W3 Lessons

Using PHP GD Library Functions. we can create Bar chart in php with dynamic data,
here is my SimpleBar Chart class to create a dynamic bar chart for your projects. you can easily add any number of columns and values also you can change your color scheme on base class.

Sample Bar Chart Using SimpleBar.class.php

SimpleBar.class.php

<?php

class SimpleBar {
		private $xgutter = 20; // left/right margin
		private $ygutter = 20; // top/bottom margin
		private $bottomspace = 30; // gap at the bottom
		private $internalgap = 20; // space between bars
		private $cells = array(); // labels/amounts for bar chart
		private $totalwidth; // width of the image
		private $totalheight; // height of the image
		private $font; // the font to use
		
		function __construct( $width, $height, $font ) {
		$this->totalwidth = $width;
		$this->totalheight = $height;
		$this->font = $font;
		}
		
		function addBar( $label, $amount ) {
		$this->cells[ $label ] = $amount;
		}
		
		private function _getTextSize( $cellwidth ) {
		$textsize = (int)($this->bottomspace);
		if ( $cellwidth < 10 ) {
		$cellwidth = 10;
		}
		foreach ( $this->cells as $key=>$val ) {
		while ( true ) {
		$box = ImageTTFbBox( $textsize, 0, $this->font, $key );
		$textwidth = abs( $box[2] );
		if ( $textwidth < $cellwidth ) {
		break;
		}
		$textsize--;
		}
		}
		return $textsize;
		}
		
		function draw() {
		$image = imagecreate( $this->totalwidth, $this->totalheight );
		$red = ImageColorAllocate($image, 230, 230, 230);
		$blue = ImageColorAllocate($image, 200, 100, 100 );
		$black = ImageColorAllocate($image, 0, 100, 255 );
		
		$max = max( $this->cells );
		$total = count( $this->cells );
		$graphCanX = ( $this->totalwidth - $this->xgutter*2 );
		$graphCanY = ( $this->totalheight - $this->ygutter*2
		- $this->bottomspace );
		$posX = $this->xgutter;
		$posY = $this->totalheight - $this->ygutter - $this->bottomspace;
		$cellwidth = (int)(( $graphCanX -
		( $this->internalgap * ( $total-1 ) )) / $total) ;
		$textsize = $this->_getTextSize( $cellwidth );
		
		foreach ( $this->cells as $key=>$val ) {
		$cellheight = (int)(($val/$max) * $graphCanY);
		$center = (int)($posX+($cellwidth/2));
		imagefilledrectangle( $image, $posX, ($posY-$cellheight),
		($posX+$cellwidth), $posY, $blue );
		$box = imageTTFbBox( $textsize, 0, $this->font, $key );
		$tw = $box[2];
		ImageTTFText( $image, $textsize, 0, ($center-($tw/2)),
		($this->totalheight-$this->ygutter), $black,
		$this->font, $key );
		$posX += ( $cellwidth + $this->internalgap);
		}
		
		imagepng( $image );
		}
}

?> 

Example Bar Chart

<?php
header("Content-type: image/png");
include("SimpleBar.class.php");

$graph = new SimpleBar( 500, 300, "verdana.ttf" );
$graph->addBar( "USA", 200 );
$graph->addBar( "India", 400 );
$graph->addBar( "UK", 240 );
$graph->addBar( "Australia", 170 );
$graph->addBar( "UAE", 270 );
$graph->draw();
?>

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