157 lines
4.5 KiB
Python
157 lines
4.5 KiB
Python
import os
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from ctypes import addressof, byref, c_double
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from django.contrib.gis.gdal.base import GDALBase
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from django.contrib.gis.gdal.driver import Driver
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from django.contrib.gis.gdal.error import GDALException
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from django.contrib.gis.gdal.prototypes import raster as capi
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from django.contrib.gis.gdal.raster.band import GDALBand
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from django.contrib.gis.gdal.srs import SpatialReference, SRSException
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from django.utils import six
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from django.utils.encoding import (
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force_bytes, force_text, python_2_unicode_compatible,
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)
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from django.utils.functional import cached_property
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from django.utils.six.moves import range
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class TransformPoint(list):
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indices = {
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'origin': (0, 3),
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'scale': (1, 5),
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'skew': (2, 4),
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}
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def __init__(self, raster, prop):
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x = raster.geotransform[self.indices[prop][0]]
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y = raster.geotransform[self.indices[prop][1]]
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list.__init__(self, [x, y])
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self._raster = raster
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self._prop = prop
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@property
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def x(self):
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return self[0]
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@property
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def y(self):
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return self[1]
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@python_2_unicode_compatible
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class GDALRaster(GDALBase):
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"""
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Wraps a raster GDAL Data Source object.
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"""
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def __init__(self, ds_input, write=False):
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self._write = 1 if write else 0
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Driver.ensure_registered()
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# If input is a valid file path, try setting file as source.
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if isinstance(ds_input, six.string_types):
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if os.path.exists(ds_input):
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try:
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# GDALOpen will auto-detect the data source type.
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self.ptr = capi.open_ds(force_bytes(ds_input), self._write)
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except GDALException as err:
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raise GDALException('Could not open the datasource at "{}" ({}).'.format(
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ds_input, err))
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else:
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raise GDALException('Unable to read raster source input "{}"'.format(ds_input))
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else:
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raise GDALException('Invalid data source input type: "{}".'.format(type(ds_input)))
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def __del__(self):
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if self._ptr and capi:
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capi.close_ds(self._ptr)
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def __str__(self):
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return self.name
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def __repr__(self):
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"""
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Short-hand representation because WKB may be very large.
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"""
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return '<Raster object at %s>' % hex(addressof(self.ptr))
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@property
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def name(self):
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return force_text(capi.get_ds_description(self.ptr))
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@cached_property
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def driver(self):
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ds_driver = capi.get_ds_driver(self.ptr)
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return Driver(ds_driver)
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@property
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def width(self):
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"""
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Width (X axis) in pixels.
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"""
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return capi.get_ds_xsize(self.ptr)
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@property
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def height(self):
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"""
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Height (Y axis) in pixels.
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"""
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return capi.get_ds_ysize(self.ptr)
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@property
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def srs(self):
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"""
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Returns the Spatial Reference used in this GDALRaster.
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"""
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try:
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wkt = capi.get_ds_projection_ref(self.ptr)
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return SpatialReference(wkt, srs_type='wkt')
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except SRSException:
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return None
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@cached_property
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def geotransform(self):
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"""
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Returns the geotransform of the data source.
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Returns the default geotransform if it does not exist or has not been
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set previously. The default is (0.0, 1.0, 0.0, 0.0, 0.0, -1.0).
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"""
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# Create empty ctypes double array for data
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gtf = (c_double * 6)()
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capi.get_ds_geotransform(self.ptr, byref(gtf))
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return tuple(gtf)
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@property
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def origin(self):
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return TransformPoint(self, 'origin')
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@property
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def scale(self):
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return TransformPoint(self, 'scale')
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@property
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def skew(self):
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return TransformPoint(self, 'skew')
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@property
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def extent(self):
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"""
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Returns the extent as a 4-tuple (xmin, ymin, xmax, ymax).
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"""
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# Calculate boundary values based on scale and size
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xval = self.origin.x + self.scale.x * self.width
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yval = self.origin.y + self.scale.y * self.height
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# Calculate min and max values
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xmin = min(xval, self.origin.x)
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xmax = max(xval, self.origin.x)
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ymin = min(yval, self.origin.y)
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ymax = max(yval, self.origin.y)
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return xmin, ymin, xmax, ymax
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@cached_property
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def bands(self):
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bands = []
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for idx in range(1, capi.get_ds_raster_count(self.ptr) + 1):
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bands.append(GDALBand(self, idx))
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return bands
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