osm.qdoc

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// Copyright (C) 2015 Aaron McCarthy <mccarthy.aaron@gmail.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
\page location-plugin-osm.html
\title Qt Location Open Street Map Plugin
\ingroup QtLocation-plugins
 
\brief Uses Open Street Map and related services.
 
\section1 Overview
 
This geo services plugin allows applications to access
\l {http://openstreetmap.org}{Open Street Map} location based services using the
Qt Location API.
 
Data, imagery and map information provided by
\l {http://www.thunderforest.com/}{ThunderForest},
\l {http://www.openstreetmap.org/copyright}{OpenStreetMap} and contributors.
The data is available under the
\l {http://www.opendatacommons.org/licenses/odbl}{Open Database License}.
 
The Open Street Map geo services plugin can be loaded by using the plugin key
"osm".
 
\note The standard map types rely on (partially) free data providers. We try to
keep the selection useful for evaluation and development purposes, but it is
your responsibility to select a data provider that fits your needs in
production. It is highly recommended to carefully read and adhere to the terms
of service of the respective providers. A list of alternative data providers is
available in the
\l{https://wiki.openstreetmap.org/wiki/Raster_tile_providers}{OpenStreetMap
wiki}. The available map types offered by this plugin may change (or be
removed) without notice depending on the actual availability of a viable openly
accessible provider for each type. This also implies that providers serving
tiles over HTTPS may be used. This becomes relevant when using the OSM plugin
on platforms, such as Android, for which SSL support is not built into Qt by
default. To prevent these changes, either a different geo service plugin should
be used, or the plugin parameter \e osm.mapping.providersrepository.address
should be set to a user-specified repository, in order to take full control
over selecting the provider that is used for each map type. Since Qt 5.9.6, the
default nominatim endpoint, used for geocoding and places, has also changed to
HTTPS-only.
 
\section1 Parameters
 
\section2 Optional parameters
The following table lists optional parameters that can be passed to the Open
Street Map plugin.
 
\note Since Qt 5.5 all parameters below must be prefixed with \c osm. Previous
versions did not require a prefix.
 
\table
\header
    \li Parameter
    \li Description
\row
    \li osm.geocoding.host
    \li Url string set when making network requests to the geocoding server.
        This parameter should be set to a valid server url with the correct OSM
        API. If not specified the default
        \l {http://nominatim.openstreetmap.org/}{url} will be used.
        \note The API documentation is available at
        \l {https://wiki.openstreetmap.org/wiki/Nominatim}{Project OSM Nominatim}.
\row
    \li osm.geocoding.debug_query
    \li Instructs the plugin to inject the query url to nominatim into the
        geocode reply, for debugging purposes.
\row
    \li osm.geocoding.include_extended_data
    \li Instructs the plugin to include Nominatim-specific information (such as
        geometry and class) into the returned Location objects, exposed as
        extendedAttributes.
\row
    \li osm.mapping.cache.directory
    \li Absolute path to map tile cache directory used as network disk cache.
 
