Takes care of writing vector tiles. More...

#include <qgsvectortilewriter.h>

Classes
class	Layer
	Configuration of a single input vector layer to be included in the output. More...

Public Member Functions
	QgsVectorTileWriter ()

QString	errorMessage () const
	Returns error message related to the previous call to writeTiles().

QgsRectangle	fullExtent () const
	Returns calculated extent that combines extent of all input layers.

void	setDestinationUri (const QString &uri)
	Sets where and how the vector tiles will be written.

void	setExtent (const QgsRectangle &extent)
	Sets extent of vector tile output.

void	setLayers (const QList< QgsVectorTileWriter::Layer > &layers)
	Sets vector layers and their configuration for output of vector tiles.

void	setMaxZoom (int maxZoom)
	Sets the maximum zoom level of tiles. Allowed values are in interval [0,24].

void	setMetadata (const QVariantMap &metadata)
	Sets that will be written to the output dataset. See class description for more on metadata support.

void	setMinZoom (int minZoom)
	Sets the minimum zoom level of tiles. Allowed values are in interval [0,24].

bool	setRootTileMatrix (const QgsTileMatrix &tileMatrix)
	Sets zoom level 0 tile matrix.

void	setTransformContext (const QgsCoordinateTransformContext &transformContext)
	Sets coordinate transform context for transforms between layers and tile matrix CRS.

QByteArray	writeSingleTile (QgsTileXYZ tileID, QgsFeedback *feedback=nullptr, int buffer=256, int resolution=4096) const
	Encodes single MVT tile.

bool	writeTiles (QgsFeedback *feedback=nullptr)
	Writes vector tiles according to the configuration.

Detailed Description

Takes care of writing vector tiles.

The intended use is to set up the class by setting the destination URI, extent, zoom level range and input vector layers. Then with a call to writeTiles() the data gets written. In case of a failure, errorMessage() returns the cause of the problem during writing.

The syntax of destination URIs is the same like the data source string used by vector tile layers: parameters are encoded as a HTTP query string, where "type" key determines the type of the destination container, the "url" key is normally the path. Currently supported types:

"xyz" - tile data written as local files, using a template where {x},{y},{z} are replaced by the actual tile column, row and zoom level numbers, e.g.: file:///home/qgis/tiles/{z}/{x}/{y}.pbf
"mbtiles" - tile data written to a new MBTiles file, the "url" key should be ordinary file system path, e.g.: /home/qgis/output.mbtiles

Currently the writer only support MVT encoding of data.

Metadata support: it is possible to pass a QVariantMap with metadata. This is backend dependent. Currently only "mbtiles" source type supports writing of metadata. The key-value pairs will be written to the "metadata" table in the MBTiles file. Some useful metadata keys listed here, but see MBTiles spec for more details:

"name" - human-readable name of the tileset
"bounds" - extent in WGS 84: "minlon,minlat,maxlon,maxlat"
"center" - default view of the map: "longitude,latitude,zoomlevel"
"minzoom" - lowest zoom level
"maxzoom" - highest zoom level
"attribution" - string that explains the sources of data
"description" - descriptions of the content
"type" - whether this is an overlay or a basemap
"version" - version of the tileset

Vector tile writer always writes "format" and "json" metadata. If not specified in metadata by the client, tile writer also writes "name", "bounds", "minzoom" and "maxzoom".

Since: QGIS 3.14

Definition at line 76 of file qgsvectortilewriter.h.

Constructor & Destructor Documentation

◆ QgsVectorTileWriter()

QgsVectorTileWriter::QgsVectorTileWriter ( )

Definition at line 37 of file qgsvectortilewriter.cpp.

Member Function Documentation

◆ errorMessage()

QString QgsVectorTileWriter::errorMessage ( ) const

inline

Returns error message related to the previous call to writeTiles().

Will return an empty string if writing was successful.

Definition at line 172 of file qgsvectortilewriter.h.

