Bug report #20880

Curved labels disappear when rendering across multiple vertices

Added by Ben Van Riper almost 5 years ago.

Affected QGIS version:3.4.2 Regression?:No
Operating System:Ubuntu 18.04.1 LTS Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:28699


Curved labels disappear when trying to render across multiple vertices (or line segments) along a line. It is as if the rendering engine treats each line segment as an individual feature, essentially ignoring the previous and next segments, resulting in labels only showing when zoomed in enough to have one segment span the width of the label to be rendered.

When I increase the inside and outside angles, the issue is not solved. Instead, the label almost seems to get cut off at the end of the segment, resulting in oddly rotated individual characters sparsely appearing.

This issue did not occur in version 2.x, nor does it occur (I think) in projects that I created in version 2.x; it only seems to happen when I create a project in version 3.x. I first noticed the issue in version 3.0 but because of my laziness, I haven't reported it until now.

See attachments for examples of the bug.

Screenshot from 2018-12-24 17-13-00.png - Missing label when the actual angle of each segment is arguably less than 25 degrees (296 KB) Ben Van Riper, 2018-12-24 11:21 PM

Screenshot from 2018-12-24 17-13-10.png - Zooming in close enough to have one segment be wide enough to fit the curved label results in the label being shown as intended (302 KB) Ben Van Riper, 2018-12-24 11:22 PM

Screenshot from 2018-12-24 17-14-11.png - The result of increasing the inside and outside angles. Notice how technically, the label could still render nicely. (301 KB) Ben Van Riper, 2018-12-24 11:22 PM

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