Home and End keys not working with the Rust version

[yan12125]

Describe the bug

When there are some texts in a text box, Home/End keys do not work when fcitx5-chewing is used with the Rust version of libchewing. With the C version (0.7.0), those keys work fine.

To Reproduce Steps to reproduce the behavior:

1. Type some random characters (ex: 中文)
2. Hit Home
3. Use arrow keys to move cursor to the beginning of the text box
4. Hit End

Expected behavior Home/End should move the cursor to beginning/end of the text box

Screenshots

Platform (please complete the following information):

• OS: Arch Linux up-to-date
• Desktop: LXQt
• IME: fcitx5-chewing 5.1.3
• Version
  • 0.8.0 rc4, built with this PKGBUILD
  • 0.7.0, from Arch Linux official packages (Rust not enabled, no issue with this version)

Additional context

I haven't had time to analyze the issue yet. As the issue happens only with the Rust version, I assume this is a libchewing issue.

Here are logs with the 0.8.0 rc4, using the command RUST_LOG=debug fcitx5 -D --verbose chewing=5:

D2024-05-10 12:26:45.765502 eim.cpp:436] KeyEvent: Home
D2024-05-10 12:26:45.765609 eim.cpp:261] [src/editor/mod.rs:730 chewing::editor] process_keyevent: key-K58-Home-�-
D2024-05-10 12:26:45.765716 eim.cpp:261] [src/editor/mod.rs:749 chewing::editor] last_key_behavior = Absorb
D2024-05-10 12:26:45.765780 eim.cpp:261] [src/editor/mod.rs:750 chewing::editor] comp: CompositionEditor { cursor: 0, cursor_stack: [], inner: Composition { symbols: [], gaps: [], selections: [] } }
D2024-05-10 12:26:45.765838 eim.cpp:610] updateUI
D2024-05-10 12:26:45.765899 eim.cpp:562] Text:  Zuin:
D2024-05-10 12:26:50.573320 eim.cpp:436] KeyEvent: End
D2024-05-10 12:26:50.573464 eim.cpp:261] [src/editor/mod.rs:730 chewing::editor] process_keyevent: key-K59-End-�-
D2024-05-10 12:26:50.573525 eim.cpp:261] [src/editor/mod.rs:749 chewing::editor] last_key_behavior = Absorb
D2024-05-10 12:26:50.573577 eim.cpp:261] [src/editor/mod.rs:750 chewing::editor] comp: CompositionEditor { cursor: 0, cursor_stack: [], inner: Composition { symbols: [], gaps: [], selections: [] } }
D2024-05-10 12:26:50.573628 eim.cpp:610] updateUI
D2024-05-10 12:26:50.573695 eim.cpp:562] Text:  Zuin:

And logs with 0.7.0:

D2024-05-10 12:27:42.539654 eim.cpp:261] [/usr/src/debug/libchewing/libchewing-0.7.0/src/chewingio.c:696 chewing_set_easySymbolInput] API call: mode = 0
D2024-05-10 12:27:42.539749 eim.cpp:436] KeyEvent: Home
D2024-05-10 12:27:42.539842 eim.cpp:261] [/usr/src/debug/libchewing/libchewing-0.7.0/src/chewingio.c:1393 chewing_handle_Home] API call:
D2024-05-10 12:27:42.539920 eim.cpp:261] [/usr/src/debug/libchewing/libchewing-0.7.0/src/mod_aux.c:425 chewing_keystroke_CheckIgnore] API call:
D2024-05-10 12:27:48.386430 eim.cpp:261] [/usr/src/debug/libchewing/libchewing-0.7.0/src/chewingio.c:696 chewing_set_easySymbolInput] API call: mode = 0
D2024-05-10 12:27:48.386464 eim.cpp:436] KeyEvent: End
D2024-05-10 12:27:48.386488 eim.cpp:261] [/usr/src/debug/libchewing/libchewing-0.7.0/src/chewingio.c:1418 chewing_handle_End] API call:
D2024-05-10 12:27:48.386506 eim.cpp:261] [/usr/src/debug/libchewing/libchewing-0.7.0/src/mod_aux.c:425 chewing_keystroke_CheckIgnore] API call:

[kanru]

Do you mean if I hit the Home key twice in a row the second Home be ignored by chewing and move the textbox cursor to the beginning of the input area?

Some existing text 中文
                   ^  ^---- pre-edit cursor
                    `--- input area cursor

Type Home Home

Some existing text 中文
^---- cursor

[yan12125]

Sorry if I was not clear. The issue happens when strings are already committed (not sure if this is the correct term). At this time, fcitx5-chewing logs show that both chewing_buffer_String_static and chewing_bopomofo_String_static return an empty string:

2024-05-10 14:30:44.334656 eim.cpp:562] Text:  Zuin:

Here are verbose steps to reproduce:

1. Type some characters and hit Enter. Now the cursor is at the end of the input area:

   中文
   ^---- input area cursor

2. Hit Home. I expect the cursor to move to the beginning of the input area:

   中文
   ^---- input area cursor

   While the cursor remains at the end of the input area

   中文
   ^---- input area cursor