Bar chart using achartengine

Question

I want to draw a bar chart which contains five individual bars - I have used Achartengine. I am able to display all five bars in the same color but I want to differentiate one bar with a different color, but I cant display more than one color. Please show me how to display different colors. My code...

         values.add(new double[] {21,56,33,10,20});         
        int[] colors = new int[] { Color.rgb(227, 121, 15) };
        XYMultipleSeriesRenderer renderer = buildBarRenderer(colors);
        setChartSettings(renderer, "", "", "", 0,5, 0,100, Color.WHITE, Color.WHITE);
        renderer.setXLabels(8);
        renderer.setYLabels(10);
        renderer.setDisplayChartValues(true);
       mChartView= ChartFactory.getBarChartView(context, buildBarDataset(titles, values), renderer,
            Type.DEFAULT);
        layout.addView(mChartView, 350, 500);

Answer 1

Can be achieved by extending the SimpleSeriesRenderer and BarChart classes. Here is my solution for RangeBarChart (all thanks to gilenodm, wish I had some reputation to upvote your answer):

import org.achartengine.renderer.SimpleSeriesRenderer;
public class AdvancedSeriesRenderer extends SimpleSeriesRenderer
{
    private int []  colors;

    public void AdvancedSeriesRenderer ()
    {
    }

    public int getColor ( int position )
    {
        return colors[position];
    }
}

import org.achartengine.chart.RangeBarChart;
import org.achartengine.model.XYMultipleSeriesDataset;
import org.achartengine.renderer.SimpleSeriesRenderer;
import org.achartengine.renderer.XYMultipleSeriesRenderer;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;

public class AdvancedRangeBarChart extends RangeBarChart
{
    private int []  barChartColors;

    public AdvancedRangeBarChart ( XYMultipleSeriesDataset dataset, XYMultipleSeriesRenderer renderer, Type type )
    {
        super ( dataset, renderer, type );
    }

    public void setColors ( int [] colorsIn )
    {
        barChartColors = colorsIn;
    }

    @Override
    public void drawSeries ( Canvas canvas, Paint paint, float [] points, SimpleSeriesRenderer seriesRenderer, float yAxisValue, int seriesIndex, int startIndex )
    {
        int seriesNr = mDataset.getSeriesCount ();
        int length = points.length;
        paint.setStyle ( Style.FILL );
        float halfDiffX = getHalfDiffX ( points, length, seriesNr );
        int start = 0;
        if ( startIndex > 0 )
        {
            start = 2;
        }
        for ( int i = start; i < length; i += 4 )
        {
            int colorIndex = (int) ( i / 4 ) % barChartColors.length;
            paint.setColor ( barChartColors[colorIndex] );
            if ( points.length > i + 3 )
            {
                float xMin = points[i];
                float yMin = points[i + 1];
                // xMin = xMax
                float xMax = points[i + 2];
                float yMax = points[i + 3];
                drawBar ( canvas, xMin, yMin, xMax, yMax, halfDiffX, seriesNr, seriesIndex, paint );
            }
        }
    }
}

Answer 2

You have to use different SimpleSeriesRenderer inside buildBarRenderer() call, and define as many serie as the desired number of colors, this way (replacing your first two lines of code):

values.add(new double[] {21});  
values.add(new double[] {56});  
values.add(new double[] {33});  
//ETC.
int[] colors = new int[] { Color.rgb(227, 121, 15),
                           Color.rgb(227, 121, 227), 
                           Color.rgb(127, 121, 127) };

The rest of code should be same as yours, but I haven't tested it. AFAIK you need different series, because every serie can only have one color.

Answer 3

It's been a while since I use achartengine, but I think each series has to have its own colour. As a workaround, you could make the bar that you want to differentiate a member of its own series, and set a different colour for that series. Perhaps someone else has a better way though.

Answer 4

I made a hack to achieve this effect. Org.achartengine.SimpleSeriesRenderer changed the class, I added an int[] colors and a boolean multipleColorsEnabled with its getters and setters. So, I changed, org.achartengine.BarChart in class, the method drawSeries, where is set the color of each bar in a loop, as follows:

int j = startIndex;
for (int i = 0; i < length; i += 2) {
    if (seriesRenderer.isMultipleColorsEnabled()) {
        paint.setColor(seriesRenderer.getColors()[j++]);
    } else {
        paint.setColor(seriesRenderer.getColor());
    }
    float x = points[i];
    float y = points[i + 1];
    drawBar(canvas, x, yAxisValue, x, y, halfDiffX, seriesNr,
        seriesIndex, paint);
}

In the class that loads the data used:

seriesRenderer.setMultipleColorsEnabled(true);
seriesRenderer.setColors(myColors);