PHP implements image upload and cropping functions
Jun 23, 2023 am 09:31 AM
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>圖片上傳</title>
</head>
<body>
<form action="upload.php" method="post" enctype="multipart/form-data">
<input type="file" name="file">
<input type="submit" value="上傳">
</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
// 指定文件上傳的目錄
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["file"]["name"]);
// 獲取文件類型
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));
// 檢查文件是否是圖片
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.";
$uploadOk = 0;
}
}
// 如果文件已經(jīng)存在，提示并退出
if (file_exists($target_file)) {
echo "Sorry, file already exists.";
$uploadOk = 0;
}
// 檢查文件大小
if ($_FILES["file"]["size"] > 500000) {
echo "Sorry, your file is too large.";
$uploadOk = 0;
}
// 允許上傳的圖片類型
if($imageFileType != "jpg" && $imageFileType != "jpeg" && $imageFileType != "png" && $imageFileType != "gif" ) {
echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
$uploadOk = 0;
}
// 如果沒有錯(cuò)誤，進(jìn)行文件上傳
if ($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:
//載入原圖
$src = imagecreatefromjpeg('test.jpg');
//裁剪原圖
$dst = imagecreatetruecolor(100, 100);
imagecopyresampled($dst, $src, 0, 0, 50, 50, 100, 100, 100, 100);
//保存裁剪后的圖片
imagejpeg($dst, 'test_crop.jpg');
//釋放原圖和裁剪后的圖片
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!
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