[RasterReader] add support for none-GDAL Rasters / generic QgsRasterDataProvider support

[jakimowb]

The RasterReader fails to read QgsRasterLayers that use other data provider than GDAL (which is the case for 6 of 7 standard QGIS QgsRasterDataProviders)

Supported QgsRasterDataProviders

• [x] QgsGdalProvider gdal
• [ ] QgsVirtualRasterProvider virtualraster
• [ ] QgsWcsProvide wcs
• [ ] QgsPostgresRasterProvider postgresraster
• [ ] QgsGrassRasterProvider grassraster
• [ ] QgsAmsProvider arcgismapserver
• [x] QgsWmsProvider wms

• The openWithGdal keyword seems to have no effect.

How to reproduce:

from enmapboxprocessing.rasterreader import RasterReader
from enmapbox.testing import start_app
from qgis.core import QgsRasterLayer
from enmapbox.qgispluginsupport.qps.utils import rasterArray

app = start_app()

wcsUri = r'dpiMode=7&identifier=OneGDev:WesternMed-MCol&tilePixelRatio=0&url=https://ogcdev.bgs.ac.uk/geoserver/OneGDev/wcs?acceptversions%3D2.0.1'
lyr = QgsRasterLayer(wcsUri, 'WCS Example', providerType='wcs')

assert lyr.isValid()
data = rasterArray(lyr)
print(data.shape)
s = ""

# now we would expect the RasterReader reads without GDAL
reader = RasterReader(lyr, openWithGdal=False)

relates to #764

[janzandr]

Hi @jakimowb, currently, the RasterReader only supports GDAL raster.

If we want to, we can also support Web Coverage Service (WCS). So far, there was no need for it.

[jakimowb]

It's not only because of WCS. There are several other data providers, e.g. for virtual rasters. Also the spectral processing widget uses its own rasterdataprovider to avoid data redundancy.

[jakimowb]

If the RasterReader supports GDAL sources only, it should be better renamed.

However, I think it would be better if it's features present a true superset of features of a standard QgsRasterLayer. It should work with any rasterlayer instance, and provides additional options in case of GDAL rasterproviders.

[janzandr]

Yes, totally agree, but let's have a seperate Issue for each new provider, which we need/want to support.

[jakimowb]

I don't think it is necessary to create an issue for each single provider. The RasterReader just should work fine with any QgsRasterData provider. On top, it might add value in case of providers like gdal, e.g. by reading metadata from extra files. However, it should still work generically with any QgsRasterData interface.

[janzandr]

WMS provider should work now (see #865)

[janzandr]

@jakimowb, which provider should be implemented next? Anything urgent before the v3.14 release?

[jakimowb]

The RasterReader should generally accept all QgsRasterLayers/QgsRasterDataProviders.

I'll enhance (somewhen) the enmapbox.testing.TestObject to provide a set of rasterlayers with different providers. See #870

[janzandr]

Waiting for enmapbox.testing.TestObject enhancement.