PHP image compression and optimization skills in small program development

PHP image compression and optimization skills in mini program development

With the popularity of WeChat mini programs, more and more developers have begun to pay attention to the performance optimization of mini programs. Among them, pictures are a key factor that takes up a lot of resources. In the development of small programs, how to efficiently compress and optimize images has become a challenge that developers must face. This article will introduce some PHP image compression and optimization techniques and provide code examples.

1. Use the Gd library for image compression

PHP provides the Gd library, which is a powerful image processing library that can be used to compress and optimize images. The following is a sample code that uses the Gd library for image compression:

function compressImage($source_path, $target_path, $quality) {
    $image_info = getimagesize($source_path);
    $image_type = $image_info[2];

    if ($image_type === IMAGETYPE_JPEG) {
        $image = imagecreatefromjpeg($source_path);
        imagejpeg($image, $target_path, $quality);
    } elseif ($image_type === IMAGETYPE_PNG) {
        $image = imagecreatefrompng($source_path);
        imagepng($image, $target_path, $quality);
    } elseif ($image_type === IMAGETYPE_GIF) {
        $image = imagecreatefromgif($source_path);
        imagegif($image, $target_path);
    }

    imagedestroy($image);
}

In the above code, $source_path is the original image path, $target_path is the compressed one Image path, $quality represents the compression quality, the value range is 0 to 100.

2. Use imagemagick for image optimization

In addition to the Gd library, PHP can also optimize images by calling the external tool imagemagick. Imagemagick is a powerful image processing tool that provides a wealth of command line tools that can perform various operations on images, including compression and optimization.

The following is a sample code for image optimization using imagemagick:

function optimizeImage($source_path, $target_path) {
    $command = "convert $source_path -strip -quality 80% $target_path";
    exec($command);
}

In the above code, $source_path is the original image path, $target_path is the optimized image path.

3. Image format conversion and size adjustment

In actual development, in order to further reduce the image size, you can consider converting the image format to a more efficient format, such as Converting JPEG images to WEBP format can reduce image size without losing too much quality.

In addition, the pictures displayed in the mini program usually have a fixed display size, so the picture size can be adjusted and reduced according to actual needs. The following is a sample code for image format conversion and size adjustment:

function convertAndResizeImage($source_path, $target_path, $format, $width, $height) {
    $command = "convert $source_path -strip -resize {$width}x{$height} -filter Lanczos -quality 80% $target_path";
    exec($command);
}

In the above code, $format represents the target format, $width and $ height represents the target size.

4. Use caching to optimize image loading

In order to improve the loading speed of the mini program, you can consider using caching technology to optimize the loading of images. You can save compressed and optimized images to a cache folder and set an appropriate cache time. In this way, when the applet is loaded again, the image can be read directly from the cache, reducing the pressure on network requests.

The following is a sample code that uses cache to optimize image loading:

function serveImage($image_path) {
    $cache_path = './cache/' . md5($image_path) . '.jpg';

    // 如果缓存文件已存在，且缓存未过期，则直接输出缓存文件
    if (file_exists($cache_path) && filemtime($cache_path) > (time() - 86400)) {
        header('Content-Type: image/jpeg');
        readfile($cache_path);
        exit;
    }

    // 如果缓存文件不存在或缓存已过期，则生成新的缓存文件
    $command = "convert $image_path -strip -resize 500x500 -filter Lanczos -quality 80% $cache_path";
    exec($command);

    header('Content-Type: image/jpeg');
    readfile($cache_path);
    exit;
}

In the above code, $image_path represents the original image path, $cache_pathRepresents the cache file path, and the cache time is set to one day (86400 seconds).

Summary:

In the development of small programs, image compression and optimization is an important technical task. By using PHP's image processing library and external tools, we can achieve efficient image compression and optimization. At the same time, combined with image format conversion, size adjustment and caching technology, the performance and user experience of the mini program can be further improved. I hope the tips provided in this article can be helpful to developers.

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