This re-lands #21163, which was reverted in #22004
Now that flutter/flutter#67359 has landed, this change will no longer cause spaces (and other shortcuts) to be ignored in text fields if there is no action associated with the intent, even if there is a shortcut key mapping to an intent.
It also no longer causes web test failures (as far as I can tell without submitting it: the same tests don't fail locally).
Here's the original PR description:
This switches from using dispatchKeyEvent to using dispatchKeyEventPreIme so that keys can be intercepted before they reach the IME and be handled by the framework.
It also now intercepts key events sent to InputConnection.sendKeyEvent, as some IMEs do (e.g. the Hacker's Keyboard), and sends the to Flutter before sending them to the IME (which it now only does if they are not handled by the framework).
This fixes the problem where pressing TAB on a hardware keyboard sends the tab to both the text field and to the focus traversal system.
Note that we still can't intercept all keystrokes given to a soft keyboard, only those which the soft keyboard decides to send to InputConnection.sendKeyEvent.
Switches the Linux embedding from the standard C API to the new proctable version, to allow for unit testing of the embedding layer separately from the embedder APIs implementation.
Currently, the Linux embedder does not handle window exposure events.
This is typically not a problem for users who use compositing window
managers, since they keep the display buffers even if the window is
completely covered. However, for users that don't use a compositor, the
window will not be redrawn by the engine if it was previously covered
until another event triggers the redraw.
This patch implements the GtkWidget draw callback to handle window
exposure events. The callback doesn't actually draw anything, it just
schedule a frame for drawing by the engine.
The engine doesn't support exposure events, so instead, we force redraw
by sending a window metrics event of the same geometry. Since the
geometry didn't change, only a frame will be scheduled.
Switches the Windows embedding from the standard C API to the new proctable version, to allow for unit testing of the embedding layer separately from the embedder APIs implementation. This includes moving some engine messaging that was still in flutter_windows to the C++ engine class to better encapsulate the proc table.
Converts the macOS embedding to use the new proc table version of the embedding API, and adds one example unit test using it to demonstrate and validate the approach.
