ca.yorku.eecs.mack.softkeyboard

Class SoftKeyboardActivity

java.lang.Object

Activity

ca.yorku.eecs.mack.softkeyboard.SoftKeyboardActivity

All Implemented Interfaces:

KeyboardPanel.OnKeystrokeListener

public class SoftKeyboardActivity
extends Activity
implements KeyboardPanel.OnKeystrokeListener

SoftKeyboard

Summary

• Android experiment software for text entry using a soft keyboard.

• The following soft keyboards are supported:
  • Qwerty
  • Opti
  • Opti II
  • Fitaly
  • Lewis-Kennedy-LaLomia
  • Metropolis

Related References

• The design and evaluation of a high performance soft keyboard, by MacKenzie and Zhang (CHI '99). This is the paper where the Opti design was introduced. Opti was the first soft keyboard to be designed using a Fitts-digram model.

• Physics-based graphical keyboard design, by Hunter, Zhai, and Smith (CHI 2000). This paper introduced the Metropolis soft keyboard, offered as an alternative Opti. Metropolis was also designed using a Fitts-digram model; however, the design process was automated using an algorithm.

• Evaluation of typing key layouts for stylus input, by Lewis, LaLomia, & Kennedy (HFES '99). This is the paper introducing the LKL (Lewis-Kennedy-LaLomia) keyboard.

• Textware Solutions web site. Textware Solutions is the company that introduced the Fitaly soft keyboard.

• Text entry for mobile computing: Models and methods, theory and practice, by MacKenzie and Soukoreff (Human-Computer Interaction, 2002). This paper includes an extensive section on soft keyboards, including a comparison of entry speed predictions using a Fitts-digram model. The comparison includes Qwerty, Opti, Opti II, Metropolis, LKL, Fitaly, and several other layouts (Figure 21).

• Theoretical upper and lower bounds on typing speed using a stylus and soft keyboard, by Soukoreff and MacKenzie (Behaviour & Information Technology, 1995). This is the paper that introduced the Fitts-digram model for designing soft keyboards.

• Phrase sets for evaluating text entry techniques, by MacKenzie, and Soukoreff (CHI 2003). This is the paper that introduced the phrase set ("phases2.txt") that is now widely used for evaluating text entry techniques.

SoftKeyboardSetup Parameters

Upon launching, the program presents a setup dialog: (click to enlarge)

The setup parameters are embedded in the application. The default settings (shown) may be changed via the setup dialog. Changes may be saved. Saved changes become the default settings when the application is next launched. The setup parameters are as follows:

Parameter	Description
Participant Code	Identifies the current participant. This is used in forming the names for the output data files. Also, the sd2 output data file includes a column with the participant code.
Session Code	Identifies the session. Useful if testing proceeds over multiple sessions to gauge the progression of learning. The session code is used in forming the name for the output data file. Also, the sd2 output data file contains a column with the session code. Note: The setup dialog does not include an entry for "Block code". The block code is generated automatically by the software.
Group Code	Identifies the group to which the participant was assigned. The group code is used in forming the name for the output data file. Also, the sd2 output data file contains a column with the group code. A group code is useful if counterbalancing was used (i.e., participants were assigned to groups to offset order effects). This is common practice for testing the levels of a within-subjects independent variable.
Condition Code	An arbitrary code used to associate a test condition with this invocation. This parameter might be useful if the software is used in an experiment that investigates conditions that are not inherently part of the application (e.g., Gender → male, female; User position → sitting, standing, walking). The condition code is used in forming the name for the output data file. Also, the sd2 output data file contains a column with the condition code.
Keyboard Layout	Used to select the keyboard layout. Different keyboard layouts are defined in resource file embedded in the application. The options currently supported are as follows: (click to enlarge) Qwerty Opti Opti II Fitaly Lewis-Kennedy-LaLomia Metropolis
Keyboard Scale	Adjusts the size of the keyboard using the specified scaling factor. This parameter allows the keyboard size to be adjusted without changing the keyboard definition in the resource file. A scale setting of 1 leaves the keyboard size as specified in the corresponding resource file. The value entered will be parsed to a float before it is passed on to the main activity. If the value entered is not parsable to a float, a 20-ms vibrotactile pulse is emitted to signal that a correction is required. The keyboard scale is used in forming the name for the output data file. Also, the sd2 output data file contains a column with the keyboard scale.
Offset From Bottom	Specifies the distance from bottom of the display where the soft keyboard is positioned. The value is in Android's "density independent pixels" (dip), where 1 inch = 160 dip. The value entered will be parsed to a float before it is passed on to the main activity. If the value entered is not parsable to a float, a 20-ms vibrotactile pulse is emitted to signal that a correction is required.
Number of Phrases	Specifies the number of phrases presented to the participant in the current block.
Phrases File	Specifies a file containing phrases of text to be presented to participants for entry. Phrases are drawn from the file at random. Typically, phrases2.txt is used. This is the phrase set published by MacKenzie and Soukoreff in 2003 (see Related References, above). Other file names may be specified. For example, the file quickbrownfox.txt contains the phrase the quick brown fox jumps over the lazy dog This phrase might be useful for demonstration or specialized testing.
Show Popup Key	A checkbox item that determines whether or not a popup key appears above an alpha key when touched.
Lowercase Only	A checkbox item that determines whether uppercase and lowercase letters are permitted in the presented text phrases. If checked, any uppercase letters in the presented text phrases are converted to lowercase.
Show Presented Text During Input	A checkbox item that determines whether or not the presented text is visible during entry of a phrase. Either way, the text phrase appears at the beginning of a trial. If this option is unchecked, the phrase will disappear when the first keystroke is entered.

