Selection glitch in SuperTextField when IME is used

[miguelcmedeiros]

The selection in SuperTextField jumps between old and current selection as shown in this recording:

Screen.Recording.2023-01-02.at.13.07.27.mov

This is reproducible in demo app ("SuperTextField" -> "Interactive demo"). If TextInputSource.keyboard is used instead, then the issue is not reproducible.

[miguelcmedeiros]

Cc @angelosilvestre

[angelosilvestre]

@miguelcmedeiros Could you enable the imeTextFieldLog logger and attach the output? This doesn't seem to be happening on windows.

[miguelcmedeiros]

@angelosilvestre
The log looks likes this:

flutter: Initializing logger: ime
flutter: (58.962) textfield.ime > FINE: Is attached to input client? true
flutter: (58.976) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (58.977) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (58.978) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (58.979) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (58.979) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (58.979) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (58.980) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (58.980) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (58.980) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (58.989) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (58.989) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (58.989) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (58.992) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (58.992) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (58.992) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (58.994) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (58.994) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (58.994) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (58.997) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (58.997) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (58.997) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (59.001) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (59.001) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (59.001) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (59.015) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (59.015) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (59.015) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (59.016) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (59.016) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
flutter: (59.017) textfield.ime > FINE: Sending TextEditingValue to platform: TextEditingValue(text: ┤Super Editor is an open source text editor for Flutter projects.├, selection: TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1))
flutter: (59.018) textfield.ime > FINE: Received text editing deltas from platform...
flutter: (59.018) textfield.ime > FINE: Processing selection/composing change:
 - oldText:Super Editor is an open source text editor for Flutter projects.
 - selection:TextSelection.collapsed(offset: 23, affinity: TextAffinity.downstream, isDirectional: false)
 - composing:TextRange(start: -1, end: -1)
.
.
.

This is only a small portion of the log. It seems that super_editor is sending TextEditingValue delta to the platform, then receives the same delta and then sends it again in a infinite loop.

[miguelcmedeiros]

Cc @matthew-carroll

[angelosilvestre]

@miguelcmedeiros Could you also attach editorImeLog logs ?

[matthew-carroll]

@miguelcmedeiros I'll investigate those logs tonight. Don't worry about it.

[matthew-carroll]

I'm starting to investigate this.

One thing I'm noticing is that, on my end, placing the caret in SuperEditor doesn't seem to trigger the problem. Also, dragging across multiple characters, very slowly, doesn't seem to trigger the problem either.

What does trigger the problem is a rapid selection across characters. I'm wondering if the problem might be due to frame scheduling on our end. We run various things, like selection changes, in post-frame callbacks.

I'll continue digging.

[matthew-carroll]

Experimentally, I found that #876 seems to fix the SuperEditor selection problem. The SuperTextField selection problem still exists in that PR, because that PR only makes changes to SuperEditor IME behavior. I'll check on SuperTextField.

After taking inventory of #876 the following seem like possible candidates for why it fixed this problem:

• Resetting the composing region whenever the selection changes: https://github.com/superlistapp/super_editor/pull/876/files#diff-50fb28a340fc8c3c83397ea611d89a32f740c1e9826ceed4150a3da41ca9c825R111
• Adjusted the behavior for document serialization before and after applying deltas: https://github.com/superlistapp/super_editor/pull/876/files#diff-48234ff20bd212a3cfb12205b0e1fc402bb55432ab106be158786bd1262d9bfeR59
• Collecting multiple changes that need to be sent to the IME and only send them one time: https://github.com/superlistapp/super_editor/pull/876/files#diff-48ecc7efb2b6ae26fc528f4fd4a2667c698e39de1168f3bd2251cbb5d65e909bR145

[matthew-carroll]

The root cause of the issue in SuperTextField seems to be that every time we received a value or delta from the IME, we would resend that value to the IME. Apparently the Mac IME automatically sends the value back to us whenever we send it to the IME. This created an infinite loop of IME communication.

[miguelcmedeiros]

@matthew-carroll, when using the latest commit from stable (cd8f719), we still have this issue in Superlist.

In the demo app (SuperTextField demo), it also show the same issue if the implementation is changed to use SuperTextField instead of SuperDesktopTextField:

Screen.Recording.2023-01-10.at.11.47.16.mov

This infinite-caret-jumping now happens when the content changes.