MP Android Chart - How to set default number of bars displayed in BarGraph view?

Question

I am new to android development and currently learning how to build charts with hopes of eventually connecting to a DB and creating dynamic charts. I used an example from MPAndroid charts GitHub page (https://github.com/PhilJay/MPAndroidChart/) and am trying to manipulate it to fit my requirements.

Right now my chart has an x-axis (days) and a y-axis (gallons).

For simplicity, I have created an array of strings "Day1" to "Day30" that I use as my X values. Y values are a random number (just to see varying bar sizes).

Currently: My graph displays all 30 days with random Y values and I am able to zoom in and out, as well as scroll left or right when zoomed in.

What I would like: When my graph is built, I would like for the default view of the graph to only show 7 Days (ex. "Day5" through "Day11") but still be able to scroll left or right on the graph to view the other days 1-30. Also , I would like to be able to zoom out from 7 days to a max of 30 days, or zoom in to view a minimum of 3 days.

This is my java file currently. I know its sloppy at the moment, Im learning

public class ConsumptionActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener, OnChartValueSelectedListener, OnSeekBarChangeListener {


    protected BarChart mChart;
    private SeekBar mSeekBarX, mSeekBarY;
    private TextView tvX, tvY;

    private Typeface mTf;
    protected String[] mDays = new String[] {
            "Day 1","Day 2","Day 3","Day 4","Day 5","Day 6","Day 7","Day 8","Day 9","Day 10","Day 11","Day 12","Day 13","Day 14","Day 15",
            "Day 16","Day 17","Day 18","Day 19","Day 20","Day 21","Day 22","Day 23","Day 24","Day 25","Day 26","Day 27","Day 28","Day 29","Day 30"};



    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_consumption);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);


        setSupportActionBar(toolbar);



        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        Intent intent = getIntent();
        LoginAuthentification loggedIn = (LoginAuthentification) intent.getExtras().getSerializable("LoginClass");


        Spinner spinner = (Spinner) findViewById(R.id.accountDropdown);

        SpinnerAdapter snprAdapter = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item, loggedIn.getAccountList());


        spinner.setAdapter(snprAdapter);

// Create an ArrayAdapter using the string array and a default spinner layout
        /*ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.test, android.R.layout.simple_spinner_item);
// Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// Apply the adapter to the spinner
        spinner.setAdapter(adapter);*/
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                // An item was selected. You can retrieve the selected item using
                // parent.getItemAtPosition(pos)
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                // Another interface callback
            }
        });

        ObjectMapper mapper = new ObjectMapper();
        APICalls accountInfo = new APICalls();
        AccountDetails accountInUse = new AccountDetails();


        try {
            accountInUse = mapper.readValue(String.valueOf(accountInfo.AccountDetails(loggedIn.getToken(),loggedIn.getAccountList().get(0))), AccountDetails.class);
        } catch (Exception e) {
            e.printStackTrace();
        }


        /*tvX = (TextView) findViewById(R.id.tvXMax);
        tvY = (TextView) findViewById(R.id.tvYMax);

        mSeekBarX = (SeekBar) findViewById(R.id.seekBar1);
        mSeekBarY = (SeekBar) findViewById(R.id.seekBar2);*/

        mChart = (BarChart) findViewById(R.id.chart1);
        mChart.setOnChartValueSelectedListener(this);

        mChart.setDrawBarShadow(false);
        mChart.setDrawValueAboveBar(true);

        mChart.setDescription("Water Consumption Details");
        mChart.animateXY(8000, 8000);
        // if more than 60 entries are displayed in the chart, no values will be
        // drawn
        mChart.setMaxVisibleValueCount(60);

        // scaling can now only be done on x- and y-axis separately
        mChart.setPinchZoom(false);

        mChart.setDrawGridBackground(true);
        // mChart.setDrawYLabels(false);

        mTf = Typeface.createFromAsset(getAssets(), "OpenSans-Regular.ttf");

        XAxis xAxis = mChart.getXAxis();
        xAxis.setPosition(XAxisPosition.BOTTOM);
        xAxis.setTypeface(mTf);
        xAxis.setDrawGridLines(false);
        xAxis.setSpaceBetweenLabels(2);


