undo does not return a point to its original position

Bug #1541176 reported by Chao-Kuei Hung on 2016-02-03
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Dr. Geo II
Undecided
Unassigned

Bug Description

Open the attached file. Notice that the angle is currently 53 deg. Drag point V0 around the circle. Click the "undo" button. It returns to a different position.

DrGeo 15.12a on lubuntu 15.04

Chao-Kuei Hung (ckhung0) wrote :
Chao-Kuei Hung (ckhung0) wrote :

Got the serious bug of #1539835 again!

I continued from g3.fgeo of this bug report. Line "G2"-"O", Line "O"-"V0", and point "G2" are hidden. A free point on the x-axis (actually line "Ha"-"Hb") is created. A vertical line at this point is created. The vertical line is intersected with line "directrix" to create a point. Then the file is saved as g4.fgeo, and g4.fgeo goes lunatic.

hilaire (hilaire-fernandes) wrote :

Indeed the undo/redo command is not symmetrical for point constrained on line.

The move command comes with a displacement vector attribute, the do command-action translate with vector, the undo command action translate with -vector. But for point constrained on a line it is not symmetrical.

Possible solution: define a specific move command for constrained point on line. Its attribute will be the point curvilinear abscissa.

I don't think this problem is related with the #1539835 bug.

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