<?php

/**
 * GD图片处理驱动
 */

namespace libraries\image;

class GdDriver implements ImageInterface {

    protected $imgRes;

    protected $info = array();

    protected $errorMsg = '';

	/**
	 * 构建函数
	 * @param string $img 图片路径
	 */
    public function __construct($img) {
    	if(!is_file($img)){
    		$this->errorMsg = '图片不存在！';
            return false;
    	}
    	$imgInfo = getimagesize($img);
    	if(empty($imgInfo)){
            $this->errorMsg = '非法图像资源！';
            return false;
    	}
    	$this->info = array(
    		'width'  => $imgInfo[0],
    		'height' => $imgInfo[1],
    		'type'   => image_type_to_extension($imgInfo[2], false),
    		'mime'   => $imgInfo['mime'],
    		);
    	$img = file_get_contents($img);
    	$this->imgRes = @imagecreatefromstring($img);
    }

    /**
     * 裁剪图片
     * @param  integer  $w      图片宽度
     * @param  integer  $h      图片高度
     * @param  integer  $x      X坐标
     * @param  integer  $y      Y坐标
     * @param  integer  $width  目标宽度
     * @param  integer  $height 目标高度
     * @return object
     */
    public function crop($w, $h, $x = 0, $y = 0, $width = null, $height = null) {
        if(empty($this->imgRes)){
            $this->errorMsg = '图像处理失败！';
            return false;
        }
    	empty($width)  && $width  = $w;
        empty($height) && $height = $h;
    	$img = imagecreatetruecolor($width, $height);
    	$color = imagecolorallocate($img, 255, 255, 255);
    	imagefill($img, 0, 0, $color);
    	imagecopyresampled($img, $this->imgRes, 0, 0, $x, $y, $width, $height, $w, $h);
    	imagedestroy($this->imgRes);
    	$this->imgRes = $img;
    	$this->info['width']  = $width;
        $this->info['height'] = $height;
        return $this;
    }

    /**
     * 缩放图片
     * @param  integer $width  图片宽度
     * @param  integer $height 图片高度
     * @param  string $type    缩放类型
     * @return object
     */
    public function thumb($width, $height, $type = 'scale'){
    	$w = $this->info['width'];
        $h = $this->info['height'];
        switch ($type) {
        	//等比缩放
        	case 'scale':
        		if($w < $width && $h < $height) return;
        		$scale = min($width/$w, $height/$h);
        		$x = $y = 0;
                $width  = $w * $scale;
                $height = $h * $scale;
                break;
        	//居中裁剪缩放
        	case 'center':
        		$scale = max($width/$w, $height/$h);
        		$w = $width/$scale;
                $h = $height/$scale;
                $x = ($this->info['width'] - $w)/2;
                $y = ($this->info['height'] - $h)/2;
        		break;
        	//固定尺寸
        	case 'fixed':
        		$x = $y = 0;
        		break;
        	default:
                throw new \Exception('无此缩图类型！');
        }
        $this->crop($w, $h, $x, $y, $width, $height);
        return $this;
    }


    /**
     * 图片水印
     * @param  string  $source 水印图片
     * @param  integer $locate 水印位置
     * @param  integer $alpha  水印透明度
     * @return object
     */
    public function water($source, $locate = 0, $alpha=80){
        if(empty($this->imgRes)){
            $this->errorMsg = '图像处理失败！';
            return false;
        }
    	$info = getimagesize($source);
    	if(!$info){
    		throw new \Exception('非法图像资源！');
    	}
    	$fun   = 'imagecreatefrom' . image_type_to_extension($info[2], false);
    	$water = $fun($source);
    	imagealphablending($water, true);
    	if(!$locate){
    		$locate = rand(1,9);
    	}
    	switch ($locate) {
    		//左上角水印
            case 1:
                $x = $y = 0;
                break;
            //上居中水印
            case 2:
                $x = ($this->info['width'] - $info[0])/2;
                $y = 0;
                break;
            //右上角水印
            case 3:
                $x = $this->info['width'] - $info[0];
                $y = 0;
                break;
            //左居中水印
            case 4:
                $x = 0;
                $y = ($this->info['height'] - $info[1])/2;
                break;
            //居中水印
            case 5:
                $x = ($this->info['width'] - $info[0])/2;
                $y = ($this->info['height'] - $info[1])/2;
                break;
            //右居中水印
            case 6:
                $x = $this->info['width'] - $info[0];
                $y = ($this->info['height'] - $info[1])/2;
                break;
            //左下角水印
            case 7:
                $x = 0;
                $y = $this->info['height'] - $info[1];
                break;
            //下居中水印
            case 8:
                $x = ($this->info['width'] - $info[0])/2;
                $y = $this->info['height'] - $info[1];
                break;
            //右下角水印
            case 9:
                $x = $this->info['width'] - $info[0];
                $y = $this->info['height'] - $info[1];
                break;
        }
        $src = imagecreatetruecolor($info[0], $info[1]);
        $color = imagecolorallocate($src, 255, 255, 255);
        imagefill($src, 0, 0, $color);
        imagecopy($src, $this->imgRes, 0, 0, $x, $y, $info[0], $info[1]);
        imagecopy($src, $water, 0, 0, 0, 0, $info[0], $info[1]);
        imagecopymerge($this->imgRes, $src, $x, $y, 0, 0, $info[0], $info[1], $alpha);
        imagedestroy($src);
        imagedestroy($water);
        return $this;
    }

    /**
     * 输出图片
     * @param  string $filename 文件名
     * @param  string $type     图片类型
     * @return boolean
     */
    public function output($filename, $type = null){
        if(empty($this->imgRes)){
            $this->errorMsg = '图像处理失败！';
            return false;
        }
        if(!$type){
            $type = $this->info['type'];
        } else {
            $type = strtolower($type);
        }
        if('jpeg' == $type || 'jpg' == $type){
        	$func = 'imagejpeg';
        }else{
        	$func = 'image'.$type;
        }
        if (!function_exists($func)) {
            $this->error = '无法对该图片格式进行处理！';
            return false;
        }
        return $func($this->imgRes, $filename);
    }

    /**
     * 获取错误信息
     */
    public function getError() {
        return $this->errorMsg;
    }

    /**
     * 获取图片信息
     */
    public function getInfo() {
        return $this->info;
    }

    /**
     * 析构函数
     */
    public function __destruct() {
        imagedestroy($this->imgRes);
    }
}