Add piechart php program.

1 files changed, 114 insertions, 0 deletions

diff --git a/piechart.php b/piechart.php
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+<?php
+
+/* 
+A small PHP program and function that draws a pie chart in SVG format. 
+
+Written by Branko Collin in 2008.
+
+This code is hereby released into the public domain. In case this is not legally
+possible: I, Branko Collin, hereby grant anyone the right to use this work for
+any purpose, without any conditions, unless such conditions are required by law.
+*/ 
+
+/* Working with relative values confused me, so I worked with absolute ones 
+instead. Generally this should not be a problem, as the only relative values you 
+need are the chart's centre coordinates and its radius, and these are a linear
+function of the bounding box size or canvas size. See the sample values for how 
+this could work out. */
+
+/* Sample values */
+$values[] = 14625;
+$values[] = 644;
+
+$width = 400; // canvas size
+$height = 400; 
+$centerx = $width / 2; // centre of the pie chart
+$centery = $height / 2;
+$radius = min($centerx,$centery) - 10; // radius of the pie chart
+if ($radius < 5) {
+	die("Your chart is too small to draw.");
+} 
+
+/* Draw and output the SVG file. */
+
+header('Content-type: image/svg+xml');
+
+echo <<<END
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns:svg="http://www.w3.org/2000/svg" xmlns="http://www.w3.org/2000/svg"
+	version="1.0" width="$width" height="$height" id="svg2">
+
+  <title>Pie chart</title>
+  <desc>Picture of a pie chart</desc>
+END;
+
+print piechart($values,200,200,190);
+
+print "\n</svg>\n";
+
+
+/* 
+	The piechart function
+	
+	Arguments are an aray of values, the centre coordinates x and y, and 
+	the radius of the piechart.
+*/
+
+function piechart($data, $cx, $cy, $radius) {
+	$chartelem = "";
+
+	$max = count($data);
+	
+//	$colours = array('#4e9a06','#a40000','#204a87','#5c3566','#ce5c00');
+	$colours = array('#73d216','#cc0000','#3465a4','#75507b','#f57900');
+//	$colours = array('#8ae234','#ef2929','#729fcf','#ad7fa8','#fcaf3e');
+	
+	$sum = 0;
+	foreach ($data as $key=>$val) {
+		$sum += $val;
+	}
+	$deg = $sum/360; // one degree
+	$jung = $sum/2; // necessary to test for arc type
+	
+	/* Data for grid, circle, and slices */ 
+	
+	$dx = $radius; // Starting point: 
+	$dy = 0; // first slice starts in the East
+	$oldangle = 0;
+	
+	/* Loop through the slices */
+	for ($i = 0; $i<$max; $i++) {
+		$angle = $oldangle + $data[$i]/$deg; // cumulative angle
+		$x = cos(deg2rad($angle)) * $radius; // x of arc's end point
+		$y = sin(deg2rad($angle)) * $radius; // y of arc's end point
+	
+		$colour = $colours[$i];
+	
+		if ($data[$i] > $jung) {
+			// arc spans more than 180 degrees
+			$laf = 1;
+		}
+		else {
+			$laf = 0;
+		}
+	
+		$ax = $cx + $x; // absolute $x
+		$ay = $cy + $y; // absolute $y
+		$adx = $cx + $dx; // absolute $dx
+		$ady = $cy + $dy; // absolute $dy
+		$chartelem .= "\n";
+		$chartelem .= "<path d=\"M$cx,$cy "; // move cursor to center
+		$chartelem .= " L$adx,$ady "; // draw line away away from cursor
+		$chartelem .= " A$radius,$radius 0 $laf,1 $ax,$ay "; // draw arc
+		$chartelem .= " z\" "; // z = close path
+		$chartelem .= " fill=\"$colour\" stroke=\"#FFFFFF\" stroke-width=\"2\" ";
+		$chartelem .= " fill-opacity=\"1.0\" stroke-linejoin=\"round\" />";
+		$dx = $x; // old end points become new starting point
+		$dy = $y; // id.
+		$oldangle = $angle;
+	}
+	
+	return $chartelem; 
+}
+
+?>