QWC2 Viewer Configuration

This chapter describes how to customize the QWC2 viewer.

First of all, it is important to keep in mind that the QWC2 Viewer is designed to be a modular and highly customizeable application. Configuration falls into three categories:

The qwc2-demo-app (and the qwc-map-viewer-demo docker image) serve as a good starting point, and for simple viewers the load-time configuration options are often sufficient to avoid the need of building a customized application.

Load-time configuration config.json

The load-time configuration config.json configuration file contains global viewer settings as well as the viewer plugin configuration for mobile and desktop devices. It is located as follows:

  • qwc-docker: qwc-docker/volumes/config-in/<tentant>/config.json
  • Standalone viewer: qwc2-app/static/config.json

Refer to the sample config.json for a concrete example.

Global settings

All settings are optional, with fallback to the default values as documented.

Setting Description
assetsPath Relative path to the assets folder. Default value: assets.
translationsPath Relative path to the translations folder. Default value: translations.
loadTranslationOverrides Whether to attempt to load tanslation overrides, see translations. Default value: false.
urlPositionFormat How to encode the current map extent in the URL, either centerAndZoom or extent. See URL parameters for details. Default value: extent.
urlPositionCrs The CRS used to encode the current map extent coordinates in the URL. Default value: the map projection.
omitUrlParameterUpdates Whether to omit updating the URL parameters. Default value: false.
defaultFeatureStyle The default style to use for selection geometries and other unstyled features. Default value: see qwc2/utils/FeatureStyles.js.
defaultMarkerStyle The default style to use as marker icon. Default value: see qwc2/utils/FeatureStyles.js.
defaultInteractionStyle The default style to use on geometries to measure, snap or edit. Default value: see qwc2/utils/FeatureStyles.js.
projections A list of map projections to register, in the format {"code": "<code>", "proj": "<proj4def>", "label": "<label>"}. By default, EPSG:3857 and EPSG:4326 are registered.
allowFractionalZoom Whether to allow arbitrary scales for viewing the map. Default value: false.
localeAwareNumbers Whether to use locale aware numbers throughout. Default value: false.
wmsHidpi Whether to honour the device pixel ratio for WMS GetMap requests. Default value: true.
wmsMaxGetUrlLength URL length limit before switching to a POST request for GetMap and GetFeatureInfo. Default: 2048.
qgisServerVersion The QGIS Server major version in use, defaults to 3.
defaultColorScheme The color scheme to use. See Color schemes for details.
startupTask Task to automatically aktivate on application start, in the format {key: "<Task>", "mode": "<Mode>"}.
storeAllLayersInPermalink Whether to store the full layertree in the permalink data, rather than only local (i.e. redlining) layers. If false, remote layers are re-queried from the respective services, if true, they are statically reloaded (meaning restored layers may be outdated compared to current service capabilities).
urlRegEx A JSON-escaped regular expression used to match URLs in feature attribute values. Default: see qwc2/utils/MiscUtils.js.
trustWmsCapabilityURLs Whether to trust the GetMap etc. URLs reported in WMS service capabilities. If not true, the protocol, host and pathname portion of the URLs are inherited from the called capabilities URL.
### Global settings, overridable per theme

The following options can be specified globally, and also overriden per theme, see themesConfig.json. All settings are optional, with fallback to the default values as documented.

Setting Description
preserveExtentOnThemeSwitch Whether to preserve the current map extent when switching theme, if possible (see below). Default value: false.
preserveBackgroundOnThemeSwitch Whether to preserve the current background layer when switching theme, if possible. Default value: false.
preserveNonThemeLayersOnThemeSwitch Whether to preserve non-theme layers when switching theme. Default value: false.
allowReorderingLayers Whether to allow re-ordering layers in the layer tree. Default value: false.
flattenLayerTreeGroups Whether to display a flat layer tree, omitting the groups. Default value: false.
allowLayerTreeSeparators Allows users to add separator items in a flat layer tree. Default value: false.
preventSplittingGroupsWhenReordering Whether to prevent splitting sibling groups or the group itself when reordering items. Default value: false.
allowRemovingThemeLayers Whether to allow removing any theme layers from the layer tree. Default value: false.
searchThemes Whether allow searching for themes from the global search field. Default value: false.
allowAddingOtherThemes Whether to allow adding another theme to a currently loaded theme. Default value: false.
disableImportingLocalLayers Whether to hide the option to import local layers from the layer tree. Default value: false.
importLayerUrlPresets A list of predefined URLs from which the user can choose when importing layers from the layer tree. Entries must be strings or objects of the format {"label": "<Label>", "value": "<URL>"}.
identifyTool The name of the identify plugin to use as default identify tool. If set to an empty string, no identify tool will be active by default. Default value: Identify.
globallyDisableDockableDialogs Whether to globally disable the dockable feature of popup dialogs. Default value: false.
globallyDisableMaximizeableDialogs Whether to globally disable the maximizeable feature of popup dialogs. Default value: false.
searchFilterRegions List of predefined search filter regions, see Search filtering.


