Geometry checker into processing

[Djedouas]

Description

Supersedes #55939

This Pull Request aims to integrate the geometry checker in the processing toolbox within the scope of QEP 236.

Each process will follow a consistent logic: one input layer and two distinct outputs.

For check processing outputs are

• a layer of the same type as the input layer with erroneous geometries only
• a point layer with the error locations and information (feature id, part and vertex number, etc.)

For fix processing outputs are

• a fixed layer of the same type as the input layer with corrected features according the the chosen method
• a point layer with the error locations and report about the fix (fixed or not, message about the processed feature)

To ensure a consistent user experience, each process will operate similarly:

A default tolerance parameter is set at 8 (for 1e-8) in the advanced settings of every processing.

Demo video

https://vimeo.com/991495790

Screenshots

1. Check errors

Check geometry: errors will be created as a point layer showing places where the angle is < min angle

Launch processing

Errors layer attribute table

Source and errors layer

2. Fix with appropriate processing

Launch the delete vertex processing With the errors layer (output from the previous check) as input

Source and fixed layer (neon red)

Report layer showing what was done

Remarks - feedbacks welcome

The new processes are grouped under new categories named "Check geometry" and "Fix geometry". Suggestions for improved naming are welcome. The aim is to unify verification and correction processes from topology and geometry_checker plugins within these categories.

The current displayName, "Check/FIX Geometry (algorithm name)", is provisional. Any suggestions for enhancing this are welcome.

To avoid overwhelming process options, I've opted to enforce the "gc_" prefix for field names (see outputFields). It's worth considering whether to make this parameter configurable.

Next

Other Geometry Checker processes will be added following this review, and we plan to include additional correction/manipulation processes.

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Funded by QGIS (Grant OpenSource 2023) and Oslandia

Part of qgis/QGIS-Enhancement-Proposals#236

cc @lbartoletti

[github-actions]

🪟 Windows builds

Download Windows builds of this PR for testing.
Debug symbols for this build are available here.
(Built from commit cc42df1)

🪟 Windows Qt6 builds

Download Windows Qt6 builds of this PR for testing.
(Built from commit cc42df1)

[lbartoletti]

Great job @Djedouas and well documented!