BarHighlighter.java

package com.github.mikephil.charting.highlight;

import com.github.mikephil.charting.components.YAxis;
import com.github.mikephil.charting.data.BarDataSet;
import com.github.mikephil.charting.data.BarEntry;
import com.github.mikephil.charting.interfaces.BarDataProvider;

/**
 * Created by Philipp Jahoda on 22/07/15.
 */
public class BarHighlighter extends ChartHighlighter<BarDataProvider> {

	public BarHighlighter(BarDataProvider chart) {
		super(chart);
	}

	@Override
	public Highlight getHighlight(float x, float y) {

		Highlight h = super.getHighlight(x, y);

		if (h == null)
			return h;
		else {

			BarDataSet set = mChart.getBarData().getDataSetByIndex(h.getDataSetIndex());

			if (set.isStacked()) {

				// create an array of the touch-point
				float[] pts = new float[2];
				pts[1] = y;

				// take any transformer to determine the x-axis value
				mChart.getTransformer(set.getAxisDependency()).pixelsToValue(pts);

				return getStackedHighlight(h, set, h.getXIndex(), h.getDataSetIndex(), pts[1]);
			} else
				return h;
		}
	}

	@Override
	protected int getXIndex(float x) {

		if (!mChart.getBarData().isGrouped()) {
			return super.getXIndex(x);
		} else {

			float baseNoSpace = getBase(x);

			int setCount = mChart.getBarData().getDataSetCount();
			int xIndex = (int) baseNoSpace / setCount;

			int valCount = mChart.getData().getXValCount();

			if (xIndex < 0)
				xIndex = 0;
			else if (xIndex >= valCount)
				xIndex = valCount - 1;

			return xIndex;
		}
	}

	@Override
	protected int getDataSetIndex(int xIndex, float x, float y) {

		if (!mChart.getBarData().isGrouped()) {
			return 0;
		} else {

			float baseNoSpace = getBase(x);

			int setCount = mChart.getBarData().getDataSetCount();
			int dataSetIndex = (int) baseNoSpace % setCount;

			if (dataSetIndex < 0)
				dataSetIndex = 0;
			else if (dataSetIndex >= setCount)
				dataSetIndex = setCount - 1;

			return dataSetIndex;
		}
	}

	/**
	 * This method creates the Highlight object that also indicates which value of a stacked BarEntry has been selected.
	 *
	 * @param old
	 *            the old highlight object before looking for stacked values
	 * @param set
	 * @param xIndex
	 * @param dataSetIndex
	 * @param yValue
	 * @return
	 */
	protected Highlight getStackedHighlight(Highlight old, BarDataSet set, int xIndex, int dataSetIndex, double yValue) {

		BarEntry entry = set.getEntryForXIndex(xIndex);

		if (entry == null || entry.getVals() == null)
			return old;

		Range[] ranges = getRanges(entry);
		int stackIndex = getClosestStackIndex(ranges, (float) yValue);

		Highlight h = new Highlight(xIndex, dataSetIndex, stackIndex, ranges[stackIndex]);
		return h;
	}

	/**
	 * Returns the index of the closest value inside the values array / ranges (stacked barchart) to the value given as
	 * a parameter.
	 *
	 * @param ranges
	 * @param value
	 * @return
	 */
	protected int getClosestStackIndex(Range[] ranges, float value) {

		if (ranges == null)
			return 0;

		int stackIndex = 0;

		for (Range range : ranges) {
			if (range.contains(value))
				return stackIndex;
			else
				stackIndex++;
		}

		int length = ranges.length - 1;

		return (value > ranges[length].to) ? length : 0;
		//
		// float[] vals = e.getVals();
		//
		// if (vals == null)
		// return -1;
		//
		// int index = 0;
		// float remainder = e.getNegativeSum();
		//
		// while (index < vals.length - 1 && value > vals[index] + remainder) {
		// remainder += vals[index];
		// index++;
		// }
		//
		// return index;
	}

	/**
	 * Returns the base x-value to the corresponding x-touch value in pixels.
	 * 
	 * @param x
	 * @return
	 */
	protected float getBase(float x) {

		// create an array of the touch-point
		float[] pts = new float[2];
		pts[0] = x;

		// take any transformer to determine the x-axis value
		mChart.getTransformer(YAxis.AxisDependency.LEFT).pixelsToValue(pts);
		float xVal = pts[0];

		int setCount = mChart.getBarData().getDataSetCount();

		// calculate how often the group-space appears
		int steps = (int) ((float) xVal / ((float) setCount + mChart.getBarData().getGroupSpace()));

		float groupSpaceSum = mChart.getBarData().getGroupSpace() * (float) steps;

		float baseNoSpace = (float) xVal - groupSpaceSum;
		return baseNoSpace;
	}

	/**
	 * Splits up the stack-values of the given bar-entry into Range objects.
	 * 
	 * @param entry
	 * @return
	 */
	protected Range[] getRanges(BarEntry entry) {

		float[] values = entry.getVals();

		if (values == null)
			return null;

		float negRemain = -entry.getNegativeSum();
		float posRemain = 0f;

		Range[] ranges = new Range[values.length];

		for (int i = 0; i < ranges.length; i++) {

			float value = values[i];

			if (value < 0) {
				ranges[i] = new Range(negRemain, negRemain + Math.abs(value));
				negRemain += Math.abs(value);
			} else {
				ranges[i] = new Range(posRemain, posRemain + value);
				posRemain += value;
			}
		}

		return ranges;
	}
}