Fix interpolated line renderer exact inverted

[elpaso]

Fix #46371

[elpaso]

@DelazJ I'd appreciate if you could test this PR (and #47174 too)

[DelazJ]

Ok @elpaso, but probably not before next week...

[DelazJ]

@elpaso I confirm that:

• I no longer get the artifacts segments as in Ignore out of range option in interpolated symbol renderer creates artifacts if start value is out of range #46362 when "ignore out of range" box is checked: the unwanted segments disappear
• The color ramp with "exact" interpolation method follows the same direction as linear or discrete, so fixes also start width > end width is ignored when using the "exact" color interpolation method #46371
• BUT there's an issue (now?) if start color is greater than end color, you get only symbol with the max color when using the exact interpolation. No issue with other methods afaics.

My start point below are the bottom points

interpostartColor.mp4

[elpaso]

@DelazJ Thank you for testing! I verified that the last issue you mention is not related with this PR (it was already there in before this PR), how do you feel about proceeding with this PR and file a separate bug for the last issue?

[DelazJ]

@elpaso Thanks for checking. Done in #47342

[github-actions]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

• that all unit tests are passing

• that all comments by reviewers have been addressed

• that there is enough information for reviewers, in particular

  • link to any issues which this pull request fixes

  • add a description of workflows which this pull request fixes

  • add screenshots if applicable

• that you have written unit tests where possible
  In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request.
  If there is no further activity on this pull request, it will be closed in a week.