Image processing technology with PHP and CGI: How to upload and edit images

Image processing technology of PHP and CGI: How to upload and edit pictures

Introduction
With the rapid development of the Internet and mobile applications, the demand for image processing technology is also increasing. In the process of image uploading and editing, PHP and CGI are two commonly used technologies. This article will introduce how to use PHP and CGI to implement image uploading and editing functions, and provide relevant code examples.

1. Image upload
First, let’s take a look at how to implement the image upload function. Users can select and upload their own images through an upload form. In PHP, you can use the $_FILES array to obtain uploaded file information.

Code example:

<form action="upload.php" method="post" enctype="multipart/form-data">
    <input type="file" name="image">
    <input type="submit" value="上传">
</form>

In the upload.php file, we can use the move_uploaded_file function to move the uploaded image to the specified directory.

Code example:

$target_dir = "uploads/";  //指定上传文件的目录
$target_file = $target_dir . basename($_FILES["image"]["name"]);  //获取上传文件的文件名
move_uploaded_file($_FILES["image"]["tmp_name"], $target_file);  //将文件从临时目录移动到指定目录

With the above code, we can implement a simple image upload function.

2. Image Editing
In the process of image editing, we can use the GD library for image processing. The GD library is an open source library for processing images that can be used in a PHP environment.

First, we need to use the GD library to open and read an image.

Code example:

$source_image = imagecreatefromjpeg("uploads/image.jpg");  //打开并读取图片

Next, we can perform various editing operations on the image, such as cropping, scaling, adding watermarks, etc.

1. Crop the image
   We can use the imagecrop function to crop the image.

Code example:

$cropped_image = imagecrop($source_image, ["x" => 100, "y" => 100, "width" => 300, "height" => 200]);  //裁剪图片

2. Scale the image
   We can use the imagescale function to scale the image.

Code example:

$scale_image = imagescale($source_image, 500, 300);  //缩放图片

3. Add watermark
   We can use the imagecopy function to add a watermark to the image.

Code example:

$watermark_image = imagecreatefrompng("watermark.png");  //打开并读取水印图片
$watermark_width = imagesx($watermark_image);
$watermark_height = imagesy($watermark_image);

imagecopy($source_image, $watermark_image, 0, 0, 0, 0, $watermark_width, $watermark_height);  //添加水印

Finally, we can save the edited image.

Code example:

imagejpeg($source_image, "edited_image.jpg");  //保存编辑后的图片

Through the above operations, we can realize the image editing function.

3. Summary
In this article, we introduced the method of using PHP and CGI to upload and edit images, and provided relevant code examples. By uploading and editing images, we can meet users' image processing needs and provide richer functions for Internet and mobile applications. Hope this article can be helpful to you.

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