This example demonstates using x zone colors - colors that change at certain x value thresholds.

In this example, x zone colors are used as the color of the line, and as the fill color of the band the surrounds the line.

The x zone color for the line is configured to change from blue to a red dash line color upon reaching a certain x value threshold. The x zone color for the band is configured to change from semi-transparent blue to semi-transparent red upon reaching the same threshold.

X zone colors are created using Layer.xZoneColor. You can use a x zone color in any ChartDirector API that expects a color. For instance, you can use a x zone color as background color, fill color of data sets, line color, etc.

A single x zone color can support one threshold value and change between two colors. The two colors can be any colors, including another x zone colors. You may create x zone colors with multiple thresholds by cascading multiple x zone colors this way.

[File: phpdemo/xzonecolor.php".]

<?php require_once("../lib/phpchartdir.php"); #The data for the chart $data = array(50, 55, 47, 34, 42, 49, 63, 62, 73, 59, 56, 50, 64, 60, 67, 67, 58, 59, 73, 77, 84, 82, 80, 84, 89); #The error data representing the error band around the data points $errData = array(5, 6, 5.1, 6.5, 6.6, 8, 5.4, 5.1, 4.6, 5.0, 5.2, 6.0, 4.9, 5.6, 4.8, 6.2, 7.4, 7.1, 6.5, 9.6, 12.1, 15.3, 18.5, 20.9, 24.1); #The labels for the chart $labels = array("Jan 01", "-", "-", "Apr", "-", "-", "Jul", "-", "-", "Oct", "-", "-", "Jan 02", "-", "-", "Apr", "-", "-", "Jul", "-", "-", "Oct", "-", "-", "Jan 03"); #Create a XYChart object of size 550 x 220 pixels $c = new XYChart(550, 220); #Set the plot area at (50, 5) and of size 480 x 180 pixels. Enabled both #vertical and horizontal grids by setting their colors to light grey (0xc0c0c0) $plotAreaObj = $c->setPlotArea(50, 5, 480, 180); $plotAreaObj->setGridColor(0xc0c0c0, 0xc0c0c0); #Add a legend box (50, 5) (top of plot area) using horizontal layout. Use 8 pts #Arial font. Disable bounding box (set border to transparent). $legendBox = $c->addLegend(50, 5, false, "", 8); $legendBox->setBackground(Transparent); #Add keys to the legend box to explain the color zones $legendBox->addKey("Historical", 0x9999ff); $legendBox->addKey("Forecast", 0xff9966); #Add a title to the y axis. $c->yAxis->setTitle("Energy Consumption"); #Set the labels on the x axis $c->xAxis->setLabels($labels); #Add a line layer to the chart $layer = $c->addLineLayer2(); #Create the color to draw the data line. The line is blue (0x333399) to the left #of x = 18, and become a red (0xd04040) dash line to the right of x = 18. $lineColor = $layer->xZoneColor(18, 0x333399, $c->dashLineColor(0xd04040, DashLine)); #Add the data line $layer->addDataSet($data, $lineColor); #Create the color to draw the err zone. The color is semi-transparent blue #(0x809999ff) to the left of x = 18, and become semi-transparent red #(0x80ff9966) to the right of x = 18. $errColor = $layer->xZoneColor(18, 0x809999ff, 0x80ff9966); #Add the upper border of the err zone $upperBorder = new ArrayMath($data); $upperBorder->add($errData); $layer->addDataSet($upperBorder->result(), $errColor); #Add the lower border of the err zone $lowerBorder = new ArrayMath($data); $lowerBorder->sub($errData); $layer->addDataSet($lowerBorder->result(), $errColor); #Set the default line width to 2 pixels $layer->setLineWidth(2); #Color the region between the err zone lines $c->addInterLineLayer($layer->getLine(1), $layer->getLine(2), $errColor); #output the chart header("Content-type: image/png"); print($c->makeChart2(PNG)); ?>