Android Open Source - customhellochartdemo Speed Chart Activity

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License

The source code is released under:

Apache License

Java Source Code

package lecho.lib.hellocharts.samples;
//from   www  .j a v  a2s .co  m
import java.util.ArrayList;
import java.util.List;

import lecho.lib.hellocharts.model.Axis;
import lecho.lib.hellocharts.model.Line;
import lecho.lib.hellocharts.model.LineChartData;
import lecho.lib.hellocharts.model.PointValue;
import lecho.lib.hellocharts.model.SimpleValueFormatter;
import lecho.lib.hellocharts.model.Viewport;
import lecho.lib.hellocharts.util.Utils;
import lecho.lib.hellocharts.view.LineChartView;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class SpeedChartActivity extends ActionBarActivity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_tempo_chart);
    if (savedInstanceState == null) {
      getSupportFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();
    }
  }

  public static class PlaceholderFragment extends Fragment {

    private LineChartView chart;
    private LineChartData data;

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      View rootView = inflater.inflate(R.layout.fragment_tempo_chart, container, false);

      chart = (LineChartView) rootView.findViewById(R.id.chart);

      generateSpeedData();

      return rootView;
    }

    private void generateSpeedData() {
      // I got speed in range (0-55) and height in meters in range(200 - 300). I want this chart to display both
      // information. Differences between speed and height values are large and chart doesn't look good so I need
      // to modify height values to be in range of speed values.

      float speedRange = 55;
      float minHeight = 200;
      float maxHeight = 300;

      float scale = speedRange / maxHeight;
      float sub = (minHeight * scale) / 2;

      int numValues = 52;

      Line line;
      List<PointValue> values;
      List<Line> lines = new ArrayList<Line>();

      // Height line, add it as first line to be drawn in the background.
      values = new ArrayList<PointValue>();
      for (int i = 0; i < numValues; ++i) {
        // Some random height values, add +200 to make line a little more natural
        float rawHeight = (float) (Math.random() * 100 + 200);
        float normalizedHeight = rawHeight * scale - sub;
        values.add(new PointValue(i, normalizedHeight));
      }

      line = new Line(values);
      line.setColor(Color.GRAY);
      line.setHasPoints(false);
      line.setFilled(true);
      line.setStrokeWidth(1);
      lines.add(line);

      // Speed line
      values = new ArrayList<PointValue>();
      for (int i = 0; i < numValues; ++i) {
        // Some random speed values, add +20 to make line a little more natural.
        values.add(new PointValue(i, (float) Math.random() * 30 + 20));
      }

      line = new Line(values);
      line.setColor(Utils.COLOR_GREEN);
      line.setHasPoints(false);
      line.setStrokeWidth(3);
      lines.add(line);

      // Data and axes
      data = new LineChartData(lines);

      // Distance axis(bottom X) with formatter that will ad [km] to values, remember to modify max label charts
      // value.
      Axis distanceAxis = new Axis();
      distanceAxis.setName("Distance");
      distanceAxis.setTextColor(Utils.COLOR_ORANGE);
      distanceAxis.setMaxLabelChars(4);
      distanceAxis.setFormatter(new SimpleValueFormatter(0, false, null, "km".toCharArray()));
      distanceAxis.setHasLines(true);
      distanceAxis.setInside(true);
      data.setAxisXBottom(distanceAxis);

      // Speed axis
      data.setAxisYLeft(new Axis().setName("Speed [km/h]").setHasLines(true).setMaxLabelChars(3)
          .setTextColor(Utils.COLOR_RED).setInside(true));

      // Height axis, this axis need custom formatter that will translate values back to real height values.
      data.setAxisYRight(new Axis().setName("Height [m]").setMaxLabelChars(3).setTextColor(Utils.COLOR_BLUE)
          .setFormatter(new HeightValueFormater(scale, sub, 0, null, null)).setInside(true));

      // Set data
      chart.setLineChartData(data);

      // Important: adjust viewport, you could skip this step but in this case it will looks better with custom
      // viewport. Set
      // viewport with Y range 0-55;
      Viewport v = chart.getMaximumViewport();
      v.set(v.left, speedRange, v.right, 0);
      chart.setMaximumViewport(v);
      chart.setCurrentViewport(v, false);

    }

    /**
     * Recalculated height values to display on axis.
     */
    private static class HeightValueFormater extends SimpleValueFormatter {

      private float scale;
      private float sub;

      public HeightValueFormater(float scale, float sub, int digits, char[] prependedText, char[] apendedText) {
        // Don't use auto digits for auto-generated axes, instead use digits number passed in parameter.
        super(digits, true, prependedText, apendedText);
        this.scale = scale;
        this.sub = sub;
      }

      @Override
      public int formatAutoValue(char[] formattedValue, float[] values, int digits) {
        int index = values.length - 1;// I just need last value from this array because SimpleValueFormatter
        // uses only last value and that is enough for axis labels.
        values[index] = (values[index] + sub) / scale;
        return super.formatAutoValue(formattedValue, values, digits);
      }
    }

  }
}

Java Source Code List

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