Undo and Redo

In GSA it is possible to undo both edits to the data and view settings. Undoing an edit results in the last edit carried out on the data being cancelled, regardless of the view in which that edit was carried out. Undoing a view results in the view reverting to the previously displayed view in that window. Undoing views is only possible in Graphic Views and Output Views. The undo edit and undo view mechanisms operate independently. Redo is available in both.

Undoing Edits

The Edit | Undo (Ctrl+Z) menu command undoes the last edit on the data.

The Edit | Redo (Ctrl+Y) menu command redoes edits that have been undone.

Data edits are preserved in an undo buffer (i.e. remembered) regardless of how the edits were applied (i.e. whether via tables, sculpt or batch operation).

Edits that are undone are preserved in a redo buffer.

The undo buffer is cleared when the file is closed. It is frozen when an analysis is done and only unfrozen when all results are deleted.

The redo buffer is cleared when any edits are carried out on the data and when the file is closed.

Edits are preserved in the undo and redo buffers as individual edit operations, though several edit operations may be associated with one undo step. So, for example, modifying 10,000 elements in one sculpt command constitutes 10,000 undo operations but just one undo step. The Undo command undoes one step.

Multiple undo and redo steps are possible.

Undo Edit Limit

There is a limit to the number of operations that are preserved in the undo and redo buffers. This limit may be adjusted in the Input Data Preferences. GSA preserves at least one undo step and one redo step if called upon to do so. In our example, even if the maximum number of preserved undo operations is set to 5,000, the 10,000 modified elements will be preserved in the undo buffer and one Undo command will undo all of the element modifications.

Undoing Analysis and Design Tasks

The option to undo analysis and design task results may be set in the Input Data Preferences. When this is set, an analysis or design task becomes an undo step and the first undo after an analysis will cause the results and any analysis cases generated during the analysis to be deleted. A subsequent undo will undo the last edit done before the analysis, etc. Redo is not available for an analysis.

When the undo analysis preference is not set, undoing an analysis is not available and the undo and redo buffers are cleared upon commencing any analysis.

Enabling / Disabling Undo

Undo for edits may be enabled or disabled in the Advanced Preferences. When Undo is disabled then the undo and redo buffers are cleared and no edits are preserved in the undo buffer until Undo is enabled again.

Undo Buffer and Computer Memory

The undo and redo buffers reside in the memory of the computer. The larger these buffers are, the greater the demand will be on the memory resources. This should be considered when adjusting the undo limit and undo analysis preferences, especially when working on a machine with limited memory available.

Note that:

• Setting the undo limit preference to a huge number will result in data for that many operations being preserved in the undo buffer.
• Switching the undo analysis preference on will result in the undo and redo buffers coexisting in memory with the results generated during the analysis.

Undoing Views

The View | Undo View (Ctrl+Alt+Z) menu command undoes the last change in view settings in the current Graphic View or Output View. Undo View is also available on the Standard toolbar.

The View | Redo View (Ctrl+Alt+Y) menu command redoes the last Undo View.

All changes to the view settings are preserved in the undo view buffer. In the case of a Graphic View this means changes in orientation (e.g. dragging to rotate), scale (e.g. zoom), content (e.g. volume and entity list), adornments (e.g. labels, diagrams and contours), case list etc.

View settings that are undone are preserved in a redo view buffer.

The undo view buffer is associated with the view. Each Graphic View and each Output View has its own undo view buffer which is cleared when the view is closed.

The redo view buffer is cleared when any changes are made to the view settings and when the view is closed.

Multiple undo view and redo view steps are possible, currently set at 32 steps. The limit is not adjustable.