代碼如下:

function my_image_resize($src_file, $dst_file, $dst_width=32, $dst_height=32) { 
if($dst_width <1 || $dst_height <1) { 
echo "params width or height error !"; 
exit(); 
} 
if(!file_exists($src_file)) { 
echo $src_file . " is not exists !"; 
exit(); 
} 

$type=exif_imagetype($src_file); 
$support_type=array(IMAGETYPE_JPEG , IMAGETYPE_PNG , IMAGETYPE_GIF); 

if(!in_array($type, $support_type,true)) { 
echo "this type of image does not support! only support jpg , gif or png"; 
exit(); 
} 

switch($type) { 
case IMAGETYPE_JPEG : 
$src_img=imagecreatefromjpeg($src_file); 
break; 
case IMAGETYPE_PNG : 
$src_img=imagecreatefrompng($src_file); 
break; 
case IMAGETYPE_GIF : 
$src_img=imagecreatefromgif($src_file); 
break; 
default: 
echo "Load image error!"; 
exit(); 
} 
$src_w=imagesx($src_img); 
$src_h=imagesy($src_img); 
$ratio_w=1.0 * $dst_width/$src_w; 
$ratio_h=1.0 * $dst_height/$src_h; 
if ($src_w<=$dst_width && $src_h<=$dst_height) { 
$x = ($dst_width-$src_w)/2; 
$y = ($dst_height-$src_h)/2; 
$new_img=imagecreatetruecolor($dst_width,$dst_height); 
imagecopy($new_img,$src_img,$x,$y,0,0,$dst_width,$dst_height); 
switch($type) { 
case IMAGETYPE_JPEG : 
imagejpeg($new_img,$dst_file,100); 
break; 
case IMAGETYPE_PNG : 
imagepng($new_img,$dst_file); 
break; 
case IMAGETYPE_GIF : 
imagegif($new_img,$dst_file); 
break; 
default: 
break; 
} 
} else { 
$dstwh = $dst_width/$dst_height; 
$srcwh = $src_w/$src_h; 
if ($ratio_w <= $ratio_h) { 
$zoom_w = $dst_width; 
$zoom_h = $zoom_w*($src_h/$src_w); 
} else { 
$zoom_h = $dst_height; 
$zoom_w = $zoom_h*($src_w/$src_h); 
} 

$zoom_img=imagecreatetruecolor($zoom_w, $zoom_h); 
imagecopyresampled($zoom_img,$src_img,0,0,0,0,$zoom_w,$zoom_h,$src_w,$src_h); 
$new_img=imagecreatetruecolor($dst_width,$dst_height); 
$x = ($dst_width-$zoom_w)/2; 
$y = ($dst_height-$zoom_h)/2+1; 
imagecopy($new_img,$zoom_img,$x,$y,0,0,$dst_width,$dst_height); 
switch($type) { 
case IMAGETYPE_JPEG : 
imagejpeg($new_img,$dst_file,100); 
break; 
case IMAGETYPE_PNG : 
imagepng($new_img,$dst_file); 
break; 
case IMAGETYPE_GIF : 
imagegif($new_img,$dst_file); 
break; 
default: 
break; 
} 
} 
}