  • The layer tree supports re-ordering layers via drag-and-drop if allowReorderingLayers = true and either preventSplittingGroupsWhenReordering = true or flattenLayerTreeGroups = true.
  • If preserveExtentOnThemeSwitch = true, the current extent is preserved if it is within the new theme extent and if the current theme map projection is equal to the new theme projection. If preserveExtentOnThemeSwitch = "force", the current extent is preserved regardless of whether it is within the new theme extent, but the current and new theme map projections must still match.

URLs of external services

Some plugins require external services (typically part of the qwc-services ecosystem). When using the qwc-docker, these configuration entries will be automatically injected into the config.json for enabled services.

Setting Description
authServiceUrl Typically the URL of a QWC authentication service like qwc-db-auth.
editServiceUrl Typically the URL of the qwc-data-service.
elevationServiceUrl Typically the URL of the qwc-elevation-service.
mapInfoService Typically the URL of the qwc-map-info-service.
permalinkServiceUrl Typically the URL of the qwc-permalink-service.
searchServiceUrl Typically the URL of the qwc-fulltext-search-service.
featureReportService Typically the URL of the qwc-document-service.

Plugin configuration

The plugin configuration is entered as follows:

"plugins": {
  "common": [{<PluginConfig>}, ...],
  "mobile": [{<PluginConfig>}, ...],
  "desktop": [{<PluginConfig>}, ...]

The final mobile and desktop configurations will be computed by merging the common configuration with the respective specific configuration. Each <PluginConfig> block is of the format

Setting Description
⁣  "name": "<name>", The plugin name.
⁣  "cfg": {...}, The plugin configuration options, see plugin reference.
⁣  "mapClickAction": <"identify"|"unset"|null>, Optional: in case the plugin activates a viewer task, determines whether a click in the map will result in the identify tool being invoked, the task being unset, or whether no particular action should be performed (default).

A particularly interesting aspect is the configuration of the entries in the application menu and toolbar, i.e. the entries in menuItems and toolbarItems in the TopBar plugin configuration. The format of these entries is as follows:

Setting Description
⁣  "key": "<key>", The name of a plugin, i.e. LayerTree. The label for the entry will be looked up from the translations using the appmenu.items.<key> message identifier (see Managing translations).
⁣  "icon": "<icon>", The icon of the entry, either a built-in icon name (see below), or :/<path_to_asset> containing the path relative to assetsPath of an asset image.
⁣  "themeBlacklist": ["<themename>", ...], Optional, allows specifying a blacklist of theme names or titles for which the entry should not be visible.
⁣  "themeWhitelist": ["<themename>", ...], Optional, allows specifying a whitelist of theme names or titles for which the entry should be visible.
⁣  "mode": "<mode>", Optional, depending on the plugin, a mode can be configured to launch the plugin directly in a specific mode. For instance, the Measure plugin supports specifying the measurement mode (Point, LineString, Polygon).
⁣  "requireAuth": "<true|false>", Optional, the entry is only visible when user is logged-in.
⁣  "shortcut": "<shortcut>" Optional, keyboard shortcut which triggers the entry, i.e. "alt+shift+a".

Note: The built-in icons are those located in qwc2-app/qwc2/icons and in qwc2-app/icons. The built-in icon names are the respective file names, without .svg extension.

Opening external websites

As a special case, entries for opening external URLs can be defined as follows:

Setting Description
⁣  "key": "<key>", An arbitrary key (not used by existing plugins), used to lookup the label for the entry from the translations.
⁣  "icon": "<icon>", As above.
⁣  "url": "<url>", The URL to open. Can contain as placeholders the keys listed in URL Parameters, encolsed in $ (i.e. $e$ for the extent). In addition, the placeholders $x$ and $y$ for the individual map center coordinates are also supported.
⁣  "target": "<target>" The target where to open the URL, if empty, _blank is assumed. Can be iframe to open the link in a iframe window inside QWC2.

