如何使用PHP制作图片的缩略图？

本文共计790个文字，预计阅读时间需要4分钟。

要使用PHP生成图片缩略图，确保你的PHP服务器安装了GD2图形库。以下是一个简单的类示例，用于生成图片缩略图：

php

function __construct($imagePath) { $this->loadImage($imagePath); }

function loadImage($imagePath) { $this->type=$this->imageType($imagePath); $this->image=$this->createImage($imagePath); $this->width=imagesx($this->image); $this->height=imagesy($this->image); }

function imageType($imagePath) { $imageInfo=getimagesize($imagePath); return $imageInfo[2]; }

function createImage($imagePath) { switch ($this->type) { case IMAGETYPE_JPEG: return imagecreatefromjpeg($imagePath); case IMAGETYPE_PNG: return imagecreatefrompng($imagePath); case IMAGETYPE_GIF: return imagecreatefromgif($imagePath); default: return false; } }

function resize() { $ratio=$this->width / $this->height; $newRatio=$this->newWidth / $this->newHeight;

if ($ratio > $newRatio) { $this->newHeight=$this->height; $this->newWidth=($this->height * $this->newWidth) / $this->newHeight; } else { $this->newWidth=$this->width; $this->newHeight=($this->width * $this->newHeight) / $this->newWidth; }

$this->imageResized=imagecreatetruecolor($this->newWidth, $this->newHeight); imagecopyresampled($this->imageResized, $this->image, 0, 0, 0, 0, $this->newWidth, $this->newHeight, $this->width, $this->height); }

function saveImage($savePath, $imageType=IMAGETYPE_JPEG, $quality=90) { switch ($imageType) { case IMAGETYPE_JPEG: imagejpeg($this->imageResized, $savePath, $quality); break; case IMAGETYPE_PNG: imagepng($this->imageResized, $savePath); break; case IMAGETYPE_GIF: imagegif($this->imageResized, $savePath); break; } imagedestroy($this->imageResized); }}?>

要使用PHP生成图片缩略图,要保证你的PHP服务器安装了GD2图形库 使用一个类生成图片的缩略图

//使用如下类就可以生成图片缩略图, <?php class resizeimage { //图片类型 var $type; //实际宽度 var $width; //实际高度 var $height; //改变后的宽度 var $resize_width; //改变后的高度 var $resize_height; //是否裁图 var $cut; //源图象 var $srcimg; //目标图象地址 var $dstimg; //临时创建的图象 var $im; function resizeimage($img, $wid, $hei,$c,$dstpath) { $this->srcimg = $img; $this->resize_width = $wid; $this->resize_height = $hei; $this->cut = $c; //图片的类型 $this->type = strtolower(substr(strrchr($this->srcimg,"."),1)); //初始化图象 $this->initi_img(); //目标图象地址 $this -> dst_img($dstpath); //-- $this->width = imagesx($this->im); $this->height = imagesy($this->im); //生成图象 $this->newimg(); ImageDestroy ($this->im); } function newimg() { //改变后的图象的比例 $resize_ratio = ($this->resize_width)/($this->resize_height); //实际图象的比例 $ratio = ($this->width)/($this->height); if(($this->cut)=="1") //裁图 { if($ratio>=$resize_ratio) //高度优先 { $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height); imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height); ImageJpeg ($newimg,$this->dstimg); } if($ratio<$resize_ratio) //宽度优先 { $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height); imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width)/$resize_ratio)); ImageJpeg ($newimg,$this->dstimg); } } else //不裁图 { if($ratio>=$resize_ratio) { $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio); imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height); ImageJpeg ($newimg,$this->dstimg); } if($ratio<$resize_ratio) { $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height); imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height); ImageJpeg ($newimg,$this->dstimg); } } } //初始化图象 function initi_img() { if($this->type=="jpg") { $this->im = imagecreatefromjpeg($this->srcimg); } if($this->type=="gif") { $this->im = imagecreatefromgif($this->srcimg); } if($this->type=="png") { $this->im = imagecreatefrompng($this->srcimg); } } //图象目标地址 function dst_img($dstpath) { $full_length = strlen($this->srcimg); $type_length = strlen($this->type); $name_length = $full_length-$type_length; $name = substr($this->srcimg,0,$name_length-1); $this->dstimg = $dstpath; //echo $this->dstimg; } } ?>

使用方法

$resizeimage = new resizeimage("图片源文件地址", "200", "100", "0","缩略图地址"); //就只用上面的一句话,就能生成缩略图,其中,源文件和缩略图地址可以相同,200,100分别代表宽和高