VectorLayerFieldRasterDataProvider constructor

[jakimowb]

Creating a QGIS layer with VectorLayerFieldRasterDataProvider as in:

# this line create QGIS messages to stderr
layer = QgsRasterLayer('?', name, VectorLayerFieldRasterDataProvider.providerKey())

assert layer.isValid()
dp: VectorLayerFieldRasterDataProvider = layer.dataProvider()
dp.setActiveFeatures(profiles, field=SpectralProfileValueConverter(field))

generates these warnings:

C:\src\osgeo4w\src\qgis-dev\qgis\src\core\raster\qgsbrightnesscontrastfilter.cpp(90) : (QgsBrightnessContrastFilter::setInput) [12766ms] No input band
C:\src\osgeo4w\src\qgis-dev\qgis\src\core\raster\qgsrasterpipe.cpp(89) : (QgsRasterPipe::connect) [0ms] cannot connect class QgsBrightnessContrastFilter to class sipQgsRasterDataProvider
C:\src\osgeo4w\src\qgis-dev\qgis\src\core\raster\qgshuesaturationfilter.cpp(95) : (QgsHueSaturationFilter::setInput) [0ms] No input band
C:\src\osgeo4w\src\qgis-dev\qgis\src\core\raster\qgsrasterpipe.cpp(89) : (QgsRasterPipe::connect) [0ms] cannot connect class QgsHueSaturationFilter to class sipQgsRasterDataProvider
C:\src\osgeo4w\src\qgis-dev\qgis\src\core\raster\qgsrasterresamplefilter.cpp(92) : (QgsRasterResampleFilter::setInput) [0ms] No input band
C:\src\osgeo4w\src\qgis-dev\qgis\src\core\raster\qgsrasterpipe.cpp(89) : (QgsRasterPipe::connect) [0ms] cannot connect class QgsRasterResampleFilter to class sipQgsRasterDataProvider

Solution:

allow to define the number of raster bands already in the uri used to initialite the data provider, e.g:

layer = QgsRasterLayer('?<fieldname>:<bands>', name, VectorLayerFieldRasterDataProvider.providerKey())