[processing][grass] Export CRS definitions as WKT2 strings instead

of proj strings wherever possible

Because proj strings are lossy

Fixes #18596

python/plugins/processing/algs/grass7/Grass7Algorithm.py

@@ -636,6 +636,8 @@ def processCommand(self, parameters, context, feedback, delOutputs=False):
                     value = '{},{}'.format(v[0], v[1])
             elif isinstance(param, QgsProcessingParameterCrs):
                 if self.parameterAsCrs(parameters, paramName, context):
+                    # TODO: ideally we should be exporting to WKT here, but it seems not all grass algorithms
+                    # will accept a wkt string for a crs value (e.g. r.tileset)
                     value = '"{}"'.format(self.parameterAsCrs(parameters, paramName, context).toProj())
             # For everything else, we assume that it is a string
             else:
@@ -1031,23 +1033,25 @@ def setSessionProjectionFromProject(self):
         We creates a PROJ4 definition which is transmitted to Grass
         """
         if not Grass7Utils.projectionSet and iface:
-            self.destination_crs = iface.mapCanvas().mapSettings().destinationCrs()
-            proj4 = iface.mapCanvas().mapSettings().destinationCrs().toProj()
-            command = 'g.proj -c proj4="{}"'.format(proj4)
-            self.commands.append(command)
-            Grass7Utils.projectionSet = True
+            self.setSessionProjection(iface.mapCanvas().mapSettings().destinationCrs())
 
     def setSessionProjectionFromLayer(self, layer):
         """
         Set the projection from a QgsVectorLayer.
         We creates a PROJ4 definition which is transmitted to Grass
         """
         if not Grass7Utils.projectionSet:
-            proj4 = str(layer.crs().toProj())
-            self.destination_crs = layer.crs()
-            command = 'g.proj -c proj4="{}"'.format(proj4)
-            self.commands.append(command)
-            Grass7Utils.projectionSet = True
+            self.setSessionProjection(layer.crs())
+
+    def setSessionProjection(self, crs):
+        """
+        Set the session projection to the specified CRS
+        """
+        self.destination_crs = crs
+        file_name = Grass7Utils.exportCrsWktToFile(crs)
+        command = 'g.proj -c wkt="{}"'.format(file_name)
+        self.commands.append(command)
+        Grass7Utils.projectionSet = True
 
     def convertToHtml(self, fileName):
         # Read HTML contents

python/plugins/processing/algs/grass7/Grass7Utils.py

@@ -31,7 +31,8 @@
 from qgis.core import (Qgis,
                        QgsApplication,
                        QgsProcessingUtils,
-                       QgsMessageLog)
+                       QgsMessageLog,
+                       QgsCoordinateReferenceSystem)
 from qgis.PyQt.QtCore import QCoreApplication
 from processing.core.ProcessingConfig import ProcessingConfig
 from processing.tools.system import userFolder, isWindows, isMac, mkdir
@@ -82,6 +83,18 @@ def grassBatchJobFilename():
             batchFile = os.path.join(gisdbase, 'grass_batch_job.sh')
         return batchFile
 
+    @staticmethod
+    def exportCrsWktToFile(crs):
+        """
+        Exports a crs as a WKT definition to a text file, and returns the path
+        to this file
+        """
+        wkt = crs.toWkt(QgsCoordinateReferenceSystem.WKT_PREFERRED)
+        wkt_file = QgsProcessingUtils.generateTempFilename('crs.prj')
+        with open(wkt_file, 'wt') as f:
+            f.write(wkt)
+        return wkt_file
+
     @staticmethod
     def installedVersion(run=False):
         """

python/plugins/processing/algs/grass7/description/r.proj.txt

@@ -1,5 +1,5 @@
 r.proj
-Re-projects a vector map from one location to the current location
+Re-projects a raster layer to another coordinate reference system
 Raster (r.*)
 QgsProcessingParameterRasterLayer|input|Input raster to reproject|None|False
 QgsProcessingParameterCrs|crs|New coordinate reference system|None|False

