我目前正在使用一个 php 脚本，它根据最大宽度和高度创建缩略图。但是，我希望它始终创建方形图像并在需要时裁剪图像。
这是我现在正在使用的：
function makeThumb( $filename, $type ) {
global $max_width, $max_height;
if ( $type == 'jpg' ) {
$src = imagecreatefromjpeg("blocks/img/gallery/" . $filename);
} else if ( $type == 'png' ) {
$src = imagecreatefrompng("blocks/img/gallery/" . $filename);
} else if ( $type == 'gif' ) {
$src = imagecreatefromgif("blocks/img/gallery/" . $filename);
}
if ( ($oldW = imagesx($src)) < ($oldH = imagesy($src)) ) {
$newW = $oldW * ($max_width / $oldH);
$newH = $max_height;
} else {
$newW = $max_width;
$newH = $oldH * ($max_height / $oldW);
}
$new = imagecreatetruecolor($newW, $newH);
imagecopyresampled($new, $src, 0, 0, 0, 0, $newW, $newH, $oldW, $oldH);
if ( $type == 'jpg' ) {
imagejpeg($new, 'blocks/img/gallery/thumbs/'.$filename);
} else if ( $type == 'png' ) {
imagepng($new, 'blocks/img/gallery/thumbs/'.$filename);
} else if ( $type == 'gif' ) {
imagegif($new, 'blocks/img/gallery/thumbs/'.$filename);
}
imagedestroy($new);
imagedestroy($src);
}
我将如何改变它来实现我想要的（方形拇指）？
提前致谢。
function makeThumb( $filename , $thumbSize=100 ){
global $max_width, $max_height;
/* Set Filenames */
$srcFile = 'blocks/img/gallery/'.$filename;
$thumbFile = 'blocks/img/gallery/thumbs/'.$filename;
/* Determine the File Type */
$type = substr( $filename , strrpos( $filename , '.' )+1 );
/* Create the Source Image */
switch( $type ){
case 'jpg' : case 'jpeg' :
$src = imagecreatefromjpeg( $srcFile ); break;
case 'png' :
$src = imagecreatefrompng( $srcFile ); break;
case 'gif' :
$src = imagecreatefromgif( $srcFile ); break;
}
/* Determine the Image Dimensions */
$oldW = imagesx( $src );
$oldH = imagesy( $src );
/* Calculate the New Image Dimensions */
$limiting_dim = 0;
if( $oldH > $oldW ){
/* Portrait */
$limiting_dim = $oldW;
}else{
/* Landscape */
$limiting_dim = $oldH;
}
/* Create the New Image */
$new = imagecreatetruecolor( $thumbSize , $thumbSize );
/* Transcribe the Source Image into the New (Square) Image */
imagecopyresampled( $new , $src , 0 , 0 , ($oldW-$limiting_dim )/2 , ( $oldH-$limiting_dim )/2 , $thumbSize , $thumbSize , $limiting_dim , $limiting_dim );
switch( $type ){
case 'jpg' : case 'jpeg' :
$src = imagejpeg( $new , $thumbFile ); break;
case 'png' :
$src = imagepng( $new , $thumbFile ); break;
case 'gif' :
$src = imagegif( $new , $thumbFile ); break;
}
imagedestroy( $new );
imagedestroy( $src );
}
向@Sam Wan致敬以获取调整后的解决方案。抱歉，我花了这么长时间才将其合并到这个答案中。
/* Calculate the New Image Dimensions */
$limiting_dim = 0;
if( $oldH > $oldW ){
/* Portrait */
$limiting_dim = $oldW;
}else{
/* Landscape */
$limiting_dim = $oldH;
}
/* Create the New Image */
$new = imagecreatetruecolor( $thumbSize , $thumbSize );
/* Transcribe the Source Image into the New (Square) Image */
imagecopyresampled( $new , $src , 0 , 0 , ($oldW-$limiting_dim )/2 , ( $oldH-$limiting_dim )/2 , $thumbSize , $thumbSize , $limiting_dim , $limiting_dim );
我没有足够的业力来评论已接受的答案（Lucanos'），但我发现上面的答案在缩略图的一侧出现了黑条。
此代码片段（与接受的答案相结合）应复制 src 图像的相关部分，而不会超出范围并产生黑条。按照原来的问题，缩略图仍然是方形的。
您想要计算出偏移量而不是新的宽度/高度，以便新样本保持比例，然后在生成新图像时使用偏移量并为其指定固定的宽度/高度，以便它将裁剪为正方形。一个可以制作 100x100 拇指的简单示例（注意：未经测试），
// Get dimensions of the src image.
list($oldW, $oldH) = getimagesize($filename);
// Work out what offset to use
if ($oldH < $oldW)
{
$offH = 0;
$offW = ($oldW-$oldH)/2;
$oldW = $oldH;
}
elseif ($oldH > $oldW)
{
$offW = 0;
$offH = ($oldH-$oldW)/2;
$oldH = $oldW;
}
else
{
$offW = 0;
$offH = 0;
}
// Resample the image into the new dimensions.
