Show Top Labels

Customize Top Labels
Set Color
Set Sort Order
Set Column/Bar Width
Hide Zero-Value Data Points

Data Mapping
Before a chart is actually created, we need to specify the data mapping information to EspressChart. To do so, we can create an instance of the colInfo class and include this in the QbChart constructor that we will call.

Explanation:
Series: Let’s assume we have four sets of two-dimensional data of the same subject (category). If we plot these four sets of data on the same graph, we would have a "series" of four data sets.  Pie charts do not support series.

Category & Value: If category is the base, the corresponding data will be value. In a vertical column chart, the columns are separated by the category data, X-Axis, while the height represents the value data, Y-Axis. Value data are usually numerical while category data are not necessarily numerical. Category data can be numbers, time, date, or alphabets, i.e. names, groups... etc.

Sub value: also referred to as "2^nd value" in EspressChart Designer, sub value index let EspressChart know where to obtain the value of a combination chart.

// Create an colInfo object that specifies infomation on data mapping
// ColInfo(int series, int category, int sumBy, int value, int subvalue)
int series = -1; // use –1 if no series
int category = 0; // category data in column 1, thus, index 0
int sumBy = -1; // use –1 if not used
int value = 2; // value data in column 3, thus, index 2
int subvalue = -1; // not plotting a combination chart, use –1
ColInfo sampleColInfo = new ColInfo(series, category, sumBy, value, subvalue);

// Alternatively, a ColInfo object can be constructed as below
ColInfo sampleColInfo = new ColInfo();
sampleColInfo.category=0;
sampleColInfo.value=2;
// QbChart(java.applet.Applet applet, int dimension, int chartType,
// IDatabaseInfo dbinfo, IColumnMap cmap, java.lang.String template)
QbChart chart = new QbChart( null, QbChart.VIEW2D, QbChart.BAR,
yourData, sampleColInfo, null);

For example, consider the following data
 
 

Name	Year	Units Ordered	Unit Sold
James	1999	34	30
James	2000	43	32
Peter	1999	23	21
Peter	2000	54	39

Sample Data

The following ColInfo can be mapped

ColInfo colInfo = new ColInfo();
colInfo.category=0;    // The Name column
colInfo.series=1;        // The Year column
colInfo.value=2;        // The Units Ordered column
colInfo.subvalue=3;        // The Units Sold column

// enable speed key (Ctrl + R) to data refresh,
// right click pop-up menu will still work
chart.setRefreshEnabled(true);

// create an IDataPointSet object, "hDataPoints"
// that has a handle on the chart’s DataPoints
IDataPointSet hDataPoints = chart.gethDataPoints();

Show Top Labels

 
// show top labels
hDataPoints.gethLabel.setVisible(true);

// show top labels for secondary axis
hDataPoints.gethSecondaryLabel().setVisible(true);

Customize Top Labels
 
// implement the IDataLabelInfo class to customize top labels
// the following example attaches a "POS : " to the original string
// of values if the data is positive, and a "NEG : " otherwise.
class LabelInfo implements IDataLabelInfo {
public String getDataLabel(PickData pickData, String originalLabel) {
return (pickData.value > 0 ? "POS : " : "NEG : ") + originalLabel;
}
}

// and in your main program create LabelInfo object and pass it to QbChart
IDataLabelInfo dataLabelInfo = new LabelInfo();
chart.gethDataPoints().setDataLabelInfo(dataLabelInfo);

// For secondary label
chart.gethDataPoints().setSecondaryDataLabelInfo(dataLabelInfo);
 

Set Color
 
// set data points’ color, use void setColors(java.awt.Color[] color)
// color array dimension must be equal to the number of data point objects
Color[] colorSet = new Color{Color.yellow, Color.red, Color.blue, Color.cyan};
hDataPoints.setColors(colorSet);
 
Set Sort Order
 
// sort value data, use public void setValueSortOrder(int type)
// QbChart.ASCENDING, or DESCENDING
hDataPoints.setValueSortOrder( QbChart.ASCENDING);
// sort data, use public void setSortOrder(int seriesType, int type);
// QbChart.VALUE, CATEGORY, or SERIES
hDataPoints.setSortOrder( QbChart.CATEGORY, QbChart.ASCENDING);
try {
// re-draws the chart based on the new ordering scheme
chart.refresh();
} catch (Exception e) { e.printStackTrace(); }
 
Set Column/Bar Width
 
// sets the ratio of the the column/bar width to the gap between two consecutive columns/bars.  Range is from 0 to 10
hDataPoints.setBarGapToWidthRatio( 3.0f );
 
