[processing] restore CreateConstantRaster algorithm (fix #14860)

(cherry picked from commit 6207412)

python/plugins/processing/algs/qgis/CreateConstantRaster.py

@@ -25,6 +25,8 @@
 
 __revision__ = '$Format:%H$'
 
+from osgeo import gdal
+
 from processing.core.GeoAlgorithm import GeoAlgorithm
 from processing.core.parameters import ParameterRaster
 from processing.core.parameters import ParameterNumber
@@ -46,18 +48,22 @@ def defineCharacteristics(self):
         self.addParameter(ParameterRaster(self.INPUT,
                                           self.tr('Reference layer')))
         self.addParameter(ParameterNumber(self.NUMBER,
-                                          self.tr('Constant value'), default=1.0))
+                                          self.tr('Constant value'),
+                                          default=1.0))
 
         self.addOutput(OutputRaster(self.OUTPUT,
                                     self.tr('Constant')))
 
     def processAlgorithm(self, progress):
         layer = dataobjects.getObjectFromUri(
             self.getParameterValue(self.INPUT))
-        value = self.getOutputValue(self.NUMBER)
+        value = self.getParameterValue(self.NUMBER)
 
         output = self.getOutputFromName(self.OUTPUT)
 
+        raster = gdal.Open(layer.source(), gdal.GA_ReadOnly)
+        geoTransform = raster.GetGeoTransform()
+
         cellsize = (layer.extent().xMaximum() - layer.extent().xMinimum()) \
             / layer.width()
 
@@ -68,7 +74,8 @@ def processAlgorithm(self, progress):
                          layer.extent().yMaximum(),
                          cellsize,
                          1,
-                         self.crs,
+                         layer.crs(),
+                         geoTransform
                          )
-        w.matrix[:] = value
+        w.matrix.fill(value)
         w.close()

python/plugins/processing/tools/raster.py

@@ -84,17 +84,18 @@ class RasterWriter:
     NODATA = -99999.0
 
     def __init__(self, fileName, minx, miny, maxx, maxy, cellsize,
-                 nbands, crs):
+                 nbands, crs, geotransform=None):
         self.fileName = fileName
         self.nx = int((maxx - minx) / float(cellsize))
         self.ny = int((maxy - miny) / float(cellsize))
         self.nbands = nbands
-        self.matrix = numpy.ones(shape=(self.ny, self.nx), dtype=numpy.float32)
-        self.matrix[:] = self.NODATA
+        self.matrix = numpy.empty(shape=(self.ny, self.nx), dtype=numpy.float32)
+        self.matrix.fill(self.NODATA)
         self.cellsize = cellsize
         self.crs = crs
         self.minx = minx
         self.maxy = maxy
+        self.geotransform = geotransform
 
     def setValue(self, value, x, y, band=0):
         try:
@@ -114,7 +115,10 @@ def close(self):
         dst_ds = driver.Create(self.fileName, self.nx, self.ny, 1,
                                gdal.GDT_Float32)
         dst_ds.SetProjection(str(self.crs.toWkt()))
-        dst_ds.SetGeoTransform([self.minx, self.cellsize, 0,
-                                self.maxy, self.cellsize, 0])
+        if self.geotransform is None:
+            dst_ds.SetGeoTransform([self.minx, self.cellsize, 0,
+                                    self.maxy, self.cellsize, 0])
+        else:
+            dst_ds.SetGeoTransform(self.geotransform)
         dst_ds.GetRasterBand(1).WriteArray(self.matrix)
         dst_ds = None