$new = imagecreatetruecolor(100, 100);
imagecopyresampled($new, $src, 0, 0, $offW, $offH, 100, 100, $oldW, $oldH);
这个修改后的功能对我来说非常有用
public function igImagePrepare($img,$name){
$dir = 'my-images/';
$img_name = $name.'-'.uniqid().'.jpg';
//Your Image
$imgSrc = $img;
//getting the image dimensions
list($width, $height) = getimagesize($imgSrc);
//saving the image into memory (for manipulation with GD Library)
$myImage = imagecreatefromjpeg($imgSrc);
$square_size = 400;
$width = imagesx( $myImage );
$height = imagesy( $myImage );
//set dimensions
if($width> $height) {
$width_t=$square_size;
//respect the ratio
$height_t=round($height/$width*$square_size);
//set the offset
$off_y=ceil(($width_t-$height_t)/2);
$off_x=0;
} elseif($height> $width) {
$height_t=$square_size;
$width_t=round($width/$height*$square_size);
$off_x=ceil(($height_t-$width_t)/2);
$off_y=0;
}
else {
$width_t=$height_t=$square_size;
$off_x=$off_y=0;
}
/* Create the New Image */
$new = imagecreatetruecolor( $square_size , $square_size );
/* Transcribe the Source Image into the New (Square) Image */
$bg = imagecolorallocate ( $new, 255, 255, 255 );
imagefill ( $new, 0, 0, $bg );
imagecopyresampled( $new , $myImage , $off_x, $off_y, 0, 0, $width_t, $height_t, $width, $height );
//final output
imagejpeg($new, $dir.$img_name);
return $dir.$img_name;
}
由于我们这里有多个部分解决方案（归功于Luke Stevenson和Sam Wan），我觉得有必要将这些部分组合在一起。这是两个答案加上一些附加功能的完整解决方案：
其他函数参数，例如基本 + 拇指目录名称。
覆盖布尔参数，以便在缩略图已经存在时快速加载页面。
检查thumb目录是否存在；如果没有，则创建。
修复了
imagedestroy($src);/**
* Function to create a thumbnail of an image.
* See https://stackoverflow.com/questions/2686000/use-php-to-create-thumbnails-cropped-to-square
* @param $basePath
* @param $filename
* @param string $thumbDirName
* @param int $thumbSize
* @param bool $overwrite
* @return bool|null
*/
function makeThumb($basePath, $filename, $thumbDirName = 'thumbs', $thumbSize = 150, $overwrite = false)
{
/* Configure paths. */
$basePath = rtrim($basePath, '/') . '/';
$thumbDirName = trim($thumbDirName, '/') . '/';
$srcFile = $basePath . $filename;
$thumbBasePath = $basePath . $thumbDirName;
if (!is_dir($thumbBasePath)) {
if(!mkdir($thumbBasePath, 0755)){
throw new RuntimeException('could not create thumb dir: ' . $thumbBasePath);
}
}
$thumbServerPath = $thumbBasePath . $filename;
if(!$overwrite){
/* Check if thumbnail exists already. */
if(file_exists($thumbServerPath)){
return null;
}
}
/* Determine the File Type */
$type = substr($filename, strrpos($filename, '.') + 1);
/* Create the Source Image */
switch ($type) {
case 'jpg' :
case 'jpeg' :
$src = imagecreatefromjpeg($srcFile);
break;
case 'png' :
$src = imagecreatefrompng($srcFile);
break;
case 'gif' :
$src = imagecreatefromgif($srcFile);
break;
default:
return false;
}
/* Determine the Image Dimensions */
$oldW = imagesx($src);
$oldH = imagesy($src);
/* Calculate the New Image Dimensions */
$limiting_dim = $oldH; /* Landscape */
if( $oldH > $oldW ){
$limiting_dim = $oldW; /* Portrait */
}
/* Create the New Image */
$new = imagecreatetruecolor( $thumbSize , $thumbSize );
/* Transcribe the Source Image into the New (Square) Image */
imagecopyresampled( $new , $src , 0 , 0 , ($oldW-$limiting_dim )/2 , ( $oldH-$limiting_dim )/2 , $thumbSize , $thumbSize , $limiting_dim , $limiting_dim );
switch ($type) {
case 'jpg' :
case 'jpeg' :
imagejpeg($new, $thumbServerPath);
break;
case 'png' :
imagepng($new, $thumbServerPath);
break;
case 'gif' :
imagegif($new, $thumbServerPath);
break;
}
imagedestroy($new);
imagedestroy($src);
return true;
}