Glass Multi-Bar Chart

This example demonstrates a multi-bar chart with glass shading effect for bars and gradient color for plot area background.

Glass lighting is a complex shading effect that gives a look and feel of tinted glass or semi-transparent plastic material. This effect involves glare and variation of lighting caused by reflection and refraction inside the material.

The gradient plot area background is configured by using BaseChart.linearGradientColor to define the gradient color, then use XYChart.setPlotArea to apply it to the plot area.
The XYChart.setPlotArea also sets the plot area border and grid line colors to white.
The glass shading effect of the bars is defined using glassEffect, then applied to the bars using Layer.setBorderColor.

[File: phpdemo/glassmultibar.php]

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

# The data for the bar chart
$data0 = array(100, 125, 245, 147, 67);
$data1 = array(85, 156, 179, 211, 123);
$data2 = array(97, 87, 56, 267, 157);
$labels = array("Mon", "Tue", "Wed", "Thur", "Fri");

# Create a XYChart object of size 540 x 375 pixels
$c = new XYChart(540, 375);

# Add a title to the chart using 18 pts Times Bold Italic font
$c->addTitle("Average Weekly Network Load", "timesbi.ttf", 18);

# Set the plotarea at (50, 55) and of 440 x 280 pixels in size. Use a vertical
# gradient color from light blue (f9f9ff) to blue (6666ff) as background. Set border
# and grid lines to white (ffffff).
$c->setPlotArea(50, 55, 440, 280, $c->linearGradientColor(0, 55, 0, 335, 0xf9f9ff,
    0x6666ff), -1, 0xffffff, 0xffffff);

# Add a legend box at (50, 28) using horizontal layout. Use 10pts Arial Bold as font,
# with transparent background.
$legendObj = $c->addLegend(50, 28, false, "arialbd.ttf", 10);
$legendObj->setBackground(Transparent);

# Set the x axis labels
$c->xAxis->setLabels($labels);

# Draw the ticks between label positions (instead of at label positions)
$c->xAxis->setTickOffset(0.5);

# Set axis label style to 8pts Arial Bold
$c->xAxis->setLabelStyle("arialbd.ttf", 8);
$c->yAxis->setLabelStyle("arialbd.ttf", 8);

# Set axis line width to 2 pixels
$c->xAxis->setWidth(2);
$c->yAxis->setWidth(2);

# Add axis title
$c->yAxis->setTitle("Throughput (MBytes Per Hour)");

# Add a multi-bar layer with 3 data sets
$layer = $c->addBarLayer2(Side);
$layer->addDataSet($data0, 0xff0000, "Server #1");
$layer->addDataSet($data1, 0x00ff00, "Server #2");
$layer->addDataSet($data2, 0xff8800, "Server #3");

# Set bar border to transparent. Use glass lighting effect with light direction from
# left.
$layer->setBorderColor(Transparent, glassEffect(NormalGlare, Left));

# Configure the bars within a group to touch each others (no gap)
$layer->setBarGap(0.2, TouchBar);

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