<?PHP
/*
salesbystate.php
Displays a map of the US color-coded to correspond with sales data
*/
// connect to a database & load sales data into an array $states
// with the state code as the key & current sales data as value
require('salesdata.php');
$im = imageCreatefrompng('usa.png') ;
// set predetermined index for each state in image usa.png
$stateIndex = array ('AL' => 16, 'AR' => 17, 'AZ' => 53, 'CA' => 57,
'CO' => 52, 'CT' => 37, 'DC' => 40, 'DE' => 38,
'FL' => 11, 'GA' => 10, 'IA' => 15, 'ID' => 1,
'IL' => 13, 'IN' => 27, 'KS' => 3, 'KY' => 26,
'LA' => 22, 'MA' => 35, 'MD' => 33, 'ME' => 28,
'MI' => 12, 'MN' => 2, 'MO' => 8, 'MS' => 21,
'MT' => 56, 'NC' => 18, 'ND' => 7, 'NE' => 4,
'NH' => 32, 'NJ' => 34, 'NM' => 55, 'NV' => 54,
'NY' => 19, 'OH' => 23, 'OK' => 9, 'OR' => 51,
'PA' => 20, 'RI' => 39, 'SC' => 29, 'SD' => 5,
'TN' => 24, 'TX' => 58, 'UT' => 63, 'VA' => 25,
'VT' => 31, 'WA' => 6, 'WI' => 14, 'WV' => 30,
'WY' => 50 );
// convert sales data values to a color range
$normalized = gradientFromRange($states);
// In order to fade from blue to white, maximize the blue component
// and then increase the other two components by the same value
foreach ($normalized as $state => $color) {
imageColorset($im,$stateIndex[$state],$color,$color,255) ;
}
header('Content-type: image/png');
imagePng($im);
imageDestroy($im);
/**
* @return array
* @param $usa array states
* @desc Normalizes an aray of a range of float values to integers
* representing gradient color values from 0 to 255
*/
function gradientFromRange($usa) {
// calculate what we can outside of the for loop
$lowest = min($usa);
$ratio = 255 / ( max($usa) - $lowest ) ;
foreach ($usa as $state => $sales) {
// subtract the lowest sales from the current sale to zero the figure
// then multiply by the $ratio to scale highest value to 255.
// Subtract total from 255 since color is additive,
// making lowest sales = highest color value (255)
// & higest sales = lowest color value (0)
$gradient[$state] = 255 - round(($sales - $lowest) * $ratio) ;
}
return $gradient ;
}
?>
|