Hide Zero-Value Data Points
 
// set data to be null if it is zero, so they would not show
// up in the chart as a thick black line
hDataPoints.setZeroAsNullData(true);

// create upper and lower bounds objects
java.sql.Date lower = new java.sql.Date(100, currentMonth, startingDay);
java.sql.Date upper = new java.sql.Date(100, currentMonth, endingDay);

// Enable Zooming, can be either DAY, MONTH, or YEAR
IZoomInfo hZoomInfo = chart.gethZoomInfo();
hZoomInfo.setMinScale(1, IZoomInfo.DAY);
hZoomInfo.setMaxScale(7, IZoomInfo.DAY);
hZoomInfo.setScale(1, IZoomInfo.DAY);
hZoomInfo.setZoomEnabled(true);

// EspressChart would "add" when combining 2 data points into 1.
// Available aggregate operators are SUM, AVG, COUNT, MIN and MAX
hZoomInfo.setAggregateOperator(IZoomInfo.SUM);

// if secondary value exists, then secondary aggregate operator is required
hZoomInfo.setSecondaryAggregateOperator(IZoomInfo.SUM);

// setting upper and lower bounds for the chart created
hZoomInfo.setLowerBound(lower);
hZoomInfo.setUpperBound(upper);

// Set Linear Scale to be true
hZoomInfo.setLinearScale(true);

// Create DrillDown Chart
// create an IDrillDown object, "hDrillDown",
// that has a handle on the chart’s DrillDown properties
IDrillDown hDrillDown = chart.gethDrillDown();

// EspressChart would "add" when combining 2 data points into 1
// Available aggregate operators are SUM, AVG, COUNT, MIN and MAX
hDrillDown.setAggregateOperator(hDrillDown.SUM);

// set drill down level template name
// first level will be "book_1.tpl", second level: "book_2.tpl"....
hDrillDown.setDrillName("book_");

try {

// addDrillDown(chartType, categoryIndex, seriesIndex,
// sumbyIndex, is2DChart)
hDrillDown.addDrillDown(QbChart.COL, 3, -1, -1, true);
// second level of drilldown
hDrillDown.addDrillDown(QbChart.COL, 2, 1, -1, true);
} catch (Exception ex) {
System.out.println("Cannot create the drill down chart");
ex.printStackTrace();
}

// alternatively, an EspressChart chart can be set up to let the users
// specify DrillDown at run time. Simply enable the dynamic
// drilldown option
// create an IDrillDown object, "hDrillDown",
// that has a handle on the chart’s DrillDown properties
IDrillDown hDrillDown = chart.gethDrillDown();

// EspressChart would "add" when combining 2 data points into 1
// Available aggregate operators are SUM, AVG, COUNT, MIN and MAX
hDrillDown.setAggregateOperator(hDrillDown.SUM);

// set drill down level template name
// "book_1.tpl" will be applied to all the drill down levels
hDrillDown.setDrillName("book_1");

try {

hDrillDown.setDynamicDrillDown(true);
} catch(Exception ex) {
ex.printStackTrace();
}

// declare constant String object
String TARGET = "EspressChart";

// create an IHyperLinkSet object, "hHyperLinks" that
// has a handle on the chart’s HyperLinks
IHyperLinkSet hHyperLinks = chart.gethHyperLinks();

//links for the Mary category "day" & hint box
// new HyperLink(series, category, sumBy, url, target);
HyperLink temp = new HyperLink( "day","Mary","",

"help/examples/data/scatter2d.cht", TARGET);


// set the hint box message
temp.setHintValue("Click Here for Mary’s data during days" );

// add the hyperlink to the set
hHyperLinks.add(temp);

// links for both Mary & Peter "night", note the second argument is
// empty, "", to include all data
hHyperLinks.add(new HyperLink( "night","","",

"http://www.quadbase.com", TARGET));


// revise new link location for Mary "night"
hHyperLinks.add(new HyperLink( "night","Mary","",

"help/examples/data/pie3d.cht",TARGET));

// Set Histogram parameters
// create an IHistogramInfo object, "hHistogramInfo", that
// has a handle on the chart’s HistogramInfo properties
IHistogramInfo hHistogramInfo = chart.gethHistogramInfo();

// set the lower & upper bounds to null to include all data points
hHistogramInfo.setLowerBound(null);
hHistogramInfo.setUpperBound(null);

// set the scale step to 1
hHistogramInfo.setScale(new Integer(1));

// show histogram in a linear scale
hHistogramInfo.setHistogram(true);
hHistogramInfo.setLinearScale(true);

// set to round data values to show all data points
hHistogramInfo.setRounded(true);