Japan Map Chart (using aka Chart API)

JapanMapChart.php

<?php

// http://code.google.com/intl/ja/apis/chart/docs/gallery/new_map_charts.html
// detectColorメソッドを実装して，値に対して色(16進数)を割り振る

abstract class JapanMapChart
{
    private
        $_baseUrl,
        $_params,
        $_glue;

    /**
     * __construct
     *
     * @return void
     */
    public function __construct($x=null, $y=null, $data=array())
    {
        $this->_baseUrl = 'http://chart.apis.google.com/chart?';

        $this->_params  = array(
            'cht' => 'map'
        );

        $this->_glue    = array(
            'chld'  => '|',
            'ch'    => ',',
            'chco'  => '|'
        );

        if ( $x !== null && $y !== null ) {
            $this->setSize($x, $y);
        }
        if ( !empty($data) ) {
            $this->setAll($data);
        }
    }

    /**
     * detectColor
     *
     * @abstract
     * @param mixed $val
     * @return string $hexColor
     */
    abstract public function detectColor($val);

    /**
     * setSize (chs)
     * http://code.google.com/intl/ja/apis/chart/docs/chart_params.html#gcharts_chs
     *
     * @param int $x
     * @param int $y
     * @return void
     */
    public function setSize($x, $y)
    {
        $size = $x*$y;

        if ( 1
            and $x <= 600
            and $y <= 600
            and $size < 300000
        ) {
            $this->_params['chs'] = $x.'x'.$y;
        } else {
            trigger_error("The parameter 'chs={$x}x{$y}' specifies a chart with $size pixels, which exceeds the maximum size of 300000 pixels.", E_USER_ERROR);
        }
    }

    /**
     * _setPrefecture (chld)
     * http://en.wikipedia.org/wiki/Prefectures_of_Japan (ISO 3166-2:JP)
     *
     * @param int|string $pref
     * @param int $fix
     * @return void
     */
    private function _setPrefecture($pref, $fix = 0)
    {
        $prefCode = strpos($pref, 'JP-') === 0 ? $pref : sprintf('JP-%02d', ($pref - $fix));
        $this->_params['chld'][] = $prefCode;
    }

    /**
     * _setColor (chco)
     *
     * @param mixed $val
     * @return void
     */
    private function _setColor($val)
    {
        $this->_params['chco'][] = $this->detectColor($val);
    }

    /**
     * set
     *
     * @param int|string $prefCode
     * @param mixed $val
     * @return void
     */
    public function set($pref, $val)
    {
        $this->_setPrefecture($pref, 10);
        $this->_setColor($val);
    }

    /**
     * setAll
     *
     * @param array $data
     * @return void
     */
    public function setAll($data)
    {
        foreach ( $data as $prefCode => $val ) {
            $this->set($prefCode, $val);
        }
    }

    /**
     * build
     *
     * @return string $comleteUrl
     */
    public function build()
    {
        $completeParams = array();

        foreach ( $this->_params as $key => $val ) {
            if ( is_array($val) ) {
                $val = implode($this->_glue[$key], $val);
            }
            $completeParams[$key] = $val;
        }

        return $this->_baseUrl.http_build_query($completeParams);
    }
}