MBTiles raster support in WMS provider

src/app/qgisapp.cpp

@@ -7008,6 +7008,16 @@ bool QgisApp::openLayer( const QString &fileName, bool allowInteractive )
     }
   }
 
+  if ( fileName.endsWith( QStringLiteral( ".mbtiles" ), Qt::CaseInsensitive ) )
+  {
+    // prefer to use WMS provider's implementation to open MBTiles rasters
+    QUrlQuery uq;
+    uq.addQueryItem( "type", "mbtiles" );
+    uq.addQueryItem( "url", QUrl::fromLocalFile( fileName ).toString() );
+    if ( addRasterLayer( uq.toString(), fileInfo.completeBaseName(), QStringLiteral( "wms" ) ) )
+      return true;
+  }
+
   // try to load it as raster
   if ( QgsRasterLayer::isValidRasterFileName( fileName ) )
   {

src/core/providers/gdal/qgsgdaldataitems.cpp

@@ -261,6 +261,18 @@ QgsDataItem *QgsGdalDataItemProvider::createDataItem( const QString &pathIn, Qgs
 #endif
   }
 
+  if ( suffix == QStringLiteral( "mbtiles" ) )
+  {
+    // handled by WMS provider
+    QUrlQuery uq;
+    uq.addQueryItem( "type", "mbtiles" );
+    uq.addQueryItem( "url", QUrl::fromLocalFile( path ).toString() );
+    QString encodedUri = uq.toString();
+    QgsLayerItem *item = new QgsLayerItem( parentItem, name, path, encodedUri, QgsLayerItem::Raster, QStringLiteral( "wms" ) );
+    item->setState( QgsDataItem::Populated );
+    return item;
+  }
+
   // Filters out the OGR/GDAL supported formats that can contain multiple layers
   // and should be treated like a DB: GeoPackage and SQLite
   // NOTE: this formats are scanned for rasters too and they are handled

src/core/qgssqliteutils.cpp

@@ -56,6 +56,13 @@ QString sqlite3_statement_unique_ptr::columnAsText( int column ) const
   return QString::fromUtf8( reinterpret_cast<const char *>( sqlite3_column_text( get(), column ) ) );
 }
 
+QByteArray sqlite3_statement_unique_ptr::columnAsBlob( int column ) const
+{
+  const void *blob = sqlite3_column_blob( get(), column );
+  int size = sqlite3_column_bytes( get(), column );
+  return QByteArray( reinterpret_cast<const char *>( blob ), size );
+}
+
 qlonglong sqlite3_statement_unique_ptr::columnAsInt64( int column ) const
 {
   return sqlite3_column_int64( get(), column );

src/core/qgssqliteutils.h

@@ -85,6 +85,11 @@ class CORE_EXPORT sqlite3_statement_unique_ptr : public std::unique_ptr< sqlite3
      */
     QString columnAsText( int column ) const;
 
+    /**
+     * Returns the column value from the current statement row as raw byte array.
+     */
+    QByteArray columnAsBlob( int column ) const;
+
     /**
      * Gets column value from the current statement row as a long long integer (64 bits).
      */

src/providers/wms/CMakeLists.txt

@@ -1,4 +1,5 @@
 SET (WMS_SRCS
+  qgsmbtilesreader.cpp
   qgswmscapabilities.cpp
   qgswmsprovider.cpp
   qgswmsconnection.cpp

