Implementation method of multi-image preview developed in PHP in WeChat mini program

With the popularity of WeChat mini programs, more and more developers are beginning to use mini programs to develop their own applications. In mini programs, PHP, as a popular backend development language, is increasingly used in mini programs. This article will introduce how to use PHP to implement the multi-image preview function in WeChat applet.

1. What is multi-image preview?

In the WeChat mini program, multi-picture preview refers to the function where users can view multiple pictures on one page. Normally, users need to click on a picture to view a specific picture, but using the multi-picture preview function can conveniently preview multiple pictures, improve user experience, and also facilitate developers to manage multiple pictures.

2. What is needed to implement the multi-image preview function in PHP?

When implementing the multi-image preview function in the WeChat applet, using PHP as the background language can easily achieve data management and processing. During specific implementation, PHP needs to be used to implement the following functions:

1. Database query: In the background, SQL statements need to be used to query the corresponding data in the database, such as the URL, name, size and other information of the picture. .
2. Image processing: Use PHP to easily convert images into binary data, and decode and encode binary data.
3. Return data: In the mini program, PHP needs to return the data required for the preview page to the mini program so that the mini program can display the preview page normally.

3. How to implement the multi-image preview function?

To specifically implement the multi-image preview function, you can follow the following steps:

1. In the background, use SQL statements to query the image data that needs to be previewed from the database, and save the data into the array.
2. Use PHP's GD library to convert the image into binary format and save it to the corresponding array.
3. Encode the data in the array into JSON format and return it to the applet.
4. In the mini program, use the wx.previewImage() method to preview the image. This method supports passing multiple image URLs and display previews on the page.

The following is an example of PHP code to implement the multi-image preview function:

<?php
// 连接数据库......
// 执行查询操作......
$result = mysqli_query($conn, "SELECT * FROM images");
if (mysqli_num_rows($result) > 0) {
    $images = array();
    while ($row = mysqli_fetch_assoc($result)) {
        $data = base64_encode(file_get_contents($row['image_url']));
        $images[] = array(
            'url' => $row['image_url'],
            'size' => $row['image_size'],
            'name' => $row['image_name'],
            'base64' => 'data:image/jpeg;base64,' . $data
        );
    }
    echo json_encode($images);
}
// 关闭数据库连接......
?>

The above code will query all image data in the database, convert it into JSON format and return it to the applet . In the mini program, use the following code to preview images:

wx.previewImage({
  current: '', // 当前显示图片的链接，不填则默认为images[0].url
  urls: [] // 需要预览的图片链接列表
})

Among them, current is the currently displayed image URL, which can be empty, and urls is an array of all image URLs that need to be previewed.

4. Summary

Using PHP to develop the multi-image preview function in the WeChat applet can easily manage and process a large amount of image data, and allows users to preview multiple images in one page. picture. Through the above introduction, I believe that readers have been able to master the method of using PHP to implement multi-image preview in WeChat mini programs. I hope it will be helpful to everyone.

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