Python QgsRasterLayer.keywords['layer_purpose']方法代码示例

# 需要导入模块: from qgis.core import QgsRasterLayer [as 别名]
# 或者: from qgis.core.QgsRasterLayer import keywords['layer_purpose'] [as 别名]
def rasterize_vector_layer(layer, width, height, extent):
    """Rasterize a vector layer to the grid given by extent and width/height.

    :param layer: The vector layer.
    :type layer: QgsVectorLayer

    :param width: The width of the output.
    :type width: int

    :param height: The height of the output.
    :type height: int

    :param extent: The extent to use.
    :type extent: QgsRectangle

    :return: The new raster layer.
    :rtype: QgsRasterLayer
    """
    name = rasterize_steps['gdal_layer_name']
    output_filename = unique_filename(prefix=name, suffix='.tif')

    extent_str = '%f,%f,%f,%f' % (
        extent.xMinimum(),
        extent.xMaximum(),
        extent.yMinimum(),
        extent.yMaximum())

    keywords = dict(layer.keywords)

    # The layer is in memory, we need to save it to a file for Processing.
    data_store = Folder(mkdtemp())
    data_store.default_vector_format = 'geojson'
    result = data_store.add_layer(layer, 'vector_layer')
    layer = data_store.layer(result[1])
    assert layer.isValid()

    field = layer.keywords['inasafe_fields'][aggregation_id_field['key']]

    # ET 21/02/17. I got some issues using rasterize algorithm from Processing.
    # I keep it in case of we need it later. Let's use gdal command line.
    use_gdal_command_line = True

    if use_gdal_command_line:
        startupinfo = None
        if sys.platform == 'win32':
            # On windows, we don't want to display the bash shell.
            # https://github.com/inasafe/inasafe/issues/3980
            startupinfo = subprocess.STARTUPINFO()
            startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
        commands = [which('gdal_rasterize')[0]]
        commands += ['-a', field]
        commands += ['-ts', str(width), str(height)]
        commands += ['-ot', 'Int16']
        commands += ['-a_nodata', "'-1'"]
        commands += [layer.source(), output_filename]

        LOGGER.info(' '.join(commands))
        result = subprocess.check_call(commands, startupinfo=startupinfo)
        LOGGER.info('Result : %s' % result)
    else:
        parameters = dict()
        parameters['INPUT'] = layer
        parameters['FIELD'] = field
        parameters['DIMENSIONS'] = 0  # output size is given in pixels
        parameters['WIDTH'] = width
        parameters['HEIGHT'] = height
        parameters['RASTER_EXT'] = extent_str
        parameters['TFW'] = False  # force generation of ESRI TFW
        parameters['RTYPE'] = 1  # raster type: Int16
        parameters['NO_DATA'] = '-1'   # nodata value
        parameters['COMPRESS'] = 4  # GeoTIFF compression: DEFLATE
        parameters['JPEGCOMPRESSION'] = 75  # JPEG compression level: 75
        parameters['ZLEVEL'] = 6  # DEFLATE compression level
        parameters['PREDICTOR'] = 1  # predictor for JPEG/DEFLATE
        parameters['TILED'] = False  # Tiled GeoTIFF?
        parameters['BIGTIFF'] = 0  # whether to make big TIFF
        parameters['EXTRA'] = ''  # additional creation parameters
        parameters['OUTPUT'] = output_filename

        result = runalg('gdalogr:rasterize', parameters)
        if result is None:
            # Let's try be removing a new parameter added between 2.14 and 2.16
            del parameters['RASTER_EXT']

        result = runalg('gdalogr:rasterize', parameters)
        assert result is not None

    layer_aligned = QgsRasterLayer(output_filename, name, 'gdal')
    assert layer_aligned.isValid()

    layer_aligned.keywords = keywords
    layer_aligned.keywords['title'] = (
        rasterize_steps['output_layer_name'] % 'aggregation')
    layer_aligned.keywords['layer_purpose'] = (
        layer_purpose_aggregation_summary['key'])
    del layer_aligned.keywords['inasafe_fields']

    check_layer(layer_aligned)
    return layer_aligned