Currently retiming is quite awkward, when you need to retime multiple
strips strips in sync. It is possible to use meta strips, but this is
still not great. This is resolved by implementing selection.
General changes:
Gizmos are removed, since they are designed to operate only on active
strip and don't support selection.
Transform operator code is implemented for retiming data, which allows
more sophisticated manipulation.
Instead of drawing marker-like symbols, keyframes are drawn to
represent retiming data. Retiming handles are now called keys. To have
consistent names, DNA structures have been renamed.
Retiming data is drawn on strip as overlay.
UI changes:
Retiming tool is removed. To edit retiming data, press Ctrl + R, select
a key and move it. When retiming is edited, retiming menu and
context menu shows more relevant features, like making transitions.
Strip and retiming key selection can not be combined. It is possible to
use box select operator to select keys, if any key is selected.
Otherwise strips are selected.
Adding retiming keys is possible with I shortcut or from menu.
Retiming keys are always drawn at strip left and right boundary. These
keys do not really exist until they are selected. This is to simplify
retiming of strips that are resized. These keys are called "fake keys"
in code.
API changes:
Functions, properties and types related to retiming handles are renamed
to retiming keys:
retiming_handle_add() -> retiming_key_add()
retiming_handle_move() -> retiming_key_move()
retiming_handle_remove() -> retiming_key_remove()
retiming_handles -> retiming_keys
RetimingHandle -> RetimingKey
Retiming editing "mode" is activated by setting `Sequence.show_retiming_keys`.
Pull Request: https://projects.blender.org/blender/blender/pulls/109044
86a0d0015a