Custom color in theming hides login image in NC18

[marius-wieschollek]

Steps to reproduce

1. Install Nextcloud 18.0.0 RC1 (Fresh install or upgrade)
2. Open the admin settings and go to "Theming"
3. (optional) Upload a "Login image"
4. Change the "Color" in the Theming settings
5. Look at the theme preview or login page

Expected behaviour

Color is changed and the background image is visible.

Actual behaviour

Only a color gradient is shown in the preview and the login page.
In the header of the first run wizard, the login image is now shown. (It was not visible there before)

Server configuration

Operating system: Ubuntu 18.04

Web server: Nginx

Database: MariaDB

PHP version: 7.3.13

Nextcloud version: 18.0.0 RC1

Updated from an older Nextcloud/ownCloud or fresh install: fresh install

Where did you install Nextcloud from: releases page on Github (also happens with official docker image nextcloud:18-beta-fpm)

Signing status:

Signing status

No errors have been found.

List of activated apps:

App list

Enabled:
  - accessibility: 1.4.0
  - activity: 2.11.0
  - cloud_federation_api: 1.1.0
  - comments: 1.8.0
  - dav: 1.14.0
  - federatedfilesharing: 1.8.0
  - federation: 1.8.0
  - files: 1.13.1
  - files_pdfviewer: 1.7.0
  - files_rightclick: 0.15.2
  - files_sharing: 1.10.1
  - files_trashbin: 1.8.0
  - files_versions: 1.11.0
  - files_videoplayer: 1.7.0
  - firstrunwizard: 2.7.0
  - logreader: 2.3.0
  - lookup_server_connector: 1.6.0
  - nextcloud_announcements: 1.7.0
  - notifications: 2.6.0
  - oauth2: 1.6.0
  - password_policy: 1.8.0
  - passwords: 2020.1.0-BUILD
  - photos: 1.0.0
  - privacy: 1.2.0
  - provisioning_api: 1.8.0
  - recommendations: 0.6.0
  - serverinfo: 1.8.0
  - settings: 1.0.0
  - sharebymail: 1.8.0
  - support: 1.1.0
  - survey_client: 1.6.0
  - systemtags: 1.8.0
  - text: 1.2.3
  - theming: 1.9.0
  - twofactor_backupcodes: 1.7.0
  - updatenotification: 1.8.0
  - viewer: 1.2.0
  - workflowengine: 2.0.0
Disabled:
  - admin_audit
  - encryption
  - files_external
  - user_ldap

Nextcloud configuration:

Config report

{
    "system": {
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "mail_smtpmode": "smtp",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "1025",
        "mail_smtpsecure": "",
        "mail_smtpauth": false,
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "passwords.local"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "18.0.0.8",
        "overwrite.cli.url": "https:\/\/localhost",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "loglevel": 0,
        "defaultapp": "passwords",
        "theme": "",
        "maintenance": false,
        "updater.release.channel": "beta"
    }
}

Are you using external storage, if yes which one: no

Are you using encryption: no

Are you using an external user-backend, if yes which one: no

Client configuration

Browser: Firefox 71

Operating system: Ubuntu 18.04

Logs

Web server error log

Web server error log

No errors

Nextcloud log (data/nextcloud.log)

Nextcloud log

No errors

Browser log

Browser log

no errors

[jancborchardt]

Yes, this is known as per the comment at #18082 (comment) and the following ones.

What we would need is that the background SVG also gets generated based on the primary color. The current background SVG uses the primary color at a certain opacity, so that it "vanishes" in the bottom left where the primary color is used, but shows the icons in the center and especially top left, where it fades into the lighter color. :)

[marius-wieschollek]

With the $has-custom-background variable from #18660 it could be possible to remove the image only when the color is changed and not custom background is used.

Right now it is confusing that the login image disappears without any explanation.

[jancborchardt]

Ah right, I get it now! :) Yes, it should be like you describe – could you submit a pull request?