◆ fullExtent()

QgsRectangle QgsVectorTileWriter::fullExtent ( ) const

Returns calculated extent that combines extent of all input layers.

Definition at line 232 of file qgsvectortilewriter.cpp.

◆ setDestinationUri()

void QgsVectorTileWriter::setDestinationUri ( const QString & uri )

inline

Sets where and how the vector tiles will be written.

See the class description about the syntax of destination URIs.

Definition at line 132 of file qgsvectortilewriter.h.

◆ setExtent()

void QgsVectorTileWriter::setExtent ( const QgsRectangle & extent )

inline

Sets extent of vector tile output.

If unset, it will use the full extent of all input layers combined

Definition at line 138 of file qgsvectortilewriter.h.

◆ setLayers()

void QgsVectorTileWriter::setLayers ( const QList< QgsVectorTileWriter::Layer > & layers )

inline

Sets vector layers and their configuration for output of vector tiles.

Definition at line 146 of file qgsvectortilewriter.h.

◆ setMaxZoom()

void QgsVectorTileWriter::setMaxZoom ( int maxZoom )

inline

Sets the maximum zoom level of tiles. Allowed values are in interval [0,24].

Definition at line 143 of file qgsvectortilewriter.h.

◆ setMetadata()

void QgsVectorTileWriter::setMetadata ( const QVariantMap & metadata )

inline

Sets that will be written to the output dataset. See class description for more on metadata support.

Definition at line 149 of file qgsvectortilewriter.h.

◆ setMinZoom()

void QgsVectorTileWriter::setMinZoom ( int minZoom )

inline

Sets the minimum zoom level of tiles. Allowed values are in interval [0,24].

Definition at line 141 of file qgsvectortilewriter.h.

◆ setRootTileMatrix()

bool QgsVectorTileWriter::setRootTileMatrix ( const QgsTileMatrix & tileMatrix )

Sets zoom level 0 tile matrix.

Definition at line 43 of file qgsvectortilewriter.cpp.

◆ setTransformContext()

void QgsVectorTileWriter::setTransformContext ( const QgsCoordinateTransformContext & transformContext )

inline

Sets coordinate transform context for transforms between layers and tile matrix CRS.

Definition at line 152 of file qgsvectortilewriter.h.

◆ writeSingleTile()

QByteArray QgsVectorTileWriter::writeSingleTile	(	QgsTileXYZ	tileID,
		QgsFeedback *	feedback = `nullptr`,
		int	buffer = `256`,
		int	resolution = `4096`
	)		const

Encodes single MVT tile.

Parameters

tileID	Tile identifier
feedback	optional, provide cancellation functionality
resolution	the resolution of coordinates of geometries within the tile. The default is 4096
buffer	size of the buffer zone around tile edges in integer tile coordinates. The default is 256 (~6%)

Returns a QByteArray with the encoded data

Since: QGIS 3.22

Definition at line 317 of file qgsvectortilewriter.cpp.

◆ writeTiles()

bool QgsVectorTileWriter::writeTiles ( QgsFeedback * feedback = nullptr )

Writes vector tiles according to the configuration.

Returns true on success (upon failure one can get error cause using errorMessage())

If a pointer to a feedback object is provided, it can be used to track progress or provide cancellation functionality.

Definition at line 54 of file qgsvectortilewriter.cpp.

The documentation for this class was generated from the following files:

/build/qgis-3.41.0+git20241214+cea29feecf2+99sid/src/core/vectortile/qgsvectortilewriter.h
/build/qgis-3.41.0+git20241214+cea29feecf2+99sid/src/core/vectortile/qgsvectortilewriter.cpp

Classes

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ QgsVectorTileWriter()

Member Function Documentation

◆ errorMessage()

◆ fullExtent()

◆ setDestinationUri()

◆ setExtent()

◆ setLayers()

◆ setMaxZoom()

◆ setMetadata()

◆ setMinZoom()

◆ setRootTileMatrix()

◆ setTransformContext()

◆ writeSingleTile()

◆ writeTiles()