        YAxisValueFormatter custom = new MyYAxisValueFormatter();

        YAxis leftAxis = mChart.getAxisLeft();
        leftAxis.setTypeface(mTf);
        leftAxis.setLabelCount(8, false);
        leftAxis.setValueFormatter(custom);
        leftAxis.setPosition(YAxisLabelPosition.OUTSIDE_CHART);
        leftAxis.setSpaceTop(15f);
        leftAxis.setAxisMinValue(0f); // this replaces setStartAtZero(true)

        YAxis rightAxis = mChart.getAxisRight();
        rightAxis.setDrawGridLines(false);
        rightAxis.setTypeface(mTf);
        rightAxis.setLabelCount(8, false);
        rightAxis.setValueFormatter(custom);
        rightAxis.setSpaceTop(15f);
        rightAxis.setAxisMinValue(0f); // this replaces setStartAtZero(true)

        Legend l = mChart.getLegend();
        l.setPosition(Legend.LegendPosition.BELOW_CHART_LEFT);
        l.setForm(Legend.LegendForm.SQUARE);
        l.setFormSize(9f);
        l.setTextSize(11f);
        l.setXEntrySpace(4f);
        //l.setExtra(ColorTemplate.VORDIPLOM_COLORS, new String[] { "abc",
        //"def", "ghj", "ikl", "mno" });
        //l.setCustom(ColorTemplate.VORDIPLOM_COLORS, new String[] { "abc",
        //"def", "ghj", "ikl", "mno" });


        setData(30, 50);

        // setting data
       /* mSeekBarY.setProgress(50);
        mSeekBarX.setProgress(12);

        mSeekBarY.setOnSeekBarChangeListener(this);
        mSeekBarX.setOnSeekBarChangeListener(this);*/

        // mChart.setDrawLegend(false);




/*
        APICalls callsForAll = new APICalls();
        try {
            callsForAll.AccountDetails(token.get(0),token.get(1));
        } catch (Exception e) {
            e.printStackTrace();
        }
        final TextView nameView = (TextView) findViewById(R.id.name);

*/
    }




    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.consumption, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_Alerts) {

        } else if (id == R.id.nav_settings) {

        }
          else if (id == R.id.nav_Logout){

           // LOGOUT LOGIC SHOULD GO HERE
            android.os.Process.killProcess(android.os.Process.myPid());
            System.exit(1);
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

   @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

    }

    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }

    private void setData(int count, float range) {

        ArrayList<String> xVals = new ArrayList<String>();
        for (int i = 0; i < count; i++) {
            xVals.add(mDays[i]);
        }

        ArrayList<BarEntry> yVals1 = new ArrayList<BarEntry>();

        for (int i = 0; i < count; i++) {
            float mult = (range + 1);
            float val = (float) (Math.random() * mult);
            yVals1.add(new BarEntry(val, i));
        }

        BarDataSet set1 = new BarDataSet(yVals1, "DataSet");
        set1.setBarSpacePercent(35f);
        ArrayList<IBarDataSet> dataSets = new ArrayList<IBarDataSet>();
        dataSets.add(set1);
        set1.setColors(new int[]{R.color.neptuneOrange,R.color.colorPrimary});

        BarData data = new BarData(xVals, dataSets);
        data.setValueTextSize(10f);
        data.setValueTypeface(mTf);

        mChart.setData(data);
    }

    @SuppressLint("NewApi")
    @Override
    public void onValueSelected(Entry e, int dataSetIndex, Highlight h) {

        if (e == null)
            return;

        RectF bounds = mChart.getBarBounds((BarEntry) e);
        PointF position = mChart.getPosition(e, AxisDependency.LEFT);

        Log.i("bounds", bounds.toString());
        Log.i("position", position.toString());

        Log.i("x-index",
                "low: " + mChart.getLowestVisibleXIndex() + ", high: "
                        + mChart.getHighestVisibleXIndex());
    }

    public void onNothingSelected() {
    };
}

Answer 1

setMaxVisibleValueCount(int count): Sets the number of maximum visible drawn value-labels on the chart. This only takes affect when setDrawValues() is enabled. Refer to the API