python/plugins/processing/algs/grass7/description/v.proj.txt

@@ -1,5 +1,5 @@
 v.proj
-Re-projects a vector map from one location to the current location
+Re-projects a vector layer to another coordinate reference system
 Vector (v.*)
 QgsProcessingParameterFeatureSource|input|Input vector to reproject|-1|None|False
 QgsProcessingParameterCrs|crs|New coordinate reference system|None|False

python/plugins/processing/algs/grass7/ext/r_proj.py

@@ -22,18 +22,19 @@
 __copyright__ = '(C) 2017, Médéric Ribreux'
 
 from qgis.core import QgsProcessingParameterString
-from ..Grass7Utils import isWindows
+from processing.tools.system import isWindows
+from processing.algs.grass7.Grass7Utils import Grass7Utils
 
 
 def processInputs(alg, parameters, context, feedback):
     # Grab the projection from the input vector layer
     layer = alg.parameterAsLayer(parameters, 'input', context)
-    layerCrs = layer.crs().toProj()
 
     # Creates a new location with this Crs
+    wkt_file_name = Grass7Utils.exportCrsWktToFile(layer.crs())
     newLocation = 'newProj{}'.format(alg.uniqueSuffix)
-    alg.commands.append('g.proj proj4="{}" location={}'.format(
-        layerCrs, newLocation))
+    alg.commands.append('g.proj wkt="{}" location={}'.format(
+        wkt_file_name, newLocation))
 
     # Go to the newly created location
     alg.commands.append('g.mapset mapset=PERMANENT location={}'.format(
@@ -48,7 +49,8 @@ def processInputs(alg, parameters, context, feedback):
 
     # Grab the projected Crs
     crs = alg.parameterAsCrs(parameters, 'crs', context)
-    alg.commands.append('g.proj -c proj4="{}"'.format(crs.toProj()))
+    wkt_file_name = Grass7Utils.exportCrsWktToFile(crs)
+    alg.commands.append('g.proj -c wkt="{}"'.format(wkt_file_name))
 
     # Remove crs parameter
     alg.removeParameter('crs')

python/plugins/processing/algs/grass7/ext/r_tileset.py

@@ -21,8 +21,11 @@
 __date__ = 'October 2017'
 __copyright__ = '(C) 2017, Médéric Ribreux'
 
+from processing.algs.grass7.Grass7Utils import Grass7Utils
+
 
 def processOutputs(alg, parameters, context, feedback):
     crs = alg.parameterAsCrs(parameters, 'sourceproj', context)
 
-    alg.commands.insert(0, 'g.proj -c proj4="{}"'.format(crs.toProj()))
+    wkt_file_name = Grass7Utils.exportCrsWktToFile(crs)
+    alg.commands.insert(0, 'g.proj -c wkt="{}"'.format(wkt_file_name))

python/plugins/processing/algs/grass7/ext/v_proj.py

@@ -22,6 +22,7 @@
 __copyright__ = '(C) 2017, Médéric Ribreux'
 
 from qgis.core import QgsProcessingParameterString
+from processing.algs.grass7.Grass7Utils import Grass7Utils
 
 
 def processInputs(alg, parameters, context, feedback):
@@ -31,9 +32,10 @@ def processInputs(alg, parameters, context, feedback):
     layerCrs = layer.crs().toProj()
 
     # Creates a new location with this Crs
+    wkt_file_name = Grass7Utils.exportCrsWktToFile(layer.crs())
     newLocation = 'newProj{}'.format(alg.uniqueSuffix)
-    alg.commands.append('g.proj proj4="{}" location={}'.format(
-        layerCrs, newLocation))
+    alg.commands.append('g.proj wkt="{}" location={}'.format(
+        wkt_file_name, newLocation))
 
     # Go to the newly created location
     alg.commands.append('g.mapset mapset=PERMANENT location={}'.format(
@@ -48,7 +50,8 @@ def processInputs(alg, parameters, context, feedback):
 
     # Grab the projected Crs
     crs = alg.parameterAsCrs(parameters, 'crs', context)
-    alg.commands.append('g.proj -c proj4="{}"'.format(crs.toProj()))
+    wkt_file_name = Grass7Utils.exportCrsWktToFile(crs)
+    alg.commands.append('g.proj -c wkt="{}"'.format(wkt_file_name))
 
     # Remove crs parameter
     alg.removeParameter('crs')