/**
* Returns the range of values the renderer requires to display all the items from the specified
* dataset.
*
* @param dataset the dataset (<code>null</code> permitted).
* @return The range (or <code>null</code> if the dataset is <code>null</code> or empty).
*/
@Override
public Range findRangeBounds(XYDataset dataset) {
if (dataset == null) {
return null;
}
double min = Double.POSITIVE_INFINITY;
double max = Double.NEGATIVE_INFINITY;
TableXYDataset d = (TableXYDataset) dataset;
int itemCount = d.getItemCount();
for (int i = 0; i < itemCount; i++) {
double[] stackValues = getStackValues((TableXYDataset) dataset, d.getSeriesCount(), i);
min = Math.min(min, stackValues[0]);
max = Math.max(max, stackValues[1]);
}
if (min == Double.POSITIVE_INFINITY) {
return null;
}
return new Range(min, max);
}
/**
* Calculates the stacked values (one positive and one negative) of all series up to, but not
* including, <code>series</code> for the specified item. It returns [0.0, 0.0] if <code>series
* </code> is the first series.
*
* @param dataset the dataset (<code>null</code> not permitted).
* @param series the series index.
* @param index the item index.
* @return An array containing the cumulative negative and positive values for all series values
* up to but excluding <code>series</code> for <code>index</code>.
*/
private double[] getStackValues(TableXYDataset dataset, int series, int index) {
double[] result = new double[2];
for (int i = 0; i < series; i++) {
double v = dataset.getYValue(i, index);
if (!Double.isNaN(v)) {
if (v >= 0.0) {
result[1] += v;
} else {
result[0] += v;
}
}
}
return result;
}