ConFoo: Call for paper is now Open

imagewebp

(PHP 5 >= 5.5.0)

imagewebpWebP 画像をブラウザあるいはファイルに出力する

説明

bool imagewebp ( resource $image , string $filename )

指定した image を、WebP 形式で出力あるいは保存します。

パラメータ

image

imagecreatetruecolor() のような画像作成関数が返す画像リソース。

filename

ファイルの保存先のパス。省略したり NULL を設定したりした場合は、画像ストリームを直接出力します。

返り値

成功した場合に TRUE を、失敗した場合に FALSE を返します。

例1 WebP ファイルの保存

<?php
// 空の画像を作成し、テキストを追加します
$im imagecreatetruecolor(12020);
$text_color imagecolorallocate($im2331491);

imagestring($im155,  'WebP with PHP'$text_color);

// 画像を保存します
imagewebp($im'php.webp');

// メモリを解放します
imagedestroy($im);
?>

add a note add a note

User Contributed Notes 1 note

up
2
orangefish at sogetthis dot com
1 year ago
WebP is a great file format, but it's basically supported only by Chrome. For WebP files with transparency it's necessary to have PNG fallback for other browsers (otherwise it won't work in iOS, Firefox, IE, etc.).

Regular truecolor PNG with alpha gives pretty large files, but there's a special smaller PNG file variant that can be created by pngquant - a command line utility.

If you have pngquant 1.8 on your server (just get package from official pngquant website), then you can create small fallback images (with quality better than from PHP's libgd):

<?php

/**
* Optimizes PNG file with pngquant 1.8 or later (reduces file size of 24-bit/32-bit PNG images).
*
* You need to install pngquant 1.8.x on the server (ancient version 1.0 won't work).
* There's package for Debian/Ubuntu and RPM for other distributions on http://pngquant.org
*
* @param $path_to_png_file string - path to any PNG file, e.g. $_FILE['file']['tmp_name']
* @param $max_quality int - conversion quality, useful values from 60 to 100 (smaller number = smaller file)
* @return string - content of PNG file after conversion
*/
function compress_png($path_to_png_file, $max_quality = 90)
{
    if (!
file_exists($path_to_png_file)) {
        throw new
Exception("File does not exist: $path_to_png_file");
    }

   
// guarantee that quality won't be worse than that.
   
$min_quality = 60;

   
// '-' makes it use stdout, required to save to $compressed_png_content variable
    // '<' makes it read from the given file path
    // escapeshellarg() makes this safe to use with any path
   
$compressed_png_content = shell_exec("pngquant --quality=$min_quality-$max_quality - < ".escapeshellarg(    $path_to_png_file));

    if (!
$compressed_png_content) {
        throw new
Exception("Conversion to compressed PNG failed. Is pngquant 1.8+ installed on the server?");
    }

    return
$compressed_png_content;
}
?>

So for example when user is uploading a PNG file:

<?php

$read_from_path
= $_FILE['file']['tmp_name'];
$save_to_path = "uploads/compressed_file.png";

$compressed_png_content = compress_png($read_from_path);
file_put_contents($save_to_path, $compressed_png_content);

// you don't need move_uploaded_file().

// and for webp:
imagewebp(imagecreatefrompng($read_from_path), $save_to_path + ".webp");
?>

And then you can use URL with .webp version in Chrome and browsers that send Accept: image/webp, and .png for the rest (and all will get small file!)
To Top