In general, the procedure for enabling a plugin is:

  • Make sure the plugin is compiled into the application (see Build-time configuration).
  • In the plugins section of config.json, below common (or mobile and/or desktop), add an entry
    "name": "<Plugin name>",
    "cfg": {
      <Plugin configuration props>
  • For most plugins (i.e. those which launch as an explicit task in the viewer), add entries in menuItems and/or toolbarItems as desired, i.e.
  "menuItems": [
    {"key": "<Plugin name>", "icon": "<icon name>", ...}

Customizing the viewer assets

The viewer assets are located as follows:

  • Standalone viewer: qwc2-app/static/assets
  • qwc-docker: qwc-docker/volumes/qwc2/assets

The default structure of the assets folder is as follows:

Path Description
└─ assets/ See Viewer assets
├─ css/ Additional style sheets, must be included by index.html.
│ ├─ colorschemes.css Additional color schemes.
│ └─ qwc2.css Additional style definitions.
├─ img/ Application logo etc.
│ ├─ genmapthumbs/ Autogenerated map thumbnails.
│ └─ mapthumbs/ Map thumbnails.
├─ templates/
│ └─ legendprint.html HTML template for the legend print.
├─ help.html Help dialog fragment, see Help dialog.
└─ searchProviders.js Additional search providers, see Search providers.

Furthermore, the application entry point index.html is located as follows:

  • Standalone viewer: qwc2-app/index.html
  • qwc-docker: qwc-docker/volumes/config-in/<tenant>/index.html

This file noteably specifies the application title, and references many of the assets located below the assets folder.

Customizing the color scheme

The QWC2 color scheme is fully customizeable via CSS. A default color-scheme is built-in (see DefaultColorScheme.css). To define a custom color scheme, copy the default color scheme to assets/css/colorschemes.css, add an appropriate class name to the :root selector, and modify the colors as desided. Two additional examples (highcontrast and dark) are provided by default inassets/css/colorschemes.css.

You can then modify the color scheme which is applied by default by setting defaultColorScheme in config.json to an appropriate class name (i.e. highcontrast or dark).

To change the color scheme at runtime in QWC2, make sure the Settings plugin is enabled, and in the Settings plugin configuration block in config.json list the color schemes below colorSchemes. Refer to the sample config.json.

Note: When changing the color scheme via Settings dialog in QWC2, the picked color scheme is stored in the browser local storage, and this setting will override the defaultColorScheme setting from config.json. Specifying the style URL-parameter (see URL parameters) will take precedence over all other settings.

Note: Make sure that assets/css/colorschemes.css is included in index.html.

Overriding component styles

Occasionally, it may be desired to customize the styling on the QWC2 components. The recommended approach is to add the corresponding style overrides to assets/css/qwc2.css.

Note: Make sure that assets/css/qwc2.css is included in index.html.

The application logo in its various shapes and sizes are located below assets/img/. In particular, the logo.svg and logo-mobile.svg images are displayed as in the top left corner of QWC2 in desktop and mobile mode respectively. If you'd like to use another format than SVG (while keeping logo and logo-mobile as base name), you can change logoFormat in the TopBar configuration block in config.json.

Providing custom map thumbnails

By default, when generating the themes configuration (see [ThemesConfiguration.md#generating-theme-configuration]), a default map thumbnail is generating via WMS GetMap, and placed below assets/img/genmapthumbs. You can provide your own thumbnail images instead by placing the corresponding images below assets/img/mapthumbs and referencing these as thumbnail in you theme configuration block in themesConig.json.

Personalizing the help dialog

You can personalize the help dialog by providing a plain HTML document fragment in static/assets/help.html and configuring the Help plugin accordingly in config.json:

  "name": "Help",
  "cfg": {
    "bodyContentsFragmentUrl": "assets/help.html"

Note: $VERSION$ can be used in the HTML document fragment as a placeholder for the application build date.

Personalizing the legend print template

The legend print template assets/templates/legendprint.html is used when printing the map legend from the layer tree. The only requirement for this template is that is must contain a <div id="legendcontainer"></div> element.

Building a custom viewer

QWC2 is divided into two repositories:

To build a custom viewer, the first step is cloning the demo application:

git clone --recursive https://github.com/qgis/qwc2-demo-app.git qwc2-app

The typical layout of a QWC2 app source tree is as follows:

Path Description
├─ static/
│ ├─ assets/ See Viewer assets
│ ├─ translations/ Translation files.
│ ├─ config.json Master configuration file.
│ └─ themes.json Full theme configuration, autogenerated from themesConfig.json.
├─ js/
│ ├─ app.jsx Entry point of the ReactJS application.
│ ├─ appConfig.js Configuration of the qwc2 core modules.
│ ├─ Help.jsx Built-in component of custom Help dialog, see Help dialog.
│ └─ SearchProviders.js Built-in custom search providers, see Search providers.
├─ icons/ Application icons.
├─ qwc2/ Git submodule containing the core qwc2 components.
├─ index.html Entry point.
├─ package.json NodeJS configuration file.
├─ themesConfig.json Themes configuration.
└─ webpack.config.js Webpack configuration.

Application build-time configuration

The js/appConfig.js is the the principal build-time configuation file, and defines: - The default application locale, built into the application. This locale is used if no available locale matches the browser locale. - Which plugins are built into the application. Plugins left out here will be completely omitted when compiling the application bundle, and will hence also reduce the size of the bundle. - Various hook functions, as documented in the sample sample js/appConfig.js.

