Implement IME primitives for PlainEditor. #136
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| #[derive(Clone, Default)] | ||
| struct ComposeState { | ||
| selection: Option<(usize, usize)>, | ||
| text: Arc<str>, |
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I feel like this should be a String. Then:
- We could mutate it and re-use the allocation when updating the pre-edit
- Setting it to empty would be allocation free
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- Setting it to empty would be allocation free
it may not matter, but it's never empty
| // Winit on some platforms delivers an empty Preedit after Commit | ||
| // so don't lock into compose when preedit is empty. | ||
| Ime::Preedit(text, None) if text.is_empty() => vec
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| CommitCompose => { | ||
| if let Some(ComposeState { text, .. }) = self.compose.clone() { | ||
| let new_insert = self.selection.insertion_index() + text.len(); | ||
| self.selection = if new_insert == self.buffer.len() { | ||
| Selection::from_index( | ||
| &self.layout, | ||
| new_insert.saturating_sub(1), | ||
| Affinity::Upstream, | ||
| ) | ||
| } else { | ||
| Selection::from_index(&self.layout, new_insert, Affinity::Downstream) | ||
| }; | ||
| } | ||
| self.compose = None; | ||
| layout_after = true; | ||
| } |
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It may not matter too much, but this does some additional work on each commit, as Winit delivers a Preedit("", None) before sending Commit. On commit, vello_editor in this PR currently clears the compose state, to immediately set it again, to then commit it. If CommitCompose takes the committed text, some of those buffer operations become unnecessary.
There also appear to be some IMEs that commit without going into compose first, so perhaps it makes sense to have SetCompose(Arc<str>, Option<(usize, usize)>), ClearCompose, and Commit(Arc<str>).
Commit(Arc<str>) would guarantee it also clears the compose state. Otherwise it's effectively the same as InsertOrReplaceSelection(Arc<str>).
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I agree, that will be the final command set as it has been requested by both you and Nico, and it clearly makes sense.
| if let Some(parley::Rect { x0, y0, x1, y1 }) = self.editor.preedit_area() { | ||
| println!("{x0} : {y0}"); | ||
| println!("{x1} : {y1}"); | ||
| render_state.window.set_ime_cursor_area( | ||
| LogicalPosition::new(x0, y0), | ||
| LogicalSize::new(x1 - x0, y1 - y0), | ||
| ); | ||
| } |
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There's discussion in #111 about when to notify the platform about the IME preedit area. @DJMcNab reported an infinite loop if the area is sent as a response to all IME events: #111 (comment). The simplest solution is to cache the previously sent area, and only send the current area if it's not the same. Unconditionally send the area on IME::Enabled.
To be a bit more conservative in reporting to the platform, the main thing missing is to easily know whether Layout has changed in response to an event, see also #111 (comment).
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Almost all events and ops affect either the cursor position or the Layout, so in the case of the example it doesn't much matter; however it might be good to make the calculation one-shot, maybe give it an observer pattern for ease of use.
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That is true, though some solution is required for the infinite loop that currently probably happens on some platforms (report area -> platform resends preedit -> report area -> …). Unfortunately I can't test this on my platform. WindowEvent::{RedrawRequested,CursorMoved} are possible exeptions.
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