IMAGETYPE_SVG constant on standard extension and source code

[llaville]

Description

While testing PHP 8.5.0RC1 on context of my project https://github.com/llaville/php-compatinfo-db, I've noticed that PHP standard extension provide a IMAGETYPE_SVG constant, but we cannot find any implementation on GH repo
(except in a test file: https://github.com/php/php-src/blob/6872cf2eef921b9d27fa300ca5a7ad3bc27aee1c/ext/libxml/tests/image/imagetype_svg.phpt)

And so the implementation came from commit 0962c32#diff-8957f0eefb83e6c580f2fc6f40c9033d68ac478fd43bab0610ab382e13908829

Search for : https://github.com/search?q=repo%3Aphp%2Fphp-src%20IMAGETYPE_S&type=code

The following code:

php --re standard | grep IMAGETYPE_

Resulted in this output:

    Constant [ <persistent> int IMAGETYPE_GIF ] { 1 }
    Constant [ <persistent> int IMAGETYPE_JPEG ] { 2 }
    Constant [ <persistent> int IMAGETYPE_PNG ] { 3 }
    Constant [ <persistent> int IMAGETYPE_SWF ] { 4 }
    Constant [ <persistent> int IMAGETYPE_PSD ] { 5 }
    Constant [ <persistent> int IMAGETYPE_BMP ] { 6 }
    Constant [ <persistent> int IMAGETYPE_TIFF_II ] { 7 }
    Constant [ <persistent> int IMAGETYPE_TIFF_MM ] { 8 }
    Constant [ <persistent> int IMAGETYPE_JPC ] { 9 }
    Constant [ <persistent> int IMAGETYPE_JP2 ] { 10 }
    Constant [ <persistent> int IMAGETYPE_JPX ] { 11 }
    Constant [ <persistent> int IMAGETYPE_JB2 ] { 12 }
    Constant [ <persistent> int IMAGETYPE_SWC ] { 13 }
    Constant [ <persistent> int IMAGETYPE_IFF ] { 14 }
    Constant [ <persistent> int IMAGETYPE_WBMP ] { 15 }
    Constant [ <persistent> int IMAGETYPE_JPEG2000 ] { 9 }
    Constant [ <persistent> int IMAGETYPE_XBM ] { 16 }
    Constant [ <persistent> int IMAGETYPE_ICO ] { 17 }
    Constant [ <persistent> int IMAGETYPE_WEBP ] { 18 }
    Constant [ <persistent> int IMAGETYPE_AVIF ] { 19 }
    Constant [ <persistent> int IMAGETYPE_HEIF ] { 20 }
    Constant [ <persistent> int IMAGETYPE_UNKNOWN ] { 0 }
    Constant [ <persistent> int IMAGETYPE_COUNT ] { 22 }
    Constant [ <persistent> int IMAGETYPE_SVG ] { 21 }

Can we have a clarification on this subject please ?

PHP Version

PHP 8.5.0RC1 (cli) (built: Sep 26 2025 21:38:33) (NTS)
Copyright (c) The PHP Group
Built by https://github.com/docker-library/php
Zend Engine v4.5.0RC1, Copyright (c) Zend Technologies
    with Zend OPcache v8.5.0RC1, Copyright (c), by Zend Technologies

Operating System

Ubuntu 22.04 LTS

[DanielEScherzer]

Can you confirm that the libxml extension is also loaded?

[llaville]

Can you confirm that the libxml extension is also loaded?

Yes I confirm : version 2.9.14

FYI, here are all extensions and librairies loaded on my test system (docker container)

