DigitalInkRecognition returns null scores

[LeFrenchTouch]

Hi,

First off thanks for the libraries, they're pretty awesome!

I was playing around with the digital ink recognition part of the example app and noticed that the scores of every RecognitionCandidate returned was null.

Reproduction steps

1. Add the following printout statement on line 80 of digital_ink_recognition.dart:

for (final candidate in state.data) {
  debugPrint(
      '$LearningDigitalInkRecognition: _startRecognition : text=${candidate.text} : score=${candidate.score}');
}

2. Launch the example app
3. On the main screen select "Digital Ink Recognition"
4. Draw a "W" on the canvas
5. Tap the "Start Recognition" button

Expected output

• A list of RecognitionCandidate, each with member variables text (String) and score (double?) set to non-null values when appropriate

Actual output

• A list of RecognitionCandidate which all have the variable text populated with a meaningful value but score is null
• As the log below shows, the first candidate at least should have a score as we can see it being printed out in both tf_recognizer.cc and helper.cc

Execution Log

I/flutter ( 1994): main
I/MddModelManager( 1994): isModelDownloadedAndValid()
I/MddModelManager( 1994): isModelDownloadedAndValid()
I/native  ( 1994): tf_recognizer.cc:192 inkhash: 59ce57784a4f74a8
I/native  ( 1994): tf_recognizer.cc:219 LabeledInkCurveProcessor returned 4 timesteps for 59ce57784a4f74a8.

I/native  ( 1994): tf_recognizer.cc:293 best result: 'W'  score: 52.4192

I/native  ( 1994): tf_recognizer.cc:345  1  request 17.71%    1.3ms  overall 24.61%    0.01s  LabeledInkProcessor
I/native  ( 1994):  2  request 55.93%    4.2ms  overall 51.79%    0.02s  RunTfLiteModelRunner
I/native  ( 1994):  3  request 26.36%    2.0ms  overall 23.60%    0.01s  Decoder
I/native  ( 1994):     request           7.5ms  overall           0.04s  Total
I/native  ( 1994):

I/native  ( 1994): helper.cc:160 Recognition result: W with score: 52.4192

I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=W : score=null

I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=w : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=Wi : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=wi : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=W  : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=WW : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=w  : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=WN : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=WV : score=null
I/flutter ( 1994): LearningDigitalInkRecognition: _startRecognition : text=Wr : score=null

Flutter Doctor

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• No issues found!