This fixes the selection and deletion during text editing on macOS so that it can handle selections that have a base (selection start) that is after the extent (selection end) in the string.
Apparently the insertText:replacementRange on macOS can supply an NSRange object that has negative values for the length (even though the length is an unsigned NSUInteger). This change checks for that case, and fixes the range of characters replaced in the text to have the right bounds.
Also, I added an additional updateEditState after the state is set from the framework, since there is a timing problem: when the delete key is pressed, it sends an insertText message, which updates the framework state after the framework has already sent its state update to delete the selected region. This additional updateEditState puts the engine and framework back in sync again. Ideally, we would just avoid sending the insertText message, but there's really no way for the engine to know if the pressed key is part of an edit sequence or not.
Renames all FLE* classes in the macOS embedding to Flutter*. With the exception
of -[FlutterDartProject engineSwitches], which is very clearly called out in the
comment, the APIs should be stable at this point, so the marker prefix is no
longer needed.
This is a breaking change for macOS embedders, but going forward breaking
changes at the source level for the macOS API should now be rare.
Some of these classes will likely merge with the iOS versions in the future (e.g.,
FlutterDartProject), but that will be an implementation detail that will not affect
clients.
Fixesflutter/flutter#31735
Greg Spencer
Francisco Magdaleno
stuartmorgan