composer show platform results

composer               2.8.12   Composer package
composer-plugin-api    2.6.0    The Composer Plugin API
composer-runtime-api   2.2.2    The Composer Runtime API
ext-apcu               5.1.27   The apcu PHP extension
ext-ast                1.1.3    The ast PHP extension
ext-bcmath             8.5.0RC1 The bcmath PHP extension
ext-bz2                8.5.0RC1 The bz2 PHP extension
ext-calendar           8.5.0RC1 The calendar PHP extension
ext-ctype              8.5.0RC1 The ctype PHP extension
ext-curl               8.5.0RC1 The curl PHP extension
ext-date               8.5.0RC1 The date PHP extension
ext-dba                8.5.0RC1 The dba PHP extension
ext-dom                20031129 The dom PHP extension
ext-ds                 1.6.0    The ds PHP extension
ext-enchant            8.5.0RC1 The enchant PHP extension
ext-exif               8.5.0RC1 The exif PHP extension
ext-fileinfo           8.5.0RC1 The fileinfo PHP extension
ext-filter             8.5.0RC1 The filter PHP extension
ext-gd                 8.5.0RC1 The gd PHP extension
ext-gettext            8.5.0RC1 The gettext PHP extension
ext-gmp                8.5.0RC1 The gmp PHP extension
ext-hash               8.5.0RC1 The hash PHP extension
ext-http               4.2.6    The http PHP extension
ext-iconv              8.5.0RC1 The iconv PHP extension
ext-imap               1.0.3    The imap PHP extension
ext-intl               8.5.0RC1 The intl PHP extension
ext-json               8.5.0RC1 The json PHP extension
ext-ldap               8.5.0RC1 The ldap PHP extension
ext-lexbor             0        The lexbor PHP extension
ext-libxml             8.5.0RC1 The libxml PHP extension
ext-lzf                1.7.0    The lzf PHP extension
ext-mailparse          3.1.9    The mailparse PHP extension
ext-mbstring           8.5.0RC1 The mbstring PHP extension
ext-mongodb            2.1.2    The mongodb PHP extension
ext-msgpack            3.0.0    The msgpack PHP extension
ext-mysqli             8.5.0RC1 The mysqli PHP extension
ext-mysqlnd            0        The mysqlnd PHP extension (actual version: mysqlnd 8.5.0RC1)
ext-oci8               3.4.0    The oci8 PHP extension
ext-odbc               8.5.0RC1 The odbc PHP extension
ext-openssl            8.5.0RC1 The openssl PHP extension
ext-opentelemetry      1.2.1    The opentelemetry PHP extension
ext-pcntl              8.5.0RC1 The pcntl PHP extension
ext-pcre               8.5.0RC1 The pcre PHP extension
ext-pdo                8.5.0RC1 The PDO PHP extension
ext-pdo_dblib          8.5.0RC1 The pdo_dblib PHP extension
ext-pdo_firebird       8.5.0RC1 The PDO_Firebird PHP extension
ext-pdo_mysql          8.5.0RC1 The pdo_mysql PHP extension
ext-pdo_odbc           8.5.0RC1 The PDO_ODBC PHP extension
ext-pdo_pgsql          8.5.0RC1 The pdo_pgsql PHP extension
ext-pdo_sqlite         8.5.0RC1 The pdo_sqlite PHP extension
ext-pgsql              8.5.0RC1 The pgsql PHP extension
ext-phar               8.5.0RC1 The Phar PHP extension
ext-posix              8.5.0RC1 The posix PHP extension
ext-pspell             1.0.1    The pspell PHP extension
ext-random             8.5.0RC1 The random PHP extension
ext-raphf              2.0.2    The raphf PHP extension
ext-rdkafka            6.0.5    The rdkafka PHP extension
ext-readline           8.5.0RC1 The readline PHP extension
ext-reflection         8.5.0RC1 The Reflection PHP extension
ext-session            8.5.0RC1 The session PHP extension
ext-shmop              8.5.0RC1 The shmop PHP extension
ext-simplexml          8.5.0RC1 The SimpleXML PHP extension
ext-snmp               8.5.0RC1 The snmp PHP extension
ext-soap               8.5.0RC1 The soap PHP extension
ext-sockets            8.5.0RC1 The sockets PHP extension
ext-sodium             8.5.0RC1 The sodium PHP extension
ext-spl                8.5.0RC1 The SPL PHP extension
ext-sqlite3            8.5.0RC1 The sqlite3 PHP extension
ext-ssh2               1.4.1    The ssh2 PHP extension
ext-sysvmsg            8.5.0RC1 The sysvmsg PHP extension
ext-sysvsem            8.5.0RC1 The sysvsem PHP extension
ext-sysvshm            8.5.0RC1 The sysvshm PHP extension
ext-tidy               8.5.0RC1 The tidy PHP extension
ext-tokenizer          8.5.0RC1 The tokenizer PHP extension
ext-uploadprogress     2.0.2    The uploadprogress PHP extension
ext-uri                8.5.0RC1 The uri PHP extension
ext-uuid               1.3.0    The uuid PHP extension
