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wp_get_webp_info()

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概述

wp_get_webp_info() 函数用于提取 WebP 文件的元信息，包括宽度、高度和类型。它验证文件是否为 WebP 格式，并返回一个包含这些信息的数组。

关键要点

  • 参数 $filename 是必需的，表示 WebP 文件的路径。
  • 返回一个数组，包含 width（成功时为整数，失败时为 false）、height（成功时为整数，失败时为 false）和 type（成功时为字符串 'lossy'、'lossless' 或 'animated-alpha'，失败时为 false）。
  • 函数首先使用 wp_get_image_mime() 检查文件是否为 WebP 格式，如果不是则返回默认值。
  • 通过读取文件头部字节来解析 WebP 信息，确保有足够的数据。
  • 相关函数包括 wp_get_image_mime()、WP_Image_Editor_GD::set_quality()、wp_getimagesize() 和 WP_Image_Editor_Imagick::set_quality()。
  • 该函数在 WordPress 5.8.0 版本中引入。

代码示例

function wp_get_webp_info( $filename ) {
    $width  = false;
    $height = false;
    $type   = false;

    if ( 'image/webp' !== wp_get_image_mime( $filename ) ) {
        return compact( 'width', 'height', 'type' );
    }

    $magic = file_get_contents( $filename, false, null, 0, 40 );

    if ( false === $magic ) {
        return compact( 'width', 'height', 'type' );
    }

    // Make sure we got enough bytes.
    if ( strlen( $magic ) > 6 ) {
        // 解析逻辑（示例中未完整显示）
    }
}
📄 原文内容

Extracts meta information about a WebP file: width, height, and type.

Parameters

$filenamestringrequired
Path to a WebP file.

Return

array An array of WebP image information.

  • width int|false
    Image width on success, false on failure.
  • height int|false
    Image height on success, false on failure.
  • type string|false
    The WebP type: one of 'lossy', 'lossless' or 'animated-alpha'.
    False on failure.

Source

function wp_get_webp_info( $filename ) {
	$width  = false;
	$height = false;
	$type   = false;

	if ( 'image/webp' !== wp_get_image_mime( $filename ) ) {
		return compact( 'width', 'height', 'type' );
	}

	$magic = file_get_contents( $filename, false, null, 0, 40 );

	if ( false === $magic ) {
		return compact( 'width', 'height', 'type' );
	}

	// Make sure we got enough bytes.
	if ( strlen( $magic ) < 40 ) {
		return compact( 'width', 'height', 'type' );
	}

	/*
	 * The headers are a little different for each of the three formats.
	 * Header values based on WebP docs, see https://developers.google.com/speed/webp/docs/riff_container.
	 */
	switch ( substr( $magic, 12, 4 ) ) {
		// Lossy WebP.
		case 'VP8 ':
			$parts  = unpack( 'v2', substr( $magic, 26, 4 ) );
			$width  = (int) ( $parts[1] & 0x3FFF );
			$height = (int) ( $parts[2] & 0x3FFF );
			$type   = 'lossy';
			break;
		// Lossless WebP.
		case 'VP8L':
			$parts  = unpack( 'C4', substr( $magic, 21, 4 ) );
			$width  = (int) ( $parts[1] | ( ( $parts[2] & 0x3F ) << 8 ) ) + 1;
			$height = (int) ( ( ( $parts[2] & 0xC0 ) >> 6 ) | ( $parts[3] << 2 ) | ( ( $parts[4] & 0x03 ) << 10 ) ) + 1;
			$type   = 'lossless';
			break;
		// Animated/alpha WebP.
		case 'VP8X':
			// Pad 24-bit int.
			$width = unpack( 'V', substr( $magic, 24, 3 ) . "x00" );
			$width = (int) ( $width[1] & 0xFFFFFF ) + 1;
			// Pad 24-bit int.
			$height = unpack( 'V', substr( $magic, 27, 3 ) . "x00" );
			$height = (int) ( $height[1] & 0xFFFFFF ) + 1;
			$type   = 'animated-alpha';
			break;
	}

	return compact( 'width', 'height', 'type' );
}

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Uses Description
wp_get_image_mime()wp-includes/functions.php

Returns the real mime type of an image file.
Used by Description
WP_Image_Editor_GD::set_quality()wp-includes/class-wp-image-editor-gd.php

Sets Image Compression quality on a 1-100% scale. Handles WebP lossless images.
wp_getimagesize()wp-includes/media.php

Allows PHP’s getimagesize() to be debuggable when necessary.
WP_Image_Editor_Imagick::set_quality()wp-includes/class-wp-image-editor-imagick.php

Sets Image Compression quality on a 1-100% scale.

Changelog

Version Description
5.8.0 Introduced.