php实现图片压缩功能

简述：

使用PHP的GD库可以将图片按固定宽高或者等比例压缩，主要利用的函数是：

imagecopyresampled：将一张图片中的一块区域复制到另一张图片上

等比例压缩

public function compressImg($src = '', $percent = 1){list($width, $height, $type, $attr) = getimagesize($src);$type = image_type_to_extension($type, false);               $fun         = "imagecreatefrom" . $type;        $image  = $fun($src);        $new_width   = $width * $percent;        $new_height  = $height * $percent;        $thump = imagecreatetruecolor($new_width, $new_height);        //将原图复制到另一张图片上，并且按照一定比例压缩        imagecopyresampled($thump, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);        imagedestroy($image);        $image = $thump;        // 1、浏览器直接输出        header('Content-Type: image/' . $type);        $funcs = "image" . $type;        $funcs($thump);        // 2、保存到对应路径        $path = 'save.'.$type;        $funcs = "image" . $type;        $funcs($thump, $path);}

按固定宽高压缩

public function compressImgWH($src = '', $new_width='', $new_height=''){list($width, $height, $type, $attr) = getimagesize($src);$type = image_type_to_extension($type, false);         $fun = "imagecreatefrom" . $type;        $image = $fun($src);        $thump = imagecreatetruecolor($new_width, $new_height);        // 处理透明背景图片变成黑色的问题        if(strtolower($type)=='png'){            imageantialias($thump, true);            $color = imagecolorallocate($thump, 255, 255, 255);            imagecolortransparent($thump, $color);            imagefill($thump, 0, 0, $color);        }        //将原图复制到其他图片上，并且按照一定宽高压缩        imagecopyresampled($thump, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);        imagedestroy($image);        // 1、浏览器直接输出        header('Content-Type: image/' . $type);        $funcs = "image" . $type;        $funcs($thump);        // 2、保存到对应路径        $path = 'save.'.$type;        $funcs = "image" . $type;        $funcs($thump, $path);}

功能演示：

来源地址：https://blog.csdn.net/u012816216/article/details/129509302