我使用以下代码在上传后调整图片大小。 请帮助我，告诉我如何更改它以调整图像大小但保持最低分辨率。现在上传的图片大小调整为宽度或高度500px，但是需要最小1200px
define("HAR_AUTO_NAME",1);
Class RESIZEIMAGE
{
var $imgFile="";
var $imgWidth=0;
var $imgHeight=0;
var $imgType="";
var $imgAttr="";
var $type=NULL;
var $_img=NULL;
var $_error="";
/**
* Constructor
*
* @param [String $imgFile] Image File Name
* @return RESIZEIMAGE (Class Object)
*/
function RESIZEIMAGE($imgFile="")
{
if (!function_exists("imagecreate"))
{
$this->_error="Error: GD Library is not available.";
return false;
}
$this->type=Array(1 => 'GIF', 2 => 'JPG', 3 => 'PNG', 4 => 'SWF', 5 => 'PSD', 6 => 'BMP', 7 => 'TIFF', 8 => 'TIFF', 9 => 'JPC', 10 => 'JP2', 11 => 'JPX', 12 => 'JB2', 13 => 'SWC', 14 => 'IFF', 15 => 'WBMP', 16 => 'XBM');
if(!empty($imgFile))
$this->setImage($imgFile);
}
/**
* Error occured while resizing the image.
*
* @return String
*/
function error()
{
return $this->_error;
}
/**
* Set image file name
*
* @param String $imgFile
* @return void
*/
function setImage($imgFile)
{
$this->imgFile=$imgFile;
return $this->_createImage();
}
/**
*
* @return void
*/
function close()
{
return @imagedestroy($this->_img);
}
/**
* Resize a image to given width and height and keep it's current width and height ratio
*
* @param Number $imgwidth
* @param Numnber $imgheight
* @param String $newfile
*/
function resize_limitwh($imgwidth,$imgheight,$newfile=NULL)
{
$image_per = 100;
list($width, $height, $type, $attr) = @getimagesize($this->imgFile);
if($width != $imgwidth && $imgwidth > 0)
$image_per = (double)(($imgwidth * 100) / $width);
if(floor(($height * $image_per)/100)!=$imgheight && $imgheight > 0)
$image_per = (double)(($imgheight * 100) / $height);
$this->resize_percentage($image_per,$newfile);
}
function resize_maxsize($maxsize,$newfile=NULL)
{
$image_per = 100;
list($width, $height, $type, $attr) = @getimagesize($this->imgFile);
if($width>$height && $maxsize>0){
$image_per = (double)(($maxsize/$width)*100);
}
if($width<$height && $maxsize>0){
$image_per = (double)(($maxsize/$height)*100);
}
$this->resize_percentage($image_per,$newfile);
}
/**
* Resize an image to given percentage.
*
* @param Number $percent
* @param String $newfile
* @return Boolean
*/
function resize_percentage($percent=100,$newfile=NULL)
{
$newWidth=($this->imgWidth*$percent)/100;
$newHeight=($this->imgHeight*$percent)/100;
return $this->resize($newWidth,$newHeight,$newfile);
}
function resize_scale($maxwidth, $maxheight, $newfile=NULL)
{
list($width, $height, $type, $attr) = @getimagesize($this->imgFile);
if ($width < $maxwidth &&
$height < $maxheight)
{
return $this->resize($width, $height, $newfile);
}
$oldprop = round($width / $height, 2);
$newprop = round($maxwidth / $maxheight, 2);
$preserveAspectx = round($width / $maxwidth, 2);
$preserveAspecty = round($height / $maxheight, 2);
if ($preserveAspectx < $preserveAspecty)
{
$newwidth = $width/($height/$maxheight);
$newheight = $maxheight;
}
else
{
$newwidth = $maxwidth;
$newheight = $height/($width/$maxwidth);
}
return $this->resize($newwidth,$newheight,$newfile);
}
/**
* Resize an image to given X and Y percentage.
