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Series marks are sometimes invisible

Original Reporter info from Mantis: Marcin Wiazowski
  • Reporter name:

Description:

Series marks are sometimes fully or partially invisible - the problem depends on:
- MarkPositions setting of the series,
- Range settings of the assigned Y axis.

Please take a look at the attached animation and the sample application. Two charts are visible, that have identical settings, with one exception - the left chart doesn't use Range.Min for Y axis, the right one uses Range.Min = -1. By using a "Move Up" button multiple times, the problem can be seen: series marks should be fully visible in all cases - but they are not.

The problem can be defined as (Lazarus 2.0.0 RC3):
- Left chart: Range.Min is not used, so the mark (description) for the first series point is fully visible for Y in range (-INF, 0> (this is OK) and fully invisible for Y in range (0, +INF) (this is NOT OK)
- Right chart: Range.Min is -1, so the mark (description) for the first series point is fully invisible for Y in range (-INF, -1) (this is OK), fully visible for Y in range <-1, 0> (this is OK), and partially invisible for Y in range (0, some positive value) (this is NOT OK)

When compiled with Lazarus 1.8.4, left chart works fully properly, and the right one works improperly (but behavior is different than in 2.0.0 RC3).

Note 1: Similar problem occurs also when setting MarkPositions of both series to lmpInside or lmpInsideCenter.

Note 2: Same problem will probably occur also when using RangeMax and MarkPositions = lmpPositive (instead of RangeMin and MarkPositions = lmpNegative as it is now).

Note 3: This bug can be used to limit height of a multiline mark's text (by using the case when the mark is partially invisible) - please see the attached "ThisBugCanBeUseful.png" image. Such a functionality is very useful - very long text doesn't occupy too much chart space, but still can bee seen when needed (by zooming in). I'm afraid that this (unintended) functionality will disappear after patching the bug - so maybe this functionality could be officially added (by adding some property to the series or marks)? This would be wonderful.

Kind regards

Mantis conversion info:

  • Mantis ID: 34819
  • Version: 2.0RC3
  • Target version: 2.0.2