CRSHandler

Import

from pyqgis_wrapper.projection import CRSHandler

Warning

The reprojection import the processing library and needs to be executed within an environment able to use it.

You can still construct CRS without it.

CRSHandler(layer, feedback=QgsProcessingFeedback(), context=QgsProcessingContext())

Handles CRS construction and reprojection

Attributes:

Name	Type	Description
ALGS	Dict[QgsMapLayer, str]	Processing algorithm for reprojection.

Parameters:

Name	Type	Description	Default
layer	qgis.core.QgsMapLayer	Layer to reproject	required
feedback	qgis.core.QgsProcessingFeedback	Feedback object if executed within QGIS, defaults to QgsProcessingFeedback()	qgis.core.QgsProcessingFeedback()
context	qgis.core.QgsProcessingContext	Context in which the algorithm is being used, defaults to QgsProcessingContext()	qgis.core.QgsProcessingContext()

Source code in pyqgis_wrapper/projection/crs_handler.py

def __init__(
    self,
    layer: QgsMapLayer,
    feedback: QgsProcessingFeedback = QgsProcessingFeedback(),
    context: QgsProcessingContext = QgsProcessingContext(),
):
    """
    :param layer: Layer to reproject
    :type layer: QgsMapLayer
    :param feedback: Feedback object if executed
    within QGIS, defaults to QgsProcessingFeedback()
    :type feedback: QgsProcessingFeedback, optional
    :param context: Context in which the algorithm is
    being used, defaults to QgsProcessingContext()
    :type context: QgsProcessingContext, optional
    """
    self.layer = layer
    self.original_crs = layer.crs()
    self.project_crs = QgsProject.instance().crs()
    self.logger = create_child_logger(__name__)
    self.feedback = feedback
    self.context = context
    # CRS bounds: [min_lon, max_lon, min_lat, max_lat]
    # Only non geographic crs should be here
    self.available_crs = self._load_available_crs()

build_crs(crs) staticmethod

Build a QgsCoordinateReferenceSystem from an epsg code

Parameters:

Name	Type	Description	Default
epsg_code	typing.Union[str, int, qgis.core.QgsCoordinateReferenceSystem]	Either an int or a string or direclt a QgsCoordinateReferenceSystem It can be : "EPSG:4326", "4326" or 4326	required

Returns:

Type	Description
QgsCoordinateTransform	Constructed CRS object

Source code in pyqgis_wrapper/projection/crs_handler.py

@staticmethod
def build_crs(
    crs: Union[str, int, QgsCoordinateReferenceSystem],
) -> QgsCoordinateReferenceSystem:
    """
    Build a QgsCoordinateReferenceSystem from an epsg code

    :param epsg_code: Either an int or a string or direclt a QgsCoordinateReferenceSystem
        It can be : "EPSG:4326", "4326" or 4326
    :type epsg_code: Union[str, int, QgsCoordinateReferenceSystem]

    :return: Constructed CRS object
    :rtype: QgsCoordinateTransform
    """
    if isinstance(crs, (int, str)):
        crs = CRSHandler._build_crs_from_epsg(crs)
    elif not isinstance(crs, QgsCoordinateReferenceSystem):
        raise TypeError(
            f"Provided CRS must be a string, an int or a "
            f"QgsCoordinateReferenceSystem, got {type(crs)}."
        )

    if not crs.isValid():
        raise ValueError(
            f"Provided CRS for reprojection is invalid, Got {crs.authid()}."
        )

    return crs

reproject(layer, target_crs=None, feedback=QgsProcessingFeedback(), context=QgsProcessingContext()) classmethod

Reproject a layer to a target CRS. If there is no target CRS provided then it'll reproject to an available CRS (m) if the layer is in a geographic (°) CRS.

Parameters:

Name	Type	Description	Default
layer	qgis.core.QgsMapLayer	Layer to reproject; It can be a vector, raster or point cloud layer.	required
target_crs	typing.Optional[typing.Union[str, int, qgis.core.QgsCoordinateReferenceSystem]]	CRS to reproject the layer to.	None

Returns:

Type	Description
QgsMapLayer	Reprojected layer

Source code in pyqgis_wrapper/projection/crs_handler.py

@classmethod
def reproject(
    cls,
    layer: QgsMapLayer,
    target_crs: Optional[Union[str, int, QgsCoordinateReferenceSystem]] = None,
    feedback: QgsProcessingFeedback = QgsProcessingFeedback(),
    context: QgsProcessingContext = QgsProcessingContext(),
) -> QgsMapLayer:
    """
    Reproject a layer to a target CRS.
    If there is no target CRS provided then it'll reproject
    to an available CRS (m) if the layer is in a geographic (°) CRS.

    :param layer: Layer to reproject; It can be a vector, raster or point cloud layer.
    :type layer: QgsMapLayer
    :param target_crs: CRS to reproject the layer to.
    :type target_crs: Optional[Union[str, int, QgsCoordinateReferenceSystem]]

    :return: Reprojected layer
    :rtype: QgsMapLayer
    """
    return cls(layer, feedback, context)._reproject_layer(target_crs)