Refer to the sample appConfig.js for a concrete example.

Overriding icons

The common application icons are located in qwc2/icons. They can be overridden by creating an icon with the same filename in the application specific icons folder.

Note: The icons in the icons folder are compiled into an icon font. The icons need to be black content on transparent background, and all drawings (including texts) must be converted to paths for the icons to render correctly.

Compiling an application bundle

After tweaking the source files as desired, compile a deployable application bundle for production running

yarn run prod

When using qwc-docker, copy the contents of the qwc2-app/prod folder to qwc-docker/volumes/qwc2 and edit the qwc-docker/docker-compose.yml to use qwc-map-viewer-base with your custom build:

  image: sourcepole/qwc-map-viewer-base:vYYYY.MM.DD
    <<: *qwc-service-variables
    - ./pg_service.conf:/srv/pg_service.conf:ro
    - ./volumes/config:/srv/qwc_service/config:ro
    - ./volumes/qwc2:/qwc2:ro

Keeping the QWC2 application up to date

As mentioned above, QWC2 is split into a common components repository and an application specific repository. The goal of this approach is to cleanly separate user-specific configuration and components which common components which serve as a basis for all QWC2 applications, and to make it as easy as possible to rebase the application onto the latest common QWC2 components.

The recommended workflow is to keep the qwc2 folder a submodule referencing the upstream qwc2 repository. To update it, just checkout/update the desired branch:

cd qwc2
git checkout master
# or
git checkout YYYY-lts
git pull

The QWC2 Upgrade Notes documents major changes, and in particular all incompatible changes between releases which require changes to the application specific code and/or configuration.


This section gives an overview of the common tasks related to the QWC2 translations.

Switching language

By default, QWC2 will attempt to load the translation matching your browser language. Alternatively, you can explicitly specify the language by adding the lang=<lang> query parameter to the application URL, i.e. lang=de-CH.

The Settings plugin furthermore allows graphically switching the language within QWC2.

Adding and modify translations

When working inside a qwc2-app source folder, the translations can be found on two levels:

  • At QWC2 components level, in qwc2-app/qwc2/translations.
  • At application level, in qwc2-app/static/translations.

A script will take care of merging the component translations into the application translations. This way, when updating the QWC2 submodule, new translations are automatically obtained. This script is automatically invoked on yarn start, but can also be manually invoked using

yarn run tsupdate

Translations are stored inside the respective translations folder as regular plain-text JSON files, named <lang>.json and can be freely edited with any text editor.

The tsconfig.json files stored inside the respective translations folder contains the list of languages for which translations should be generated and a list of message IDs to include in the translation. The tsupdate script will automatically scan the code for message IDs (looking for static strings passed to LocaleUtils.tr and LocaleUtils.trmsg), store these in tsconfig.json and automatically create resp. update the translation files.

In some cases tsconfig.json will not pick up a message ID (for instance, if it is computed at runtime). In these cases, the message IDs can be added manually to the extra_strings section of the tsconfig.json.

Also it may be desired to override a translation inherited from the QWC2 components at application level. To prevent tsupdate from continuously reverting the overridden translation, the respective message IDs can be added to the overrides section in the application tsconfig.json file.

To add a new language, list it in qwc2-app/qwc2/translations/tsconfig.json and run yarn run tsupdate, then complete the messages taking the english translation file as reference.

When adding or modifying translations at QWC2 components level, please contribute them by submitting a pull request to the upstream qwc2 repository.

Selectively overriding translation strings

Occasionally, it is desireable to selectively override specific translation strings. While one can modify the full translation file as described above, especially when using the qwc-map-viewer-demo docker image, it is easier to just selectively override the desired translation strings and leave the original file unchanged and avoid having to compile a custom viewer (or overwriting the entire file with a docker volume mount).

To do this:

  • Set loadTranslationOverrides to true in config.json.
  • Create a <lang>_overrides.json containing just the ovverridden strings, for example en-US_overrides.json:
  "messages": {
    "appmenu": {
      "items": {
        "LayerTree": "Layers"
  • Place this file inside the translations folder of your production build. When using qwc-docker, you can place this file in qwc-docker/volumes/qwc2/translations/ and mount this file inside the container, i.e. :
  image: sourcepole/qwc-map-viewer-demo:vYYYY.MM.DD
    - ./volumes/qwc2/translations/en-US_overrides.json:/qwc2/translations/en-US_overrides.json:ro

Specifying the default fallback translation

When no translation exists for the requested language (i.e. the current browser language), QWC2 will fall back to the default translation specified as defaultLocaleData in qwc2-app/js/appConfig.js. For the demo viewer, the default fallback translation is en-US.