ApplyEditHistory
Forms, interaction, edit history
Description
Internal helper of TPDFlibFormSession that replays exactly one retained history entry and backs UndoEdit and RedoEdit
Undoing verifies that the entry's inserted text is still present at its start index, splices the removed text back and restores the anchor and caret captured before the change; redoing verifies the removed text, splices the inserted text and restores the positions captured after the change
When the verification or the restored selection bounds fail, the call returns 0 without touching any state
The replay updates the transient value, display value and directed selection, rebuilds the cached Unicode boundary tables, recomputes Modified and moves the history position
The whole operation runs behind an applying-history guard, so no form actions and no host edit callbacks are redispatched
Declaration
function ApplyEditHistory(Undoing: Boolean): Integer;Parameters
| Undoing | True reverses the entry below the current history position, False replays the entry above it |
|---|
Return value
Returns 1 when the entry was replayed, otherwise 0 because the call was reentrant, no edit is active, no entry is available in the requested direction or verification failed
See also
UndoEdit, RedoEdit, CanUndoEdit, CanRedoEdit, AddEditHistory, ClearEditHistory, EditValue, TPDFlibFormSession