    The default place for the cache is the \c{QtLocation/osm} subdirectory in
    the location returned by QStandardPaths::writableLocation(), called with
    QStandardPaths::GenericCacheLocation as a parameter. On systems that have
    no concept of a shared cache, the application-specific
    \l{QStandardPaths::CacheLocation} is used instead. \row
    \li osm.mapping.cache.disk.cost_strategy
    \li The cost strategy to use to cache map tiles on disk.
        Valid values are \b bytesize and \b unitary.
        Using \b bytesize, the related size parameter
        (\b osm.mapping.cache.disk.size) will be interpreted as bytes. Using
        \b unitary, they will be interpreted as number of tiles. The default
        value for this parameter is \b bytesize.
\row
    \li osm.mapping.cache.disk.size
    \li Disk cache size for map tiles. The default size of the cache is 50 MiB
        when \b bytesize is the cost strategy for this cache, or 1000 tiles,
        when \b unitary is the cost strategy.
\row
    \li osm.mapping.cache.memory.cost_strategy
    \li The cost strategy to use to cache map tiles in memory.
        Valid values are \b bytesize and \b unitary.
        Using \b bytesize, the related size parameter
        (\b osm.mapping.cache.memory.size) will be interpreted as bytes.
        Using \b unitary, they will be interpreted as number of tiles.
        The default value for this parameter is \b bytesize.
\row
    \li osm.mapping.cache.memory.size
    \li Memory cache size for map tiles. The default size of the cache is 3 MiB
        when \b bytesize is the cost strategy for this cache, or 100 tiles, when
        \b unitary is the cost strategy.
\row
    \li osm.mapping.cache.texture.cost_strategy
    \li The cost strategy to use to cache decompressed map tiles in memory.
        Valid values are \b bytesize and \b unitary.
        Using \b bytesize, the related size parameter
        (\b osm.mapping.cache.texture.size) will be interpreted as bytes.
        Using \b unitary, they will be interpreted as number of tiles.
        The default value for this parameter is \b bytesize.
\row
    \li osm.mapping.cache.texture.size
    \li Texture cache size for map tiles. The default size of the cache is 6 MiB
        when \b bytesize is the cost strategy for this cache, or 30 tiles, when
        \b unitary is the cost strategy. Note that the texture cache has a hard
        minimum size which depends on the size of the map viewport (it must
        contain enough data to display the tiles currently visible on the
        display). This value is the amount of cache to be used in addition to
        the bare minimum.
\row
    \li osm.mapping.custom.datacopyright
    \li Custom data copryright string is used when setting the
        \l{Map::activeMapType} to \l{mapType::style}{MapType.CustomMap} via
        urlprefix parameter. This copyright will only be used when using the
        CustomMap from above. If empty no data copyright will be displayed for
        the custom map.
\row
    \li osm.mapping.custom.host
    \li The url string of a custom tile server. This parameter should be set to a
        valid server url offering the correct OSM API. The postfix
        "%z/%x/%y.png" will be added to the url. Since 6.5 the postfix will not
        be added if the url ends with ".png". If the server requires an apikey, it
        has to be added to the url string. To use this server, the
        \l{Map::activeMapType} parameter of the \l Map should be set to the
        supported map type whose type is \l{mapType::style}{MapType.CustomMap}.
        This map type is only be available if this plugin parameter is set, in
        which case it is always
        \l{Map::supportedMapTypes}[supportedMapTypes.length - 1].
        \note Setting the mapping.custom.host parameter to a new server renders
        the map tile cache useless for the old custommap style.
\row
    \li osm.mapping.custom.mapcopyright
    \li Custom map copryright string is used when setting the
        \l{Map::activeMapType} to \l{mapType::style}{MapType.CustomMap} via
        urlprefix parameter. This copyright will only be used when using the
        CustomMap from above. If empty no map copyright will be displayed for
        the custom map.
\row
    \li osm.mapping.highdpi_tiles
    \li Whether or not to request high dpi tiles. Valid values are \b true and
        \b false. The default value is \b false. Please note that not all map
        types are available in high dpi. Setting this parameter to true might
        even have no effect if no map type is available in high dpi at the
        moment. Provider information files for high dpi tiles are named
        \tt{street-hires}, \tt{satellite-hires}, \tt{cycle-hires},
        \tt{transit-hires}, \tt{night-transit-hires}, \tt{terrain-hires} and
        \tt{hiking-hires}. These are fetched from the same location used for the
        low dpi counterparts.
\row
    \li osm.mapping.offline.directory
    \li Absolute path to a directory containing map tiles used as an offline
        storage. If specified, it will work together with the network disk
        cache, but tiles won't get automatically inserted, removed or updated.
        The format of the tiles is the same used by the network disk cache.
        There is no default value, and if this property is not set, no directory
        will be indexed and only the network disk cache will be used to reduce
        network usage or to act as an offline storage for the currently cached
        tiles.
\row
    \li osm.mapping.prefetching_style
    \li This parameter allows to provide a hint how tile prefetching is to be
        performed by the engine. The default value, \tt{TwoNeighbourLayers},
        makes the engine prefetch tiles for the layer above and the one below
        the current tile layer, providing ready tiles when zooming in or out
        from the current zoom level. \tt{OneNeighbourLayer} only prefetches the
        one layer closest to the current zoom level. Finally, \tt{NoPrefetching}
        allows to disable the prefetching, so only tiles that are visible will
        be fetched. Note that, depending on the active map type, this hint might
        be ignored.
\row
    \li osm.mapping.providersrepository.address
    \li The OpenStreetMap plugin retrieves the provider's information from a
        remote repository. This is done to prevent using hardcoded servers by
        default, which may become unavailable. By default this information is
        fetched from \l {http://maps-redirect.qt.io} {maps-redirect.qt.io}.
        Setting this parameter changes the provider repository address to a
        user-specified one, which must contain the files \tt{street},
        \tt{satellite}, \tt{cycle}, \tt{transit}, \tt{night-transit},
        \tt{terrain} and \tt{hiking}, each of which must contain valid provider
        information.
\row
    \li osm.mapping.providersrepository.disabled
    \li By default, the OpenStreetMap plugin retrieves the provider's
        information from a remote repository to avoid a loss of service due to
        unavailability of hardcoded services. The plugin, however, still
        contains fallback hardcoded provider data, in case the provider
        repository becomes unreachable. Setting this parameter to \b true makes
        the plugin use the hardcoded urls only and therefore prevents the plugin
        from fetching provider data from the remote repository.
 