src/providers/wms/qgsmbtilesreader.cpp

@@ -0,0 +1,124 @@
+/***************************************************************************
+  qgsmbtilesreader.cpp
+  --------------------------------------
+  Date                 : January 2020
+  Copyright            : (C) 2020 by Martin Dobias
+  Email                : wonder dot sk at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsmbtilesreader.h"
+
+#include "qgslogger.h"
+#include "qgsrectangle.h"
+
+#include <QImage>
+
+
+QgsMBTilesReader::QgsMBTilesReader( const QString &filename )
+  : mFilename( filename )
+{
+}
+
+bool QgsMBTilesReader::open()
+{
+  if ( mDatabase )
+    return true;  // already opened
+
+  sqlite3_database_unique_ptr database;
+  int result = mDatabase.open_v2( mFilename, SQLITE_OPEN_READONLY, nullptr );
+  if ( result != SQLITE_OK )
+  {
+    QgsDebugMsg( QStringLiteral( "Can't open MBTiles database: %1" ).arg( database.errorMessage() ) );
+    return false;
+  }
+  return true;
+}
+
+bool QgsMBTilesReader::isOpen() const
+{
+  return bool( mDatabase );
+}
+
+QString QgsMBTilesReader::metadataValue( const QString &key )
+{
+  if ( !mDatabase )
+  {
+    QgsDebugMsg( QStringLiteral( "MBTiles database not open: " ) + mFilename );
+    return QString();
+  }
+
+  int result;
+  QString sql = QStringLiteral( "select value from metadata where name='%1'" ).arg( key );
+  sqlite3_statement_unique_ptr preparedStatement = mDatabase.prepare( sql, result );
+  if ( result != SQLITE_OK )
+  {
+    QgsDebugMsg( QStringLiteral( "MBTile failed to prepare statement: " ) + sql );
+    return QString();
+  }
+
+  if ( preparedStatement.step() != SQLITE_ROW )
+  {
+    QgsDebugMsg( QStringLiteral( "MBTile metadata value not found: " ) + key );
+    return QString();
+  }
+
+  return preparedStatement.columnAsText( 0 );
+}
+
+QgsRectangle QgsMBTilesReader::extent()
+{
+  QString boundsStr = metadataValue( "bounds" );
+  if ( boundsStr.isEmpty() )
+    return QgsRectangle();
+  QStringList boundsArray = boundsStr.split( ',' );
+  if ( boundsArray.count() != 4 )
+    return QgsRectangle();
+
+  return QgsRectangle( boundsArray[0].toDouble(), boundsArray[1].toDouble(),
+                       boundsArray[2].toDouble(), boundsArray[3].toDouble() );
+}
+
+QByteArray QgsMBTilesReader::tileData( int z, int x, int y )
+{
+  if ( !mDatabase )
+  {
+    QgsDebugMsg( QStringLiteral( "MBTiles database not open: " ) + mFilename );
+    return QByteArray();
+  }
+
+  int result;
+  QString sql = QStringLiteral( "select tile_data from tiles where zoom_level=%1 and tile_column=%2 and tile_row=%3" ).arg( z ).arg( x ).arg( y );
+  sqlite3_statement_unique_ptr preparedStatement = mDatabase.prepare( sql, result );
+  if ( result != SQLITE_OK )
+  {
+    QgsDebugMsg( QStringLiteral( "MBTile failed to prepare statement: " ) + sql );
+    return QByteArray();
+  }
+
+  if ( preparedStatement.step() != SQLITE_ROW )
+  {
+    QgsDebugMsg( QStringLiteral( "MBTile not found: z=%1 x=%2 y=%3" ).arg( z ).arg( x ).arg( y ) );
+    return QByteArray();
+  }
+
+  return preparedStatement.columnAsBlob( 0 );
+}
+
+QImage QgsMBTilesReader::tileDataAsImage( int z, int x, int y )
+{
+  QImage tileImage;
+  QByteArray tileBlob = tileData( z, x, y );
+  if ( !tileImage.loadFromData( tileBlob ) )
+  {
+    QgsDebugMsg( QStringLiteral( "MBTile data failed to load: z=%1 x=%2 y=%3" ).arg( z ).arg( x ).arg( y ) );
+    return QImage();
+  }
+  return tileImage;
+}

src/providers/wms/qgsmbtilesreader.h

@@ -0,0 +1,50 @@
+/***************************************************************************
+  qgsmbtilesreader.h
+  --------------------------------------
+  Date                 : January 2020
+  Copyright            : (C) 2020 by Martin Dobias
+  Email                : wonder dot sk at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSMBTILESREADER_H
+#define QGSMBTILESREADER_H
+
+
+#include "sqlite3.h"
+#include "qgssqliteutils.h"
+
+class QImage;
+class QgsRectangle;
+
+class QgsMBTilesReader
+{
+  public:
+    explicit QgsMBTilesReader( const QString &filename );
+
+    bool open();
+
+    bool isOpen() const;
+
+    QString metadataValue( const QString &key );
+
+    //! given in WGS 84 (if available)
+    QgsRectangle extent();
+
+    QByteArray tileData( int z, int x, int y );
+
+    QImage tileDataAsImage( int z, int x, int y );
+
+  private:
+    QString mFilename;
+    sqlite3_database_unique_ptr mDatabase;
+};
+
+
+#endif // QGSMBTILESREADER_H

src/providers/wms/qgswmscapabilities.cpp

@@ -53,7 +53,8 @@ bool QgsWmsSettings::parseUri( const QString &uriString )
   mAuth.mReferer = uri.param( QStringLiteral( "referer" ) );
   mXyz = false;  // assume WMS / WMTS
 
-  if ( uri.param( QStringLiteral( "type" ) ) == QLatin1String( "xyz" ) )
+  if ( uri.param( QStringLiteral( "type" ) ) == QLatin1String( "xyz" ) ||
+       uri.param( QStringLiteral( "type" ) ) == QLatin1String( "mbtiles" ) )
   {
     // for XYZ tiles most of the things do not apply
     mTiled = true;
@@ -75,6 +76,9 @@ bool QgsWmsSettings::parseUri( const QString &uriString )
     mImageMimeType.clear();
     mCrsId = QStringLiteral( "EPSG:3857" );
     mEnableContextualLegend = false;
+
+    mIsMBTiles = uri.param( QStringLiteral( "type" ) ) == QLatin1String( "mbtiles" );
+
     return true;
   }
 

src/providers/wms/qgswmscapabilities.h

@@ -588,6 +588,8 @@ class QgsWmsSettings
     bool                    mTiled;
     //! whether we actually work with XYZ tiles instead of WMS / WMTS
     bool mXyz;
+    //! whether we are dealing with MBTiles file rather than using network-based tiles
+    bool mIsMBTiles = false;
     //! chosen values for dimensions in case of multi-dimensional data (key=dim id, value=dim value)
     QHash<QString, QString>  mTileDimensionValues;
     //! name of the chosen tile matrix set