<?php

/**

 * 图片处理，生成缩略图和添加水印图片

 * Created by PhpStorm.

 * User: andy

 * Date: 17-1-3

 * Time: 上午11:55

 */

class Image

{

    //原图

    private $imgPath;   //图片地址

    private $width;     //图片宽度

    private $height;    //图片高度

    private $type;      //图片类型

    private $img;       //图片(图像流)

    //缩略图

    private $newImg;    //缩略图(图像流)

    private $newWidth;

    private $newHeight;

    //水印图路径

    private $waterMarkPath;

    //输出图像质量,jpg有效

    private $quality;

    /**

     * Image constructor.

     * @param string $imagePath 图片路径

     * @param string $markPath 水印图片路径

     * @param int $new_width 缩略图宽度

     * @param int $new_height 缩略图高度

     * @param int $quality JPG图片格输出质量

     */

    public function __construct(string $imagePath,

                                string $markPath = null,

                                int $new_width = null,

                                int $new_height = null,

                                int $quality = 75)

    {

        $this->imgPath = $_SERVER['DOCUMENT_ROOT'] . $imagePath;

        $this->waterMarkPath = $markPath;

        $this->newWidth = $new_width ? $new_width : $this->width;

        $this->newHeight = $new_height ? $new_height : $this->height;

        $this->quality = $quality ? $quality : 75;

        list($this->width, $this->height, $this->type) = getimagesize($this->imgPath);

        $this->img = $this->_loadImg($this->imgPath, $this->type);

        //生成缩略图

        $this->_thumb();

        //添加水印图片

        if (!empty($this->waterMarkPath)) $this->_addWaterMark();

        //输出图片

        $this->_outputImg();

    }

    /**

     *图片输出

     */

    private function _outputImg()

    {

        switch ($this->type) {

            case 1: // GIF

                imagegif($this->newImg, $this->imgPath);

                break;

            case 2: // JPG

                if (intval($this->quality) < 0 || intval($this->quality) > 100) $this->quality = 75;

                imagejpeg($this->newImg, $this->imgPath, $this->quality);

                break;

            case 3: // PNG

                imagepng($this->newImg, $this->imgPath);

                break;

        }

        imagedestroy($this->newImg);

        imagedestroy($this->img);

    }

    /**

     * 添加水印

     */

    private function _addWaterMark()

    {

        $ratio = 1 / 5; //水印缩放比率

        $Width = imagesx($this->newImg);

        $Height = imagesy($this->newImg);

        $n_width = $Width * $ratio;

        $n_height = $Width * $ratio;

        list($markWidth, $markHeight, $markType) = getimagesize($this->waterMarkPath);

        if ($n_width > $markWidth) $n_width = $markWidth;

        if ($n_height > $markHeight) $n_height = $markHeight;

        $Img = $this->_loadImg($this->waterMarkPath, $markType);

        $Img = $this->_thumb1($Img, $markWidth, $markHeight, $markType, $n_width, $n_height);

        $markWidth = imagesx($Img);

        $markHeight = imagesy($Img);

        imagecopyresampled($this->newImg, $Img, $Width - $markWidth - 10, $Height - $markHeight - 10, 0, 0, $markWidth, $markHeight, $markWidth, $markHeight);

        imagedestroy($Img);

    }

    /**

     * 缩略图(按等比例,根据设置的宽度和高度进行裁剪)

     */

    private function _thumb()

    {

        //如果原图本身小于缩略图，按原图长高

        if ($this->newWidth > $this->width) $this->newWidth = $this->width;

        if ($this->newHeight > $this->height) $this->newHeight = $this->height;

        //背景图长高

        $gd_width = $this->newWidth;

        $gd_height = $this->newHeight;

        //如果缩略图宽高，其中有一边等于原图的宽高，就直接裁剪

        if ($gd_width == $this->width || $gd_height == $this->height) {

            $this->newWidth = $this->width;

            $this->newHeight = $this->height;

        } else {

            //计算缩放比率

            $per = 1;

            if (($this->newHeight / $this->height) > ($this->newWidth / $this->width)) {

                $per = $this->newHeight / $this->height;

            } else {

                $per = $this->newWidth / $this->width;

            }

            if ($per < 1) {

                $this->newWidth = $this->width * $per;

                $this->newHeight = $this->height * $per;

            }

        }

        $this->newImg = $this->_CreateImg($gd_width, $gd_height, $this->type);

        imagecopyresampled($this->newImg, $this->img, 0, 0, 0, 0, $this->newWidth, $this->newHeight, $this->width, $this->height);

    }

    /**

     * 缩略图(按等比例)

     * @param resource $img 图像流

     * @param int $width

     * @param int $height

     * @param int $type

     * @param int $new_width

     * @param int $new_height

     * @return resource

     */

    private function _thumb1($img, $width, $height, $type, $new_width, $new_height)

    {

        if ($width < $height) {

            $new_width = ($new_height / $height) * $width;

        } else {

            $new_height = ($new_width / $width) * $height;

        }

        $newImg = $this->_CreateImg($new_width, $new_height, $type);

        imagecopyresampled($newImg, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

        return $newImg;

    }

    /**

     * 加载图片

     * @param string $imgPath

     * @param int $type

     * @return resource

     */

    private function _loadImg($imgPath, $type)

    {

        switch ($type) {

            case 1: // GIF

                $img = imagecreatefromgif($imgPath);

                break;

            case 2: // JPG

                $img = imagecreatefromjpeg($imgPath);

                break;

            case 3: // PNG

                $img = imagecreatefrompng($imgPath);

                break;

            default: //其他类型

                Tool::alertBack('不支持当前图片类型.' . $type);

                break;

        }

        return $img;

    }

    /**

     * 创建一个背景图像

     * @param int $width

     * @param int $height

     * @param int $type

     * @return resource

     */

    private function _CreateImg($width, $height, $type)

    {

        $img = imagecreatetruecolor($width, $height);

        switch ($type) {

            case 3: //png

                imagecolortransparent($img, 0); //设置背景为透明的

                imagealphablending($img, false);

                imagesavealpha($img, true);

                break;

            case 4://gif

                imagecolortransparent($img, 0);

                break;

        }

        return $img;

    }

}