 110, max_days, 0);
+        if (maxValue == 0.0) {
+            maxValue = 100;
+        } else {
+            maxValue += 20;
+        }
+
+        Viewport v = new Viewport(0, (int)maxValue, maxDays, 0);
         chartTop.setMaximumViewport(v);
         chartTop.setCurrentViewport(v, true);