*
* @param Number $xpercent
* @param Number $ypercent
* @param String $newfile
* @return Boolean
*/
function resize_xypercentage($xpercent=100,$ypercent=100,$newfile=NULL)
{
$newWidth=($this->imgWidth*$xpercent)/100;
$newHeight=($this->imgHeight*$ypercent)/100;
return $this->resize($newWidth,$newHeight,$newfile);
}
/**
* Resize an image to given width and height
*
* @param Number $width
* @param Number $height
* @param String $newfile
* @return Boolean
*/
function resize($width,$height,$newfile=NULL)
{
if(empty($this->imgFile))
{
$this->_error="File name is not initialised.";
return false;
}
if($this->imgWidth<=0 || $this->imgHeight<=0)
{
$this->_error="Could not resize given image";
return false;
}
if($width<=0)
$width=$this->imgWidth;
if($height<=0)
$height=$this->imgHeight;
return $this->_resize($width,$height,$newfile);
}
/**
* Get the image attributes
* @access Private
*
*/
function _getImageInfo()
{
@list($this->imgWidth,$this->imgHeight,$type,$this->imgAttr)=@getimagesize($this->imgFile);
$this->imgType=$this->type[$type];
}
/**
* Create the image resource
* @access Private
* @return Boolean
*/
function _createImage()
{
$this->_getImageInfo();
if($this->imgType=='GIF')
{
$this->_img=@imagecreatefromgif($this->imgFile);
}
elseif($this->imgType=='JPG')
{
$this->_img=@imagecreatefromjpeg($this->imgFile);
}
elseif($this->imgType=='PNG')
{
$this->_img=@imagecreatefrompng($this->imgFile);
}
if(!$this->_img || !@is_resource($this->_img))
{
$this->_error="Error loading ".$this->imgFile;
return false;
}
return true;
}
/**
* Function is used to resize the image
*
* @access Private
* @param Number $width
* @param Number $height
* @param String $newfile
* @return Boolean
*/
function _resize($width,$height,$newfile=NULL)
{
if (!function_exists("imagecreate"))
{
$this->_error="Error: GD Library is not available.";
return false;
}
$newimg=@imagecreatetruecolor($width,$height);
//imagecolortransparent( $newimg, imagecolorat( $newimg, 0, 0 ) );
if($this->imgType=='GIF' || $this->imgType=='PNG')
{
/** Code to keep transparency of image **/
$colorcount = imagecolorstotal($this->_img);
if ($colorcount == 0) $colorcount = 256;
imagetruecolortopalette($newimg,true,$colorcount);
imagepalettecopy($newimg,$this->_img);
$transparentcolor = imagecolortransparent($this->_img);
imagefill($newimg,0,0,$transparentcolor);
imagecolortransparent($newimg,$transparentcolor);
}
@imagecopyresampled ( $newimg, $this->_img, 0,0,0,0, $width, $height, $this->imgWidth,$this->imgHeight);
if($newfile===HAR_AUTO_NAME)
{
if(@preg_match("/\..*+$/",@basename($this->imgFile),$matches))
$newfile=@substr_replace($this->imgFile,"_har",-@strlen($matches[0]),0);
}
elseif(!empty($newfile))
{
if(!@preg_match("/\..*+$/",@basename($newfile)))
{
if(@preg_match("/\..*+$/",@basename($this->imgFile),$matches))
$newfile=$newfile.$matches[0];
}
}
if($this->imgType=='GIF')
{
if(!empty($newfile))
@imagegif($newimg,$newfile);
else
{
@header("Content-type: image/gif");
@imagegif($newimg);
}
}
elseif($this->imgType=='JPG')
{
if(!empty($newfile))
@imagejpeg($newimg,$newfile);
else
{
@header("Content-type: image/jpeg");
@imagejpeg($newimg);
}
}
elseif($this->imgType=='PNG')
{
if(!empty($newfile))
@imagepng($newimg,$newfile);
else
{
@header("Content-type: image/png");
@imagepng($newimg);
}
}
@imagedestroy($newimg);
}
}
答案 0 :(得分：0)
调整大小的质量取决于您使用的图像库。您正在使用GD。我建议使用ImageMagic（Imagick）调整图像大小。
http://php.net/manual/en/book.imagick.php
你最好试验自己，看看哪种效果最好，好像你在大众GD中做这件事要快得多。