PHP 图片上传时的大小调整

PHP 1年前 121

在 PHP 中，我们可以在上传时调整图像大小。PHP 有一个内置库 gd 来执行图像操作；我们可以创建函数来调整上传图像的大小。

本教程演示了在 PHP 中调整图像大小的不同方法。

使用 PHP `gd` 库在上传时调整图像大小

PHP 有一个 gd 库来对图像执行操作。打开你的 php.ini 文件并执行以下操作：

;extension=php_gd2.dll

在 php.ini 中搜索 gd 并删除评论 ; 在 PHP 8 中，它是 gd，而 PHP 8 之前的版本是 gd2。

extension=php_gd2.dll

重新启动服务器，一切顺利。

上传图片并调整大小的示例：

test.php：

<!DOCTYPE html>
<html>
<head>
    <title>PHP Resize Image On upload</title>
</head>
<body>
<div>
    <form action="action.php" method="post" enctype="multipart/form-data">
        <input type="file" name="uploadimage" />
		<br><br>
        <input type="submit" name="upload" value="Upload" />
    </form>
</div>
</body>
</html>

action.php：

<?php
if(isset($_POST["upload"])) {
    if(is_array($_FILES)) {
        $uploaded_file = $_FILES['uploadimage']['tmp_name'];
        $upl_img_properties = getimagesize($uploaded_file);
        $file_name_id= rand(10,100);
		$new_file_name = "Resized Image_".$file_name_id;
        $folder_path = "upload/";
        $img_ext = pathinfo($_FILES['uploadimage']['name'], PATHINFO_EXTENSION);
        $image_type = $upl_img_properties[2];
        switch ($image_type) {
			//for PNG Image
            case IMAGETYPE_PNG:
                $image_type_id = imagecreatefrompng($uploaded_file);
                $target_layer = image_resize($image_type_id, $upl_img_properties[0], $upl_img_properties[1]);
                imagepng($target_layer, $folder_path. $new_file_name. ".". $img_ext);
                break;
            //for GIF Image
            case IMAGETYPE_GIF:
                $image_type_id = imagecreatefromgif($uploaded_file);
                $target_layer = image_resize($image_type_id, $upl_img_properties[0], $upl_img_properties[1]);
                imagegif($target_layer, $folder_path. $new_file_name.".". $img_ext);
                break;
            //for JPEG Image
            case IMAGETYPE_JPEG:
                $image_type_id = imagecreatefromjpeg($uploaded_file);
                $target_layer = image_resize($image_type_id, $upl_img_properties[0], $upl_img_properties[1]);
                imagejpeg($target_layer, $folder_path. $new_file_name.".". $img_ext);
                break;
            default:
                echo "Please select a 'PNG', 'GIF'or JPEG image";
                exit;
                break;
        }
        //for the record move the uploaded file to the resized image directory
        move_uploaded_file($uploaded_file, $folder_path. "Original Uploaded Image_".$file_name_id.".". $img_ext);
        echo "Image is resized according to given Width and Height";
    }
}
function image_resize($image_type_id, $img_width, $img_height) {
    $target_width =1000;
    $target_height =1000;
    $target_layer= imagecreatetruecolor($target_width, $target_height);
    imagecopyresampled($target_layer, $image_type_id,0,0,0,0, $target_width, $target_height, $img_width, $img_height);
    return $target_layer;
}
?>