Add support for point cloud expressions to Processing expression parameter (Request in QGIS)

[qgis-bot]

Request for documentation

From pull request qgis/QGIS#52730
Author: @alexbruy
QGIS version: 3.32

Add support for point cloud expressions to Processing expression parameter

PR Description:

Description

With addition of filtering capabilities to point cloud algorithms, we need a userfriedly way to build point cloud expressions similarly to the QGIS native expressions.

To make it possible this pull-request adds a Type enum to QgsProcessingParameterExpression parameter with two options Qgis and PointCloud. If parameter has a PointCloud type, it will use new widget wrapper with GUI point cloud expression builder.

To maintain backward compatibility, by default expression parameter uses Qgis expression type.

The QgsPointCloudExpression class was extented with the new method to convert QGIS point cloud expressions to PDAL expressions.

All PDAL algorithms using expression filter were updated to use expression parameter instead of strings.

Commits tagged with [need-docs] or [FEATURE]

[DelazJ]

The QgsPointCloudExpression class was extented with the new method to convert QGIS point cloud expressions to PDAL expressions.

@alexbruy What does this mean? When does one would use this feature? It does not mean that in QGIS (e.g. provider filter dialog or expression from PDAL alg) we can use PDAL-like expressions, right? As far as I could see, some of the examples in the PDAL docs do not pass in QGIS. Can you clarify, please? Thanks.