Enhancement: Curved labels for polygons

[qgib]

Author Name: Alister Hood (@AlisterH)
Original Redmine Issue: 3482

Redmine category:labelling

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It would be nice (although possibly quite difficult!) to have an option for curved labels on polygon layers. e.g. see the labels for China and Nepal in this map.
https://trac.osgeo.org/qgis/attachment/ticket/3481/asia_map.jpg

[qgib]

Author Name: bderstine - (bderstine -)

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This is called "splining" by ESRI. I agree that this is a good enhancement not only for polygon features but also for polyline features. This is a must for snaking rivers, curved roads, and oblong polygon features.

[qgib]

Author Name: Alister Hood (@AlisterH)

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The "new" labelling engine can already do curved labels for polylines.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• fixed_version_id was changed from Version 1.7.0 to Version 1.7.4

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• fixed_version_id was changed from Version 1.7.4 to Version 2.0.0

[qgib]

Author Name: Alister Hood (@AlisterH)

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New link for that map:
https://issues.qgis.org/attachments/3102/asia_map.jpg

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• category_id was changed from Symbology to Labelling
• pull_request_patch_supplied was configured as 0
• status_info was changed from 0 to
• assigned_to_id removed nobody

[qgib]

Author Name: Pirmin Kalberer (Pirmin Kalberer)

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• fixed_version_id was changed from Version 2.0.0 to Future Release - Nice to have

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• easy_fix was configured as 0

[pjshelton]

The underlining curve for the curved label for a polygon would need to be calculated first. Similar to the centre line requirement of #23329

The curve would have to be long enough for all the label. my suggestion of exposing a function for the spatial length of a label could be useful here. see #13541 and #24291

this is still missing in version 3.16.3