PHP如何制作长尾词图片缩略图？

本文共计788个文字，预计阅读时间需要4分钟。

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

phpclass ResizeImage { // 图像类型 var $type; // 实际宽度 var $width; // 实际高度 var $height; // 缩略图宽度 var $newWidth; // 缩略图高度 var $newHeight;

function ResizeImage($image, $newWidth, $newHeight) { // 获取图像信息 $this->image=$image; $this->newWidth=$newWidth; $this->newHeight=$newHeight; $this->getWidthHeight(); $this->resizeImage(); }

function getWidthHeight() { // 获取图像宽度和高度 $this->width=imagesx($this->image); $this->height=imagesy($this->image); // 判断图像类型，并设置类型变量 if ($this->image===IMAGETYPE_JPEG) { $this->type=IMAGETYPE_JPEG; } elseif ($this->image===IMAGETYPE_GIF) { $this->type=IMAGETYPE_GIF; } elseif ($this->image===IMAGETYPE_PNG) { $this->type=IMAGETYPE_PNG; } }

function resizeImage() { // 计算缩放比例 $ratio1=$this->width / $this->newWidth; $ratio2=$this->height / $this->newHeight; $ratio=min($ratio1, $ratio2); $newWidth=$this->newWidth / $ratio; $newHeight=$this->newHeight / $ratio; // 创建新图像 $this->imageResized=imagecreatetruecolor($newWidth, $newHeight); // 裁剪图像 imagecopyresampled($this->imageResized, $this->image, 0, 0, 0, 0, $newWidth, $newHeight, $this->width, $this->height); }

function outputImage() { // 输出图像 switch ($this->type) { case IMAGETYPE_JPEG: imagejpeg($this->imageResized); break; case IMAGETYPE_GIF: imagegif($this->imageResized); break; case IMAGETYPE_PNG: imagepng($this->imageResized); 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