ext-xhprof             2.3.10   The xhprof PHP extension
ext-xlswriter          1.5.8    The xlswriter PHP extension
ext-xml                8.5.0RC1 The xml PHP extension
ext-xmlreader          8.5.0RC1 The xmlreader PHP extension
ext-xmlrpc             1.0.0RC3 The xmlrpc PHP extension
ext-xmlwriter          8.5.0RC1 The xmlwriter PHP extension
ext-xsl                8.5.0RC1 The xsl PHP extension
ext-yac                2.3.1    The yac PHP extension
ext-yaml               2.2.5    The yaml PHP extension
ext-yar                2.3.4    The yar PHP extension
ext-zend-opcache       8.5.0RC1 The Zend OPcache PHP extension
ext-zip                1.22.6   The zip PHP extension
ext-zlib               8.5.0RC1 The zlib PHP extension
lib-bz2                1.0.8    The bz2 library
lib-curl               8.14.1   The curl library
lib-curl-libssh2       1.11.1   curl libssh2 version
lib-curl-openssl       3.5.1    curl OpenSSL version (3.5.1)
lib-curl-zlib          1.3.1    curl zlib version
lib-date-timelib       2022.14  date timelib version
lib-date-zoneinfo      2025.2   zoneinfo ("Olson") database for date
lib-fileinfo-libmagic  5.46     fileinfo libmagic version
lib-gd                 2.0.35   The gd library
lib-gd-freetype        2.13.3   freetype version for gd
lib-gd-libjpeg         6.2      libjpeg version for gd
lib-gd-libpng          1.6.48   libpng version for gd
lib-gd-libxpm          3.4.11   libxpm version for gd
lib-gmp                6.3.0    The gmp library
lib-iconv              2.41     The iconv library
lib-icu                76.1     The ICU unicode and globalization support library
lib-icu-cldr           46       ICU CLDR project version
lib-icu-unicode        16.0.0   ICU unicode version
lib-icu-zoneinfo       2024.2   zoneinfo ("Olson") database for icu
lib-ldap-openldap      2.6.10   OpenLDAP version of ldap
lib-libsodium          1.0.18   The libsodium library
lib-libxml             2.9.14   libxml library version
lib-libxslt            1.1.35   The libxslt library
lib-libxslt-libxml     2.9.14   libxml version libxslt is compiled against
lib-mbstring-libmbfl   1.3.2    mbstring libmbfl version
lib-mbstring-oniguruma 6.9.9    mbstring oniguruma version
lib-mongodb-libbson    1.30.5   libbson version of mongodb
lib-mongodb-libmongoc  1.30.5   libmongoc version of mongodb
lib-openssl            3.5.1    OpenSSL 3.5.1 1 Jul 2025
lib-pcre               10.46    The pcre library
lib-pcre-unicode       16.0.0   PCRE Unicode version support
lib-pdo_pgsql-libpq    17.6     libpq for pdo_pgsql
lib-pdo_sqlite-sqlite  3.46.1   The pdo_sqlite-sqlite library
lib-pgsql-libpq        17.6     libpq for pgsql
lib-rdkafka-librdkafka 2.8.0    librdkafka for rdkafka
lib-sqlite3-sqlite     3.46.1   The sqlite3-sqlite library
lib-ssh2-libssh2       1.11.1   The ssh2-libssh2 library
lib-yaml-libyaml       0.2.5    libyaml version of yaml
lib-zip-libzip         1.11.3   The zip-libzip library
lib-zlib               1.3.1    The zlib library
php                    8.5.0RC1 The PHP interpreter
php-64bit              8.5.0RC1 The PHP interpreter, 64bit
php-ipv6               8.5.0RC1 The PHP interpreter, with IPv6 support

[nielsdos]

I added a plugin system so that other extensions can add file format support.
The implementation is here: https://github.com/php/php-src/blob/master/ext/libxml/image_svg.c

[llaville]

@nielsdos OK, after looking into source code you pointed, I realized by searching this code

https://github.com/search?q=repo%3Aphp%2Fphp-src%20PHP_IMAGE_CONST_NAME&type=code

That the IMAGETYPE_SVG is a dynamic constant (reason of your plugin), see

https://github.com/php/php-src/blob/PHP-8.5/ext/standard/php_image.h#L83

BTW, the stub file does not reflect such dynamic constants

https://github.com/php/php-src/blob/PHP-8.5/ext/standard/basic_functions.stub.php#L523-L640

Is it always TRUE ?

[nielsdos]

These constants coming from plugins for the image types (currently only IMAGETYPE_SVG) will never be defined in the stub and will always be created dynamically.
IMAGETYPE_SVG will always be available when the libxml extension is loaded

[llaville]

I've well understood the situation.
BTW, I've one remark about your implementation, even if it's only for SVG and you hardcoded it in uppercase.
In case this plugin should be reused and we forgot to pasd suffix in uppercase, it will lead to inconsistent name character.

I.e: IMAGETYPE_foo

Hope you will understand my comment.