Merge pull request #4593 from alexbruy/create-raster-api

[API] convenience API call to create empty raster file with given number of bands
qgis · May 30, 2017 · 9e11082 · 9e11082
2 parents b2ba450 + ca7cd63
commit 9e11082
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diff --git a/python/core/raster/qgsrasterfilewriter.sip b/python/core/raster/qgsrasterfilewriter.sip
@@ -53,6 +53,23 @@ class QgsRasterFileWriter
  :rtype: QgsRasterDataProvider
 %End
 
+    QgsRasterDataProvider *createMultiBandRaster( Qgis::DataType dataType,
+        int width, int height,
+        const QgsRectangle &extent,
+        const QgsCoordinateReferenceSystem &crs,
+        int nBands ) /Factory/;
+%Docstring
+ Create a raster file with given number of bands without initializing the pixel data.
+ Returned provider may be used to initialize the raster using writeBlock() calls.
+ Ownership of the returned provider is passed to the caller.
+.. note::
+
+   Does not work with tiled mode enabled.
+ :return: Instance of data provider in editing mode (on success) or None on error.
+.. versionadded:: 3.0
+ :rtype: QgsRasterDataProvider
+%End
+
     WriterError writeRaster( const QgsRasterPipe *pipe, int nCols, int nRows, const QgsRectangle &outputExtent,
                              const QgsCoordinateReferenceSystem &crs, QgsRasterBlockFeedback *feedback = 0 );
 %Docstring

diff --git a/src/core/raster/qgsrasterfilewriter.cpp b/src/core/raster/qgsrasterfilewriter.cpp
@@ -41,6 +41,18 @@ QgsRasterDataProvider *QgsRasterFileWriter::createOneBandRaster( Qgis::DataType
   return initOutput( width, height, crs, geoTransform, 1, dataType, QList<bool>(), QList<double>() );
 }
 
+QgsRasterDataProvider *QgsRasterFileWriter::createMultiBandRaster( Qgis::DataType dataType, int width, int height, const QgsRectangle &extent, const QgsCoordinateReferenceSystem &crs, int nBands )
+{
+  if ( mTiledMode )
+    return nullptr;  // does not make sense with tiled mode
+
+  double pixelSize;
+  double geoTransform[6];
+  globalOutputParameters( extent, width, height, geoTransform, pixelSize );
+
+  return initOutput( width, height, crs, geoTransform, nBands, dataType, QList<bool>(), QList<double>() );
+}
+
 QgsRasterFileWriter::QgsRasterFileWriter( const QString &outputUrl )
   : mMode( Raw )
   , mOutputUrl( outputUrl )

diff --git a/src/core/raster/qgsrasterfilewriter.h b/src/core/raster/qgsrasterfilewriter.h
@@ -67,6 +67,19 @@ class CORE_EXPORT QgsRasterFileWriter
         const QgsRectangle &extent,
         const QgsCoordinateReferenceSystem &crs ) SIP_FACTORY;
 
+    /** Create a raster file with given number of bands without initializing the pixel data.
+     * Returned provider may be used to initialize the raster using writeBlock() calls.
+     * Ownership of the returned provider is passed to the caller.
+     * \note Does not work with tiled mode enabled.
+     * \returns Instance of data provider in editing mode (on success) or nullptr on error.
+     * \since QGIS 3.0
+     */
+    QgsRasterDataProvider *createMultiBandRaster( Qgis::DataType dataType,
+        int width, int height,
+        const QgsRectangle &extent,
+        const QgsCoordinateReferenceSystem &crs,
+        int nBands ) SIP_FACTORY;
+
     /** Write raster file
         \param pipe raster pipe
         \param nCols number of output columns

diff --git a/tests/src/core/testqgsrasterfilewriter.cpp b/tests/src/core/testqgsrasterfilewriter.cpp
@@ -48,6 +48,7 @@ class TestQgsRasterFileWriter: public QObject
 
     void writeTest();
     void testCreateOneBandRaster();
+    void testCreateMultiBandRaster();
   private:
     bool writeTest( const QString &rasterName );
     void log( const QString &msg );
@@ -211,6 +212,63 @@ void TestQgsRasterFileWriter::testCreateOneBandRaster()
   delete rlayer;
 }
 
+void TestQgsRasterFileWriter::testCreateMultiBandRaster()
+{
+  // generate unique filename (need to open the file first to generate it)
+  QTemporaryFile tmpFile;
+  tmpFile.open();
+  tmpFile.close();
+  QString filename = tmpFile.fileName();
+
+  QgsRectangle extent( 106.7, -6.2, 106.9, -6.1 );
+  int width = 200, height = 100, nBands = 1;
+
+  QgsRasterFileWriter writer( filename );
+  QgsRasterDataProvider *dp = writer.createMultiBandRaster( Qgis::Byte, width, height, extent, QgsCoordinateReferenceSystem( "EPSG:4326" ), nBands );
+  QVERIFY( dp );
+  QCOMPARE( dp->xSize(), width );
+  QCOMPARE( dp->ySize(), height );
+  QCOMPARE( dp->extent(), extent );
+  QCOMPARE( dp->bandCount(), 1 );
+  QCOMPARE( dp->dataType( 1 ), Qgis::Byte );
+  QVERIFY( dp->isEditable() );
+  delete dp;
+
+  QgsRasterLayer *rlayer = new QgsRasterLayer( filename, "tmp", "gdal" );
+  QVERIFY( rlayer->isValid() );
+  QCOMPARE( rlayer->width(), width );
+  QCOMPARE( rlayer->height(), height );
+  QCOMPARE( rlayer->extent(), extent );
+  QCOMPARE( rlayer->bandCount(), 1 );
+  QCOMPARE( rlayer->dataProvider()->dataType( 1 ), Qgis::Byte );
+  delete rlayer;
+
+  nBands = 3;
+  dp = writer.createMultiBandRaster( Qgis::Byte, width, height, extent, QgsCoordinateReferenceSystem( "EPSG:4326" ), nBands );
+  QVERIFY( dp );
+  QCOMPARE( dp->xSize(), width );
+  QCOMPARE( dp->ySize(), height );
+  QCOMPARE( dp->extent(), extent );
+  QCOMPARE( dp->bandCount(), nBands );
+  for ( int i = 1; i <= nBands; i++ )
+  {
+    QCOMPARE( dp->dataType( i ), Qgis::Byte );
+  }
+  QVERIFY( dp->isEditable() );
+  delete dp;
+
+  rlayer = new QgsRasterLayer( filename, "tmp", "gdal" );
+  QVERIFY( rlayer->isValid() );
+  QCOMPARE( rlayer->width(), width );
+  QCOMPARE( rlayer->height(), height );
+  QCOMPARE( rlayer->extent(), extent );
+  QCOMPARE( rlayer->bandCount(), nBands );
+  for ( int i = 1; i <= nBands; i++ )
+  {
+    QCOMPARE( rlayer->dataProvider()->dataType( i ), Qgis::Byte );
+  }
+  delete rlayer;
+}
 
 void TestQgsRasterFileWriter::log( const QString &msg )
 {