Program Operation

The experiment launches with the selected soft keyboard displayed and with a text phrase presented for input. The text phrase is selected at random from the phrase set specified in the setup dialog.

Text is entered by tapping with a finger on keys on the soft keyboard. The transcribed text appears below the presented text in a separate text field. Timing and data collection begin with the first tap on the soft keyboard.

An example using a Google Nexus 4 with the Qwerty keyboard is shown below on the left: (click to enlarge)

Since the user's finger is likely to obscure the intended key, a popup key appears above the touched key. This is shown in the middle image above (the user's finger is on the c-key). The popup key only appears if the corresponding option in the setup dialog is selected. If the wrong key appears, the user may slide her finger to the correct key. As the finger slides, the popup key changes accordingly. Selection occurs on finger-lift. Input is aborted if the finger slides off the keyboard before finger-lift.

If a mistake is made, the "Bksp" may be tapped to erase the last character entered.

At the end of a phrase, the user taps "Enter", whereupon timing and data collection end. A results popup shows the presented and transcribed text phrases, the entry speed (in words per minute), the error rate (%), and the keystrokes per character (KSPC). An example is shown in the right image above.

When the user taps "OK", the next phrase appears for input. After the specified number of phrases are entered, the application terminates.

Below are examples of the UI showing the effect of different settings from the setup dialog. The device is a Google Nexus 5. In the image on the left, "Keyboard Scale" = 1.0 and "Offset From Bottom" = 40. In the image on the right, "Keyboard Scale" = 0.75 and "Offset From Bottom" = 440.

Output Data Files

As entry proceeds, user performance data are written to files. The files are stored into a directory called "SoftKeyboardExperimentData" – a sub-directory within the device's public external storage directory. This is typically a location in the device's SD memory card.

There are two output data files, an "sd1" file and an "sd2" file. ("sd" is for "summary data".) The sd1 file contains data on a keystroke by keystroke basis, including timestamps. The sd2 file contains summary data for each phrase, one line per phrase. Examples follow:

• sd1 example
• sd2 example

Actual output files use "SoftKeyboardExperiment" as the base filename. This is followed by the participant code, the session code, the block code, the group code, the condition code, and the layout name. An example might be SoftKeyboardExperiment-P01-S01-B01-G01-C01-Qwerty-Scale_0.8.sd1.

In most cases, the sd2 data files are the primary files used for data analyses in an experimental evaluation. The data in the sd2 files are full-precision, comma-delimited, to facilitate importing into a spreadsheet or statistics application. Below is an example for the sd2 file above, after importing into Microsoft Excel: (click to enlarge)

Future Enhancements

The soft keyboards implemented in this application are bare-bones, and are limited to the entry of lowercase alpha characters. The only non-alpha keys are SPACE, BACKSPACE, and ENTER. This is sufficient for a basic evaluation of soft keyboard layouts; however, a comprehensive evaluation should include the additional characters and interactions typically used for text entry. These features are noted here as possible future enhancements, and include the following:

• Shift Mode – a dedicated key labeled SHIFT maps the alpha characters to uppercase. Shift mode could include shift lock whereby, for example, two taps on SHIFT lock the keyboard in shift mode. A subsequent tap returns the keyboard to normal mode. Or, perhaps shift could use swipes: touch a key, then swipe upward off the key to generate the uppercase version of the alpha character.

• Symbol Mode – a mechanism to enter the myriad of non-alpha characters required for text entry. Tapping a SYMBOL key remaps the characters appearing on keys. As with shift mode, a symbol lock mode could be considered.

• Word Completion – a dedicated area above the keyboard presents suggested words completing the current word stem. Tap the word to enter it.

The issues of "basic evaluation" versus "comprehensive evaluation" (see above) bear on internal validity and external validity in conducting a user study to evaluate soft keyboards. While it might seem that a comprehensive evaluation is always preferred over a basic evaluation, this is not necessarily the case. Further discussion is found in the Soukoreff and MacKenzie paper, Phrase sets for evaluating text entry techniques (CHI 2003).

Miscellaneous

When using this program in an experiment, it is a good idea to terminate all other applications and disable the system's network connection. This will maintain the integrity of the data collected and ensure that the program runs without hesitations.

Author:

(c) Scott MacKenzie, 2015-2025

Constructor Summary

Constructors

Constructor and Description
SoftKeyboardActivity()

Method Summary

Modifier and Type	Method and Description
void	doEndOfPhrase()
void	doNewPhrase()
int	getDefaultDeviceOrientation()
void	onCreate(Bundle savedInstanceState)
void	onKeystroke(ca.yorku.eecs.mack.softkeyboard.KeyboardEvent ke)
static float	wpm(java.lang.String text, long msTime)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SoftKeyboardActivity

public SoftKeyboardActivity()

Method Detail

wpm

public static float wpm(java.lang.String text,
                        long msTime)

onCreate

public void onCreate(Bundle savedInstanceState)

getDefaultDeviceOrientation

public int getDefaultDeviceOrientation()

onKeystroke

public void onKeystroke(ca.yorku.eecs.mack.softkeyboard.KeyboardEvent ke)

Specified by:

onKeystroke in interface KeyboardPanel.OnKeystrokeListener

doNewPhrase

public void doNewPhrase()

doEndOfPhrase

public void doEndOfPhrase()