图像重采样调整大小

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//图像重采样调整大小，如果成功，返回一个数组，有两个值，第一个是调整后的宽度，第二个是调整后的高度，
//参数的含义：
//imageurl:    要调整的图像文件名
//$seze:    调整目标大小的像素数，一个参数，表示一个正方形的区域
//$quality:    如果是JPEG图像，则可以指定，目标图像的品质，范围：[0,100]
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function imageresize($imageurl,$size=800,$quality=75)
{
    $size=intval($size);
    if($size<=0)
        $size=1024;

    $quality=intval($quality);
    if($quality<0)
        $quality=0;
    if($quality>100)
        $quality=100;
    
    if(!file_exists($imageurl))
    {
        return array(-1,-1);
    }else
    {
        $ext=strtolower(substr($imageurl,strrpos($imageurl,".")+1));
        if($ext=='jpg'||$ext=='jpeg'||$ext=='gif'||$ext=='png'||$ext=='bmp')
        {
            $imagewh=getimagesize($imageurl);
            $Ws=$imagewh[0];
            $Hs=$imagewh[1];
            
            if($Ws>=$Hs)
            {
                if($Ws<=$size)
                    return getimagesize($imageurl);
                else
                {
                    $Wt=$size;
                    $Ht=intval(($Hs/$Ws)*$size);
                }
            }else


            {
                if($Hs<=$size)
                    return getimagesize($imageurl);
                else
                {
                    $Wt=intval(($Ws/$Hs)*$size);
                    $Ht=$size;
                }
            }
    
            switch($ext)
            {
                case 'jpg':
                case 'jpeg':
                    $imgs=@imagecreatefromjpeg($imageurl);
                    $imgt=@imagecreatetruecolor($Wt,$Ht)
                          or die ("Cannot Initialize new GD image stream");
                    imagecopyresampled($imgt,$imgs,0,0,0,0,$Wt,$Ht,$Ws,$Hs);
                    imagejpeg($imgt,$imageurl);
                    imagedestroy($imgs);
                    imagedestroy($imgt);
                    return array($Wt,$Ht);
                break;
                
                case 'bmp':
                    $imgs=@imagecreatefromjpeg($imageurl);
                    $imgt=@imagecreatetruecolor($Wt,$Ht)
                          or die ("Cannot Initialize new GD image stream");
                    imagecopyresampled($imgt,$imgs,0,0,0,0,$Wt,$Ht,$Ws,$Hs);
                    imagewbmp($imgt,$imageurl);
                    imagedestroy($imgs);
                    imagedestroy($imgt);
                    return array($Wt,$Ht);
                break;
    
                case 'gif':
                    $imgs=@imagecreatefromjpeg($imageurl);
                    $imgt=@imagecreatetruecolor($Wt,$Ht)
                          or die ("Cannot Initialize new GD image stream");
                    imagecopyresampled($imgt,$imgs,0,0,0,0,$Wt,$Ht,$Ws,$Hs);
                    imagegif($imgt,$imageurl);
                    imagedestroy($imgs);
                    imagedestroy($imgt);
                    return array($Wt,$Ht);
                break;
    
                case 'png':
                    $imgs=@imagecreatefromjpeg($imageurl);
                    $imgt=@imagecreatetruecolor($Wt,$Ht)
                          or die ("Cannot Initialize new GD image stream");
                    imagecopyresampled($imgt,$imgs,0,0,0,0,$Wt,$Ht,$Ws,$Hs);
                    imagepng($imgt,$imageurl);
                    imagedestroy($imgs);
                    imagedestroy($imgt);
                    return array($Wt,$Ht);
                break;
                
                default:
                    return array(-1,-1);
            }
        }else
        {
            return array(-1,-1);
        }
    }
}
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