图像截取类

<?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), $this->height);
                header("content-type:image/png\r\n");
                imagepng($newimg);
                //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)/$resize_ratio));
                header("content-type:image/png\r\n");
                imagepng($newimg);
                //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, $this->height);
                header("content-type:image/png\r\n");
                imagepng($newimg);
                //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, $this->height);
                header("content-type:image/png\r\n");
                imagepng($newimg);
                //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;

    }
}

$resizeimage = new resizeimage("bdxz_btn.jpg", "200", "200", "0","1500_s1.jpg");
?>

可以根据实际需求修改成生成但不输出图像，只返回地址

<?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(){}

    function resize($img,$length,$width,$dstpath='')
    {
        if(!file_exists($img)) {
            return "notexsit";
        } 

        $this->srcimg = $img;
        
        //$this->cut = $c;
        $this->cut = 0;
        //图片的类型
    
        $this->type = strtolower(substr(strrchr($this->srcimg,"."),1));
        
        //初始化图象
        $this->initi_img();
        
        //获取图像高宽
        $this->width = imagesx($this->im);
        $this->height = imagesy($this->im);
        //if(PHONEWIDTH === DEFAULT_WIDTH) {
            //return $img;
        //} else{
            //$this->resize_width = PHONEWIDTH / DEFAULT_WIDTH * $this->width;
            //$this->resize_height = PHONEWIDTH / DEFAULT_WIDTH * $this->height;
        //}

        $this->resize_width = $width;
        $this->resize_height = $length;
        
        //目标图象地址
        if($dstpath){
            $this->dstimg = $dstpath;
        }else{
            $this -> dst_img();
        }        
        
        //生成图象
        if(!file_exists($this->dstimg)) {
            ob_start();
            $this->newimg();
            imagedestroy ($this->im);
            ob_clean();
            return $this->dstimg;
        } else {
            return $this->dstimg;
        }
    }
    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), $this->height);
                //header("content-type:image/png\r\n");
                imagepng($newimg);
                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)/$resize_ratio));
                //header("content-type:image/png\r\n");
                imagepng($newimg);
                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, $this->height);
                //header("content-type:image/png\r\n");
                imagepng($newimg);
                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, $this->height);
                //header("content-type:image/png\r\n");
                imagepng($newimg);
                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()
    {
        $full_length  = strlen($this->srcimg);

        $type_length  = strlen($this->type);
        $name_length  = $full_length-$type_length;

        $name         = substr($this->srcimg,0,$name_length-1);
        //$this->dstimg = $dstpath;
        $this->dstimg = $name . PHONEWIDTH . "." . $this->type;

    }
}
?>

调用的例子

<?php
include("image.php");
define("PHONEWIDTH",$_GET['w']);
defined("DEFAULT_WIDTH") || define("DEFAULT_WIDTH",300);
defined("PHONEWIDTH") || define("PHONEWIDTH",300);
$resizeimage = new ResizeImage();
?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3c.org/TR/1999/REC-html401-19991224/loose.dtd">
<HTML xmlns="http://www.w3.org/1999/xhtml">
<HEAD>
<META content="IE=7.0000" http-equiv="X-UA-Compatible">
<title></title>
<META content="text/html; charset=utf-8;charset=utf-8" http-equiv=Content-Type>
</HEAD>
<BODY>
<img src="<?php echo $resizeimage -> resize("bdxz_btn.jpg");?>" />
</BODY>
</HTML>