Development of text entry speed and accuracy is the key concern for designing and evaluating a soft keyboard. Bangla language has large collection of characters and it is hard to design a single layered fixed layout keyboard to provide high-performance in today’s small mobile device. The traditional soft keyboards available in the market are multi-layered and menu based hierarchical keyboard which offer poor text entry speed. This presentation of associated paper describes the design, implementation and evaluation of a fixed layout single layered press and swipe type soft keyboard. Analysis of the comfort zone and movement of fingers, placement of characters and keys based on monograph, implementation on android platform and evaluation comparing with QWERTY keyboard have been described.

1. Designing A Press and Swipe
Type Single Layered Bangla
Soft Keyboard for Android
Devices
Presented By
Kaidul Islam
Dept. Of Computer Science &
Engineering
Khulna University of Engineering and
Technology

2. This paper is authored by
Kaidul Islam
Dept. of Computer Science & Engineering,
Khulna University of Engineering and
Technology
http://kaidul.web44.net/
Bishnu Sarker
Lecturer, Dept. of Computer Science & Engineering,
Khulna University of Engineering and Technology
http://www.kuet.ac.bd/cse/bishnu/

3. Abstract & Goal
• Development of text entry speed and accuracy
is the key concern
• Bangla language has a large collection of
characters & symbols
– Most are multi-layered and menu based hierarchical
– Hard to design a single layered keyboard
• Goal – Develop a fixed layout single layered
press and swipe type soft keyboard
• This paper describes
– Design, Implementation & Evaluation of proposed
keyboard
– Comparison with other layout(s)

4. Background Analysis
• Numerous remarkable researches have
been conducted based on
– Data-mining
– Finger and character frequency
– Text-to-Image replacement
• Bijoy keyboard, Bangla inscript keyboard of
MS, QWERTY layout for Bangla and some
others
• But performance, speed and accuracy is
still a question!!

5. Background Analysis
• QWERTY is a probably a done-deal due to
large world-wide user base and scientific
significance of design for English, but not
for Bangla.
– English has only 26 characters
– Bangla has almost 70 in total which are
impossible to place

6. Background Analysis

7. Design
• A more practical square shape is more
practical for graphic design and still gives
sufficient flexibility for optimization

8. Design
• Intension is to arrange all key in one layer.
• Tradeoff is – tiny key will create lack of
accuracy and discomfort

9. Design

10. Design
• Arrange the letter in a
proper order based on
char. freq – monograph,
diagraph or develop a
proper algorithm is a
challenging task
– User experiment didn’t
yield any confidential
result
• So, we arranged them in
our own fashion and
based on empirical

11. Design
Bangla Character Frequency

12. Design
• Algorithm on Rearranging the key level:
1. Take all enlisted letters & symbols
of frequency chart into a stack
2. Pick a letter from the top of the
stack and place it in the most
comfortable zone available on the
corresponding key. If it is already in
the desired place, then skip this
step otherwise replace with the
character of most comfortable
zone.
3. Mark the popped letter and zone
4. Repeat step 2 and 3 until stack is
empty
Fig: User Comfort zone of
Finger Movement. The
lower the Value, the best
the zone is.
Middle > top > bottom >
right > left

13. Design
Skeleton of Proposed Keyboard Layout

14. Implementation
• Developed for world most popular Linux
based OS Android platform
• Extensive Knowledge on Android IME
Lifecycles
• No need to code from scratch level
• Based on Open Source and free project
– Android GingerBread Keyboard by Steven Lin
– S9 Keyboard by Gilbert

15. Implementation
Keyboard in Portrait Orientation

16. Implementation: Features
•
•
•
•
•
Prediction and Candidate View
Quick Fixing
Learning
Additional Popup Selection & Key Preview
Multi-Tapping

17. Implementation: Features
Prediction Text on Candidate View

18. Implementation: Features
•
•
•
•
•
Prediction and Candidate View
Quick Fixing
Learning
Additional Popup Selection & Key Preview
Multi-Tapping

19. Implementation: Features
• Prediction and Candidate View
• Quick Fixing
• Learning
– Add word(s) by long pressing on Candidate
view to Binary dictionary
• Additional Popup Selection & Key Preview
• Multi-Tapping

20. Implementation: Features
•
•
•
•
•
Prediction and Candidate View
Quick Fixing
Learning
Additional Popup Selection & Key Preview
Multi-Tapping

21. Implementation: Features
Popup Selection and Key Preview

22. Implementation: Features
•
•
•
•
•
Prediction and Candidate View
Quick Fixing
Learning
Additional Popup Selection & Key Preview
Multi-Tapping
– Like old hard keyboard
– Pressing one time gives middle letter, two
times gives upper, three times gives lower.......

23. Outcome

24. Evaluation
• Laws to evaluate and verify typing speed,
movement latency, reaction time for
decision making
– Fitts’s Law
– Hick-Hyman Law
• Time per Character, (WPM) word per
minute
• User Experiment

25. Evaluation
• Laws to evaluate and verify typing
speed, movement latency, reaction time
for decision making
– Fitts’s Law
– Hick-Hyman Law
• Time per Character, (WPM) word per
minute
• User Experiment

26. User Experiment
• 10 correspondents
– advance Android users of at least 1 year
– Use Bangla Keyboards to write blogs and
update Facebook status
– Trained for 15 sessions each belongs to 10
minutes

27. User Experiment: Our vs.
QWERTY

28. User Experiment: Error
Rate

29. Future Plan
• Tradeoff between small display unit and
text entry performance
– Rigorous research and development needed
• Letter distribution and arrangement can
be further developed by
– Diagraph-Trigraph, Data Mining, Machine
Learning
• Prompt it as most promising, adaptive and
versatile layout for Bangla.

30. Thank you!