Custom Scatter Labels

This example demonstrates adding custom labels to data points.

The red glassy spheres in this example come from a scatter layer created using XYChart.addScatterLayer.
The custom labels in this example is contained in an array variable, and is added as an extra field to the chart using Layer.addExtraField.
The data label format is set using Layer.setDataLabelFormat to show the extra field.
The font for the data labels is set to 8 points Arial Bold using Layer.setDataLabelStyle.
Layer.setDataLabelStyle returns a TextBox object representing the prototype of the data labels. In this example, the TextBox object is used to customize the background colors, 3D borders, position offsets and alignments of the data labels.

[File: phpdemo/scatterlabels.php]

<?php
require_once("../lib/phpchartdir.php");

# The XY points for the scatter chart
$dataX = array(150, 400, 300, 1500, 800);
$dataY = array(0.6, 8, 5.4, 2, 4);

# The labels for the points
$labels = array("Nano\n100", "SpeedTron\n200 Lite", "SpeedTron\n200",
    "Marathon\nExtra", "Marathon\n2000");

# Create a XYChart object of size 450 x 400 pixels
$c = new XYChart(450, 400);

# Set the plotarea at (55, 40) and of size 350 x 300 pixels, with a light grey border
# (0xc0c0c0). Turn on both horizontal and vertical grid lines with light grey color
# (0xc0c0c0)
$c->setPlotArea(55, 40, 350, 300, 0xffffff, -1, 0xc0c0c0, 0xc0c0c0, -1);

# Add a title to the chart using 18 pts Times Bold Itatic font.
$c->addTitle("Product Comparison Chart", "timesbi.ttf", 18);

# Add a title to the y axis using 12 pts Arial Bold Italic font
$c->yAxis->setTitle("Capacity (tons)", "arialbi.ttf", 12);

# Add a title to the x axis using 12 pts Arial Bold Italic font
$c->xAxis->setTitle("Range (miles)", "arialbi.ttf", 12);

# Set the axes line width to 3 pixels
$c->xAxis->setWidth(3);
$c->yAxis->setWidth(3);

# Add the data as a scatter chart layer, using a 15 pixel circle as the symbol
$layer = $c->addScatterLayer($dataX, $dataY, "", GlassSphereShape, 15, 0xff3333,
    0xff3333);

# Add labels to the chart as an extra field
$layer->addExtraField($labels);

# Set the data label format to display the extra field
$layer->setDataLabelFormat("{field0}");

# Use 8pts Arial Bold to display the labels
$textbox = $layer->setDataLabelStyle("arialbd.ttf", 8);

# Set the background to purple with a 1 pixel 3D border
$textbox->setBackground(0xcc99ff, Transparent, 1);

# Put the text box 4 pixels to the right of the data point
$textbox->setAlignment(Left);
$textbox->setPos(4, 0);

# Output the chart
header("Content-type: image/png");
print($c->makeChart2(PNG));
?>