\row
    \li osm.places.debug_query
    \li Set this parameter to true to have an extended attribute in each result
        named "requestUrl", and containing the url used for the query. Default
        is \b false.
\row
    \li osm.places.host
    \li Url string set when making network requests to the places server.
        This parameter should be set to a valid server url with the correct OSM
        API. If not specified the default
        \l {http://nominatim.openstreetmap.org/search}{url} will be used.
        \note The API documentation is available at
        \l {https://wiki.openstreetmap.org/wiki/Nominatim}{Project OSM Nominatim}.
\row
    \li osm.places.page_size
    \li The amount of results in a page. Note that this value might be clamped
        server side. The typical maximum in standard nominatim instances is 50.
 
\row
    \li osm.routing.apiversion
    \li String defining the api version of the (custom) OSRM server. Valid
        values are \b{v4} and \b{v5}. The default is \b{v5}. This parameter
        should be set only if \tt{osm.routing.host} is set, and is an OSRM v4
        server.
\row
    \li osm.routing.host
    \li Url string set when making network requests to the routing server.
        This parameter should be set to a valid server url with the correct OSRM
        API. If not specified the default
        \l {https://project-osrm.org/docs/v5.24.0/api/#}{url} will be used.
        \note The API documentation and sources are available at
        \l {https://project-osrm.org/}{Project OSRM}.
 
\row
    \li osm.useragent
    \li User agent string set when making network requests. This parameter
        should be set to a value that uniquely identifies the application. Note
        that providers might block applications not setting this parameter,
        leaving it to the stock plugin user agent (e.g.,
        \l {http://wiki.openstreetmap.org/wiki/Nominatim_usage_policy}{Nominatim}
        for geocoding)
\endtable
 
\section1 Parameter Usage Example
 
The following example shows how to create an OSM plugin instance with parameters
supplied for an useragent, and if necessary, a custom server url plus the
corresponding copyright information for the tile provider. Additionally, it is
possible to choose another routing server than the public osrm one.
 
\section2 QML
 
\code
Plugin {
    name: "osm"
    PluginParameter { name: "osm.useragent"; value: "My great Qt OSM application" }
    PluginParameter { name: "osm.mapping.host"; value: "http://osm.tile.server.address/" }
    PluginParameter { name: "osm.mapping.copyright"; value: "All mine" }
    PluginParameter { name: "osm.routing.host"; value: "http://osrm.server.address/viaroute" }
    PluginParameter { name: "osm.geocoding.host"; value: "http://geocoding.server.address" }
}
\endcode
 
\section1 Other Plugin-specific Information
 
\section2 Tile cache
 
The tiles are cached in a \c{QtLocation/osm} directory in
\l {QStandardPaths::writableLocation()}{QStandardPaths::writableLocation}
(\l{QStandardPaths::GenericCacheLocation}). On systems that have no concept of a
shared cache, the application-specific \l{QStandardPaths::CacheLocation} is used
instead.
*/