PHP implements image upload and cropping functions
PHP, as a commonly used back-end programming language, is widely used in the field of website development. Among them, image uploading and cropping are one of the commonly used functions in website development. The following will introduce how to use PHP to implement image upload and cropping functions.
1. Image upload function
First introduce the implementation of the image upload function. The following code implements a simple image upload function:
<html>
<head>
<meta charset="UTF-8">
<title>图片上传</title>
</head>
<body>
<form action="upload.php" method="post" enctype="multipart/form-data">
<input type="file" name="file">
<input type="submit" value="上传">
</form>
</body>
</html>There is a form on this page, and the action attribute of the form points to a processing script named upload.php. The form's enctype attribute must be set to "multipart/form-data" before binary files can be uploaded. A simple form is provided here and can be modified as needed.
The following is the processing script for upload.php:
<?php
// 指定文件上传的目录
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["file"]["name"]);
// 获取文件类型
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));
// 检查文件是否是图片
if(isset($_POST["submit"])) {
$check = getimagesize($_FILES["file"]["tmp_name"]);
if($check !== false) {
echo "File is an image - " . $check["mime"] . ".";
$uploadOk = 1;
} else {
echo "File is not an image.";
$uploadOk = 0;
}
}
// 如果文件已经存在，提示并退出
if (file_exists($target_file)) {
echo "Sorry, file already exists.";
$uploadOk = 0;
}
// 检查文件大小
if ($_FILES["file"]["size"] > 500000) {
echo "Sorry, your file is too large.";
$uploadOk = 0;
}
// 允许上传的图片类型
if($imageFileType != "jpg" && $imageFileType != "jpeg" && $imageFileType != "png" && $imageFileType != "gif" ) {
echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
$uploadOk = 0;
}
// 如果没有错误，进行文件上传
if ($uploadOk == 0) {
echo "Sorry, your file was not uploaded.";
} else {
if (move_uploaded_file($_FILES["file"]["tmp_name"], $target_file)) {
echo "The file ". basename( $_FILES["file"]["name"]). " has been uploaded.";
} else {
echo "Sorry, there was an error uploading your file.";
}
}
?>This script first obtains the uploaded file processing target path and file type, and then checks the file type and file size. If the file type and size meet the standards, the file will be uploaded, otherwise an error message will be prompted.
2. Image cropping function
The image cropping function refers to cropping the image after uploading it, so that the image size, proportion, etc. meet the requirements. The following describes how to use PHP to implement the image cropping function. In this article, we use the PHP library-GD library to process images.
- Install the GD library
Before using the GD library, you need to ensure that the library has been installed, otherwise it needs to be installed. In Linux systems, you can install the GD library through the following command:
sudo apt-get install php7.2-gd
In Windows systems, find the following statement in the php configuration file php.ini:
;extension=php_gd2.dll
Change it to:
extension=php_gd2.dll
Save and restart php.
- Crop pictures
Before using the GD library, you need to load the picture into the program. You can use functions such as Imagecreatefromjpeg(), Imagecreatefrompng(), Imagecreatefromgif() to load images in different formats. The following is a simple cropping program:
//载入原图
$src = imagecreatefromjpeg('test.jpg');
//裁剪原图
$dst = imagecreatetruecolor(100, 100);
imagecopyresampled($dst, $src, 0, 0, 50, 50, 100, 100, 100, 100);
//保存裁剪后的图片
imagejpeg($dst, 'test_crop.jpg');
//释放原图和裁剪后的图片
imagedestroy($src);
imagedestroy($dst);This program uses the image processing function imagecreatetruecolor() to generate a blank image, and then uses the imagecopyresampled() function to crop and copy the original image to the blank image. Finally, use the imagejpeg() function to save the cropped image.
3. Summary
In PHP, you can easily upload and crop images using the upload form and GD library. This function is very commonly used in website development. Mastering the basic skills of uploading and cropping images will be of immeasurable help to students who are new to website development.
The above is the detailed content of PHP implements image upload and cropping functions. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian
Dec 24, 2024 pm 04:42 PM
PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati
7 PHP Functions I Regret I Didn't Know Before
Nov 13, 2024 am 09:42 AM
If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op
How To Set Up Visual Studio Code (VS Code) for PHP Development
Dec 20, 2024 am 11:31 AM
Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c
Explain JSON Web Tokens (JWT) and their use case in PHP APIs.
Apr 05, 2025 am 12:04 AM
JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,
How do you parse and process HTML/XML in PHP?
Feb 07, 2025 am 11:57 AM
This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an
PHP Program to Count Vowels in a String
Feb 07, 2025 pm 12:12 PM
A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total
Explain late static binding in PHP (static::).
Apr 03, 2025 am 12:04 AM
Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.
What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases?
Apr 03, 2025 am 12:03 AM
What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.
