PHP用GD库生成高质量的缩略图片

PHP 2018-12-30

以下是PHP源代码(ResizeImage.PHP)。
<div class="codetitle"><a style="CURSOR: pointer" data="61732" class="copybut" id="copybut61732" onclick="doCopy('code61732')"> 代码如下:

<div class="codebody" id="code61732">
<?PHP
$FILENAME="image.thumb";
// 生成图片的宽度
$RESIZEWIDTH=400;
// 生成图片的高度
$RESIZEHEIGHT=400; function ResizeImage($im,$maxwidth,$maxheight,$name){
$width = imagesx($im);
$height = imagesy($im);
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
if($maxwidth && $width > $maxwidth){
$widthratio = $maxwidth/$width;
$RESIZEWIDTH=true;
}
if($maxheight && $height > $maxheight){
$heightratio = $maxheight/$height;
$RESIZEHEIGHT=true;
}
if($RESIZEWIDTH && $RESIZEHEIGHT){
if($widthratio < $heightratio){
$ratio = $widthratio;
}else{
$ratio = $heightratio;
}
}elseif($RESIZEWIDTH){
$ratio = $widthratio;
}elseif($RESIZEHEIGHT){
$ratio = $heightratio;
}
$newwidth = $width $ratio;
$newheight = $height $ratio;
if(function_exists("imagecopyresampled")){
$newim = imagecreatetruecolor($newwidth,$newheight);
imagecopyresampled($newim,$im,$newwidth,$newheight,$width,$height);
}else{
$newim = imagecreate($newwidth,$newheight);
imagecopyresized($newim,$height);
}
ImageJpeg ($newim,$name . ".jpg");
ImageDestroy ($newim);
}else{
ImageJpeg ($im,$name . ".jpg");
}
} if($_FILES['image']['size']){
if($_FILES['image']['type'] == "image/pjpeg"){
$im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
}elseif($_FILES['image']['type'] == "image/x-png"){
$im = imagecreatefrompng($_FILES['image']['tmp_name']);
}elseif($_FILES['image']['type'] == "image/gif"){
$im = imagecreatefromgif($_FILES['image']['tmp_name']);
}
if($im){
if(file_exists("$FILENAME.jpg")){
unlink("$FILENAME.jpg");
}
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
ImageDestroy ($im);
}
}
?>

以下是测试代码(demo.PHP)
<div class="codetitle"><a style="CURSOR: pointer" data="53446" class="copybut" id="copybut53446" onclick="doCopy('code53446')"> 代码如下: