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       1                 :            : /***************************************************************************
       2                 :            :   qgsvectortilewriter.h
       3                 :            :   --------------------------------------
       4                 :            :   Date                 : April 2020
       5                 :            :   Copyright            : (C) 2020 by Martin Dobias
       6                 :            :   Email                : wonder dot sk at gmail dot com
       7                 :            :  ***************************************************************************
       8                 :            :  *                                                                         *
       9                 :            :  *   This program is free software; you can redistribute it and/or modify  *
      10                 :            :  *   it under the terms of the GNU General Public License as published by  *
      11                 :            :  *   the Free Software Foundation; either version 2 of the License, or     *
      12                 :            :  *   (at your option) any later version.                                   *
      13                 :            :  *                                                                         *
      14                 :            :  ***************************************************************************/
      15                 :            : 
      16                 :            : #ifndef QGSVECTORTILEWRITER_H
      17                 :            : #define QGSVECTORTILEWRITER_H
      18                 :            : 
      19                 :            : #include <QCoreApplication>
      20                 :            : #include "qgsrectangle.h"
      21                 :            : #include "qgscoordinatetransformcontext.h"
      22                 :            : 
      23                 :            : class QgsFeedback;
      24                 :            : class QgsTileMatrix;
      25                 :            : class QgsTileXYZ;
      26                 :            : class QgsVectorLayer;
      27                 :            : 
      28                 :            : 
      29                 :            : /**
      30                 :            :  * \ingroup core
      31                 :            :  * \brief Takes care of writing vector tiles. The intended use is to set up the class
      32                 :            :  * by setting the destination URI, extent, zoom level range and input vector
      33                 :            :  * layers. Then with a call to writeTiles() the data gets written. In case
      34                 :            :  * of a failure, errorMessage() returns the cause of the problem during writing.
      35                 :            :  *
      36                 :            :  * The syntax of destination URIs is the same like the data source string
      37                 :            :  * used by vector tile layers: parameters are encoded as a HTTP query string,
      38                 :            :  * where "type" key determines the type of the destination container,
      39                 :            :  * the "url" key is normally the path. Currently supported types:
      40                 :            :  *
      41                 :            :  * - "xyz" - tile data written as local files, using a template where {x},{y},{z}
      42                 :            :  *   are replaced by the actual tile column, row and zoom level numbers, e.g.:
      43                 :            :  *   file:///home/qgis/tiles/{z}/{x}/{y}.pbf
      44                 :            :  * - "mbtiles" - tile data written to a new MBTiles file, the "url" key should
      45                 :            :  *   be ordinary file system path, e.g.: /home/qgis/output.mbtiles
      46                 :            :  *
      47                 :            :  * Currently the writer only support MVT encoding of data.
      48                 :            :  *
      49                 :            :  * Metadata support: it is possible to pass a QVariantMap with metadata. This
      50                 :            :  * is backend dependent. Currently only "mbtiles" source type supports writing
      51                 :            :  * of metadata. The key-value pairs will be written to the "metadata" table
      52                 :            :  * in the MBTiles file. Some useful metadata keys listed here, but see MBTiles spec
      53                 :            :  * for more details:
      54                 :            :  *
      55                 :            :  * - "name" - human-readable name of the tileset
      56                 :            :  * - "bounds" - extent in WGS 84: "minlon,minlat,maxlon,maxlat"
      57                 :            :  * - "center" - default view of the map: "longitude,latitude,zoomlevel"
      58                 :            :  * - "minzoom" - lowest zoom level
      59                 :            :  * - "maxzoom" - highest zoom level
      60                 :            :  * - "attribution" - string that explains the sources of data
      61                 :            :  * - "description" - descriptions of the content
      62                 :            :  * - "type" - whether this is an overlay or a basemap
      63                 :            :  * - "version" - version of the tileset
      64                 :            :  *
      65                 :            :  * Vector tile writer always writes "format" and "json" metadata. If not specified
      66                 :            :  * in metadata by the client, tile writer also writes "name", "bounds", "minzoom"
      67                 :            :  * and "maxzoom".
      68                 :            :  *
      69                 :            :  *
      70                 :            :  * \since QGIS 3.14
      71                 :            :  */
      72                 :          0 : class CORE_EXPORT QgsVectorTileWriter
      73                 :            : {
      74                 :          0 :     Q_DECLARE_TR_FUNCTIONS( QgsVectorTileWriter )
      75                 :            : 
      76                 :            :   public:
      77                 :            :     QgsVectorTileWriter();
      78                 :            : 
      79                 :            :     /**
      80                 :            :      * \ingroup core
      81                 :            :      * \brief Configuration of a single input vector layer to be included in the output
      82                 :            :      * \since QGIS 3.14
      83                 :            :      */
      84                 :          0 :     class Layer
      85                 :            :     {
      86                 :            :       public:
      87                 :            :         //! Constructs an entry for a vector layer
      88                 :          0 :         explicit Layer( QgsVectorLayer *layer )
      89                 :          0 :           : mLayer( layer )
      90                 :            :         {
      91                 :          0 :         }
      92                 :            : 
      93                 :            :         //! Returns vector layer of this entry
      94                 :          0 :         QgsVectorLayer *layer() const { return mLayer; }
      95                 :            : 
      96                 :            :         //! Returns filter expression. If not empty, only features matching the expression will be used
      97                 :          0 :         QString filterExpression() const { return mFilterExpression; }
      98                 :            :         //! Sets filter expression. If not empty, only features matching the expression will be used
      99                 :          0 :         void setFilterExpression( const QString &expr ) { mFilterExpression = expr; }
     100                 :            : 
     101                 :            :         //! Returns layer name in the output. If not set, layer()->name() will be used.
     102                 :          0 :         QString layerName() const { return mLayerName; }
     103                 :            :         //! Sets layer name in the output. If not set, layer()->name() will be used.
     104                 :          0 :         void setLayerName( const QString &name ) { mLayerName = name; }
     105                 :            : 
     106                 :            :         //! Returns minimum zoom level at which this layer will be used. Negative value means no min. zoom level
     107                 :          0 :         int minZoom() const { return mMinZoom; }
     108                 :            :         //! Sets minimum zoom level at which this layer will be used. Negative value means no min. zoom level
     109                 :          0 :         void setMinZoom( int minzoom ) { mMinZoom = minzoom; }
     110                 :            : 
     111                 :            :         //! Returns maximum zoom level at which this layer will be used. Negative value means no max. zoom level
     112                 :          0 :         int maxZoom() const { return mMaxZoom; }
     113                 :            :         //! Sets maximum zoom level at which this layer will be used. Negative value means no max. zoom level
     114                 :          0 :         void setMaxZoom( int maxzoom ) { mMaxZoom = maxzoom; }
     115                 :            : 
     116                 :            :       private:
     117                 :            :         QgsVectorLayer *mLayer;
     118                 :            :         QString mFilterExpression;
     119                 :            :         QString mLayerName;
     120                 :          0 :         int mMinZoom = -1;
     121                 :          0 :         int mMaxZoom = -1;
     122                 :            :     };
     123                 :            : 
     124                 :            :     /**
     125                 :            :      * Sets where and how the vector tiles will be written.
     126                 :            :      * See the class description about the syntax of destination URIs.
     127                 :            :      */
     128                 :          0 :     void setDestinationUri( const QString &uri ) { mDestinationUri = uri; }
     129                 :            : 
     130                 :            :     /**
     131                 :            :      * Sets extent of vector tile output. Currently always in EPSG:3857.
     132                 :            :      * If unset, it will use the full extent of all input layers combined
     133                 :            :      */
     134                 :          0 :     void setExtent( const QgsRectangle &extent ) { mExtent = extent; }
     135                 :            : 
     136                 :            :     //! Sets the minimum zoom level of tiles. Allowed values are in interval [0,24]
     137                 :          0 :     void setMinZoom( int minZoom ) { mMinZoom = minZoom; }
     138                 :            :     //! Sets the maximum zoom level of tiles. Allowed values are in interval [0,24]
     139                 :          0 :     void setMaxZoom( int maxZoom ) { mMaxZoom = maxZoom; }
     140                 :            : 
     141                 :            :     //! Sets vector layers and their configuration for output of vector tiles
     142                 :          0 :     void setLayers( const QList<QgsVectorTileWriter::Layer> &layers ) { mLayers = layers; }
     143                 :            : 
     144                 :            :     //! Sets that will be written to the output dataset. See class description for more on metadata support
     145                 :          0 :     void setMetadata( const QVariantMap &metadata ) { mMetadata = metadata; }
     146                 :            : 
     147                 :            :     //! Sets coordinate transform context for transforms between layers and tile matrix CRS
     148                 :          0 :     void setTransformContext( const QgsCoordinateTransformContext &transformContext ) { mTransformContext = transformContext; }
     149                 :            : 
     150                 :            :     /**
     151                 :            :      * Writes vector tiles according to the configuration.
     152                 :            :      * Returns TRUE on success (upon failure one can get error cause using errorMessage())
     153                 :            :      *
     154                 :            :      * If a pointer to a feedback object is provided, it can be used to track progress or
     155                 :            :      * provide cancellation functionality.
     156                 :            :      */
     157                 :            :     bool writeTiles( QgsFeedback *feedback = nullptr );
     158                 :            : 
     159                 :            :     /**
     160                 :            :      * Returns error message related to the previous call to writeTiles(). Will return
     161                 :            :      * an empty string if writing was successful.
     162                 :            :      */
     163                 :          0 :     QString errorMessage() const { return mErrorMessage; }
     164                 :            : 
     165                 :            :     //! Returns calculated extent that combines extent of all input layers
     166                 :            :     QgsRectangle fullExtent() const;
     167                 :            : 
     168                 :            :   private:
     169                 :            :     bool writeTileFileXYZ( const QString &sourcePath, QgsTileXYZ tileID, const QgsTileMatrix &tileMatrix, const QByteArray &tileData );
     170                 :            :     QString mbtilesJsonSchema();
     171                 :            : 
     172                 :            :   private:
     173                 :            :     QgsRectangle mExtent;
     174                 :            :     int mMinZoom = 0;
     175                 :            :     int mMaxZoom = 4;
     176                 :            :     QList<Layer> mLayers;
     177                 :            :     QString mDestinationUri;
     178                 :            :     QVariantMap mMetadata;
     179                 :            :     QgsCoordinateTransformContext mTransformContext;
     180                 :            : 
     181                 :            :     QString mErrorMessage;
     182                 :            : };
     183                 :            : 
     184                 :            : #endif // QGSVECTORTILEWRITER_H