PHP 生成缩略图片的问题
我是这样想....
我设置要生成的缩略图片大小为100*50
我的原图片是1000*600
我想把原图片等比缩放，水平或垂直居中.其它的地方用白色填充，不知道我的意思表达清了没
[解决办法]
原图 w1 h1
新图 w2 h2
if w1/h1 > w2/h2 //缩放后高度不足
新图高 h = h2/w2*w1
垂直居中时的偏移y = (h2-h)/2
x = 0
if w1/h1 < w2/h2 //缩放后宽度不足
新图宽 w = w2/h2*h1
水平居中时的偏移x = (x2-x)/2
y = 0
[解决办法]
某cms的图片处理类
<?php /** * 图像处理类 */class image{ var $attachinfo; var $targetfile; //图片路径 var $imagecreatefromfunc; var $imagefunc; var $attach; var $animatedgif; var $watermarkquality; var $watermarktext; var $thumbstatus; var $watermarkstatus; // 析构函数,兼容PHP4 function image($targetfile, $cfg_thumb, $cfg_watermarktext, $photo_waterpos, $photo_diaphaneity, $photo_wheight, $photo_wwidth, $cfg_watermarktype, $photo_marktrans,$trueMarkimg, $attach = array()) { $this->__construct($targetfile, $cfg_thumb, $cfg_watermarktext, $photo_waterpos, $photo_diaphaneity, $photo_wheight, $photo_wwidth, $cfg_watermarktype, $photo_marktrans,$trueMarkimg, $attach); } // 析构函数 function __construct($targetfile, $cfg_thumb, $cfg_watermarktext, $photo_waterpos, $photo_diaphaneity, $photo_wheight, $photo_wwidth, $cfg_watermarktype, $photo_marktrans,$trueMarkimg, $attach = array()) { $this->thumbstatus = $cfg_thumb; $this->watermarktext = $cfg_watermarktext; $this->watermarkstatus = $photo_waterpos; $this->watermarkquality = $photo_marktrans; $this->watermarkminwidth = $photo_wwidth; $this->watermarkminheight = $photo_wheight; $this->watermarktype = $cfg_watermarktype; $this->watermarktrans = $photo_diaphaneity; $this->animatedgif = 0; $this->targetfile = $targetfile; $this->attachinfo = @getimagesize($targetfile); $this->attach = $attach; switch($this->attachinfo['mime']) { case 'image/jpeg': $this->imagecreatefromfunc = function_exists('imagecreatefromjpeg') ? 'imagecreatefromjpeg' : ''; $this->imagefunc = function_exists('imagejpeg') ? 'imagejpeg' : ''; break; case 'image/gif': $this->imagecreatefromfunc = function_exists('imagecreatefromgif') ? 'imagecreatefromgif' : ''; $this->imagefunc = function_exists('imagegif') ? 'imagegif' : ''; break; case 'image/png': $this->imagecreatefromfunc = function_exists('imagecreatefrompng') ? 'imagecreatefrompng' : ''; $this->imagefunc = function_exists('imagepng') ? 'imagepng' : ''; break; }//为空则匹配类型的函数不存在 $this->attach['size'] = empty($this->attach['size']) ? @filesize($targetfile) : $this->attach['size']; if($this->attachinfo['mime'] == 'image/gif') { $fp = fopen($targetfile, 'rb'); $targetfilecontent = fread($fp, $this->attach['size']); fclose($fp); $this->animatedgif = strpos($targetfilecontent, 'NETSCAPE2.0') === false ? 0 : 1; } } /** * 生成缩略图 * * @access public * @param int $thumbwidth 图片宽度 * @param int $thumbheight 图片高度 * @param int $preview 是否预览 * @return void */ function thumb($thumbwidth, $thumbheight, $preview = 0) { $this->thumb_gd($thumbwidth, $thumbheight, $preview); if($this->thumbstatus == 2 && $this->watermarkstatus) { $this->image($this->targetfile, $this->attach); $this->attach['size'] = filesize($this->targetfile); } } /** * 使用gd生成缩略图 * * @access public * @param int $thumbwidth 图片宽度 * @param int $thumbheight 图片高度 * @param int $preview 是否预览 * @return void */ function thumb_gd($thumbwidth, $thumbheight, $preview = 0) { if($this->thumbstatus && function_exists('imagecreatetruecolor') && function_exists('imagecopyresampled') && function_exists('imagejpeg')) { $imagecreatefromfunc = $this->imagecreatefromfunc; $imagefunc = $this->thumbstatus == 1 ? 'imagejpeg' : $this->imagefunc; list($imagewidth, $imageheight) = $this->attachinfo; if(!$this->animatedgif && ($imagewidth >= $thumbwidth || $imageheight >= $thumbheight)) { $attach_photo = $imagecreatefromfunc($this->targetfile); $x_ratio = $thumbwidth / $imagewidth; $y_ratio = $thumbheight / $imageheight; if(($x_ratio * $imageheight) < $thumbheight) { $thumb['height'] = ceil($x_ratio * $imageheight); $thumb['width'] = $thumbwidth; } else { $thumb['width'] = ceil($y_ratio * $imagewidth); $thumb['height'] = $thumbheight; } $targetfile = !$preview ? ($this->thumbstatus == 1 ? $this->targetfile.'.thumb.jpg' : $this->targetfile) : './watermark_tmp.jpg'; $thumb_photo = imagecreatetruecolor($thumb['width'], $thumb['height']); imagecopyresampled($thumb_photo, $attach_photo, 0, 0, 0, 0, $thumb['width'], $thumb['height'], $imagewidth, $imageheight); if($this->attachinfo['mime'] == 'image/jpeg') { $imagefunc($thumb_photo, $targetfile, 100); } else { $imagefunc($thumb_photo, $targetfile); } $this->attach['thumb'] = $this->thumbstatus == 1 ? 1 : 0; } } } }//End Class