Show remaining character count in SMS app
Summary
This adds character counter below the “Send” button in SMS conversation. It uses format XXX/Y where XXX is number of characters that can be added without splitting the SMS into multiple messages (see article Concatenated SMS on Wikipedia). Y is number of messages in in current concatenated SMS. The counter is not visible when insertion of 10 7-bit or 16-bit (depends on SMS encoding) does not create concatenated SMS.
SMS encoding is automatically guessed. 8-bit encodings are not supported. If the message contains characters that are not supported by GSM 7-bit encoding, counter automatically switches to UCS-2.
Test Plan
Try entering some text that is longer than 150 characters in GSM 03.38 encoding or 60 characters in UCS-2. Number of remaining characters should be visible below the “Send” button. The character counter should show 0
at exactly 160 or 70 characters. Inserting one character should switch the counter to Concatenated SMS mode when number of messages is shown.
It should show exactly same number as SMS app in Android.
Screenshots
These images are in APNG.