Soft Multi-Bar Chart

This example demonstrates a multi-bar chart with soft lighting effects for bars and gradient color for plot area background.

Soft lighting is a special shading effect that look like gradient coloring. In this example, soft lighting effect is applied to the bars with the light coming from the left direction.

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 soft lighting effect of the bars is defined using softLighting, then applied to the bars using Layer.setBorderColor.

See Soft Bar Shading for another example of soft lighting effect with the light coming from the left direction.

[File: phpdemo/softmultibar.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 red (ffdddd) to dark red (880000) as background. Set
# border and grid lines to white (ffffff).
$c->setPlotArea(50, 55, 440, 280, $c->linearGradientColor(0, 55, 0, 335, 0xffdddd,
    0x880000), -1, 0xffffff, 0xffffff);

# Add a legend box at (50, 25) using horizontal layout. Use 10pts Arial Bold as font,
# with transparent background.
$legendObj = $c->addLegend(50, 25, 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 and 4 pixels 3D depth
$layer = $c->addBarLayer2(Side, 4);
$layer->addDataSet($data0, 0xffff00, "Server #1");
$layer->addDataSet($data1, 0x00ff00, "Server #2");
$layer->addDataSet($data2, 0x9999ff, "Server #3");

# Set bar border to transparent. Use soft lighting effect with light direction from
# top.
$layer->setBorderColor(Transparent, softLighting(Top));

# 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));
?>