PHP实现图片指定宽高缩放的两种方法

<选修php
// 指定图片路径
$image_path = 'path/to/your/image.jpg';
 
// 指定缩搁后的严度以及下度
$new_width = 两00;
$new_height = 150;
 
// 猎取图片疑息
list($width, $height, $type) = getimagesize($image_path);
 
// 依照图片范例建立图片资源
switch ($type) {
    case IMAGETYPE_JPEG:
        $image = imagecreatefromjpeg($image_path);
        break;
    case IMAGETYPE_PNG:
        $image = imagecreatefrompng($image_path);
        break;
    case IMAGETYPE_GIF:
        $image = imagecreatefromgif($image_path);
        break;
    default:
        die('Unsupported image type');
}
 
// 创立一个新的空缺图象
$new_image = imagecreatetruecolor($new_width, $new_height);
 
// 坚持 PNG 以及 GIF 图象的通明度
if ($type == IMAGETYPE_PNG || $type == IMAGETYPE_GIF) {
    imagealphablending($new_image, false);
    imagesavealpha($new_image, true);
    $transparent = imagecolorallocatealpha($new_image, 两55, 两55, 两55, 1二7);
    imagefilledrectangle($new_image, 0, 0, $new_width, $new_height, $transparent);
}
 
// 将本图象复造到新图象并入止缩搁
imagecopyresampled($new_image, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
 
// 输入新图象
header('Content-Type: image/' . image_type_to_extension($type, false));
// 将新图象生产到目的路径
$target_path = 'path/to/your/image_100_150.png';
imagepng($new_image, $target_path);
 
// 开释内存
imagedestroy($image);
imagedestroy($new_image);
必修>

$image = \think\Image::open('./image.png');
// 依照本图的比例天生一个最小为150*150的缩略图并生产为thumb.png
$image->thumb(150, 150)->save('./thumb.png');